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Synthesis, structure and properties of some transition metal hexafluorophosphate and hexafluoroarsenate… Morrison, Raymond Maxwell 1980

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SYNTHESIS, STRUCTURE AND PROPERTIES OF SOME TRANSITION METAL HEXAFLUOROPHOSPHATE AND HEXAFLUOROARSENATE COMPLEXES by RAYMOND MAXWELL MORRISON B.Sc,  The U n i v e r s i t y o f B r i t i s h Columbia, 1975  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE  REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY  in THE  FACULTY OF GRADUATE STUDIES (Chemistry)  We accept t h i s t h e s i s as conforming to t h e r e q u i r e d  THE  standard  UNIVERSITY OF BRITISH COLUMBIA March, 1980  ©  Raymond Maxwell M o r r i s o n , 1980  In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l an advanced degree at  further  of the requirements  the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I agree  the L i b r a r y s h a l l make i t I  fulfilment  freely  thesis  f o r s c h o l a r l y purposes may be granted by the Head of my Department  of this  It  thesis for financial  g a i n s h a l l not be allowed without my  of  The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5  DE-6  B P 75-51 1 E  or  i s understood t h a t c o p y i n g or p u b l i c a t i o n  written permission.  Department  that  a v a i l a b l e f o r r e f e r e n c e and s t u d y .  agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying of t h i s  by h i s r e p r e s e n t a t i v e s .  for  ABSTRACT  A number o f p y r i d i n e , 3 - m e t h y l p y r i d i n e , and p y r i d i n e complexes o f c o b a l t ( I I ) , n i c k e l ( I I ) ,  and  4-methyl-  copper(II)  hexafluorophosphate  and h e x a f l u o r o a r s e n a t e h a v e b e e n s y n t h e s i z e d  and  The  characterized.  p h y s i c a l methods o f  w h i c h were used i n c l u d e v i b r a t i o n a l spectroscopy,  spectroscopy,  e l e m e n t a l a n a l y s i s , and m a g n e t i c  measurements. included  investigation electronic  susceptibility  I n a d d i t i o n c h a r a c t e r i z a t i o n o f some c o m p l e x e s  s i n g l e c r y s t a l and powder X - r a y d i f f r a c t i o n s t u d i e s ,  e l e c t r o n s p i n r e s o n a n c e s p e c t r o s c o p y , mass s p e c t r o m e t r y , d i f f e r e n t i a l thermal The  analysis.  compounds s t u d i e d w e r e o f two  t a i n i n g non-coordinated  have t h e c o m p o s i t i o n  The  M(py) (EF ) , g  g  M'  i s Co,  2  g  N i , and  p y r i d i n e , and  2  M"  class  M(4mepy) (H 0) (EF ) ,  2  g  4  Cu,  conthose  compounds i n t h e f o r m e r  M ' ( 3 m e p y ) ( H 0 ) ( E F ) , and M " L ( E F ) 2  types, those  h e x a f l u o r o m e t a l l a t e a n i o n s and  with coordinated anions.  6  and  g  2  2  g  2  ( w h e r e M i s Co and  2  Ni,  i s Co,  and  L i s p y r i d i n e , 3-methyl-  4-methylpyrid;ine,  and  E i s P and  pounds i n t h e l a t t e r c l a s s a r e N i L ^ ( E F ) g  2  and  As)  The  com-  CuL (EF ) .  S p e c t r a l and m a g n e t i c s t u d i e s on t h e  4  g  2  M(py) (EF ) g  g  2  2+ compounds show them t o c o n t a i n t h e c a t i o n i c  species M(py)  where s i x p y r i d i n e l i g a n d s a r e o c t a h e d r a l l y c o o r d i n a t e d the metal  ion.  S i n g l e c r y s t a l X-ray d i f f r a c t i o n  Co(4mepy) (H 0) (PF ) , Ni(4mepy) (H 0) (PF ) , g  (H 0) (PF ) 2  2  g  2  2  2  6  2  show t h e m e t a l  Q  2  2  g  2  g  ,  to  s t u d i e s on and  i o n t o be c o o r d i n a t e d by  Ni(3mepy) g  four  n i t r o g e n d o n o r s and B a s e d on  two  oxygen  (f^O)  donors i n these complexes.  c o m p a r i s o n s o f e l e c t r o n i c s p e c t r a and  p e r t i e s , the  magnetic  s t r u c t u r e s of a l l M ( 4 m e p y ) ( H 0 ) ( E F ) g  2  2  g  M ' ( 3 m e p y ) g ( H 0 ) 2 ( E F g ) 2 compound a r e c o n s i d e r e d S p e c t r a l and  m a g n e t i c s t u d i e s on  i n d i c a t e they  the CoL^(EFg)  , where  four n i t r o g e n ligands are  t e t r a h e d r a l l y coordinated  the c o b a l t ( I I ) i o n .  s t r u c t u r e has  s i n g l e c r y s t a l X-ray d i f f r a c t i o n study The  anion  symmetry, a l t h o u g h Studies  on  low  been confirmed on  site  i o n s have o c t a h e d r a l  symmetry e f f e c t s a r e  anions.  The g  donors are  2  The  the e l e c t r o n i c p r o p e r t i e s of the  e l e c t r o n i c p r o p e r t i e s of the metal  complexes i n d i c a t e t h a t the  four  in axial positions.  The  -  study  complex, N i ( p y ) ^ ( A s F g ) ^ < i -  i t s s t r u c t u r e i s l i k e t h a t of other  the  on  anions are very weakly  K t o a d i f f e r e n t low  ion  stereochemistry  c o m p l e x e s a t room t e m p e r a t u r e , i t u n d e r g o e s an t o 160  spectra  nitrogen  i n f r a r e d s p e c t r a o f t h e a n i o n s and  i n d i c a t e t h a t the EFg  f r o m 220  metal  vibrational  r e s u l t s of a s i n g l e c r y s t a l X-ray d i f f r a c t i o n  in that, while  evident.  for anionic  s t r o n g l y bound w i t h s q u a r e p l a n a r  about n i c k e l .  (0^)  coordinated  s t r u c t u r e o f t h e complex and  i n the N i L ^ ( E F )  2  a 2  included a c o n s i d e r a t i o n of c r i t e r i a  ion, molecular  (PFg)  by  Co(4mepy)^(PFg) •  t h e compounds c o n t a i n i n g  c o o r d i n a t i o n b a s e d on  of the  around  bands i n t h e i n f r a r e d s p e c t r a o f t h i s c l a s s o f  compounds i n d i c a t e t h a t t h e EFg  anions,  similar.  complexes 2+  2  c o n t a i n t h e c a t i o n i c s p e c i e s , CoL^  This  and  2  t o be  2  pro-  s  Ni(4mepy) coordinated  unique NiL^EFg^  isomerization  temperature isomer.  The  4  iv  electronic spectra in  the  p r o p e r t i e s of the  indicate that low  the  nitrogen  copper, with  istry in  of the  The  the  complexes  anions are  strength  t h e s e copper complexes i s c o n s i d e r e d  t o be  nickel  i n the  low  significantly  complexes  indicate  coordinated  tetragonally distorted octahedral The  temperature greater  studied.  coordinated  electronic properties  CuL^fEFg^  l i g a n d s and  around c o p p e r ( I I ) .  that present and  spectra  the v i b r a t i o n a l  a n i o n s a r e more s t r o n g l y  temperature isomer.  vibrational both the  the  n i c k e l ( I I ) i o n and  of  anion  t o be  isomer of  and that to  stereochem-  coordination  comparable  to  Ni(py) (AsF )  than t h a t present  4  g  2  i n a l l other  V  TABLE OF CONTENTS  ABSTRACT  i i  LIST OF TABLES  x i i  LIST OF FIGURES  x  LIST OF ABBREVIATIONS  x  i  ACKNOWLEDGEMENTS CHAPTER 1: 1.1  x  x  PREVIOUS WORK  2  Hexafluorophosphate and hexafluoroarsenate s a l t s  1.1.2  x  x  INTRODUCTION  1.1.1  i  v  2  C o o r d i n a t i o n chemistry o f hexafluorophosphate and h e x a f l u o r o a r s e n a t e anions  1.2  PURPOSE OF THE PRESENT WORK  1.3  ORGANIZATION OF THE THESIS  2.2  INTRODUCTION  8 10  CHAPTER 2: THEORY AND BACKGROUND 2.1  3  12  TO THE THEORIES OF  TRANSITION METAL COMPLEXES  13  PHYSICAL METHODS OF INVESTIGATION  16  2.2.1  E l e c t r o n i c spectroscopy  17  2.2.2  Magnetic  18  2.2.3  Electron spin  2.2.4  susceptibility resonance  spectroscopy  21  V i b r a t i o n a l spectroscopy  24  2.2.4.1  Pyridine,  4-methyl-  p y r i d i n e and 3-methylpyridine  24  vi  2.2.4.2  Hexafluorophosphate and  2.2.5  X-ray  hexafluoroarsenate  crystallography  ELECTRONIC STRUCTURE AND  STEREO-  CHEMISTRY 2.3.1  Cobalt(II) 2.3.1.1  Octahedral  Cobalt(II)-  Electronic  spectral  properties 2.3.1.2  Octahedral Cobalt(II)Magnetic  2.3.1.3  properties  Tetrahedral Electronic  Cobalt(II)spectral  properties 2.3.1.4  Tetrahedral Magnetic  2.3.2  Cobalt(II)-  properties  Nickel(II) 2.3.2.1  Octahedral Distorted  and  Tetragonal  Octahedral  Nickel(II)-Magnetic spectral 2.3.2.2  and  properties  Square P l a n a r N i c k e l ( I I ) M a g n e t i c and e l e c t r o n i c spectral  2.3.3  Copper(II)  properties  vii  2.3.3.1  Copper(II)-Electronic spectral properties  2.3.3.2  2.4 CHAPTER 3:  50  Copper(II)-Electron  spin  resonance spectroscopy  52  APPROACH TO COMPOUND CHARACTERIZATION  57  COMPOUNDS CONTAINING NON-COORDINATED HEXAFLUOROPHOSPHATE  AND HEXAFLUORO-  ARSENATE  59  3.1  INTRODUCTION  60  3.2  OCTAHEDRAL PYRIDINE COMPLEXES OF COBALT(II); C o ( p y ) ( E F ) g  INTRODUCTION  62  3.2.2  R e s u l t s and D i s c u s s i o n  65  E l e c t r o n i c s p e c t r a and magnetic p r o p e r t i e s  65  3.2.2.2  V i b r a t i o n a l spectroscopy  70  3.2.2.3  Thermal s t a b i l i t y  72  OCTAHEDRAL PYRIDINE COMPLEXES OF NICKEL(II); N i ( p y ) ( E F ) g  3.4  62  2  3.2.1  3.2.2.1  3.3  g  g  78  2  3.3.1  Introduction  78  3.3.2  R e s u l t s and d i s c u s s i o n  78  OCTAHEDRAL METHYLPYRIDINE COMPLEXES OF COBALT(II), NICKEL(II), AND COPPER(II); M(4mepy) (H 0) (EF ) 8  (EF ) g  3.4.1  2  2  g  2  and M ( 3 m e p y ) ( H 0 ) ~ g  2  2  83  2  Introduction  83  viii  3.4.2  R e s u l t s and D i s c u s s i o n  84  3.4.2.1  V i b r a t i o n a l Spectra  84  3.4.2.2  E l e c t r o n i c s p e c t r a l and magnetic p r o p e r t i e s and molecular s t r u c t u r e 3.4.2.2.1  91  Co(4mepy)g(H 0) (EF ) 2  3.4.2.2.2  2  6  2  91  2  96  Ni(4mepy)g(H 0) (EF ) 2  3.4.2.2.3  2  6  Ni(3mepy) 6  (H 0) (EF ) 2  3.4.2.2.4  2  6  2  103  2  112  2  116  Co(3mepy) 6  (H 0) (EF ) 2  3.4.2.2.5  2  6  Cu(3mepy) 6  (H 0) (EF ) 2  3.4.3 3.5  2  6  R e l a t i o n t o other work  121  TETRAHEDRAL-PYRIDINE AND METHYLPYRIDINE COMPLEXES OF COBALT(II); Co(3mepy) (EFg) 4  2  Co(py) (EF ) , 4  g  and C o ( 4 m e p y ) ( E F g ) 4  2  2  3.5.1  Introduction  128  3.5.2  R e s u l t s and D i s c u s s i o n  129  3.5.2.1  E l e c t r o n i c s p e c t r a and magnetic p r o p e r t i e s  3.5.2.2  M o l e c u l a r s t r u c t u r e of Co(4mepy) (PF ) 4  3.5.2.3 3.5.3  129  6  2  V i b r a t i o n a l spectra  R e l a t i o n t o o t h e r work  134 140 144  ix  CHAPTER 4:  COMPOUNDS CONTAINING COORDINATED HEXAFLUOROPHOSPHATE AND HEXAFLUOROARSENATE  4.1  C R I T E R I A FOR COORDINATION  4.2  COMPLEXES OF N I C K E L ( I I ) ;  150 NiL (EF ) 4  6  156  2  4.2.1  Introduction  156  4.2.2  R e s u l t s and D i s c u s s i o n  157  4.2.2.1  4.2.2.2 4.2.2.3  E l e c t r o n i c s p e c t r a l and magnetic p r o p e r t i e s  157  V i b r a t i o n a l spectra  161  Molecular  structure of  Ni(4mepy) (PF ) 4  4.2.2.4  6  166  2  Low t e m p e r a t u r e i s o m e r i z a t i o n of N i ( p y ) ( A s F ) 4  4.2.2.4.1  g  174  2  M a g n e t i c and electronic spectral properties  4.2.2.4.2  Electronic structure and  4.2.2.4.3  174  stereochemistry  189  Vibrational spectroscopy  4.2.2.5  191  Thermal s t u d i e s 4.2.2.5.1  199  Thermal of and  preparations  Ni(4mepy) (PF ) 4  magnetic  of products  g  2  properties 199  X  4.2.2.5.2  Thermal  Decomposition  Studies  of ML (EFg) 4  2  Compounds 4.2.2.5.3  Thermal of and  2 02  preparation  Ni(py) (AsF ) 4  6  2  properties of  this material 4.2.3  Factors in  4.3  NiL A 4  CHAPTER 6  Complexes  215 4  g  220  2  4.3.1  Introduction  220  4.3.2  Results  222  and D i s c u s s i o n  4.3.2.1  Magnetic p r o p e r t i e s  222  4.3.2.2  Electronic spectral properties  223  4.3.2.3  Electron spin  4.3.3. R e l a t i o n  5.1  2  Coordination  COMPLEXES OF C O P P E R ( I I ) : C u L ( E F )  4.3.2.4  CHAPTER 5  Determining Anion  210  resonance  spectroscopy  230  V i b r a t i o n a l spectroscopy  236  t o other  24 3  work  4.3.3.1  Cu(py) (PF )  4.3.3.2  Comparison o f M L ( E F )  4  6  SUGGESTIONS FOR FURTHER STUDY SUGGESTIONS FOR FURTHER STUDY EXPERIMENTAL  243  2  4  g  2  Complexes  24 3 2 53 254 2 57  6.1  MATERIALS  258  6.2  PREPARATIONS  259  xi  6.2.1  P y r i d i n e Complexes  261  6.2.2  4 - m e t h y l p y r i d i n e Complexes  267  6.2.3  3 - m e t h y l p y r i d i n e Complexes  271  6.2.4  Thermal  27 5  6.2.5  Unsuccessful Preparations  Studies  27 8  6.3  ANALYTICAL DATA  27 9  6.4  PHYSICAL EXPERIMENTAL TECHNIQUES  27 9  6.5  6.4.1  Magnetic  S u s c e p t i b i l i t y Measurements  279  6.4.2  Infrared  Spectroscopy  28 0  6.4.3  Electronic  Spectroscopy  282  6.4.4  Electronic  S p i n Resonance S p e c t r o s c o p y  283  6.4.5  Single Crystal  6.4.6  Raman S p e c t r o s c o p y  284  6.4.7  Other  284  X-ray  Diffraction  283  Methods  SINGLE CRYSTAL X-RAY DIFFRACTION RESULTS 6.5.1  Tetrakis(4-methylpyridine)cobalt(II) hexafluorophosphate  6.5.2  g  286  2  Ni(4mepy) (PF ) 4  g  291  2  Ni(3mepy) (H 0) (PF ) g  2  2  g  2  295  Hexakis(3-methylpyridine)diaquocobalt(II) hexafluorophosphate  6.5.5  4  H e x a k i s ( 3 - m e t h y l p y r i d i n e ) d i a q u o n i c k e l (II) hexafluorophosphate  6.5.4  Co(4mepy) ( P F )  Tetrakis(4-methylpyridine)nickel(II) hexafluorophosphate  6.5.3  2 86  Co(3mepy) (H 0) (PF ) g  2  2  g  2  299  Hexakis(3-methylpyridine)diaquocopper(II) hexafluorophosphate  Cu(3mepy) (H 0) (PF ) g  2  2  g  2  299  REFERENCES  301  APPENDICES  311  xii  L I S T OF  TABLES  I- 1  Magnetic  moments o f some NiL^Ag. compounds  II- l  V i b r a t i o n a l s p e c t r a o f some M ( E F g )  2  28  (E=P,As) s a l t s II-2  Correlation lower  II-3  o f EFg  (0^) v i b r a t i o n s  i n some  symmetries  .... 29  Spin-allowed t r a n s i t i o n energy  expressions  for octahedral or tetrahedral  T  l (g) 9  r o u n (  ^  terms II- 4  .... 35  Spin allowed t r a n s i t i o n energy for octahedral or tetrahedral  expressions  n  A ^ 2  ground 40  terms III- l Electronic  spectral data  for  Co(py)g(EFg)  66 2  III-2 Selected i n f r a r e d spectral data f o r Co(py) (EF ) 6  6  71 2  2+ III-3 Electronic III-4  s p e c t r a l data f o r 'Ni(py)g  Selected i n f r a r e d spectral data Ni(py) (EF ) 6  I I I - 5 Anion  6  for  bands i n t h e i n f r a r e d s p e c t r a o f 8  2  2  6  2  6  and  2  M (3mepy)g1  of the M(4mepy)g(H 0) (EFg) 2  III-7 Electronic (H 0) (EFg) 2  85  2  I I I - 6 S e l e c t e d 4mepy b a n d s i n t h e i n f r a r e d  2  81  2  M(4mepy) (H 0) (EF ) (H 0) (EF ) 2  ....79  1  2  2  spectra 90  compounds  s p e c t r a l data f o r Co(4mepy) g  92 2  Xlll  III-8  E l e c t r o n i c s p e c t r a l data f o r Ni(4mepy)g(H 0) (EF ) 2  III-9  2  6  Electronic  s p e c t r a l data f o r Ni(3mepy)g-  (H 0) (EF ) 2  2  2  6  2  111-10 Bond d i s t a n c e s a n d a n g l e s (H 0) (PF ) 2  III-ll  2  6  Electronic 2  6  111-12 M a g n e t i c  2  p r o p e r t i e s o f Co(3mepy)g-  (H 0) (PF ) 2  2  s p e c t r a l d a t a f o r Co(3mepy)g-  (H 0) (PF ) 2  i n Ni(3mepy)g-  2  6  2  111-13 E l e c t r o n i c p r o p e r t i e s o f C u ( 3 m e p y ) g (H 0) (EF ) 2  2  6  111-14 E l e c t r o n i c 111-15 L i g a n d  2  spectral data f o r CoL (EFg)  field  4  parameters f o r C o L ( E F g ) 4  2  2  111-16 Summary o f t h e m a g n e t i c p r o p e r t i e s o f CoL (EFg) 4  2  111-17 Bond d i s t a n c e s a n d a n g l e s  i n Co(4mepy) 4  (PFg), 111-18 S e l e c t e d n e u t r a l l i g a n d b a n d s i n t h e infrared  spectra of  CoL (EFg) 4  111-19 A n i o n b a n d s i n t h e i n f r a r e d CoL (EFg) 4  111-20 L i g a n d  2  spectra of  2  field  p a r a m e t e r s o f some t e t r a h e d r  complexes o f c o b a l t ( I I )  xiv  IV-1  Electronic  IV-2  Selected spectra  IV-3  4  neutral  g  4  g  ....162  2  A n i o n bands i n t h e i n f r a r e d s p e c t r a 4  6  ....159  2  l i g a n d bands i n t h e i n f r a r e d  of N i L ( E F )  NiL (EF ) IV-4  spectral data f o r N i L ( E F )  of  :  .164 2  Bond d i s t a n c e s and a n g l e s i n N i ( 4 m e p y ) ~ 4  (PF ) 6  .170 2  spectrum o f  Ni(py) (AsF )  .189  IV-5  Electronic  IV-6  T e t r a g o n a l p a r a m e t e r s f o r some N i ( p y ) A  4  g  2  4  2  .190  complexes IV-7  V i b r a t i o n a l spectral data f o r N i ( p y ) ~ 4  (ASF ) 6  IV-8  193  2  Infrared  spectral  data f o r N i ( p y ) ( P F ) 4  g  s u b l i m a t e and r e s i d u e  . .. .204 205  IV-9  Mass s p e c t r a l d a t a f o r pyPF,.  IV-10  Mass s p e c t r a l d a t a f o r pyAsF,-  IV-11  Mass s p e c t r a l d a t a f o r 4 m e p y P F  IV-12  d spacings of N i ( p y ) ( A s F ) 4  and  Ni(4mepy) (PF ) 4  g  g  206 207 5  ( a a n d 3)  2  ,224  Electronic  IV-14  E.s.r. s p e c t r a l data f o r C u L ( E F )  IV-15  Selected  IV-16  4  g  g  g  2  .233  2  .237  2  A n i o n bands i n t h e i n f r a r e d s p e c t r a 4  g  infrared spectral data f o r  CuL (EF ) VI-1  spectral data f o r C u L ( E F ) 4  4  ,213  2  IV-13  CuL (EF )  2  of .238  2  A n a l y t i c a l data f o r pyridine  compounds  266  XV  VI-2  A n a l y t i c a l data f o r 4-methylpyridine complexes  VI-3  A n a l y t i c a l data f o r 3-methylpyridine complexes  VI-4  Thermal p r e p a r a t i o n s o f N i ( 4 m e p y ) ( P F ) 4  g  2  XVI  LIST  2.1  Tanabe-Sugano  OF  FIGURES  diagram  for cobalt(II)  ....3 3  4 2.2  T, lg  term  bations  under  of  the  spin  simultaneous  orbit  coupling  pertur-  and  low  symmetry  . . . . 37  2.3  Tanabe-Sugano  2.4  E f f e c t on  2.5  )  n i c k e l (II)  the  increasing  real  "d"  Correlation chemistry  o f band  of  elongated  f o r S=l/2  axial  copper(II)  3.1  spectrum Magnetic  properties  3.2  Infrared  spectrum  Infrared  of  Visible  48  and  1=3/2  e.s.r.  of Co(py)g(EFg)  (1000-400  cm  - 1  )  51  ....53 .55 .69  2  of .73  Co(py) (AsFg)  (900-300  cm  1  )  of .74  2  spectra  of cobalt(II)-pyridine .76  complexes 3.5  45  2  spectrum  g  stereo-  diagram  Appearance  6  and  chromophores  2.8  6  distortion  CuN _g 4  level  Co(py) (PF )  tetragonal  maxima  Energy  3.4  in axially  of  orbitals  2.7  3.3  levels  ....42  symmetry  Effect of on  2.6  4 h  for nickel(II)  e l e c t r o n i c energy  octahedral (D  diagram  Infrared  spectra  (4000-2000  cm ) - 1  of . .87  M(4mepy) (H 0) (AsFg) g  2  2  2  XVll  Infrared spectra  (4000-2000 cm ) o f x  M(3mepy) (H 0) (PF ) 6  2  2  6  2  Magnetic p r o p e r t i e s o f (H 0) (EF ) 2  2  6  Co(4mepy)g-  2  2+ Co(4mepy) (0H (4mepy) ) 2+ Ni(4mepy) (0H (4mepy) ) 2+  View o f  4  View o f  4  2  2  2  2  2  View o f N i ( 3 m e p y ) ( 0 H ( 3 m e p y ) ) 4  2  2  View of N i ( 3 m e p y ) ( 0 H ( 3 m e p y ) ) ( P F ) 4  E.s.r  2  2  g  2  spectrum o f C u ( 3 m e p y ) ( H 0 ) ( P F g ) g  Infrared spectra  2  2  (4000-2000 cm ) -1  2  of  Cu(3mepy) (H 0) (EFg) Stereoview showing the packing of anions 6  2  2  about a c a t i o n  (Co(4mepy) (PFg) ) 2+ Stereoview o f the Co(4mepy) cation 4  2  4  V i s i b l e spectra of N i L ( A s F g ) 4  Infrared spectra Ni(py) (EF ) 4  6  (1000-300  2  cm ) -1  of  2  View o f N i ( 4 m e p y ) ( P F g ) 4  2  Stereoview o f N i ( 4 m e p y ) ( P F g ) 4  2  Magnetic s u s c e p t i b i l i t i e s o f N i ( p y ) ( E F g ) 4  Magnetic s u s c e p t i b i l i t y of N i ( p y ) ( A s F g ) 4  Electronic  spectrum of N i ( p y ) ( A s F g ) 4  (300 and 80 K) Electronic  spectra of N i ( p y ) ( A s F g ) 4  80 K and N i ( p y ) ( C 1 0 ) 4  4  2  (300 K)  2  3 P l o t o f InK* a g a i n s t 10 /temperature P l o t o f AE a g a i n s t temperature  2  2  XVIIX  4.11  Infrared  spectra  Ni(py) (AsFg) 4  4.12  Infrared 4  4.14  Magnetic  susceptibility  Differential  thermograms  4.17  E.s.r.  4  susceptibility  electronic spectrum  E.s.r.  of  spectra  80  Infrared  4  o f t h e a and  of  3  CuL (EFg) 4  Cu(py) (PFg)2 4  K 4  solution  CuL (PF )  2  Infrared  spectra  6  Infrared  i n  2  a t 300  4  Infrared  K  Infrared NiL (PFg)  2  a  n  spectra  2  )  of  (900-350 c m  - 1  )  of  (900-350 c m  - 1  )  of  2  spectra A  - 1  2  NiCpyr) 4-| 'sFg) v  (1000-400 c m  spectra  NiL (AsFg)  4  M'(py) -  of Cu(py) (PFg)  spectra  4  4.23  2  K  CuL (AsFg)  4.22  of  spectra  a p o w d e r a t 3 00  4  4.21  thermal  Ni(4mepy) (PFg)  dichloromethane  4.20  o f the  4  Visible  4.19  of  of Ni(py) (AsFg)2  4.16  and  )  2  Magnetic  as  - 1  80K)  of  forms  4.18  (900-400 c m  (300 a n d  2  ~~) o f  80K)  preparations  (PFg) 4.15  (300 a n d  2  spectra  Ni(py) (PFg) 4.13  ( 8 0 0 - 3 5 0 cm  ( 9 0 0 - 3 5 0 cm" ') o f . 1  d  C  u  (PY)  4(  (1000-400  A s F  6)  2  cm  - 1  )  of  2  L I S T OF ABBREVIATIONS  s  strong  m  medium  w  weak  vw  very  br  broad  asy  asymmetric  sh  shoulder  n.o.  not  py  weak  observed  pyridine  4m.epy  4-methylpyridine  3raepy  3-methylpyridine  pyz  pyrazine  XX  ACKNOWLEDGEMENTS I w o u l d l i k e t o e x p r e s s my g r a t i t u d e t o D r . R.C. Thompson f o r h i s g u i d a n c e d u r i n g t h e c o u r s e o f t h i s  work.  I would l i k e t o thank P r o f . J . T r o t t e r f o r l e t t i n g me do some X - r a y c r y s t a l l o g r a p h i c work w i t h o u t a f o r m a l relationship.  P r o f . T r o t t e r , D r . S. R e t t i g , D r . T.  Greenhough,  D r . R. B a l l a n d R i c h a r d P a u p . t i t w e r e -very h e l p f u l d u r i n g work a n d I would l i k e t o e x p r e s s s i n c e r e t h a n k s .  I would  this also  l i k e t o a c k n o w l e d g e t h e u s e o f t h e r e s u l t s o f two c r y s t a l s t r u c t u r e d e t e r m i n a t i o n s performed by P r o f . T r o t t e r and D r . S.  Rettig. I am e x t r e m e l y g r a t e f u l t o D r . F. A u b k e , K e i t h L e e ,  a n d D r . P a t r i c k L e u n g f o r a l l o w i n g me t o u s e t h e i r l o w t e m p e r a t u r e c e l l s a n d t h e i r h e l p i n o p e r a t i n g t h e P e r k i n - E l m e r 225 and Ramalog  5 spectrometers.  -1-  CHAPTER 1  INTRODUCTION  T h i s t h e s i s d e s c r i b e s t h e s y n t h e s i s and s t r u c t u r a l c h a r a c t e r i z a t i o n of p y r i d i n e (py), 4-methylpyridine and  3-methylpyridine  and  copper(II) hexafluorophosphate  (4mepy),  (3mepy) c o m p l e x e s o f c o b a l t ( I I ) ,  nickel(II),  and h e x a f l u o r o a r s e n a t e .  Some g e n e r a l p r o p e r t i e s o f t h e s e h e x a f l u o r o - a n i o n s a n d a r e v i e w o f t h e p r e v i o u s w o r k o n t h e i r compounds w i t h row t r a n s i t i o n m e t a l s w i l l  be b r i e f l y p r e s e n t e d  first  i n this  chapter.  The p u r p o s e o f t h e p r e s e n t w o r k a n d t h e o r g a n i z a t i o n o f t h e thesis w i l l  a l s o be o u t l i n e d .  -2-  1.1 PREVIOUS WORK 1.1.1 HEXAFLUOROPHOSPHATE AND HEXAFLUOROARSENATE SALTS Compounds  c o n t a i n i n g the hexafluorophosphate  h e x a f l u o r o a r s e n a t e anions were i n i t i a l l y e a r l y decades o f t h i s c e n t u r y .  The f i r s t  phate compound i s o l a t e d was n i t r o n i u m C  20 16 4 " 6 ' H  N  H  P F  b  y  L  a  n  9  e  i  n  t  h  e  l  a  t  prepared  i n the  hexafluorophos-  hexafluorophosphate,  1920's(l).  e  and  I t was formed  by the a d d i t i o n o f n i t r o n t o a e q u i l i b r i u m mixture c o n t a i n i n g hexafluorophosphoric  acid.  The f i r s t  compound prepared was SCl^AsFg  hexafluoroarsenate  i n 1906  ( 2 ) . I t was formed  by the r e a c t i o n o f S C l ^ and AsF^ and was i n i t i a l l y as S C l ^ A s F ^ ^ *  g r e a t many more compounds  A  formulated  c o n t a i n i n g these  anions were known by the 'early 1960's (2,3). The octahedron in  s t r u c t u r e o f these anions, E F  g  , i s t h a t o f an  o f f l u o r i d e s about the c e n t r a l Group VA  the formal o x i d a t i o n s t a t e of +5.  which were determined  i n the c r y s t a l  The E-F d i s t a n c e s s t r u c t u r e s o f NaPF (4) g  and KAsFg(5) are 1.58A* and I . 8 0 8 r e s p e c t i v e l y . al  The v i b r a t i o n -  s p e c t r a o f simple s a l t s , M'^EFg, which are c o n s i s t e n t with  an o c t a h e d r a l E F in  element  section  g  moiety (6-8), are d i s c u s s e d i n more d e t a i l  2.2.4.2.  The EFg~ s p e c i e s are g e n e r a l l y q u i t e s t a b l e . fluorophosphate  Hexa-  i s s t a b l e i n b a s i c , n e u t r a l and weakly a c i d i c  s o l u t i o n ; h y d r o l y s i s doesn't  take p l a c e u n l e s s the pH i s l e s s  than 3 (1). K i n e t i c evidence(9)  suggests  the h e x a f l u o r o -  arsenate anion i s more s t a b l e to h y d r o l y s i s than the h e x a f l u o r o phosphate anion i n a c i d i c s o l u t i o n s .  The thermal  stability  -3-  o f the s a l t s i n the s o l i d s t a t e and whether they melt w i t h or without decomposition depends upon the nature o f the c a t i o n present.  For example(10)} KPF  decomposition  melts a t 575°C w i t h  g  to PF,. and KF, L i P F  s o c i a t i o n pressure  g  slow,  has an a p p r e c i a b l e d i s -  (PF,.) a t o r d i n a r y temperatures,  and  NMe.PF i s s t a b l e up t o 400°C. 4 b r  1.1.2  COORDINATION CHEMISTRY OF HEXAFLUOROPHOSPHATE  AND  HEXAFLUOROARSENATE ANIONS. S e v e r a l t r a n s i t i o n metal compounds c o n t a i n i n g hexafluorophosphate and h e x a f l u o r o a r s e n a t e have been r e p o r t e d i n the l i t e r a t u r e . of particular  There are two types of compounds which are  r e l e v e n c e to t h i s study.  anhy'drous compounds of the type M ( E F g )  These are simple, 2  (E=P,As) and t h e i r i; ^.  p y r i d i n e or s u b s t i t u t e d p y r i d i n e complexes w i t h f i r s t t r a n s i t i o n metals i n the +2 oxid.ati.pn-.  state.  row  These compounds  are o f i n t e r e s t because they can be used t o c o r r e l a t e the c o o r d i n a t i n g s t r e n g t h of anions with t h e i r b a s i c p r o p e r t i e s . Anions  such as p e r c h l o r a t e (ClO^ ), t e t r a f l u o r o b o r a t e  and s u b s t i t u t e d sulphates The EF,  (XSO^  (BF^ ),  ) have been s t u d i e d i n t h i s  anions can be c o n s i d e r e d t o be weakly b a s i c ,  although  D  the anhydrous a c i d s HEF  cannot be  g  The compounds M ( E F g )  2  isolated.  are not w e l l c h a r a c t e r i z e d .  In f a c t , t h e r e have not been any r e p o r t s i n the o f the s y n t h e s i s of M ( P F ) g  formation or attempted  2  literature  compounds w h i l e some r e p o r t s of  formation o f M ( A s F ) g  2  wa^  compounds have  -4-  appeared  (11,12).  The  o x i d a t i o n o f manganese, i r o n ,  and  n i c k e l metal with  and  MF(AsF^) f o r the o t h e r s b  (12)  on  a r s e n i c p e n t a f l u o r i d e y i e l d e d Mn(AsFg)^ (11).  S i m i l a r s t u d i e s by  t h e o x i d a t i o n o f n i c k e l and  Ni(AsFg) (S0 )2 2  and  2  solvent).  The  Cu(AsFg)  unsolvated  (sulphur  d i o x i d e was  compound N i ( A s F - )  has  n  i n monel v e s s e l s  ( 1 3 ) . The  M(AsF ) g  Ni,Cu) cannot,at t h i s time,be c o n s i d e r e d  compounds,  u s e d as been  the  reported  Z  f o r m e d when t h e N F ^ - F ^ A s F , . s y s t e m i s h e a t e d  pressure  Dean  c o p p e r y i e l d e d two  b  t o be  cobalt  2  under  compounds  t o be  (M=Co,  well  characterized. Some p y r i d i n e and nickel(II)  and  copper(II)  namely, N i ( p y ) ( P F ) , g  Cu(py) (PF )2 4  g  of techniques.  g  and  2  s u b s t i t u t e d p y r i d i n e complexes  h e x a f l u o r o p h o s p h a t e have been  Ni (py) (PF ) , 4  g  2  Ni(4mepy) (PF ) , 4  t h e y h a v e b e e n c h a r a c t e r i z e d by  No  hexafluoroarsenate  have been r e p o r t e d .  The  compounds o f  I n one  a variety  4  2  type  hexafluorophosphate radically  from those c o n t a i n i n g o t h e r weakly b a s i c  case, N i ( p y ) ( P F g ) /  reported, and  2  compounds o f t h i s  h a v e some i n t e r e s t i n g p r o p e r t i e s , i n some c a s e s different  g  the observed magnetic  anions. properties  are anomalous f o r a n i c k e l ( I I ) s p e c i e s . The  r e a c t i o n of n i c k e l ( I I ) n i t r a t e hexahydrate,  ammonium h e x a f l u o r o p h o s p h a t e , and aqueous  s o l u t i o n was  . give Ni(py),(PF-.)_. o 6 Z  of  an e x c e s s o f p y r i d i n e i n  f o u n d by M a y f i e l d  and  Bull  (14)  A s i m i l a r r e a c t i o n of n i c k e l ( I I )  to  -5-  p e r c h l o r a t e h e x a h y d r a t e i n a q u e o u s s o l u t i o n w i t h an e x c e s s o f pyridine  gave  the product N i ( p y ) ( C 1 0 ) 4  4  ( 1 6 ) . The  2  character-  i z a t i o n o f N i (py) , (PF,.) „ s u g g e s t e d t h a t t h e s t r u c t u r e i n v o l v e d 6 6 2 2+  Ni(py)^ c a t i o n s a n d n o n - c o o r d i n a t e d PF,. a n i o n s . In contrast, 6 6 N i ( p y ) ( C 1 0 ) 2 has been a s s i g n e d a p s e u d o - o c t a h e d r a l f i r s t 4  4  c o o r d i n a t i o n sphere w i t h the p e r c h l o r a t e These r e s u l t s i l l u s t r a t e coordination a b i l i t i e s  anions  coordinated.  the s i g n i f i c a n t difference i n the  of C10  4  a n d PFg  and p r o v i d e d t h e 2+  first  i n d i c a t i o n t h a t complex c a t i o n s such as M(py)g  more l i k e l y t o be o b t a i n e d w i t h P F g C10 o r r e l a t e d i o n s such as B F . 4  the in  than  with  4  The s y n t h e s i s o f M ( p y ) g is  counterions  are  not a simple  task  2+  (17);.. i n d e e d  species  i n the s o l i d  Ni(py)g(PFg)  2  was  state  only  second w e l l documented example o f t h i s t y p e o f s p e c i e s the s o l i d  state.  (Fe(py) )(Fe C0 ) g  4  (18) was t h e f i r s t .  1 3  2-  The i s o l a t i o n o f s u c h s p e c i e s w i t h t h e P F g  and F e C O . ^ 4  a n i o n s s u g g e s t s t h e need f o r l a r g e and w e a k l y b a s i c to s t a b i l i z e N l  the c r y s t a l  (PY)4(  P F  6)2  w  lattice. a  s  p r e p a r e d by h e a t i n g  a t 100°C " i n v a c u o " a n d N i ( 4 m e p y ) ( P F g ) 4  the  same r o u t e  anions  2  Ni(py)g(PFg)  was d e r i v e d v i a  f r o m a compound o f unknown c o m p o s i t i o n  similar to Ni(py)g(PFg)  2  2  but  ( 1 4 ) . The m a g n e t i c p r o p e r t i e s o f  t h e s e compounds a n d t h e a n a l o g o u s p e r c h l o r a t e compounds show some i n t e r e s t i n g f e a t u r e s a s i l l u s t r a t e d N i (py) 4 ( 1C>4) 2 C  n  a  s  i n T a b l e 1-1.  magnetic and s p e c t r a l p r o p e r t i e s  typical  -6-  TABLE 1-1 MAGNETIC MOMENTS FOR SOME N i L A 4  COMPLEX  u  Ni(py) (PF ) 4  Ni(py)  4  6  2  (cio ) 4  2  Ni(4mepy) (PF ) 4  g  2  Ni(4mepy) (C10 ) 4  (a)  4  e f f  (B.M.)  REFERENCE  1.98  (14)  3.24  (16)  0.0  (14)  0.0  2  (19-22)  a t room t e m p e r a t u r e ,  octahedral  enviornment.  have t h e magnetic associated  structure  4  4  (PF ) g  properties  2  comfirms  h a s a n anomalous  and B u l l  (14), s t a t e  where t h e r e  accessible  and Busch  2  dilute  systems  two p o s s i b l e  i s a s i n g l e t ground  triplet  excited  s t a t e as  H 0 ; and: t h e s e c o n d , where 2  this  or the  (24) m o d e l f o r t h e m a g n e t i c  of ~Ni(TAAB)Cl  usually  magnetic  of either the octahedral  the f i r s t ,  and a t h e r m a l l y  t h e Melson  2  4  form o f n i c k e l ( I I ) i n m a g n e t i c a l l y  authors, Mayfield  state  compounds  n i c k e l ( I I ) ; the single c r y s t a l  study o f N i ( 4 m e p y ) ( C 1 0 )  moment; i t i s n o t t y p i c a l  explanations:  pseudo-  and e l e c t r o n i c s p e c t r a l p r o p e r t i e s  (23). N i ( p y )  square p l a n a r  distorted  The two 4 - m e t h y l p y r i d i n e  w i t h square planar  X-ray d i f f r a c t i o n  in  COMPLEXES  a  o f ,. t h e n i c k e l ( I I ) i o n i n a t e t r a g o n a l l y  The  2  -7-  there  i s a mixture  of  spin  free  ( y  e  f  f  (RT)  ^3.2  B.M.)  (hexafluorophosphato)tetrakis(pyridine)nickel(II) coordinated  anions  and  spin-paired  hexafluorophosphate  anions.  situation  the  This  yellow  (25,26). favored netic  form For  the  of  the  the  spectrum  initive  explanation but  planar  was  complex  of  conditions  McWhihftie was  not  (27)  to  anions  refer  as  a mixture nickel(II)  data et  Mayfield on  al  that  this  and  Bull  compound  (15), although  the  The  led to (14)  characterization  4  (ClO^) . 2  the  def-  a  square  planar  the  and  pyridine  experimental  isolation  of  Cu(py) (PF ) . 4  reported  g  2  by  of preparation of  this  anions  c o p p e r ( I I ) , a l t h o u g h more w e a k l y i n Cu(py)  on  obtained  method  hexafluorophosphate  not  from  Using  have been  the  electron-  species.  t o p r e v i o u s work  which  was  2  square  those  to  The  arising  of  mag-  differentiate  performed.  similar  specified.  indicated  could  hexafluorophosphate.  2  e.s.r.  we  authors  temperature  copper(II)  6  The  interpreted  pseudo-octahedral  Ni(py) (PFg) '  the  4  species or  Finally,  not  in  dichloroacetate  reported for Ni(py) (PFg)  i t c o u l d be  nickel(II)  tetragonal  "non-coordinated"  complex,  which  were  tetrakis-  encountered  variable  measurements  possibilities  which  since  been  hexafluorophosphate  first  two  has  with  bis(mesostilbene)nickel(II)  susceptibility  between ic  latter  with  (diamagnetic)  (pyridine)nickel(II)  bis-  than  are  compound coordinated  the p e r c h l o r a t e  -8-  1.2  PURPOSE OF THE  Our chemistry was  initial  PRESENT WORK  i n t e r e s t i n the  of hexafluorophosphate and  coordination hexafluoroarsenate  t o examine the v a r i a b l e temperature magnetic  p r o p e r t i e s o f N i (py) ^ ( g ) 2 pF  a n <  ^  v a r i a b l e temperature behavior  susceptibility  s i m i l a r compounds. of N i ( p y ) ( P F g ) 4  ions  The  should  2  have"provided more i n f o r m a t i o n on the o r i g i n o f the anomalous room temperature moment . mentioned i n 1.1.2. these  I f , indeed,  anomalous p r o p e r t i e s a r i s e from a s p i n s i n g l e t - t r i p l e t  thermal  e q u i l i b r i u m (as favored by M a y f i e l d and B u l l ) the  phenomenon should manifest  i t s e l f by g i v i n g a temperature  dependent magnetic moment. moment i s due  On the o t h e r hand, i f the anomalous  to a mixture o f paramagnetic and  diamagnetic  s p e c i e s , a l a r g e l y temperature independent magnetic moment should be observed. NiL^(EFg)2  systems  From some p r e l i m i n a r y s t u d i e s on (28)/ we  found t h a t we  c o u l d not  the p u b l i s h e d magnetic p r o p e r t i e s o f N i ( p y ) ( P F ) 4  g  2  reproduce and  l e d to a thorough i n v e s t i g a t i o n of t h i s compound and  this  a wide  range o f r e l a t e d compounds. -"The  purpose of the p r e s e n t work then was  to  a range of m e t a l ( I I ) - p y r i d i n e - E F g compounds with the of o b t a i n i n g complex c a t i o n s u n a t t a i n a b l e w i t h }  c o o r d i n a t i n g anions  and  synthesize expectation  other more  of o b s e r v i n g h i g h l y t e t r a g o n a l s p e c i e s  i n complexes where the anions  are c o o r d i n a t e d .  Included  in  -9-  t h i s work are t h e p r e v i o u s l y Ni(py)  studied  compounds N i ( p y )  ( P F ) , N i ( 4 m e p y ) ( P F g ) , and C u ( p y ) ( P F g ) . g  2  4  2  4  c h a r a c t e r i z a t i o n t e c h n i q u e s were e l e m e n t a l vibrational  (mainly i n f r a r e d )  scopy, v a r i a b l e temperature m e a s u r e m e n t s , and The  The  2  (C, H, N)  spectroscopy, e l e c t r o n i c  magnetic  susceptibility  s i n g l e c r y s t a l X-ray  low  l o g r a p h y , and mass s p e c t r o m e t r y w e r e u s e d w h e r e  (Gouy)  temperature  on t h e c o m p l e x s p e c i e s and properties.  crystal-  applicable.  r e s u l t s o f t h e c h a r a c t e r i z a t i o n s t u d i e s were used  molecular structure with electronic  spectro-  crystallography.  techniques o f • e l e c t r o n spin resonance,  structural information  main  analysis,  v i b r a t i o n a l and e l e c t r o n i c s p e c t r o s c o p y , powder X - r a y  The  (PF,)„,  r  to  to  obtain  correlate  -10-  1.3  ORGANIZATION OF THE THESIS  The b a s i c o u t l i n e o f t h e o r g a n i z a t i o n o f t h i s thesis i s :  background and t h e o r y ; r e s u l t s and d i s c u s s i o n ;  s u g g e s t i o n s f o r f u r t h e r s t u d y ; and e x p e r i m e n t a l d e t a i l s . The a p p e n d i c e s c o n t a i n t h e i n f r a r e d a n d m a g n e t i c  susceptibility  d a t a and X-ray d i f f r a c t i o n d a t a t a b l e s . Chapter 2 w i l l for of  d e s c r i b e some b a c k g r o u n d  material  t h e p h y s i c a l t e c h n i q u e s used i n t h e c h a r a c t e r i z a t i o n t h e compounds.  The l i g a n d f i e l d  metal complexes w i l l  theory of t r a n s i t i o n  be v e r y b r i e f l y  i n t r o d u c e d as w i l l  some f a c e t s o f some o f t h e p h y s i c a l t e c h n i q u e s u s e d . derivation of various ligand f i e l d ions studied here w i l l  The  parameters f o r the metal  be .reviewed.  F i n a l l y , t h e approaches '  we u s e d t o c h a r a c t e r i z e t h e compounds w i l l be o u t l i n e d . Chapter 3 w i l l  discuss the characterization of the  c o o r d i n a t i o n compounds w h e r e t h e h e x a f l u o r o m e t a l l a t e a n i o n i s p r e s e n t i n t h e l a t t i c e as a c o u n t e r i o n n o t d i r e c t l y coordinated to the metal.  The compounds d i s c u s s e d h e r e a r e  M(py) (EF ) , M(4mepy) (H 0) (EFg) , 6  6  2  and M " L ( E F g ) 4  4mepy, 3mepy. for  8  2  2  2  2  M'(3mepy)g(H 0) (EFg) 2  2  w h e r e M=Co, N i , M'=Co,Ni,Cu, E=P,As a n d L=py, The s t e r e o c h e m i s t r y a n d l i g a n d  each c a t i o n i c  field  parameters  s p e c i e s w i l l be d e r i v e d a n d t h e r e s u l t s  d i s c u s s e d i n r e l a t i o n t o o t h e r systems-. c a t i o n - a n i o n i n t e r a c t i o n s on t h e i n f r a r e d discussed.  2  The e f f e c t s o f spectrum w i l l  be  -11-  Chapter  4 will  discuss the characterization of  t h e c o m p l e x e s where t h e E F coordinated  t o the metal  ion.  d i s c u s s i o n o f t h e concept ization and  o f t h e compounds N i L ( E F ) 4  concept.  system,  g  2  (L=py, 4mepy, 3mepy  and i s d i s c u s s e d i n r e l a t i o n t o  thermal  t o those  degradation  s t u d i e s which  of previous reports.  the c h a r a c t e r i z a t i o n o f the C u L ( E F g ) 4  3mepy a n d also, will  The c h a r a c t e r -  A l a r g e amount o f work was done o n t h i s  including  our r e s u l t s of  The c h a p t e r b e g i n s w i t h a  of coordination.  E = P , As) i s o u t l i n e d  this  a n i o n s a r e c o n s i d e r e d t o be  g  E=FP,AS)  infrared  system  criteria  will  2  relate  Then, t h e r e s u l t s (L=py., 4mepy,  be discussed.  In this  f o r c o o r d i n a t i o n o f the E F  g  section anions  b e summarized. Chapter  5 will  propose  Chapter  6 will  describe the experimental  suggestions  for further  study.  of  t h i s work.  the d e t a i l s  The m a t e r i a l s u s e d ,  of the physical  experimental  details  studies w i l l  be p r e s e n t e d .  the preparative details,  techniques  of the single  details  e m p l o y e d , and t h e  crystal  X-ray  diffraction  -12-  CHAPTER 2  THEORY AND BACKGROUND  This chapter w i l l  present a b r i e f description of  the t h e o r y and o t h e r background m a t e r i a l a p p r o p r i a t e t o t h i s study. to  I t i s n o t meant t o be a t h o r o u g h  s i m p l y i n t r o d u c e t h e t e r m i n o l o g y and c o n c e p t s  remainder of  review but instead  of the thesis.  F i r s t , an i n t r o d u c t i o n t o t h e t h e o r i e s  t r a n s i t i o n metal complexes w i l l  p h y s i c a l methods o f i n v e s t i g a t i o n ; magnetic s u s c e p t i b i l i t y , s p i n resonance  be p r e s e n t e d . electronic  vibrational  Then, t h e  spectroscopy,  spectroscopy,  electron  s p e c t r o s c o p y , v i b r a t i o n a l s p e c t r o s c o p y , and  s i n g l e c r y s t a l X-ray  crystallographyw i l l  be d i s c u s s e d .  correlation of stereochemistry with electronic cobalt(II), nickel(II), F i n a l l y , o u r approach compounds w i l l  used i n t h e  and c o p p e r ( I I ) w i l l  structure f o r  be s u m m a r i z e d .  t o the c h a r a c t e r i z a t i o n of these  be d i s c u s s e d .  The  -13-  2.1  INTRODUCTION TO THE THEORY OF TRANSITION METAL  The those and  t r a n s i t i o n metals  have b e e n d e f i n e d  e l e m e n t s w h i c h have p a r t i a l l y  those  e l e m e n t s where p a r t i a l l y  filled filled  COMPLEXES  (29) a s  "d" o r " f " o r b i t a l s "d" o r " f " o r b i t a l s  a r e p r e s e n t i n some o f t h e i r common o x i d a t i o n s t a t e s . name " t r a n s i t i o n m e t a l s "  has n o r m a l l y been a p p l i e d t o t h e d  b l o c k elements o f t h e f i r s t third  (Ta-Au) rows.  chemistry  (Ti-Cu),  second  As a g e n e r a l r u l e ,  of a transition  ( Z r - A g ) , and  the coordination  element m a n i f e s t s  itself  i n the  element's p o s i t i v e o x i d a t i o n ( e l e c t r o n d e f i c i e n t ) The  magnetic  spectral be  (susceptibility  (visible,  The  and n e a r  and s p i n infrared  states.  r e s o n a n c e ) and e l e c t r o n i c regions) p r o p e r t i e s can  e x p l a i n e d , a s w e l l a s some s t r u c t u r a l  p r e f e r e n c e s and  thermodynamic p r o p e r t i e s , i n terms d f t h e d e l e c t r o n c o n f i g u r a t i o n o f the metal  ion.  Some a p p r o a c h e s t o t h i s  are described  below. The  t h e o r i e s w h i c h have b e e n u s e d  p r o p e r t i e s o f t r a n s i t i o n metal bond t h e o r y field  (30), ligand  theory)  angular  o v e r l a p model  t r a n s i t i o n metal usually  complexes i n c l u d e v a l e n c e  field  and a m o l e c u l a r  theory orbital  (a.o.m.).  chemistry  g i v e some i n s i g h t s  to explain the  (including  crystal  approach termed t h e  Standard  textbooks  on  ( r e f e r e n c e s 31-35, f o r example) into  the h i s t o r i c a l  ment, a d v a n t a g e s and d i s a d v a n t a g e s  develop-  o f each theory.  Valence  -14-  bond  theory  because  is  not  i t is  electronic  too  the  used  approach  to  explain  C.F.T.,  the  be  electrostatic the  surrounded  in  by  The  free  d  ion  orbitals are  symmetry:  t  The  separation  energy  defined the  as  ^  complex  c • • • figurations  2  o c  (Ze  is  the  radius  ^  ,  first  approach  used  in  i t s basis  in  y z  ,  d  of  the  into  the  lODq.  d  two  The  and sets  electronic  by  the  is  charge  that  to  be  of  the  sets y  an  five  in  and  symmetry  energy d  to  symmetric  x  0^  model.  octahedral  (d 2_ 2  various  thesis.  vertices  g  in  row  considered  the  e  commonly  crystal  degenerate  )  row  this  an  spherically  two x z  in  orbitals  conjunction  considered  is  at  in  most  point  is  ion  charges  and  of  a  example  metal  the  split d  being  For  determined  0^ d 2)  is  levels  electron  .  z  of con-  ,, m n. (t e ). 2g g 0  the  2-4 5 / r_/a )/6  crystal where  electronic of  x y  or  are  In as  (d  g  of  has  explain  first  properties  interaction  negative  of  to  more  utilize  properties  latter  on  although  to  chemistry  attempt  the  central  effect  no  is  theory the  metal  theory  the  nature.  point  degenerate  gaseous  the  metal-ligand  positive  octahedron. fold  field  difficult  field  is  (C.F.T.),  In  complex,  It  makes  (36-38),  bulk  Ligand  metals.  theory  is  transition  and  a.o.m.  observable,  Ligand field  The  metals.  transition  modern  satisfying,  normal  transition  in  qualitative  spectra.  theoretically with  used  the  d  Z  field is  charge,  orbitals,  model,  the -4 r and  Dq  effective  is a  the is  is  nuclear  fourth the  parameterized charge,  power o f  metal-ligand  the bond  e  mean  -15-  length.  The m a t h e m a t i c a l  than  0^ o r T^  some  cases,  parameter, parameter of  treatments  (as shown b y G e r l o c h  introduce Cp, w h i c h  a second  and Slade  order  radial  lower  (33))i n ligand  field  -2 a s 2 Ze r ~ . T h i s 7 a i t i s n e e d e d t o e x p l a i n some  i s parameterized  i s important  the observed  o f symmetries  since  magnetic  and s p e c t r a l p r o p e r t i e s  of d  , d ,  p and  d  or  ions  where  effects and  The  (which  also  free  energy  between  as  can  the energy  o f D q , B,  bonding  and C as compared B to metal-ligand Since  B  field  a n d C.  i n terms  of t h e gaseous configurations).  free  ion i s  states  correspondence  and i n  i o n c a n be  The e f f e c t s  repulsion  of  intermediate expressed  metal-ligand  and i n t e r e l e c t r o n r e p u l s i o n  o f the values to i t s value  to the free covalency  i s a measure  i n the d orbitals, displacement  field  one-to-one  of the metal  Dq a s c o m p a r e d  the radial  states  field  configurations)  interelectronic  i s a  a n d weak  levels  be e v a l u a t e d  by  field  o f the gaseous  There  and covalent  electrons  lowered  o f t h e Racah  B a n d C.  of  the crystal  the so-called strong  ordering  octahedral  present.  includes  t h e symmetry  the strong  obtained:  theory  are  ( g i v i n g t h e s o - c a l l e d weak  level  functions  ionic  give  as a f u n c t i o n  parameters  cases  field  considers  i o n (39)  known  of  or tetragonally distorted  tetrahedral.stereochemistries Ligand  B  trigonally  o f D q , B,  and C  i n other, complexes;  i o n values. i s described  The r e l a t i o n s h i p next.  of the repulsive interactions i ti s primarily affected  of these  orbitals.  Any  ligand  -16-  which  reduces  ion  and thus  the  mean  electron of  B.  field the is  expands  radial over  These  usually  the d electron  two p r i n c i p a l  lower  t h e most  than  fact  for  the introduction  For d  a s p i n - f r e e ground  from  the electronic Further  not  appropriate  the  textbooks  6.4. a n d 6.5. physical  forthis  that  reflects  the fact  i o n value  i s partially  i n ligand  , d  state,  3  into  , d  7  field an  B  covalent. theory  allows  essentially  , and d  a value  thesis. field  8  metal  complexes  o f B c a n be d e r i v e d  H e r e we  field  Readers  theory are  are referred  to  theory.  INVESTIGATION  experimental  of  central  The f a c t  d i s c u s s i o n s on l i g a n d  on l i g a n d  methods  are called  spectrum.  P H Y S I C A L METHODS OF  The  2  the value  important.  of covalency  with  decreases  of the d  with  interaction  model.  or increases  covalency  that B i s a variable  electrostatic  o f the metal  restricted  the free  the metal-ligand  cloud  mechanisms  and symmetry  probably  charge  by d e l o c a l i z a t i o n  t h e m e t a l - l i g a n d bond  The  2.2  nuclear  displacement  covalency  former  that  the effective  details  provide  are described  some b a c k g r o u n d  investigation.  i n section  concerning  various  -17-  2.2.1  E L E C T R O N I C SPECTROSCOPY  First absorption in  bands  (which  the near-infrared  magnetic can as  row t r a n s i t i o n  spectrum.  predicted  and v i s i b l e  by the l i g a n d  model.  Section  metal(II)  2.2.2  ions  metal upon  chemistry metal.  (208  cm  - 1  magnetic various  upon  cases,  the context of used  this  f o rthe  t h e ground  U ff/ e  term  arrangement  and o r b i t a l state  state.  i o ni s  (£) a n g u l a r  and s t a t e s  stereochemistries,' o f the metal 2.3.  around t h e  o f the metal  within  The  and i t s temperature  i n Section  i s dependent  p o p u l a t i o n s and the s t e r e o -  a t 300K) o f t h e g r o u n d moment,  probe the  of the transition  ground  susceptibility  the spin(s)  with  presented  In these  measurements  term  by t h e l i g a n d  The atomic  associated  ground  i o n d electron  produced  dependent  states  the procedures  susceptibility  The n a t u r e o f t h i s  the metal  cases,  here.  of the electronic ion.  i n some  SUSCEPTIBILITY  Magnetic nature  transitions)  electronic  model.  t o Dq a n d B w i t h i n  studied  MAGNETIC  energies,  between  field  2.3 d e s c r i b e s  have  regions o f the electro-  The t r a n s i t i o n  c a n be f i t t e d  generally  c a n b e a s s i g n e d t o d+d  be a s s i g n e d t o t r a n s i t i o n s  they  are  metals  momentum kT  effective  dependence f o r  i o n studied,  here  -18-  The p r i n c i p l e s i n v o l v e d i n t h e o p e r a t i o n o f t h e Gouy a n d F a r a d a y b a l a n c e s (4 0)  used i n t h i s s t u d y and t h e  theory of atomic s u s c e p t i b i l i t i e s  (30,40,41)  are discussed  in  numerous t e x t b o o k s o n t h e s u b j e c t .  The m a g n e t i c moment  of  a m e t a l i o n h a v i n g s p i n ( s ) and o r b i t a l ( & )  in  t h e absence o f s p i n - o r b i t c o u p l i n g i s :  u = (4s ( s + D + AU+1) )  a n g u l a r momenteum,  ( i n Bohr magnetons)  h  When a p a r a m a g n e t i c b o d y e x p e r i e n c e s a m a g n e t i c field,  t h e r e i s a change i n t h e e n e r g e t i c s o f t h e system.  M o d e l l i n g t h e paramagnetic metal i o n as a magnetic the  dipole,  d i p o l e can a l i g n w i t h o r against the d i r e c t i o n o f the  magnetic f i e l d .  I n quantum m e c h a n i c a l t e r m s , t h i s i s  e q u i v a l e n t t o removing t h e degeneracy o f t h e magnetic q u a n t u m number, m ; g  electron.  t h i s i s r e p r e s e n t e d below f o r a s i n g l e  The e n e r g y d i f f e r e n c e  (hv) b e t w e e n  t h e two m  m =h ( + )  7.  s  AE=hv m =-3s( + ) s  APPLIED  FIELD  s t a t e s i s shown i n e q u a t i o n 2.2; w h e r e h i s Planck's c o n s t a n t  hv=g8H  (2.2)  -19-  6.6256x10 -2 7 e r g - s , v i s the t r a n s i t i o n frequency t y p i c a l l y 10 a radiofrequency factor  ( 10  y  H e r t z ) , g i s the Lande s p l i t t i n g  (2.002317 f o r a f r e e e l e c t r o n ) , 3 i s the Bohr magneton -20  (0.92731x10  -1  e r g gauss  a p p l i e d magnetic f i e l d  ) and H i s the magnitude i n gauss.  of the  For an a p p l i e d f i e l d o f  3 00 G. on the f r e e e l e c t r o n , the s e p a r a t i o n of two m -1 l e v e l s would be 0.23 cm which i s much l e s s than kT.  g  ' The  d i s t r i b u t i o n o f the metal i o n d i p o l e s having one of the two o r i e n t a t i o n s w i l l be governed by a Boltzmann  distribution  and there i s a small excess i n the lower l e v e l .  As a r e s u l t  o f t h i s excess, t h e r e i s net magnetic d i p o l e g i v i n g r i s e to a magnetic s u s c e p t i b i l i t y and because o f the Boltzmann (molar, x m »  d i s t r i b u t i o n , the s u s c e p t i b i l i t i e s are temperature  a  n  d  xg)  gram,  dependent.  The phenomenon d e s c r i b e d above i s the f i r s t o r d e r Zeeman e f f e c t .  S i n c e bulk magnetic s u s c e p t i b i l i t y measure-  ments measure only the r e s i d u a l excess s p i n s i n the ground s t a t e , the magnitude  o f the s u s c e p t i b i l i t y i s determined  by the s e p a r a t i o n o f these s t a t e s .  Moreover, i n cases where  no o t h e r e l e c t r o n i c s t a t e s are w i t h i n kT o f the ground  state  the s u s c e p t i b i l i t y i s i n v e r s e l y p r o p o r t i o n a l t o temperature (41) and as a r e s u l t U £ ( = 2 . 8 2 8 ( x x T ) ) i s temperature inde2  e  pendent.  f  m  T h i s i s the s i t u a t i o n f o r t r a n s i t i o n metal  w i t h A o r E ground s t a t e s . w i t h T^ and  However, t r a n s i t i o n metal  ground e l e c t r o n i c s t a t e s  complexes complexes  (and t h e r e f o r e o r b i t a l  -20-  angular  momenta  dependent  moments;  in  the  presence  of  the  ground  4  a  two  other  affect order  of  at  state  least  the  Zeeman  lower  and  show  i n these state  2.3.1.2 d e s c r i b e s  than  ion -  and  temperature  cases,  results  within  kT  the model  r e s u l t of  some e x c i t e d When  the  i s known,  a  t.i.p.;  the  cubic  state  for  t.i.p.  less  (x  than  constant. 1/Xm  1  S  The  plotted  second  xm  T  should  -  9,  ,  intercept  xm  against  can  a A  are  present  Zeeman into  applied inde-  effect is the  ground  for a  be  i . e . X £f  made  E  metal =  e  i n Section or  the  diagram  presence m a  Y  where of  second  ground  6.3.2. state  is  be i n v e r s e l y p r o p o r t i o n a l  the  symmetry,  a  i s temperature  order  level  defined  ion with  In  may  paramagnetism  that  i s mixed  correction  1/T) .  cubic  proportional to  name i m p l i e s  are  are  i s i n d u c e d by  character  symbols  terms,  symmetry.  o v e r a l l energy  symmetry,  temperature  T^)  this  When a m e t a l a  effects  E  which  They  independent  coupling  the  and  present  xm«  of  contribution  as  for A  t o be  dependence  (0^ and  t.i.p.  that  shown  (temperature  cubic  The  state.  been  spin-orbit  pendent. that  have  effect  field  of  usually  spin-orbit  mentioning,  temperature  magnetic  in  them)  coupling,  one  (Section  i s worth  The  A  spin-orbit  factors  (t.i.p.))  X  with  term) . It  in  associated  the  be 8  of  ligand  temperature  temperature  fields  inversely,  i s the  (in Kelvin  to  - -  Weiss axis  when  ) gives  6  -21-  in  Kelvin  .  For  to  second  order  environments  2.2.3  have  with  been  respect  Of  mental  the  n i c k e l ( I I ) and  E.s.r. ments  of  2.2.2.,  technique. spin  of  Equation the from  2.2  the  the  has  low  been  related  symmetry  ligand  v  SPECTROSCOPY.  electron  spin  resonance  metals  studied  spectrohere,  observable powder;  nitrogen  H,  where  at  magnetic  the  resonance  the  g  values  the  but  The  needed  is a to  field  condition, can  be  spectra are  helium  also  experi-  solution;  reported  liquid  magnetic  the  copper(II)  susceptibility  energy  applied  under  solutions).  complexes or  only  temperature  technique  measures i n an  spectra  "frozen"  the  a magnetic  (Co,Ni,Cu)  room  lattices  i s , like  and  studied  temperatures. measure-  resonance  reverse (m and  derived  -m  the ).  knowing directly  spectrum. The  from  give  describes  of  metals  i n host  electron  values  in  transition  cobalt(II)  E.s.r.  a  of  the  used:  (liquid  observed  to  three  conditions  usually  constant  (43-45).  generally  glasses  RESONANCE  fundamentals  reviewed  complexes  this  spin-orbit coupling  ELECTRON SPIN  scopy,  of  terms,  2  (42).  The  and  A  free  dependent.  g  values  electron  For  obtained  are  g  g  value,  different  , and  e l e c t r o n s • p.ossessi-ng  in  magnitude  also  may  be  orientation  spin  and  orbital  -22-  a n g u l a r momentum w h i c h c o u p l e t o g e t h e r t o f o r m J , t h e f o r m of t h e g f a c t o r i s as i n e q u a t i o n 2 . 3 .  Since ligand  q u e n c h a n g u l a r momentum, A and E g r o u n d t e r m s  fields  (eg. c o p p e r ( I I ) )  g = 3 J ( J + 1 ) + S(S+1) + L ( L + 1 ) 2J(J+1) should not possess g values observed with excited  orbital  a n g u l a r momenta;• h o w e v e r , t h e  are not generally g .  Spin-orbit coupling  s t a t e s i n t r o d u c e s some e x c i t e d  i n t o t h e ground s t a t e .  (2.3)  Equation  state character  2 . 4 shows t h e r e l a t i o n s h i p  between t h e g v a l u e s where n i s d e t e r m i n e d  by t h e e x c i t e d  state. g = g  (1 - ( n X / A ) )  e  (2.4)  A l s o , t h e g v a l u e may be o r i e n t a t i o n i.e.  dependent,  e a c h c a r t e s i a n a x i s may h a v e a c h a r a c t e r i s t i c  T h i s depends upon t h e symmetry a r o u n d t h e m e t a l c u b i c symmetry, t h e g v a l u e of the molecule  (g  = g  x  lower  i s independent  ion.  In  of the orientation  = g ) and i s termed i s o t r o p i c . y  In  z  symmetry, t h e g v a l u e i s o r i e n t a t i o n dependent and  termed a n i s o t r o p i c .  In axial  symmetry  (g x  is  g value.  d e f i n e d a s g± a n d g  z  i s d e f i n e d as g  J t  = g  ^ g ), g y  (=g„) x  In symmetries  (eg. rhombic) a l l t h r e e g v a l u e s a r e d i f f e r e n t .  I n some s o l u t i o n s p e c t r a , t h e g v a l u e s o b s e r v e d appear i s o t r o p i c ,  y  when b y c o n v e n t i o n ,  z i s t h e a x i s w i t h t h e h i g h e s t symmetry a b o u t i t . lower than a x i a l ,  z  even though t h e m o l e c u l a r  will  s p e c i e s may h a v e  anistropic  (axial) g values.  This occurs  when t h e t u m b l i n g  of the paramagnetic ions i s f a s t e r than the time s c a l e of t h e e . s . r . measurement.  Equation  2.5 shows t h e r e l a t i o n s h i p  o f t h e observed s o l u t i o n g v a l u e , g , and t h e a x i a l g v a l u e s , g  A  a n d g„ , g  Q  = 1/3  (2g +g„)  (2.5)  x  The a p p e a r a n c e o f t h e e . s . r . s p e c t r u m w i l l  be a f f e c t e d by  hyperfine interaction of the electron spin with the nuclear s p i n o f copper.  T h i s , along w i t h t h e form o f equation  as a f u n c t i o n o f s t e r e o c h e m i s t r y presented  i n Section  2.3.3.2.  f o rcopper(II), w i l l  2.4 be  -24-  2.2.4= VIBRATIONAL SPECTROSCOPY  T h i s s e c t i o n d e a l s " w i t h p r e v i o u s work (Raman and i n f r a r e d spectr-a) on the n e u t r a l l i g a n d s s t u d i e d here (py, 4mepy, 3mepy) i n metal complexes and 6n< the a p p r o p r i a t e hexafluorometallate anions.  2.2.4.1  PYRIDINE, 4-METHYLPYRIDINE, AND  3-METHYLPYRIDINE.  The v i b r a t i o n a l spectrum of p y r i d i n e has been s t u d i e d and u n e q u i v o c a l assignments made (46-47).  The  d i f f e r e n c e s i n the i n f r a r e d spectra o f p y r i d i n e as a f r e e base and o f p y r i d i n e present i n c o o r d i n a t i o n compounds have been s t u d i e d by G i l l and co-workers (48) .  For most  of the bands, t h e r e are minor s h i f t s upon c o o r d i n a t i o n ; however,  f o r t h r e e bands 8a, 6a, and 16b  403 c m  i n the f r e e base) there are s i g n i f i c a n t  -1  to h i g h e r energy '(^2 0 cm ^) .  (1572, 603, and shifts  These authors found few s y s t e m a t i c  changes i n the band p o s i t i o n w i t h changes i n mass, e l e c t r o n e g a t i v i t y , or v a l e n c y o f the c e n t r a l atom or w i t h changes i n the o t h e r l i g a n d s bonded t o the m e t a l . M(py) 2' X  2  w  n  e  r  e  In the compounds  M=Mn,Fe,Co,Ni,Cu, and Zn and X=C1  and Br,,.  however, the 6a and 16b v i b r a t i o n s have been shown to have e n e r g i e s which decrease w i t h the i n c r e a s i n g p o l a r i z i n g power o f the metal i o n .  -25-  Well defined  s p l i t t i n g s have been observed f o r  some o f t h e f u n d a m e n t a l v i b r a t i o n s o f p y r i d i n e .  Since  these fundamental v i b r a t i o n s a r e n o t degenerate v i b r a t i o n s , the  s p l i t t i n g s a r e l i k e l y due t o one o r more o f :  actions site  between m o l e c u l e s i n t h e u n i t c e l l ;  symmetry f o r t h e c o m p l e x ;  (iii)  about the metal-nitrogen and  co-workers  bond.  ( i i ) low l a t t i c e  differences  extent of r o t a t i o n o f the coordinated  pyridine  As p o i n t e d  (48), i t i s d i f f i c u l t  (i) inter-  i n the  molecules  o u t by  Gill  t o r e l a t e these  s p l i t t i n g s t o t h e o v e r a l l c o n f i g u r a t i o n o f t h e complex. Little  and Long  (49) h a v e s t u d i e d  t h e complexes  F e ( p y ) X„ w h e r e X=C1, B r , I , NCO, NCS, a n d NCSe a n d x=2 or  4.  They have n o t e d l a r g e  pyridine* base.  shifts  f o r f i v e bands o f  '8a, 1, 1 1 , 6 a , a n d 16b, c o m p a r e d t o t h e f r e e  They b e l i e v e t h a t t h e i n c r e a s e  i s a result of  pyridine ring/pyridine ring interactions i n the tetrakis( p y r i d i n e ) complexes and p y r i d i n e  ring/bridging  i n t e r a c t i o n s i n t h e b i s ( p y r i d i n e ) complexes. t h a t each o f t h e normal v i b r a t i o n s t o move t h e p y r i d i n e and  v i b r a t i o n a l modes i n c r e a s e pyridine molecules.  state tend  o f t h e complex  energy because t h e  the s t e r i c i n t e r a c t i o n of adjacent  These a u t h o r s r e p o r t  working on a normal coordinate ideas  They  ( e x c e p t 11) w i l l  towards the center  t h e s e bands t h e n s h i f t t o h i g h e r  ligand(X)  that  they are  a n a l y s i s t o v e r i f y these  b u t t h i s work had n o t appeared i n t h e l i t e r a t u r e  when t h i s t h e s i s was w r i t t e n .  The  s p e c t r a o f c o o r d i n a t i o n compounds,  containing coordinated.pyridine bands a t  1572,  603,  and  These bands, 8a, 6a, and  only, should not show  403  16b,  cm"  1  i n . the i n f r a r e d . r e g i o n .  u n l i k e t h e 1 and  11 bands,  are w e l l s e p a r a t e d from o t h e r bands and thus p r o v i d e test for pyridine  a good  coordination.  Goodgame and  Hayward have s t u d i e d t h e e f f e c t o f  c o o r d i n a t i o n t o m e t a l i o n s on the v i b r a t i o n s o f 4-methylp y r i d i n e (50) .  As i n the s t u d i e s on p y r i d i n e , most o f  the  bands o b s e r v e d i n the f r e e base spectrum appear i n the spectrum o f the c o o r d i n a t e d random s h i f t s i n energy. significant shift; 997, The  800,  and  515  base w i t h minor and  There are f i v e bands w h i c h undergo  8a, 9a, 1, 10b+12, and cm  1  good e v i d e n c e  l i g a n d s i n a complex are  A g a i n , some minor s p l i t t i n g may  to i n e g u i v a l e n t 4-methylpyridine  be observed  ligands.  S t u d i e s of the e f f e c t of c o o r d i n a t i o n on v i b r a t i o n s of 3-methylpyridine literature.  1224,  r e s p e c t i v e l y i n the f r e e base.  t h a t a l l the 4 - m e t h y l p y r i d i n e  due  6a a t 1608,  absence o f t h e s e f r e e base bands p r o v i d e s  coordinated.  generally  the  have not been r e p o r t e d  In our work, t h e 3 - m e t h y l p y r i d i n e  i n the  bands i n  t h e i n f r a r e d s p e c t r a o f the compounds w i l l be compared t o the f r e e base and the s h i f t s  some attempt w i l l be made t o c o r r e l a t e  (see Appendix. 1, T a b l e Al-3)..  -27-  2.2.4.2  HEXAFLUOROPHOSPHATE AND HEXAFLUOROARSENATE  T h e r e a r e many h e x a f l u o r o - m e t a l l a t e  species,  M F , , known (where n = - 3 , - 2 , - 1 , 0 d e p e n d i n g o n M a n d i t s n  oxidation state)  ( 5 1 ) . The g r o u p  theory  and a n a l y s i s o f t h e  v i b r a t i o n a l modes o f t h e h e x a f l u o r o m e t a l l a t e m o i e t y i n octahedral  symmetry r e q u i r e s t h a t t h e y  vibrations; and  2  T  ( i n f r a r e d a c t i v e ) and an ^ f  ' '  A  s  l u  shows t h e b a n d p o s i t i o n s a n d a s s i g n -  hexafluoroarsenate anions  s p e c t r a o f some  salts.  hexafluorophosphate  A s w o u l d b e e x p e c t e d when  p o s s e s s 0^ s y m m e t r y , t h r e e b a n d s a r e o b s e r v e d  i n t h e Raman s p e c t r a a n d two b a n d s i n t h e i n f r a r e d . p o s i t i o n o f t h e ^^(^2^ a t 402 c m  - 1  for PFg  -  v  l  k  r  a  tion  The  has been c a l c u l a t e d ;  (7) a n d a t 228 c m  I f t h e EF ~ a n i o n b  - 1  f o r AsFg" ( 8 ) .  has a symmetry l o w e r  a p p e a r a n c e o f t h e Raman a n d i n f r a r e d Table  2g'  ( n e i t h e r i n f r a r e d n o r Raman a c t i v e ) .  ments i n t h e v i b r a t i o n a l  these  T  ( a l l t h r e e Raman a c t i v e ) a n d a T„ 2u  Table I I - l  and  a  g  a n Eg v i b r a t i o n  vibration  have s i x fundamental  t h a n 0, n  the  s p e c t r a may c h a n g e .  }i'II-2 shows t h e c o r r e l a t i o n f o r t h e E F g (0^) v i b r a t i o n s  i n some l o w e r  symmetries.  T h e i r Raman a n d / o r  infrared  a c t i v i t i e s are also indicated(55). One o b j e c t i v e o f .the c u r r e n t w o r k i s t o . c o r r e l a t e the observed anion  infrared  "spectra w i t h t h e anion  m e n t s i n t h e compounds s t u d i e d .  environ-  Q u e s t i o n s t h a t we h a v e  TABLE I I - 1 VIBRATIONAL SPECTRA OF SOME M(EFg)  INFRARED REFERENCE  COMPOUND  ' V lu> T  (E=P, A s ) SALTS  RAMAN  ( a )  V lu> T  w  w  580 (2)  477 (4)  830s  558m  751(10)  ( b )  837s  559s  767(10)  580 (3)  475 (5)  ( C )  830s  565s 562s  748 (10)  580 ( .4)  476 (.1)  (52)  698s  382s  692  580  375  CsAsFg  (7)  699s  392m  685(10)  576 (2.3)  372 (2.6)  AsCl AsFg  (51)  706  402 389  682  583  372  KPF, 6  (7)  NaPFg  (53)  NH.PF, 4 6  (54)  KAsFg  4  (a) numbers i n b r a c k e t s i n d i c a t e r e l a t i v e (b)  s p e c t r u m a t 25°C  (c) s p e c t r u m a t 298 K  intensity  TABLE 11-2 CORRELATION OF E F " ( O ) VIBRATIONS g  D  l u  (  I  *  )  2u  A  + A (I,R) 1  ( I )  -> E  +E ( I ) u  I N SOME LOWER SYMMETRIES  2v  ^ °3  4v  + 4h  °h T  h  (I,R)  -A (I)  A  2  ( I ,R)  1  •> B ( I , R )  E (I,R)  1  B (I,R) 2  A  l g  (R)  E (R) g  T  2 g  (R)  A  l g  (R)  -> A ( I , R )  + A (R)  + A  l g  (R)  -> A ( I , R )  -> E ( I , R )  + B  l g  (R)  •+ B ( R )  + B  2 g  (R)  -  *  g  E  1  1  B (R) 2  (I,R)  ( I ,R)  1  A-^ ( I , R ) -> A ( R ) 2  1  + E  ( R )  -* A  1  -> A _(R)  -> A^ ( I , R)  -> E  -> B ( I , R )  ]  (I,R)  1  -»• B ( I , R ) 2  T  2u (  }  ^ 2u B  (  )  -»-B (R)  ->A (R)  ->A (R)  ->E (I.,R)  ""E ( I , R )  -*B (I R)  1  1  2  1  ^B  (I)  infrared active,  (R) Raman a c t i v e ,  (-) i n f r a r e d  a n d Raman  2  f  (I,R)  -30-  asked  include:  anion  i s i n low s i t e  spectrum a  when t h e  metal  of  "What  ion?";  "What  i s perturbed  " I n any o f t h e s e  spectrum  when t h e  i s the typical  by t h e presence o f  cases,  i s there  splitting  vibrations, activation of formally  (O ) v i b r a t i o n s , o r s i g n i f i c a n t  shifts  h  position?"; anion  symmetry?";  anion  the degenerate  bidden  i s the typical  " I fthere  t o a metal,  are cases  what  for-  i n band  of coordination  of the  i s the infrared criterion f o r  coordination?".  2.2.5  X-RAY  The of ;  X-ray  standard  historical  textbooks symbols  their  national  Tables  meaning  f o r X-ray  with  employed  methods  The m o l e c u l a r  used  as given  i n a number o f The  crystal-  i n this  thesis  i n the "Inter-  Crystallography" (59).  are described  semi-automated  ment.  and nomenclature  methods  determinations  are dealt  and e s t a b l i s h e d p r i n c i p l e s  (5.6-58. f o r e x a m p l e ) ..  conventional  The  the  development  crystallography  lographic have  CRYSTALLOGRAPHY  i n the i n i t i a l i n Section  of reflection  structures  by  the use by the Patterson  as  described  were  function  i n the appropriate  part  space  group.,  6.3.5, a l o n g  with  i n t e n s i t y measure-  determined  either  o r by d i r e c t of Section  methods  6.5.  -31-  2.3  ELECTRONIC STRUCTURE AND STEREOCHEMISTRY  This section deals with the c o r r e l a t i o n of the observable  magnetic and s p e c t r a l p r o p e r t i e s o f c o b a l t ( I I ) ,  nickel(II),  and c o p p e r ( I I )  stereochemistry•of the metal i o n . for  c o o r d i n a t i o n compounds w i t h t h e  t h e f i r s t c o o r d i n a t i o n sphere about  The t h r e e d o m i n a n t s o l i d  these metal(II)  may n o t s t r i c t l y  stereochemistries  ions a r e square p l a n a r ( D ^ ^ ) ,  h e d r a l ( T ^ ) , and o c t a h e d r a l Although,  state  tetra-  (0^).  t h e microsymmetry about t h e metal i o n  be D ^ ,  T^, o r 0^, o f t e n t h e o b s e r v a b l e  p r o p e r t i e s may be u n d e r s t o o d b y t h e a n a l y s i s u s i n g one o f these formal a NiN^^ D^  symmetries.  F o r example, i n a complex w i t h  chromophore t h e h i g h e s t microsymmetry p o s s i b l e i s  b u t i f t h e e l e c t r o n i c s p e c t r u m a n d t h e m a g n e t i c moment  d i f f e r o n l y m a r g i n a l l y from t h a t e x p e c t e d and seen f o r nickel(II)  complexes w i t h 0  c a n be a s s i g n e d  h  symmetry  (eg. NiNg) , t h e s t r u c t u r e  t o an " o c t a h e d r a l " complex o f n i c k e l ( I I ) .  same a p p l i e s t o t e t r a h e d r a l a n d s q u a r e p l a n a r The will  complexes.  c o b a l t ( I I ) , n i c k e l ( I I ) , and c o p p e r ( I I )  be d i s c u s s e d  i n order.  The  ions  The f r e e i o n s t a t e s a n d t h e  correlation with the ligand f i e l d  states i n octahedral,  t e t r a g o n a l l y d i s t o r t e d o c t a h e d r a l , and t e t r a h e d r a l c o o r d i n a t i o n geometry w i l l The  be d i s c u s s e d  f o r c o b a l t ( I I ) and n i c k e l ( I I ) .  square p l a n a r c o o r d i n a t i o n geometry o f n i c k e l ( I I )  -32-  and  the tetragonally  copper(II) For  will  be  "octahedral"  only  the high  2.3.1  distorted  discussed  and  spin  coordination  i n terms  "tetrahedral"  systems w i l l  COBALT(II)  geometry o f  of d orbital  coordination  be  splittings.  geometries,  covered.  (60)  C o b a l t (II)  has seven  d electrons  i n -its- v a l e n c e  .shell.  4 In  the gaseous  absence same and  free  of spin-orbit  spin 172  (  g  becomes  (  g  )  a  4  T  lg*  expect  )  2  ligand  F,  a higher of B  Q  i n the  P term  and X  Q  of the  (31) a r e 9 7 1  o f an  octahedral  f i e l d , the free i o n ground term i s , a n d T4 t e r m s a n d t h e P4  g  )  1  (  g  )  The c o r r e l a t i o n field  of the free i o n  states-is  COBALT(II)  an o c t a h e d r a l  The t h r e e  i s  4  (  term.  OCTAHEDRAL  In T  4  a n d weak  2.3.1.1  4  1  ligand , T4  state  In the presence  -  2  with  The v a l u e s  cm "'", r e s p e c t i v e l y .  4  is  coupling,  multiplicity.  or tetrahedral split into A  states  i o n , the ground  shown  - ELECTRONIC  ligand  spin-allowed  to. see i n t h e e l e c t r o n i c  field,  SPECTRAL  the ground  transitions spectra  i n Figure  one  PROPERTIES  term  would  are to the  2.1  -34-  T  4  , A „ , and T , (P) e x c i t e d s t a t e s . 2g' 2g' lg 4  Table II-3 shows  4  0  the dependence o f the t r a n s i t i o n e n e r g i e s as a f u n c t i o n of Dq and B o n l y two 4  T  In p r a c t i c e ,  r e l a t i v e l y s t r o n g bands are observed  (F)* T 4  l g  (from r e f . 32 p. 181).  2 g  (v ) 1  and  4  T  (F)+ T 4  l g  l g  ( P ) (v >; 3  the  usually  due 4  T  to - A 4  l g  2 g  (v,)  t r a n s i t i o n i s much weaker because i t i s f o r m a l l y a  two 5 2 e l e c t r o n t r a n s i t i o n (strong f i e l d c o n f i g u r a t i o n (t ) (e ) g g 3 4 • . -*(t„ ) (e ) ). Given the two observed t r a n s i t i o n e n e r g i e s 2g g p  v^'and v^, v a l u e s of Dq and B can be o b t a i n e d by i n t o the e x p r e s s i o n s of Table I I - 3 . v-^, v , and  substitution  C a l c u l a t e d values of  can then be o b t a i n e d and compared w i t h the  2  observed  t r a n s i t i o n energies.  2.3.1.2  OCTAHEDRAL COBALT(II)-MAGNETIC PROPERTIES 4 The ground term,  T  ]_g' p o s s e s s e s both s p i n  e l e c t r o n s , S=3/2) and o r b i t a l The value o f V ff e  expected  (Lrl)  (3 unpaired  angular momentum.  f o r an o c t a h e d r a l c o b a l t ( I I )  complex would be h i g h e r than the s p i n o n l y moment (3.87 and be expected t o be temperature p r o p e r t i e s observed  for  dependent.  The magnetic  o c t a h e d r a l c o b a l t ( I I ) complexes-  are very complex and F i g g i s  1  f o u r parameter model  (61)  has been used t o e x p l a i n these magnetic p r o p e r t i e s . 4T ^  g  B.M.)  The model c o n s i d e r s the energy l e v e l s o f the . ground s t a t e under the simultaneous perturbations  TABLE I I - 3 SPIN ALLOWED TRANSITION ENERGY OR TETRAHEDRAL  = ( T  T  ±  (  g  )  OCTAHEDRAL  GROUND TERMS *  5Dq-7.5B+^(225B +100Dq +180DqB) ** 2  n  2  n  EXPRESSIONS FOR  1 ( g )  (F)->  n  A  2 g  2  )  = 15Dq-7.5B+35 (225B +100Dq +180DqB) 2  ( T n  3  =  (F)* T n  1 ( g )  1 ( g  )  ( P  »»  (225B +100Dq +180DqB) 2  2  * n = 2S+1, n=4  2  2  f o r octahedral  nickel(II)  cobalt(II)  a n d n= 3 f o r t e t r a h e d r a l  -36-  of  low  The A;  symmetry  four  parameters  Figure  mined  ligand  fields  used  and  i n the model  2.2  represents  the  "A"  i s derived  from  from  the  spin-orbit  electronic  a r e A,k', X,  relationships the  Dg  spectrum.  coupling.  and  and  between  them.  B values  deter-  I t i s a. m e a s u r e  of  the  4 interaction  of  the ground  state  T  ig(F)  a  n  d  t  n  excited  e  4 state  T^g(P);  symmetry to  1.0  how  they  (T^^).  (strong  "A"  interact  "A"  varies  field  because from  limit).  they have  1.5  (weak  Equations  similar  field  2.6  limit)  and  2.7  may b e calculated: c=1.5-(7.5Dq/B-{25+45B/Dq+225/4 ( B / D q ) } A=(1.5-c )/(l+c ) 2  2  show  . . . (2.6) ...(2.7)  3 2  2  4 A  i s the  splitting  of  the  T  i g state  in  sym-  4 metry  and  lower  i n energy  from  the  curve.  i s positive  f i tof  reduction  used  in and  k  Kelvin k').  values  T  A  1  the  +  E  4 g^ 4h^ D  experimental data  spin-orbit  i n the  fitting  singlet  parameter  a  n  to  s  and  is  2  """  d  the  procedure,  ( A g) d  e  r  i  v  e  d  theoretical  i s treated k'  i s the  as  a  orbital  factor. The  (where  the o r b i t a l  4 4 ( ig(°j ^ 2g  X i s the  variable  when  experimental data are plotted,  i s the Boltzmann ), and  fitted  Computer  o f kT/X,  v,  c o n s t a n t and  to a  and  k'  curve  V ^f Q  are available  vs.  e  i s the  theoretical  generated values of A,  T  V ff  for  kT/X  temperature (A,v=(A/X), different  i n the  literature(61).  -37-  CUBIC FIELD  FIG  TETRAGONAL DISTORTION (a) 2.2  4  T  n  lg  TERM  a+b  SPIN-ORBIT COUPLING (b)  UNDER T H E S I M U L T A N E O U S  SPIN-ORBIT  C O U P L I N G AND  LOW  CUBIC FIELD  PERTURBATIONS  SYMMETRY.  OF  -38-  The  approximations  (i)  the low  i n h e r e n t i n t h i s model are  symmetry l i g a n d  are of a x i a l r a t h e r than of lower (ii)  the substances  (iii) field  field  (iv)  excited  configuration  components  symmetry.  are magnetically d i l u t e ,  the magnitude o f the low  i s independent of  symmetry  ligand  temperature. terms are not important  ( i . e . no  interaction).  F i g g i s e t a l . have  also  used t h i s type o f model t o  the magnetic behavior of other high spin o r b i t a l l y ground s t a t e s . available ground  (61):  The  degenerate  r e s u l t s of these i n v e s t i g a t i o n s  i n the l i t e r a t u r e f o r T 2  2 g  (62),  5  T  2 g  explain  (63),  are T (64)  3  ; L  states.  2.3.1.3  TETRAHEDRAL C O B A L T ( I I ) - ELECTRONIC SPECTRAL PROPERTIES  In a t e t r a h e d r a l 4  is 4  A .  The  2  T , 2  4T  1  ligand  field,  the ground  .  three s p i n allowed t r a n s i t i o n s from  ( F ) , and  4 T-  s h o u l d be o b s e r v e d .  L  (P)  (v^,  v , 2  and  v^,  4  A  term to  2  respectively)  I n p r a c t i c e , h o w e v e r , v-^ i s o f t e n  n o t r e p o r t e d because i t i s a t low energy i n t h e  near-  i n f r a r e d o r i n f r a r e d r e g i o n s , out of the range  covered  by t h e e x p e r i m e n t . energies  The  expressions  f o r the t r a n s i t i o n  f o r the three spin-allowed t r a n s i t i o n s are  given  -39-  in  Table  the  II-4.  The  quadratic  values  equations  of  Dq  and  B  can  be  calculated  from  (65 ) :  340Dq -18 (V^+v^-Dq+VjV-^O  ....(2.8)  2  B=(v +v -30Dq)/15 2  2.3.1.4  (2.9)  3  TETRAHEDRAL  COBALT(II)-MAGNETIC  PROPERTIES  4 The  A  ground  2  momentum  associated  expected  to  be  independent. be. d i r e c t l y (9^0) to  are  the  with  ligand  i t .  The  magnetic  T^  to  the  field.  excited  to  The  to: u - =y  as  T  (S 3/2)  value  a  and  reciprocal of  but  deviations  of  result  the  angular  the  temperature  x  should  m  from  this  from  spin-orbit  the  coupling  moment  is  (l-4A/10Dq)  f  behavior  components  moment  magnetic  be  be  symmetry  e f f e c t s of  no  moment w o u l d  the  deviation the  but  =  i n d i c a t i n g low  indicates  states;  spin-only  symmetry,  observed  value  according  spin  proportional  often  spin-only  has  with  close In  term  modified  (2.10)  or y  X  is  the  (varies factor  e f f  =  U  s . o . (1-4 ( k ^ A ^ l O D q )  spin-orbit coupling depending  and  X  Q  on  i s the  the  parameter  complex),  free-ion  (2.11)  k  1  for  i s the  the  complex  orbital  spin-orbit coupling  reduction constant.  TABLE I I - 4 SPIN-ALLOWED  T R A N S I T I O N ENERGY  OR  v  l  ( n A  2(g)"  =  V  n A  n T  TETRAHEDRAL  2(g)  R  A , 2 0  EXPRESSIONS N  GROUND TERMS  (g)  *  )  n T  l(g)  ( F ) )  = 7.5B+15Dq-%(225B +100Dq -180DqB) 2  n  OCTAHEDRAL  lODq  2(gr  V W  FOR  n  T  l(g)  (  P  )  2  2  )  = 7.5B+15Dq+i5(225B +100Dq -180DqB) 2  2  ^  2  o  I  *n=2S+l,  n=4  for tetrahedral  nickel(II)  cobalt(II)  a n d n=3  for  octahedral  -41-  2.3.2  NICKEL(II)  (66)  Nickel(II) In  t h e gaseous o  energy "  P.  r>  The v a l u e s  3  3  d  the free  T ~ , ,, a n d 2(g)  J  electrons  the ground  of B  o  state  i n i t svalence 3  i s  F with  o f an o c t a h e d r a l  i o n ground  o  T,, terms 1(g)  term  and the  N  a  X ^ a r e 1 0 8 0 .and 172 o  and  In the presence  field,  A ~ , ., 2(g)  eight  free-ion,  respectively. ligand  has  i s split 3 P term  or  cm  shell  higher -1  (31)  tetrahedral  into becomes  a  T-, , > t e r m . The c o r r e l a t i o n o f t h e f r e e i o n s t a t e s and t h e 1 (g) w e a k - f i e l d l i g a n d f i e l d s t a t e s f o r two s t e r e o c h e m i s t r i e s are shown  i n Figure The  nickel(II) distorted of  electronic  in ligand  t h e compounds  tetrahedral considered  2.3. spectral  octahedral, field  square  planar,  environments w i l l  i n this  environment, here.  and magnetic  study  revealed  so t h i s  be  properties  and  tetragonally  recounted.  nickel(II)  situation will  of  in a  h o t be  None  ' t o  TETRAHEDRAL  OCTAHEDRAL  C/B FOR TETRAHEDRAL =4.42 C/B FOR OCTAHEDRAL =4.7 2  -43-  2.3.2.1  OCTAHEDRAL AND  TETRAGONALLY  NICKEL(II)-MAGNETIC AND  The  DISTORTED OCTAHEDRAL  SPECTRAL PROPERTIES  g r o u n d t e r m o f n i c k e l ( I I ) i n an  octahedral  3 field Dq  is  A  2g*  T  ^  e  t  r  a  n  s  i  t  l  o  energies  n  and B a r e shown i n T a b l e I I - 4 .  as f u n c t i o n s  The v a l u e s o f Dq a n d  B c a n be c a l c u l a t e d a s i n t h e c o b a l t ( I I ) or  by u s i n g  and of  the  tetrahedral  2  cussed the  ( 6 7 ) . We p r e f e r  tetrahedral  ( f r e e o f b a c k g r o u n d ) c a n be  cobalt(II)  with our treatment o f  complexes.  3 The m a g n e t i c b e h a v i o r o f t h e A . t e r m i s s i m i l a r of the A term o f t e t r a h e d r a l c o b a l t ( I I ) except 2q  4  9  *2  for  t h e m a g n i t u d e o f t h e moment.  two  unpaired  the  s i g n i f i c a n c e of the  electrons  The s p i n - o n l y  i s 2.83 B.M.  t h e same as r e c o u n t e d  The t . i . p .  Weiss c o n s t a n t  c o r r e l a t i o n of the variance are  dis-  t o u s e t h e f o r m e r method b e c a u s e  d i f f u s e r e f l e c t a n c e bands  to that  values  The r e l a t i v e m e r i t s o f b o t h methods h a v e b e e n  u s e d and a l s o b e c a u s e i t i s c o n s i s t e n t the  case  e n e r g y a s lODq, c a l c u l a t i n g B f r o m  t h e n comparing t h e c a l c u l a t e d and e x p e r i m e n t a l v .  of  of U f£ e  i n section  value f o r correction,  ( 8 ) , and t h e  f r o m .the s p i n - o n l y  value  2.3.1.4.  T e t r a g o n a l d i s t o r t i o n a r i s i n g from t h e d e c r e a s e o f the  ligand  field  strength  along the z axis  can i n octahedral  -44-  nickel(II) to  complexes  be s p l i t  cause the o r b i t a l l y degenerate T  terms  i n t o two c o m p o n e n t s g i v i n g a t o t a l o f s i x s p i n -  allowed electronic t r a n s i t i o n s . nickel(II)  i n 0^ and  The  symmetries  c o r r e l a t i o n diagram f o r i s given i n Figure  2.4.  To a f i r s t a p p r o x i m a t i o n , t h e e n e r g i e s o f t h e s e l o w e r symmetry  (D^)  E( B 3  2 g  states  )=10Dq  3  (E( B ^ ) = 0 ) a r e g i v e n b e l o w : g  x y  E( E )=10Dq -(35/4)Dt 3  g  E( A  x y  )=10Dq +12B-4Ds-5Dt 2g' ^xy  3  a  E( E )-10Dq +12B+2Ds-25/4Dt g ^xy 3  b  E ( E )=20Dq -Ds-10Dt+3B g xy 3  C  M  Dq  i s the e q u a t o r i a l p l a n e l i g a n d f i e l d parameter, B has xy i t s u s u a l m e a n i n g , and Ds and Dt a r e t e t r a g o n a l p a r a m e t e r s . The is  3  s p l i t t i n g of the  T  2 g ^  (35/4) Dt and o f t h e  e q u a l t o 4/7(Dq  -Dq  l g  term  (0 )  i n  t  E  Dt i s field  z  Ds i s e q u a l t o  ( P y ~ P ) w h e r e Cp c  c  X  z  (33) and t h e s u b s c r i p t s  e q u a t o r i a l p l a n e and a x i a l s i t u a t i o n s . The i n c l u s i o n o f c o n f i g u r a t i o n 3  l o w e r symmetry  e  i s the a x i a l ligand  z  order r a d i a l parameter  the  n  t e r m i s 6Ds-(5/4) Dt.  h  ) w h e r e Dq  xy parameter.  3 r r  ^°h^  i s the  second  indicate  interaction  between  t e r m s i s a f u r t h e r p e r t u r b a t i o n w h i c h c a n be c o n s i d e r e d g  The d i a g o n a l i z a t i o n o f t h e c o n f i g u r a t i o n i n t e r a c t i o n m a t r i x with  3  E , g a  3  E , and g b  3  E  C  as t h e b a s i s g 3  from the t r a n s i t i o n energy o f of  determined xy  3  ]_g"*" 2 g ^  B  Ds, D t , a n d B more t h e o r e t i c a l l y  order).  (Dq' i s Dq  B  should give values  correct  T h i s d e t e r m i n a n t i s g i v e n as  (i.e.  follows:  to  second  -45-  FIG.  2.4  EFFECT  ON  NICKEL(II)  o  E L E C T R O N I C ENERGY IN A X I A L L Y  LEVELS  OF  ELONGATED*(D) 4n  OCTAHEDRAL SYMMETRY  -46-  10Dq'-35Dt-E  (3^/4) (4Ds+5Dt)  (3 /4)(4Ds+5Dt) %  0  lODq'+Ds-(25/4)Dt+12B-E 6B  0  A computer  6B 20Dq'-Ds-10Dt+3B-E  program which s o l v e s t h i s d e t e r m i n a n t , g i v e n  Dq , E ( B , -> E ) , E ( B , + E ) , and E ( B + E ° ) , has ^xy lg g lg g lg g  been  w r i t t e n b y F . G . H e r r i n g and J.Mayo o f t h i s D e p a r t m e n t  and  3  3  a  3  3  b  3  3  1  been used t o c a l c u l a t e the t e t r a g o n a l parameters d e r i v e d a part of this  has as  work. 3  The m a g n e t i c p r o p e r t i e s a s s o c i a t e d w i t h  the 3  ground term are s i m i l a r t o those a s s o c i a t e d w i t h the term of octahedral  nickel(II).  a r e u s u a l l y g r e a t e r t h a n 3.0 constants 2.3.2.2  A^^  The moments o f t h e s e compounds  B.M.  and n o n - z e r o C u r i e - W e i s s  are expected. SQUARE PLANAR N I C K E L ( I I ) - M A G N E T I C  AND  ELECTRONIC  SPECTRAL.PROPERTIES  If nickel(II)  i s s u r r o u n d e d by f o u r s t r o n g l y b o u n d  l i g a n d s w i t h t h e m e t a l a n d t h e l i g a n d d o n o r atoms the  stereochemistry  i s termed square p l a n a r .  co-planar,  The c h a r a c t e r i s t -  i c e l e c t r o n i c s p e c t r a l and m a g n e t i c p r o p e r t i e s o f s q u a r e planar nickel(II) sometimes  complexes  a r e : ( i ) an one b a n d  w i t h a weak b a n d a t l o w e r e n e r g y ; and  e f f e c t i v e m a g n e t i c moment o f z e r o ( o r s o m e t i m e s >0 due t o r e s i d u a l p a r a m a g n e t i s m ) .  spectrum, (ii)an slightly  -47-  The  e l e c t r o n i c s t r u c t u r e of square planar  has been a f i e l d b e c a u s e a l l d-d 2.5  o f i n t e r e s t s i n c e t h e e a r l y 1960's  paired three  (68)  t r a n s i t i o n s p o s s i b l e are not observed.  shows t h e d o r b i t a l s p l i t t i n g w i t h i n c r e a s i n g  distortion  complexes  (axial elongation). A  ((e )  1  4  tetragonal  symmetry o f t h e  g  (a  l g  )  2  spin  2 0 ( 2g^ ^ l g ^ ^ w i t h 1 4 2 possible excited electronic states: A g((eg) ( ig) ~ ground s t a t e i s  1  The  Figure  b  b  a  2  (b„ ) ( b ) ) ; B , ( (e ) ( a ) ( b ) ( b , ) ) ; and "'"E (e ) 2g lg lg g lg 2g' lg g g 2 2 1 1  1  2  1  n  (a^g)  1  2  (b2g)  ( ^ i ) )•  T h r e e d-d  g  1  3  0  n  t r a n s i t i o n s are possible  o n l y one, o r p e r h a p s two t r a n s i t i o n s , a r e o b s e r v e d . sibility  e x i s t s t h a t t h e two o r t h r e e  a n d -^g) a  due  a  r  e  sets  pos-  (e , b„  ,  c l o s e i n e n e r g y and t h e o b s e r v e d s p e c t r u m i s  t o two o r t h r e e  2.3.3  orbital  The  but  o f t h e s e t r a n s i t i o n s i n t h e band e n v e l o p e (6.8.)  COPPER(II)  Copper ( I I ) has a d In the f r e e - i o n , t h i s gives  q  valence electron configuration. 2  rise to a  D ground s t a t e which  i n the presence of a regular cubic l i g a n d f i e l d s p l i t s i n t o 2 2 -1 T > . and E, > t e r m s . X f o r t h e f r e e - i o n i s 830 cm 2(g) (g) 0  Regular cubic of J a h n - T e l l e r  f i e l d s are not obtained distortions.  t h a t any n o n - l i n e a r  The J a h n - T e l l e r  because  theorem(69)  states  m o l e c u l a r system i n a degenerate e l e c t r o n i c  s t a t e w i l l be u n s t a b l e to s p l i t  f o r copper(II)  and w i l l  the degenerate s t a t e .  undergo This  some k i n d o f  distortion  i s , perhaps, best understood  -48-  CUBIC SYMMETRY  D  SYMMETRY 4n • (AXIAL ELONGATION) INCREASING TETRAGONAL DISTORTION  FIG.  2. 5  EFFECT REAL  OF  INCREASING  "d" ORBITALS.  TETRAGONAL  DISTORTION  ON T H E  -49-  i n terms of the d o r b i t a l s p l i t t i n g and the "hole" formalism. F i g u r e 2.5 ion,  cubic  shows the d o r b i t a l s p l i t t i n g f o r the f r e e  (0^) f i e l d ,  and i n c r e a s i n g  tetragonal d i s t o r t i o n .  C o n s i d e r i n g the c u b i c f i e l d  copper(II) has a "hole" i n the e d  (axial elongation)  g  case  s e t , the h o l e can be i n  2 2 or d 2 and by d e f i n i t i o n i s a degenerate s t a t e . x -y :z J  3  i s e n e r g e t i c a l l y f a v o r a b l e f o r copper (II) d i s t o r t i o n such t h a t the d 2 _ 2 and d 2 x  i n energy the  y  It  to undergo a  are no l o n g e r degenerate  z  (the lowering i n the energy of the system i s 1/2  s e p a r a t i o n o f the d 2 2 (b, ) and d 2(a, ) o r b i t a l s . ^ x -y lg z lg  There i s no reason f o r one type o f d i s t o r t i o n a c c o r d i n g t o t h i s argument, i . e . a x i a l e l o n g a t i o n vs.  a x i a l compression  (d 2 lower i n energy) z  (d 2_ 2, lower i n energy), to be favored x y  over the o t h e r but most " o c t a h e d r a l " complexes have the former type o f d i s t o r t i o n  o f copper (II)  (7 0 ) .  The magnetic and e l e c t r o n i c s p e c t r a l p r o p e r t i e s of  c o p p e r ( I I ) complexes  chemistry f o r CuN^  have been c o r r e l a t e d w i t h s t e r e o -  g chromophores by Hathaway  (71).  Magnetic  s u s c e p t i b i l i t y measurements are g e n e r a l l y . n o t u s e f u l f o r characteri z a t i o n except t o d i s t i n g u i s h between m a g n e t i c a l l y d i l u t e and concentrated copper (II) B.M.  species.  A magnetic moment of 1.8-2.0  which i s e s s e n t i a l l y temperature independent  m a g n e t i c a l l y d i l u t e c o p p e r , i . e . a mononuclear E l e c t r o n i c and e . s . r .  indicates  complex.  ( s e c t i o n 2.2.3) spectroscopy are more  u s e f u l f o r s t r u c t u r a l assignment and a r e d i s c u s s e d i n more d e t a i l here.  -50-  2.3.3.1  COPPER(II)-ELECTRONIC  Considering ligand  d->d  transition  very  few  compounds  than  two  bands.  clearly a  low  of  a  yield  energy  band  of  of  band  Cu^Oy  phore  CuN  g  the  the  spectra,  yield  spectra  complexes  In  pos-  practice of  no  more  involving  show a m a i n  with  band  possible  four  indication  one  of  two band  resolved.  indication  Hathaway's  of  the  correlation  gravity of predicted  present  g  (71). of  (4-x+y-6)  (72),  Other  splitting  This  also.  overlap  and  main  diagram  of  the  in  scales  i t i s hard  some  as  for  systems  f o r the to  the  serves  stereochemistry But  of  absorption  stereochemistry  the  f o r example)  the  diagram  chromo-  distinguish  stereochemistries.  electronic  molecular  any  partially  f o r assignment  Section of  give  only  and  stereochemistry  between  observed.  shoulder  center  chromophores  (CuN^. a n d  in principle  be  many  shows  CuN _ , 4  but  f o r the  (71).  2.6  the  u s e f u l guide  should  PROPERTIES  splittings  are,  copper (II)  only  copper(II)  chromophore, a  of  bands,  Figure the  there  which  frequency  second  orbital  Some c o m p l e x e s  resolved  complexes or  d  stereochemistries,  sible  with  the  SPECTRAL  4.3.2.1 spectra,  of  this  derived  structure determinations for very  thesis describes from and  single  crystal  polarized  tetragonally distorted  the  details X-ray  electronic  octahedral  complexes.  CIS-DISTORTED  OCTAHEDRAL  TRIGONAL PYRAMIDAL  SQUARE  TRIGONAL  OCTAHEDRAL  RESTRICTED  CuN  CuNg  CuN  BASED PYRAMIDAL  FIG.  5  RHOMBIC O C T A H E D R A L  CuNg  g  TETRAGONAL  OCTAHEDRAL  CuNg  COMPRESSED  10  CuN  11  13  2.6  C O R R E L A T I O N OF  14 ENERGY  TETRAGONAL  TETRAHEDRAL  (kK= 10  BAND MAXIMA  AND  ^  .cm  CuN  OCTAHEDRAL  CuNg  SQUARE  COPLANAR  CuN  4  )  STEREOCHEMISTRY FOR  CuN _g 4  CHROMOPHORES  4  -52-  2.3.3.2  COPPER(II)-ELECTRON  As of  a  of  the  has  mentioned  copper(II)  attempted  about  to  yields  axial  gonally  and  The  forms  line  shape w i t h  will  only  )  octahedral  equation  octahedral  2.4  which  copper(II)  g„=  g  ( 1 - (8 X/E ( d 2 _ 2 - d  gi=  g (l-(2X/E(d 2_ 2-d  e  x  e  y  x  y  x y  case  field  where  and  apply  for  tetra-  are:  )))  x z  ,d  y z  (2.12) )))  g„ =  g  5x=  g d-(6X/E(d 2-d  .  e  e  (2.14) z  x y  ,d  y z  ) ))  the  compressed  acts  with  rise  to  the  nuclear  +  ( s = l / 2)  (21+1)  Am =0;  Am  value.  of  (2.15) can  g | ,where g j = (  g  (  apparently,  be  indicates  an  g  octahedron.  spin  in Figure  g  value  The  four  ....(2.13)  compression:  by  each  the  complexes  distinguished  for  stereochemistry  spectra.  tetragonal distortions  rules:  the  ligand  of  trated  characteristic  Hathaway  consider  types  axially  are  spectrum  elongation:  for axial  two  e.s.r.  an  unit.  gn of  2.2.3,  i n that molecular  distorted  (gj. a n d  SPECTROSCOPY  which  We  g  RESONANCE  values  (73).  distorted  axial  yields  correlate  is in a  The  for  ion  copper(II)  copper(II)  i n section  complex  copper(II)  SPIN  spin  of  the  copper(II)  (1=3/2)  of  s t a t e s f o r each  2.7 =1)  where are  the  g  the  shown.  copper  value.  allowed There  d  electron nucleus,  This  transitions are  four  is  intergiving  illus-  (selection  transitions  -53-  FIG.  2. 7  ENERGY  LEVEL  DIAGRAM  FOR S = l / 2  AND  1=3/2  -54-  The nuclear in  spin  axial  interaction  c a n be r e p r e s e n t e d  symmetry  as  H=8(g  H S +g  l (  z  6 i s t h e Bohr  along  each  , , x'y'z  S , , x  Z axis  coupling  x  y  spin ^  y  y  H x  z  'y'z  a t each  constants  spin  and the  H a m i l t o n i a n H (7.4)  B(S L  z +  x  """ * S t  parallel  i e  x +  S L ) y  field  on each  axis,  and A and B a r e t h e  and p e r p e n d i c u l a r The magnitude  moment  to the  and  on t h e i n t e r a c t i o n between  and t h e magnetic  . . (2.16)  y  magnetic  spin  axis,  respectively.  A and B a r e dependent moment  x  i s the electron  z  o f the molecule  magnetic  by t h e s p i n  (H S +H S ) ) + A S I  x  magneton,.  i s the nuclear  hyperfine  of  axis,  the electron  below:  z  where  I  between  sign  the nuclear  of the unpaired  d  electron. It spectrum set  spectrum A  g .  a n d how  Q  symmetry  shows  B i s usually  t h e spectrum.  will  the  e.s.r.  consist  x  very  small  However,  strong  the appearance  gu, g  of a  of this  and A c a n be  and cannot  i f an i s o t r o p i c  B c a n be c a l c u l a t e d  derived  from  be  solution  the value  ( c f . g , e q u a t i o n 2.5) b y u s e o f e q u a t i o n 2 . 1 7 . Q  Q  = 1/3  E.s.r. absorption  axial  2.8  (75) t h a t  gu a n d a s e t o f f o u r  the parameters  i s available,  A  of  Figure  x  from  i n axial  l i n e s around  t h e spectrum.  derived  of  weak  around  situation from  shown b y Sand  of copper(II)  of four  lines  has been  spectrum  (A + 2B)  spectra  spectra. have  (2.17)  are recorded  as t h e f i r s t  The components  different line  (g  shapes  f>  derivatives  and g )  (76).  of the  x  g  x  c a n be  A  I Ul l  JL4H,  H„ HFIG.  2.8  APPEARANCE  OF A X I A L  COPPER(II)  E.S.R.  SPECTRUM  -56-  determined from t h e l a r g e i n f l e c t i o n p o i n t o f t h e spectrum whereas g  )(  has t o be d e t e r m i n e d from t h e H^^.^(maxima o f  the peaks i n t h e f i r s t d e r i v a t i v e spectrum) v a l u e s and the A value  (H^^y  H  A (I+l)^* m  A  n  o  t  n  e  r  method t o d e t e r m i n e g„  i f the i s o t r o p i c s o l u t i o n spectrum i s a v a i l a b l e i s by use o f e q u a t i o n 2:. 5 (page 23).  T h i s i s d e s i r a b l e when the components  o f t h e p e r p e n d i c u l a r spectrum o v e r l a p w i t h the p a r a l l e l spectrum.  -57-  2.4  A P P R O A C H E S TO  When infrared  COMPOUND  a compound  spectrum  for  the presence  and  lattice  I f these  was  obtained.  compound  was  pure,  were  spectra)  consistent basic  the standard  derived  from  these  be  used  metal  results  sensitive  some  stoichiometry  the effects  for different  the different metals.  techniques  test  3.2.2)  reflectance) electronic were  magnetic  insensitive.  susceptibility  f o r paramagnetic  complex.  (section  the  measurements self-  stereochemistry, The  the  information  other  measure-  applicable) field of the  techniques  showed  i n the  c o b a l t ( I I ) sample w o u l d be  (diffuse  that  could on t h e anion.  are  more  F o r example, t h e c h a r a c t e r i z a -  tetrahedral cobalt(II) species  octahedral  elemental  electronic  of the ligand  of  2  the  s t u d i e s were  (along with  of Co(py)g(EFg)  how  of  t o be known.  tion  of  and  s t u d i e s , e t c . where  cases,  2.2.4)  indicated  i o n and t o i n v e s t i g a t e the environment In  a  (section  not present,  of these  measurements  to evaluate  and examined  susceptibility  considered  ments, e . s . r . , X - r a y  ligand  the  r e f l e c t a n c e , and, i f p o s s i b l e ,  I f the results  s t r u c t u r e was  as a powder,  obtained  techniques  and m a g n e t i c  f o r a given  isolated  was  were  I f these  (mull, d i f f u s e  performed.  first  of non-coordinated  analysis  solution  was  o f t h e compound  water.  spectroscopy  CHARACTERIZATION  seen  that  the  predominantly only  by  spectroscopy.  Section  presence  4.2.2.5  the use The  other  illustrates  measurements p r o v i d e  impurities i n a diamagnetic  a  sensitive nickel(II)  -58-  The the data  results and  presented magnetic  next  of  the  our  spectral  appropriate  and  infrared  spectral  (other than  data  presented  are  chapters  will  investigations.  infrared  i n the data  two  due  to  The  bands  section  spectral the  i n Appendices  present  EF 1  g  of  and  electronic the  along data.  anions with The  species) and  discuss  2  spectral will  be  selected complete  and  infrared  magnetic  respectively.  CHAPTER 3  COMPOUNDS CONTAINING NON-COORDINATED  HEXAFLUORO-  PHOSPHATE AND HEXAFLUOROARSENATE  T h i s c h a p t e r d e s c r i b e s and d i s c u s s e s t h e c h a r a c t e r i z a t i o n o f t h o s e compounds w h e r e t h e h e x a f l u o r o p h o s p h a t e o r hexafluoroarsenate anions are present i n the s o l i d l a t t i c e as c o u n t e r i o n s and do n o t d i r e c t l y metal  ions.  state  interact with the  Of i n t e r e s t a r e t h e p r o p e r t i e s a n d s t r u c t u r e s o f  the complex c a t i o n s and t h e n a t u r e o f t h e a n i o n  environment  as e v i d e n c e d by v i b r a t i o n a l  studies.  (infrared) spectral  -60-  3 .1  INTRODUCTION  I n t e r e s t i n forming with f i r s t  a species o f the type  row t r a n s i t i o n m e t a l  c h a r a c t e r i z i n g these  M(py)  2+ g  elements i s i n p r o p e r l y  h i g h l y symmetric s p e c i e s f o r comparison 2+  with other c l a s s i c a l Although  complex c a t i o n s , such as M ( H 0 ) 2  many c o m p l e x e s c o n t a i n i n g c o o r d i n a t e d p y r i d i n e a r e  known, p r e v i o u s w o r k e r s h a v e e x p e r i e n c e d  considerable  f i c u l t y i n o b t a i n i n g complex s p e c i e s , p a r t i c u l a r l y solid  g  dif-  i nthe  s t a t e , where o n l y p y r i d i n e i s c o o r d i n a t e d t o t h e m e t a l .  A v a r i e t y o f r e a s o n s c a n be a d v a n c e d f o r t h i s i n c l u d i n g s o l u t i o n and l a t t i c e e n e r g y e f f e c t s , e n t r o p y f a c t o r s and s t e r i c  and k i n e t i c  factors(17). 2+  By t h e e a r l y 1 9 7 0 ' s , t h e o n l y two M ( p y ) characterized i n the s o l i d (18)  and N i ( p y ) ( P F ) g  g  2  g  species  s t a t e were i n ( F e ( p y ) ) ( F e C 0 ) g  (14).  X-ray s t r u c t u r a l  4  1 3  s t u d i e s on 2+  the  f o r m e r compound showed t h e p r e s e n c e o f t h e F e ( p y )  cationic unit.  The e l e c t r o n i c s p e c t r u m o f t h e l a t t e r  g  compound  was s i m i l a r t o t h e s o l u t i o n s p e c t r u m o f N i (py) (Cl'O.^) i n 4  p y r i d i n e w h i c h had been a s s i g n e d  to a Ni(py)  2  2+ g  species.  2+  The  formation o f the M(py)  suggests  g  species i n these  situations  t h a t a l a r g e w e a k l y b a s i c a n i o n i s needed t o s t a b i l i z e  the l a r g e c a t i o n i n the s o l i d  state.  There has been a v e r y r e c e n t r e p o r t o f t h e X-ray c r y s t a l and m o l e c u l a r  s t r u c t u r e o f R u ( p y ) ( B F ) ( 7 7) • g  4  2  This  -61-  structure  shows  row t r a n s i t i o n weakly  basic  metal)  o f M(py)g  chapter  compounds  npn^coordinated tions  (inthis 2+  instance with  again with  a  a large  second  and  anion.  This several  the presence,  d e s c r i b e s the s y n t h e s i s and study  that  c o n t a i n complex  EFg " a n i o n s ,  Included  7  o f Co(py)g(EFg)2  cationic here  s p e c i e s and  are the  characteriza-  and N i ( p y ) ( E F ) ( E = P , ' A s ) . g  g  of  Ni(py) (PF )  2  g  g  2+ has  been  solid  shown p r e v i o u s l y t o h a v e  state  shown h e r e work,  and the o t h e r t o have  Instead  simil-ar  we  and  obtained  g  2  2  3-methylpyridine  2  coordination  sphere  synthesis  of a  L=py,  chapter series  4mepy,  revealed that these 2+ CoL species  In these  around  donor molecules This  complexes  2  2  complexes  i n the present  where L i s  where M-Co,Ni,  2  the  first  ion contains  (L) a n d two w a t e r  a n d 3mepy compounds  o f the type  a n d E=P,  As.  four  molecules.  includes a description  o f compounds  are  were u n s u c c e s s f u l .  the metal(II)  also  i n the  the stoichiometry g  and E=P,As.  nitrogen  with  "Attempts,"  and M ' ( 3 m e p y ) ( H 0 ) ( E F g )  M'=Co,Ni,Cu,  4  (MLg)(EFg)2  species  of the series  structures.  compounds  M(4mepy) (H 0) (EFg)  where  t h r e e members  t o o b t a i n analogous  4-methylpyridine  t h e M(py)g  of the  CoL (EFg) 4  Our work  contain the novel  2  has  tetrahedral  2  -62-  3.2  OCTAHEDRAL P Y R I D I N E  3.2.1  - C O M P L E X E S OF  COBALT(II);-Co(py) (EFg) g  2  INTRODUCTION  Herlocker prior  t o 1970  and Rosenthal  and concluded  that  (7 8)  reviewed  at that  time  the "no  literature completely  2+ documented  case  presented." Co(py)gX ,  When  Many  compounds  had been  2  previous  f o r the existence o f Co(py)g  t o 1970  2  units  prepared  t h e r e was  X i s a halide  Co(py)^X  with  or a  the empirical  as s o l i d  pseudohalide,  (NO^  units  of non-coordinated  for (7 9)  t h e compound no  sphere that (8 0)  evidence around  with  ) the l a t t i c e  Herlocker  the characterization  6  3  1 3  )  electronic  consists  of  pyridine.  spectrum  and  assigned  the  r e p o r t of Jones  consists  and Rosenthal  o f t h e compound  for  Co(py)g  of Co(py) (BF ) 2+ 4  i t t o the Co(py)g and B u l l  4  provided coordination  point out  (Co ( p y ) g ) ( C o ( C O ) ) 2  i n dried  species. ( 8 1 ) who  have  2+ Co(py)g'  has  been  solution  distilled  They  g  to  contain  reported the 2  2  Unfortunately  i n solution  and Rosenthal  of  Co(py)^(NO^)  of the f i r s t  i n p r e p a r a t i o n , i t may 2+  Herlocker  itself.  pyridine.  however, s i n c e i t i s s i m i l a r  Some e v i d e n c e presented.  f o r Co(py)g  X as p e r c h l o r a t e t h e workers  cobalt.  (Fe(py) )(Fe (CO)  materials but 2+  the l a t t i c e  regarding the nature  i s incomplete;  formula,  of non-coordinated  When X i s n i t r a t e and 3 moles  state  no e v i d e n c e  and 2 moles  has y e t been  also  claimed  pyridine  criticized  t o observe  the  -63-  2+ electronic solved  o f Co(py)g  i n pyridine.  dissolve found to  spectrum  4  When H e r l o c k e r  Co(py)^(ClO^)  that  when C o ( p y ) ( C l O ^ )  i n dried  2  i t was i n s o l u b l e ;  and Rosenthal  distilled  on  t h e p y r i d i n e complexes  tried  pyridine,  however, they  be s o l u b l e i n n o n - d i s t i l l e d pyridine. I n 19 72 B e e c h ( 8 2 ) r e p o r t e d some  i s dis-  2  found  to  they  t h e compound  thermal  studies  o f c o b a l t ( I I ) p e r c h l o r a t e andc o n -  2+ eluded This red  t h e Co(py)g,  species  c o n c l u s i o n was b a s e d data  This a  that  and t h e r e s u l t s  evidence  detailed  should  study  on a n a l y t i c a l  n o t be c o n s i d e r e d  of the electronic  o f t h e compound.  properties  show w e l l  and  permit  In reported Cd.  data  properties  t h e CoNg  a n d , i n some  cases,  are consistent with  without  and magnetic because  these  chromophore.  and coworkers  o f Co(py)gM(NCS) , 4  (room  calorimetry.  f o roctahedral c o b a l t ( I I )  1 9 7 5 , R. R i v e s t , P . P . S i n g h  The magnetic  moment)  one t o i d e n t i f y  infra-  satisfactory  i s necessary  defined behavior  the characterization  2  scanning  spectral  This  i n Co (py) g ( C l O ^ ) .  data, l i m i t e d  of differential  properties  should  i s present  temperature  the visible  the presence  (83)  M=Zn o r  magnetic  electronic  spectral 2+  o f t h e Co(py)g  species  2and  M(NCS)  4  counter  ions.  that  the analytical  good  and t h e assignments  definitive. parameters  data  As noted  One c r i t i c i s m  (C,H,N,S)  work i s  were n o t p a r t i c u l a r l y  of the electronic  i n Section  of this  s p e c t r a were n o t  2.3.2.1, t h e l i g a n d  f o r c o b a l t ( I I ) compounds  a r e d e r i v e d by  field fitting  -64-  calculated  and  t r a n s i t i o n s t o the observed e n e r g i e s .  I t i s unwise t o use v a weak band. v  2  and  2  i n the c a l c u l a t i o n since i t i s usually  These a u t h o r s , however, were f o r c e d t o use  i n t h e i r c a l c u l a t i o n o f Dq and B s i n c e they d i d  not observe v-^ (the n e a r - i n f r a r e d r e g i o n o f t h e spectrum was not s t u d i e d ) .  I n " a d d i t i o n , t h e e l e c t r o n i c spectrum^ o f t h e compound  w i t h M=Zn (two bands) i s d i f f e r e n t t h a n t h a t f o r t h e compound w i t h M=Cd ( s i x bands) and t h i s i s d i f f i c u l t t o e x p l a i n . The room t e m p e r a t u r e magnetic moments o b s e r v e d f o r t h e s e compounds may a l s o be m e a n i n g l e s s , s i n c e t h e m i c r o a n a l y t i c a l data i n d i c a t e  some i m p u r i t i e s may have been p r e s e n t .  In short,  t h e c h a r a c t e r i z a t i o n o f t h e s e compounds has n o t p r o v i d e d a c l e a r p i c t u r e o f t h e e l e c t r o n i c s p e c t r a l and magnetic 2+ o f t h e Co(py)g  species.  A f t e r o u r work on t h e C o ( p y ) ( E F ) g  completed  properties  g  systems was  (and r e p o r t e d i n I n o r g a n i c and N u c l e a r C h e m i s t r y  L e t t e r s V o l . 12, p. 937 ( 1 9 7 6 ) ) , R. R i v e s t , P.P. S i n g h , and coworkers  (84) r e p o r t e d t h e s y n t h e s i s and c h a r a c t e r i z a t i o n  o f t h e compound, C o ( p y ) Z n ( N C S e ) g  4  which i s thought t o c o n t a i n  2+ t h e Co(py)g P.P.  species.  In l a t e r reports  (1978 and 1979),  S i n g h and coworkers have r e p o r t e d t h e compounds C o ( p y ) g -  (M (SCNp^,-where M' i s A g 1  1  (85) and C u  (86)/ and where a g a i n t h e  1  2+ Co(py)g  s p e c i e s i s t h o u g h t t o be p r e s e n t i n t h e s o l i d 2+  The e l e c t r o n i c s p e c t r a o f t h e C o ( p y )  6  state.  species i n these  l a t e r r e p o r t s a r e d i f f e r e n t from t h o s e r e p o r t e d f o r t h e compounds, Co(py)gM(NCS)  4  d i s c u s s e d i n t h e previous paragraph.  We w o u l d n o t e x p e c t  Co(py)g  2 +  t o have a d i f f e r e n t  electronic  spectrum w i t h d i f f e r e n t non-coordinating anions. we n o t e  t h a t t h i o c y a n a t o and s e l e n o c y a n a t o  Moreover,  complex anions a r e  p o o r c h o i c e s a s n o n - c o o r d i n a t i n g a n i o n s b e c a u s e NCS h a v e two p o t e n t i a l l i g a t i n g  a n d NCSe--  s i t e s a n d t h u s c o u l d be  present  as b r i d g i n g l i g a n d s , t h u s c o m p l i c a t i n g t h e s t r u c t u r a l  3.2.2  RESULTS AND  possibilities.  DISCUSSION  D e t a i l s o f the s y n t h e s i s o f t h e complexes a r e g i v e n in  Chapter  6.  On t h e b a s i s o f t h e o b s e r v e d  electronic  spectra  and m a g n e t i c p r o p e r t i e s , t h e compounds Co (py) g (EFg) , E=P a n d 2  2+  As,  have been a s s i g n e d  s t r u c t u r e s - c o n t a i n i n g t h e Co(py)g  c a t i o n s and n o n - c o o r d i n a t e d presented  EF,  anions.  These d a t a w i l l  and compared t o t h e work o f H e r l o c k e r and  previously described.  As w e l l ,  be  Rosenthal  the nature of the i n s t a b i l i t y  o f t h e compounds w i t h r e g a r d t o l o s s o f t h e f i f t h a n d s i x t h pyridine ligands w i l l 3.2.2.1  be d i s c u s s e d .  ELECTRONIC SPECTRA AND MAGNETIC PROPERTIES  The e l e c t r o n i c s p e c t r a o f C o ( p y ) g ( P F g ) Co(py)g(AsFg) to and  2  are v i r t u a l l y  s h o u l d e r on  and  i d e n t i c a l a n d may be a s s i g n e d  a cobalt(II) octahedral species. assignments'  2  a r e shown i n T a b l e  The t r a n s i t i o n III-l.  The h i g h  energies energy  i s probably best assigned t o a spin forbidden  -66-  TABLE  III-l  ELECTRONIC SPECTRAL DATA FOR  Band Co(py) (PF )  COMPOUND  6  (a)  ASSIGNMENT  Sg *Sg ( F )  6  Co(py) (EF ) g  g  2  p o s i t i o n (kK)  2  (b)  Co(py) (ASF ) 6  (a)  6  2  (b) 8. 70m  8.70m  2g  18.5sh  18.5sh  18.5sh  18.5sh  -> T (P)  19. 6s  19.8s  19.6s  19. 8s  20.6sh  20.6sh  20.4sh  20.6sh  A  4  l g  (a) d i f f u s e (b) m u l l  reflectance  spectrum  -67-  transition  (8;7.) .  determined  using  valuesof  T h e Dq a n d B v a l u e s t h e method  of Section  8 . 6 5 , 1 8 . 4 5 a n d 1 9 . 8 0 kK  tively,  i n excellent  o f 9 8 5 a n d 8 2 0 cm~.^, 2.3.1.1  for  agreement w i t h  give  calculated  , v , and  respec-  2  the observed  transition  energies. The very  spectra  similar  pyridine  (1017 the  g  to the solution  (78) .  parameters  of the Co(py) (EF )  Although  calculated  solution  spectrum  close  and B  spectrum.  This  compounds a r e  2  of Co(py) (BF^) 4  t h e agreement  i s quite  v s 985) i s l a r g e r  g  of the ligand  we  do n o t e  that  (797 v s 820) i s s m a l l e r may  reflect  i n  2  field Dq i n  a difference  i nthe  2+ nature Dq  of the solvated  i s dependent  upon  and s o l i d  state  the reciprocal  Co(py)  o f bond  species.  g  length  to the  -5 fifth is  (a  probably  The  larger  with is  power  this  longer value  since  electron  suggests  i n the solid  the longer  Co(py) (EFg) 6  temperature a t 80 K,  variations 2  compounds  t h e average  state  of B i n the solid  than  state  t h e Co-N b o n d  delocalization  The  and  ) so t h i s  f f  the e f f e c t i v e magnetic i t has dropped  i s also  likely  bond.  identical.  moment  t o around  consistant  the less  w i t h .temperature  are virtually  distance  i n solution.  i n the metal-ligand  of;- .u -  Co-N  f o r the A t room  i s 5.11-5.12  4.5 B.M.  The A  B.M. value  -68-  c a l c u l a t e d from Dq and B i s 1.40 and t h i s v a l u e was used f o r f i t t i n g t h e magnetic d a t a i n F i g g i s ' f o u r parameter model ( S e c t i o n 2.4.1.1). for  F i g u r e 2.1 compares t h e t h e o r e t i c a l c u r v e  k'=1.0, A=1.40, v=0, and A=-14 5 cm  1  with the experimental  d a t a and shows e x c e l l e n t agreement between t h e o r y and e x p e r i m e n t . The p a r a m e t e r s , v=0, A=0, d e r i v e d from t h e magnetic data i n d i c a t e that the  T^^(F) ground term i s n o t a p p r e c i a b l y  s p l i t by a t e t r a g o n a l d i s t o r t i o n .  This c a n be t a k e n t o i n f e r  t h a t t h e symmetry o f t h e CoNg chromophore i s 0^ and t h i s v i r t u a l l y e x c l u d e s a weakly c o o r d i n a t i n g s p e c i e s , i e . PFg or  AsFg  , from t h e f i r s t c o o r d i n a t i o n s p h e r e .  of  X, t h e s p i n - o r b i t c o u p l i n g c o n s t a n t , i s reduced t o -145 cm  compared t o t h e f r e e i o n v a l u e of-172 cm \  The magnitude 1  The v a l u e o f  '(A/A ) =0.843 i s almost i d e n t i c a l t o t h e v a l u e o f 6 ( B / B ) = Q  0.844 c a l c u l a t e d from t h e e l e c t r o n i c spectrum. The correspondence of  t h e two r a t i o s g i v e s a f u r t h e r degree o f c o n f i d e n c e i n t h e  t h e o r e t i c a l t r e a t m e n t o f b o t h t h e e l e c t r o n i c s p e c t r a and t h e magnetic p r o p e r t i e s s i n c e t h e r a t i o s o b t a i n e d by t h e d i f f e r e n t t e c h n i q u e s g i v e semi-independent measures o f t h e e l e c t r o n d e l o c a l i z a t i o n present.  The magnetic s u s c e p t i b i l i t y measure-  ments and t h e e l e c t r o n i c s p e c t r a l assignment a r e c o n s i s t e n t . • A c o m p a r i s o n o f t h e A, A, Dq, and B v a l u e s f o r t h e CoNg chromophore i n t h e s e compounds w i t h t h e v a l u e s f o r a CoOg chromophore g i v e s n o t unexpected r e s u l t s .  CotSO^F^  was chosen f o r t h e comparison s i n c e A=0 and t h e r e f o r e t h e e f f e c t o f anisotropy i s absent.  The A, A, Dq, and B v a l u e s (88)  -69-  GD5.2H  100  FIG.  3.1  MAGNETIC PROPERTIES OF  (line  a i s the theoretical  200  300  Temperature (K)  Co(py) (EF ) g  curve  g  2  f o r A=l.40,A=-145 cm  v = 0 , a n d k'=1.0; t h e u n s h a d e d a n d s h a d e d c i r c l e s the data p o i n t s  f o r E=As a n d E=P , r e s p e c t i v e l y )  -1  arethe  -70-  reported 860  cm  and  Dq  for this  respectively.  1  are  The  This  strength  the  of  3.2.2.2.  these  than  i s consistent oxygen  donor  VIBRATIONAL  The  1.42,  values  s m a l l e r i n magnitude  compounds.  of  compound  cm  A,  - X ,  of  observed  with  \ and  to  cm  B  and  greater  Co(py)g(EFg)  ligand  our  ^  are  i n our  a weaker  compared  7 65  2  field  nitrogen  donor.  SPECTROSCOPY  magnetic  Co(py)g(EFg)  17 0  and  electronic  compounds  2  spectral properties  are  consistent  with  the  2 + Co(py)g  cation  present  as  infrared through  and  counter-ions  spectral the  data  vibrations  Table  III-2  stereochemically vibrations There be are  i s no  625  vibrations those  EFg  and of  observed  the  infrared  pyridine  603 1  i n the  salts,  and  1  and  are KPFg  not and  anion. assigned  show no  to  pyridine  403  cm  1  ;  The  greatly CsAsFg  non-coordinated v^,  information  Co:(py) g (EF.g)'  respectively.  anion  "ionic",  cm  EFg  v i b r a t i o n s and  f o r the  The  this  bands  for non-coordinated  EFg  modes,  u  the  moiety  cm  active  T^  pyridine  anions,  lattice.  and  426-430  with  state  of  at  consistent  solid  complement  bands  the  non-coordinated  c o n f i r m and  shows  evidence by  i n the  sensitive  of.the  indicated at  therefore with  to  the  the internal  complexes.  2  as  would  these  bands  internal different (Table  anions.  splitting  and  from  II-l),  The  infrared  have  also  -71-  TABLE  INFRARED  (ii)  FOR  1  6  Pyridine 8  DATA(cm" )  Co(py) (PF )  COMPOUND  (i)  III-2  6  2  Co(py) (EFg) g  2  Co(py) (AsF ) 6  vibrations 1601m  a  1601m  6a  623m  6  2  5  m  16b  430m  4  2  6  m  EFg v v  vibrations  ( ) l u T  3  u  4  1  (  l u  A  )  l g  )  v (E ) 2  v (T 5  839vs  698vs  556s  393s  738vw  (a)  ;  V (T v  418w  2 g  569vw  (b)  g  )  n.o.  n  (a)  possibly  obscured  by  v  3  (b)  possibly  obscured  by  v  4  - ° -  6  2  -72-  identical  energies  t o those  i n the s a l t s .  modes w h i c h a r e f o r m a l l y f o r b i d d e n are  observed  and  Co(py)g(AsFg) f  to  2  site  and by  a s weak  symmetry  and  of  3.3  of  respectively,  2  show - t h e i n f r a r e d  6  3.2.2.3  6.2.1.2, loss  and  2  THERMAL  As  to  v  the formally allowed  Co(py) (PFg)  2  Co ( p y ) ^ ( E F g ) 2  cm  i f present,  T^  - 1  bands  u  )  due  Co(py)g(PFg)  w o u l d be  obscured  vibrations.  Figures  (1000-400  "*") f o r  for  cm  2  3.2  Co(py)g(AsFg) . 2  STABILITY  i n the experimental  Co(py)g(EFg)  of pyridine  Co(py)g(EFg)  and  spectra  (1000-350  noted  these  Co(py)g(PFg)2  of  present  2  2  and.which  respectively, are probably The  v  and  symmetry  i n the spectra  effects.  Co(py)g(AsFg) one  bands  i n 0^  The  loses  at  pyridine  are formed.  characterization  compounds  2  i n a vacuum two  of these  section  are very  room  ligands,  Section  3.5  compounds  6.2.1.1  and  susceptible  temperature. the  When  compounds  describes the  as h a v i n g  structures  2+ containing  tetrahedral  coordinated takes dish  place, i n color  color  be  anions.  the  original  and  As  light  easily  nonligands  m a t e r i a l becomes the deep  red-  red-purple  derivative.  of Co(py)^(EFg) by  , and  of pyridine  pink  eventually attains  presence  detected  Co(py)^  the loss  o f the t e t r a k i s (pyridine); The  can  EF,.  cobalt(II),  diffuse  2  impurity  reflectance  in  Co(py)g(EFg)  spectroscopy.  2  FIG  3.2 INFRARED SPECTRUM  (1000-400 cm" ) OF  Co(py) (PF ) g  g  2  -74-  FIG.  3.3  INFRARED SPECTRUM  (1000-350 cm" ) OF  Co(py) (AsF ) g  g  2  -75-  The  visible  band  extinction  of  "octahedral"  coefficient  of around  Co(py)^(BF )2  i n pyridine  "tetrahedral"  cobalt  4  M  '"cm  ^  .£= 611 have 565  Section  nm,  maximum  extinction  the  be  would  probably  .of  the  C  (PY) (  1:1.  505 p  F  4  The  C  o  (  p  y  would  ^6^  be  4  Co(py)g(C10 )2'  T  n  4  are very  Co(py)„ ( C 1 0 . )  4  Q  0  A  e  P  F  6^2  more an  example  of the  a  n  505  a  impurity  extinction  a t 505  5%  and  shift  m  i  x  t  u  r  e  o  565  f  t  n  e  t  ([PFg)  coefficients  w  2  bands range)  energy of  o  -  the presence  i n B e e c h ' s (82')  ( i n dichloromethane; A  nm  spectra  to detect  f o r both the  to  Co ( p y ) ^  to lower  the  2  and  ( % in this  2  shows  d  600  cobalt(II) /  4  3.4  of  extinction  Co.(py) ( P F g ) a  of  4  separated  Co ( p y ) • ( P F g )  as  band  Co ( p y ) ( E F g )  the r e l a t i v e  difficult  similar  and  2  tetrahedral  itself  Figure  Co ( p y ) ( C 1 0 ) 2 a s 4  95%  presence.of  band.  g)2'  and  intensity  manifest  nm  It  positions  Assuming  an  i n dichloromethane  2  g  for a  relative  "'"(for  has  coefficient  Co (py) (EFg)  absorbances well  then  would  of  an  of octahedral  t o 600,  ''"cm  usually  (78))whereas the v i s i b l e  3.5.2.1).  respectively.  mixture  o  M  4  their  30  has  30  (for example,Co(4mepy) (PFg)  coefficients be  cobalt(II)  compound,  and  band  pseudo-octahedral  max  i s 525  nm,  e=17)  2+ and  the Co(py)g  sensitive  test It  measurements the  cation, for this  and  presence of  elemental small  one  would  n o t have  a  impurity.  i s interesting and  therefore  to note that  magnetic  (C,H,N) a n a l y s e s  amounts  would  of Co(py) (EFg) 4  2  susceptibility not  i n the  detect  F I G . 3.4  V I S I B L E SPECTRA OF C O B A L T ( I I ) - P Y R I D I N E  COMPLEXES  -77-  corresponding temperature of  Co ( p y ) g ( E F g )  Co(py) (PFg) 4  4.33 a n d 5 . 1 1 B.M.  2  respectively.  the observed  uishable  due t o e x p e r i m e n t a l  a  Co(py)g(PFg) . 2  moment w o u l d  A t 80 K,  m o m e n t o f 4.49 B.M.,  for  Co(py)g(PFg) . 2  mixture  would  agreement for  with  almost  2  have  at  from  the mixture exactly  o f 43.76,  values  I f t h e r e was a b e 5.07 B.M.,  room  y  5%/95%  indisting-  t h e 5 . 1 1 B.M. above  would  t h e 4.50 B.M.  o f C, H a n d N  expected yield  expected  for this  3.63, a n d 10.11 a l l w i t h i n  the values 2  error  The p e r c e n t a g e  be 43.38,  Co(py)g(PFg) .  F o r example,  and C o ( p y ) g ( P F g )  2  mixture,  for  sample.  acceptable  3.67, a n d 10.20  calculated  3 .3  OCTAHEDRAL; PYRIDINE..COMPLEXES'^F  3.3.1  previously  compound,  Ni(py)g(PFg) ,has  by M a y f i e l d and B u l l  the study  (14) .  of the Ni(py)g(EFg)  i s t o confirm the observed  Moreover, pure of  and be w e l l 4  6.2.7  RESULTS The  Chap.6.  the  t  o  s  t  d y  u  2  that  (16)  r e q u i r e s pure  using and III-3  compounds  be  obtained  described later  2  Ni(py)g(EFg)  t o be  2  i n sections effective.  DISCUSSION  details  of the syntheses  III-3  Ni(py)g(PFg)2  cases,  properties.  s i n c e t h e method o f p r e p a r a t i o n  4  Table  solution  these  and N i ( p y ) ( A s F g )  AND  the  spectral properties  i t scryomagnetic  lists  N i ( p y ) , ( E F , ) „ compounds b b 2.  Bull's  two  d  contribution  of the hexafluoroarsenate  characterized  a n d 6.2.8a  3.3.2  n  i t i s important  Ni(py) (PFg)  in  2  characterized  compounds, b e s i d e s  derivative,  a  time  2  Our  f o r the f i r s t  Ni(py)g(PFg)2  been  2  preparation  of  (EFg)  g  INTRODUCTION  The  to  N I C K E L ( I I ) ; " N i (py)  prepared  the ligand  field  the experimental  are calculated  4  B.  value  here,  2  i n pyridine.  parameters  were  o f v-^ a s 10  The v a l u e s  o f Dq  Dq  complexes a r e g i v e n  spectral  data f o r  f o r M a y f i e l d and  and f o r R o s e n t h a l  of Ni(py) (BF )  to calculate  the .electronic  compound 4  of these  and  In the  Drago's latter  calculated and u s i n g  and B  by t h e q u a d r a t i c e q u a t i o n  by 10  i n Table method  Dq  TABLE  III-3  ELECTRONIC SPECTRAL DATA FOR  Ni(py) (PF )  COMPOUND  6  6  2  Ni ( p y ) ( P F ) 6  6  Ni(py) (AsF )  2  6  REFERENCE  (14)  t h i s work  this  TECHNIQUE  (a)  (b)  (b)  (c)  A  3 * 2g  2g  T  . T 3  l g  (F)  10.05m  10.2m  16.7m  16.4m  21.74w  23. 5w T  (  P  )  4  4  (e)  (d)  (kK)  10.0m  9.88  9.57(9)  16.5m 16.0m  16.50  16.47 (15)  n.o.  n.o.  26.67  26.73(31)  26.0s 26.04s  1000  1035  1030  (cm )  870  800  800  808  820  - 1  spectra,80K.  (b) m u l l  s o l u t i o n spectrum brackets.  spectra,room  2  (16)  1000  (c) d i f f u s e r e f l e c t a n c e ,  in  (c)  21.74  26.04s  Ni(py) (BF )  1037  (a) m u l l  (e)  26.3s  27.4s  2  )  Dq(cm B  l g  16.0m  6  2+, 6  work  BAND POSITION  ASSIGNMENT 3  'Ni(py)  temperature,  (d) s o l u t i o n s p e c t r u m  (nitromethane-pyridine);  (pyridine) molar e x t i n c t i o n  coefficient  -80-  described  i n section  in  although  nature  transition spectra  there  energies  were  2.3.1.3.  The  a r e some s m a l l  (these  run i n  A l lof the spectra  may  due  different  magnetic  are  similar  differences i n the  to the fact  that the  conditions).  properties  o f these  compounds  are  3 consistent  with  the presence  typical  of octahedral  moments  a t 300K  phosphate are  indicative  The Weiss  are assigned  pyridine.and  in  Table  exists  the  f o r the  compounds  independent  small  and a r e  magnetic  hexafluoro-  r e s p e c t i v e l y and  i n the  temperature  4.0.K,  for both,  distortion  -  of the NiN  spectra,  to. t h e s t e r e o c h e m i c a l l y  No  evidence  observed  of these  .  g  The  anions  g  shifts  of pyridine  compounds  sensitive vibrations  f o r noncoordinated  spectra.  s e n s i t i v e bands  as those  B.M.  i n the infrared  i n the infrared  anion  3.11  state  The  to the vibrations of the E F  III-4.  chemically  ground  g  symmetry .  bands  of  2  constants.are  o f some  from  The  same  temperature  perhaps  chromophore  that  and  and h e x a f l u o r o a r s e n a t e  studied.  A  n i c k e l ( I I ) complexes.  a r e 3.06  essentially  range  o f an  are  pyridine  i n the  stereo-  are essentially  f o r t h e Co ( p y ) ( E F ) g  g  2  listed  compounds  the as a r e  vibrations. It  i s interesting  t o note  that  Mayfield  and  Bull  h a v e a s s i g n e d a v e r y w e a k b a n d a t 4 69 cm to the formally f o r b i d d e n v '(T ) v i b r a t i o n o f P F , .(14). No e v i d e n c e f o r 5 2g 6 t h i s band appears i n t h e i n f r a r e d spectrum o f t h e N i ( p y ) ( P F ) 1  n  g  g  2  -81-  TABLE  INFRARED DATA  (ii)  ) FOR  Ni(py) (PFg)  COMPOUND  (i)  (cm  III-4  6  Pyridine  2  Ni(py) (EF ) g  g  2  Ni(py) (AsF ) g  6  vibrations 1605s  8a  1605s  6a  628m  626m-s  16b  439m  439m  842vs  699vs,br  EFg  vibrations  v (T 3  V  T  1  l u  )  )  U  v (A x  l g  5  )  v (E ) 2  V (T 5  g  2 g  5  8  392s  3  740vw  (a)  (b)  570vw n. o.  )  (a) p o s s i b l y o b s c u r e d  by v  3  (b) p o s s i b l y o b s c u r e d b y v  4  2  -82-  s y n t h e s i z e d here nor was i t o b s e r v e d i n t h e i n f r a r e d of  Co (py)  (PF,.) „ .  spectrum  I t i s i m p o r t a n t t o note t h a t t h e N i (py) , (EF ) „  compounds a r e s u s p e c t i b l e t o l o s s o f t h e f i f t h and s i x t h p y r i d i n e l i g a n d s a l t h o u g h they a r e n o t as l a b i l e as i n t h e C o ( p y ) g ( E F g ) 2 compounds.  Twenty-four hours o f pumping " i n  vacuo" w i l l cause a y e l l o w - o r a n g e c o l o r to  (due t o N i ( p y ) ( E F g ) ) 4  appear i n t h e r o b i n ' s egg b l u e c o l o r o f N i (py) g (EFg) • 2  We have found (see s e c t i o n 4.2.2.2 ) a band a t 47 0 cm  1  a s s i g n e d t o t h e 8a v i b r a t i o n o f p y r i d i n e i n t h e i n f r a r e d spectra"  o f N i ( p y ) ( E F g ) compounds and we c o n c l u d e t h a t t h e  4 69 cm  band r e p o r t e d by M a y f i e l d and B u l l i s p r o b a b l y t h i s  1  4  band a r i s i n g in their  from  sample.  2  t h e p r e s e n c e o f N i ( p y ) (PFg) 4  2  impurity  2  -83-  3.4  OCTAHEDRAL METHYLPYRID.INE  : COMPLEXES OF COBALT(II),  NICKEL(II), AND COPPER(II); AND M ( 3 m e p y ) g ( H 0 ) ( E F g )  M(4mepy) (H 0) (EFg) Q  2  2  1  2  3.4.1  2  2  . INTRODUCTION  The compounds t o be d i s c u s s e d M(4mepy) (H 0) (EFg) 8  2  2  2  i n this section are  and M ' ( 3 m e p y ) ( H 0 ) ( E F ) g  2  2  g  2  (where  M=Co, N i and M'=Co, N i , Cu and E=P, A s ) . The s t o i c h i o m e t r i e s o f these compounds are d i f f e r e n t from t h a t o f the p y r i d i n e complexes, M ( p y ) g ( E F g ) , d i s c u s s e d 2  general,  there are s i m i l a r i t i e s .  e a r l i e r ; however, i n The l a t t i c e  structures  o f a l l these compounds a r e s i m i l a r as shown by i n f r a r e d s t u d i e s which a r e c o n s i s t e n t with non-coordinated anions and t h e r e f o r e w i t h l a r g e complex c a t i o n i c s p e c i e s .  A l s o , when  the compounds a r e transformed t o complexes c o n t a i n i n g pyridine or methylpyridine species  a r e very  four  l i g a n d s p e r metal i o n , the M'L^tEFg),,  s i m i l a r f o r a given metal i o n i n terms o f  molecular and e l e c t r o n i c s t r u c t u r e . Our i n i t i a l  s t u d i e s on the e l e c t r o n i c s p e c t r a and  magnetic p r o p e r t i e s o f the complexes  M(4mepy)g(H 0) (EFg) 2  and M ' ( 3 m e p y ) g ( H 0 ) ( E F g )  2  of the metal i o n .  the r a t i o o f p o t e n t i a l n e u t r a l  2  2  Since  indicated octahedral  2  2  coordination  l i g a t i n g s p e c i e s t o metal i o n i n these complexes was found to be g r e a t e r than s i x , some u n c e r t a i n t y e x i s t e d as t o t h e  -84-  nature That  of the first  i s , was t h e w a t e r  water present "MN 0 " 4  on  coordination  coordinated  as l a t t i c e  water  Co(4mepy) (H 0) (PF ) , 8  2  2  6  Ni(3mepy) (H 0) (PFg) 6  "MN G "  2  2  chromophores  2  This tional  spectra  description magnetic molecular will  here  properties  are given  3.4.2.1  SPECTRA  Table  lists  III-5  and  M (3mepy)g(H 0) (EFg) .  species,  by a  t h e c r y s t a l and  Finally,  i n relation  these to  results  previous  o f t h e complexes  E F ~ , i n t h e compounds g  2  for  2  forbidden  These  bands  the M(py)g(EF ) g  ( i n 0^ symmetry)  formally  i s followed  t h e i n f r a r e d bands  1  allowed  to contain  described  DISCUSSION  VIBRATIONAL  observed  and  2  6.  anionic  those  This  appropriate,  and discussed  i n Chapter  2  g  a description of the vibra-  determinations.  R E S U L T S AND  2  studies  o f t h e e l e c t r o n i c s p e c t r a l and  the  the  with  a n d , when  structure  chromophores o f  diffraction  the structures  complexes.  and a n a l y s i s  2  ,  cases.  Details of the synthesis  3.4.2.  to  shown  begins  o f these  be summarized  work.  g  in--a 1-1  section  metal-ligand  The X-ray  ion.  o r was t h e  Ni(4mepy) (H 0) (PF )  2  have  2  o f t h e metal  t o the metal  with  o r "MNg", r e s p e c t i v e l y ?  2  4  sphere  T^  2  a  n  d  E  g^ 2^ v  to  M ( 4 m e p y ) (H^O)  are very  compounds.  vibrations  A-^C^)  assigned  are strong  g  2  (EFg)  2  similar The f o r m a l l y bands and  vibrations are  -85-  III-5  TABLE  ANION BANDS I N THE INFRARED SPECTRA OF M(4mepy) (H^O) ^CEFg) g  AND M ' ( 3 m e p y ) ( H 0 ) ( E F ) 6  (i)  M(4mepy) (H 0) :(-EF ) 8  2  2  V lu> T  4  V  (  T  lu  3  g  M=Ni E=P  M=Co E=As  M=Ni E=As  8 35vs  840vs  694vs  695vs  553s  554s  394s  392s  740vw  739vw  ___< )  2  a  (b)  2  g  n.o.  57 5 v w  2  M'-=Co E=As  M'=Ni E=As  M'=Cu E=As  839vs  700vs  700vs  699  555vs  555vs  395s  395s  395s  740w  n.o.  M'=Cu E=P  M'=Co E=P  M'=Ni E=P  839vs,br  830vs,br  555s 741w  lu>  V lu T  }  V V V  2  M=Co E=P  M'(3mepy) (H 0) (EF )  ( T  6  2  (b)  (ii)  2  )  W W  v  6  2  2 V (  (a) p o s s i b l y  2  (b)  (b)  !(b)  o b s c u r e d by v  3  of AsF  (b) p o s s i b l y o b s c u r e d b y v  4  ofPF  g  g  (a) 570vw  (a) 568w  vs  _(a) 570vw  -86-  observed  as weak b a n d s  respectively.  This  suggests,  are  basically  are  s u b j e c t t o lower  evidence  bands  due  a n d 3mepy  4000-2000  cm  HCB  spectra 2500  cm  that  the infrared  has  a  s t r o n g band  The  spectra  are due  close  are very Figure  assigned  t o v(O-H)  t o t h e v(O-H)  the "molecular  3.4.2.2.1  1  ( F i g . 3.5) when  both  .  and  the region g  cm  1  has a s t r o n g ,  b u t as t h e  a very  Others  broad  have  a t 3550-3200  hydrogens  cm  3.4.. 2 . 2 . 2 ) .  The  infrared^-spectra  region are different  •- -  1  from  compounds; s e e  •  (89(a)). and  molecule  (as s h o w n  section .  o f -the 3 - m e t h y l p y r i d i n e  and a r e i l l u s t r a t e d  water  this  o f the water  t o 4-methylpyridine molecules  and  shown  (non-coordinated)  are different  structures of these  2  (hexachloro-  Nujol  have  cm  some  Ni(4mepy) (H^O) (AsFg)  a n d HCB  respectively.  t o 3100  no  show  shows  of  2950-2800  and  different for  3.5  spectrum  of lattice  observed  Again,  The p o s i t i o n  spectrum  "hydrogen-bonded"  this  .  1  anions  lattice  compounds  shows, a l l o f t h e compounds centered  state  of these  a b s o r p t i o n i n the range  mull  the  symmetry.  i n Nujol  2  that  observed.  complexes.  2  compounds  was  absorptions  and N u j o l mulls  absorption  in  site  of the infrared 2  broad  by  0^  Co(4mepy)g(H 0) (AsFg) ,  butadiene)  are  - 1  as b e f o r e ,  ) vibration  above  of these  4mepy  and  infrared  2  and AsFg  i n the solid  than  (T  t o water  appearance the  counterions  f o r the The  f o r t h e PFg  • complexes  i n Figure  3.6.  2  -87-  4000  3000  ENERGY FIGURE 3.5 (Spectrum  2000  (cm ) _ 1  INFRARED SPECTRUM OF M ( 4 m e p y ) ( H 0 ) ( A s F ) g  I i s Ni(mepy) (H 0) R  II  i s Ni(4mepy)g(H 0) (AsF )  is  Co(4mepy) (H 0) (AsF )  2  8  2  2  (AsFg)  2  2  6  6  2  2  2  2  2  6  2  m u l l e d i n HCB;  mulled i n Nujol;  mulled i n Nujol.  spectrum  spectrum I I I  * Nujol  band)  -88-  FIGURE 3.6  INFRARED SPECTRA OF M(3mepy)  ( Spectrum spectrum  I i s Co(3mepy) (H 0) (AsF ) g  I I i s Ni(3mepy)  * N u j o l band)  2  2  g  (HjO) (AsFg) 2  (H 0) (AsF ) 2  2  g  mulled  2  2  mulled  2  i n Nujol; i n Nujol.  -89-  The  band  the  4-methylpyridine  bands  s t r u c t u r e f o r t h e s e compounds  i n the region;  centered there or  ^2800  cm  latter a  with  infrared  6  where  crystal  to that  2  4mepy four water  2  the  2  ( s e e ..  2  i s  hydrogen  hydrogen-bonded  i s weakly  interacting  bands  o f 4mepy  2  shows  i s no  although there  2  cell  the positions  this  3.4.2.2.5).  of the  stereochemically  M(4mepy) (H^O) (EFg) R  2  2  evidence f o r"non-coordinated"  and  four  and 1 v i b r a t i o n s  (X-ray) m o l e c u l a r  with  spectrum of  t y p e s o f 4mepy  hydrogen-bonded  T h e a s s i g n m e n t o f two b a n d s  o f 4mepy m o i e t i e s  i s  2  parameters' i n d i c a t e  (see s e c t i o n  i n the  2  a n d t h e two  2  i s n o t isomorphous  a r e two d i f f e r e n t  to the metal  molecules.  2  The u n i t  different  III-6  There  of Co(3mepy)g(H 0) (PFg)  and t h e i n f r a r e d  2  Table  6 a , 10b+12,  types  g  2  i s slightly  bonded  2  of Ni(3mepy)g(H 0) (PFg)  Ni(3mepy)g(H 0) (PFg)  the  2  structure  similar. 2  compounds.  radically  anion.  are very  sensitive  molecules  structure  one hydrogen  Cu(3mepy)g(H 0) (PFg)  compound  complexes,  m o l e c u l e s a r e i n two  3mepy m o i e t y a n d t h e o t h e r  isomorphous  two  and one broad,  1  types o f water  The m o l e c u l a r  of  o f Ni@mepy) ( H 0 ) ( P F ) - • c o n f i r m s t h e  possibility;  the EFg  cm  from that  a r e now  In the 3-methylpyridine  o f the water  3.4.2.2.3)  there  s h a r p a t 3500  environments.  The  that  since  two d i f f e r e n t  the hydrogens  section  one  .  1  are either  different  to  complexes  :is d i f f e r e n t  reflects  present:  to  to each o f  t h e two  different  expected from the stoichiometry  structure  determinations.  and  -90-  The i n f r a r e d s p e c t r a l bands o f 3mepy i n t h e M'(3mepy) (H 0) (EF ) g  2  2  6  complexes  2  do n o t show t h e w e l l d e f i n e d in  ( s e e A p p e n d i x 1, T a b l e A l - 3 )  splittings  a s t h e bands o f 4mepy  t h e M ( 4 m e p y ) ( H 0 ) ( E F ) c o m p l e x e s show. 8  2  2  g  2  TABLE  III-6  SELECTED 4MEPY BANDS IN THE INFRARED SPECTRA OF THE M(4mepy) (H 0) (EFg) 8  2  2  2  COMPOUNDS  BAND POSITION M=Ni  M=Ni  E=As  E=P  E=As  526m  526m  525m  526m  536sh  538m  540m  54 0m  810vs  800m  805s  810m  816s  M=Co  VIBRATION  E=P  (a)  10b+12  1  M=Co  4-METHYLPYRIDINE  6a  (cm" )  1010s  1007s  1007s  1007s  1017s  1020s  1024s  1026s  9a  1230s  1227s  1229m  1229m,1235sh  19a  1504w  1504w  1509w  1506w  8a  1608s  1610s  1611s  1610s  1  1622sh  (a) t h i s  band i s  o b s c u r e d by  t h e v CI\ ) o f PF ~ lu 6 3  -91-  3.4.2.2  ELECTRONIC  SPECTRAL  MOLECULAR  3.4.2.2.1  electronic  compounds  parameters and  1010  2  spectra  Dq  spectrum  and B d e r i v e d \  kK  f o r E = A s •, a n e x c e l l e n t calculated  (E=P)  of  (E=As),  compounds The  are  (E=P)  a n d 4.86  4.58  B.M.  excellent moments  995  ligand  a n d 840  cm  - 1  a n d 8.91  transition  of  field  ,  E=P,  positions  f i tto the observed  which  i o n i n an  the assignment The  f o r E=P  of  and  of  20.40  spectra.  energy  a r e w i t h i n ' 4 0 nm of i t si n t r i n s i c  a r e 18.7 of the weakness,  by v^. - The A v a l u e c a l c u l a t e d f o r  i s 1.40. magnetic  dependent. (E=As)  a t 80K  B.M.  moments  agreement  between  of these  T h e moments  compounds  a t 3 0 0 K a r e ' 4.85  and t h e y d r o p  respectively.  and t h e o r y .  cobalt(II)  kK  and,-- b e c a u s e  effective  temperature  shows  The c a l c u l a t e d  V  :x>2 i s o v e r - s h a d o w e d both  20.20  properties  a cobalt(II)  basis.  are:  values of the 2  a n d 19.0 kK  band, maxima  and  with  III-7  E=As.  and  The  a r e 8.78  AND  2  and magnetic  on t h i s  v  3  6  are consistent  a n d 8 4 5 cm  v  2  environment. T a b l e  electronic  PROPERTIES  STRUCTURE  R  octahedral the  MAGNETIC  Co(4mepy) (H 0) (EF )  The these  AND  Figure  t o 4.51  and  3 .'7 s h o w s t h e  the experimental magnetic  The m a g n e t i c  data  ion i s i n a tetragonally  indicate  distorted  that  the  octahedral  -92-  III-7.  TABLE ELECTRONIC  SPECTRAL  DATA  FOR Co (4mepy)  BAND COMPOUND  POSITION  Co(4mepy)g(H 0) (PF ) 2  2  (a)  (b)  g  2  g  (-I^O)  2  (EFg)  2  (kK)  Co(4mepy) (H 0) (AsF ) Q  (a)  2  2  (b)  ASSIGNMENT 4  T-, (F) + T (F) lg 2g 4  0  -> T  (P)  4  n  8.77m  —  8.93m  20.0s  20.0s  20.8s  20.4s  ig 20.8sh Dq(cm B  _ 1  )  (cm I x)  (a)  mull  spectra  (b)  diffuse  reflectance  21.1sh  21.5sh  995  1010  840  845  g  2  -93-  CD5.2-  200  100  FIGURE 3.7 (for see  300  Temperature (K)  MAGNETIC PROPERTIES OF C o ( 4 m e p y ) ( H 0 ) ( E F ) g  description  of line  F i g . 3.1 p . 6 9 ; l i n e  2  2  ( a ) , shaded and unshaded (b) i s t h e t h e r e o t i c a l  2  circles  curve f o r  A=1.40, v=5 ,A=-150cm , a n d k ' = . 9 3 ; l i n e (c) i s t h e -1  thereotical  c u r v e f o r A=1.40, v=5 , A=-150cm , a n d 1  k'=.88; t h e s h a d e d a n d u n s h a d e d p o i n t s f o r E=P a n d E=As,  squares are the data  respectively)  -94-  environment i n b o t h compounds.  The s p l i t t i n g  (A) o f t h e  c u b i c ^ ^ g term due t o low symmetry i s a p p r o x i m a t e l y (vX) T  750 c m  -1  a l t h o u g h t h e s i g n of A i s n o t d e f i n i t e . The c r y s t a l and m o l e c u l a r s t r u c t u r e o f Co(4mepy)g-  (1^0) (PFg) 2  2  was d e t e r m i n e d by s i n g l e c r y s t a l X-ray d i f -  f r a c t i o n methods by Dr. S. R e t t i g and P r o f . J . T r o t t e r on t h e c r y s t a l p r o v i d e d by us.  T h i s work, w h i c h e s t a b l i s h e s  t h e d e t a i l s o f t h e m o l e c u l a r s t r u c t u r e geometry about t h e m e t a l i o n , w i l l be b r i e f l y d e s c r i b e d h e r e .  The m o l e c u l a r  s t r u c t u r e c o n s i s t s of d i s c r e t e c a t i o n s , C o ( 4 m e p y ) ^ ( O H 2 ( 4 m e p y ) 2 ) and a n i o n s , PFg cation.  .  F i g u r e 3.8. shows t h e s t r u c t u r e o f t h e  The c o b a l t ( I I ) i o n i s c o o r d i n a t e d by f o u r n i t r o g e n  ( 4 - m e t h y l p y r i d i n e ) atoms and two oxygen form a trans-CoN^C^ chromophore.  (water) atoms t o  A l l o f t h e a d j a c e n t bond  a n g l e s around c o b a l t a r e c l o s e t o 90°.  The Co-N  distances  a r e 2.22 and 2.20 2 and t h e Co-0 d i s t a n c e s a r e 2.11  S,  i n d i c a t i v e o f an a x i a l l y compressed t e t r a g o n a l environment around c o b a l t (approximate D ^  symmetry).  The m o l e c u l a r arrangement o f the a x i a l l i g a n d m o i e t i e s i s also of i n t e r e s t .  Each w a t e r m o l e c u l e i s a p p a r e n t l y  a s s o c i a t e d w i t h two 4 - m e t h y l p y r i d i n e groups w i t h 0 d i s t a n c e s o f 2.75  N  and 2.80 S and an N-O-N' angle of 90.2°.  The i n f r a r e d spectrum i n d i c a t e d t h a t t h e v(O-H) bands are n o t those o f f r e e water thus c o n f i r m i n g t h e presence o f a hydrogen-bonded  i n t e r a c t i o n between t h e oxygen atom and  the 4 - m e t h y l p y r i d i n e m o l e c u l e s .  I  2+ 2  -95-  FIGURE  3.8  VIEW  OF  Co(4mepy) (0H (4mepy) 4  2  2  -96-  The  molecular  structure  ( H 0 ) ( P F , ) „ and t h e s p e c t r a l Z Z o Z  and magnetic  o  the  Co(4mepy) (H 0) (EFg) 8  presence types  2  of the discrete  were  "Octahedral"  symmetry  features  are confirmed  3.4.2.2.2  calculated,  electronic  assuming  t o lODq  from  field.  and agrees  f or  >Ni (4mepy)  the presence  8  i o n was  indicated In  o f a low  A l lof  these  structure- determination.  2  data  f o r these  The v a l u e s  the diffuse  2.3.2.1.  spectra.  the presence  o c t a h e d r a l symmetry,  reflectance  fairly  well  with  The s t r u c t u r e  (H^O) ( P F g ) 2 g i v e s  o f a low symmetry  were  u s i n g t h e ^2  transition  2  compounds  o f Dq a n d B  The  i n t h e two compounds.  observed of  III-8.  energies  of section  2  spectral  i n Table  transition  values  2  different  properties.  by: t h e . . m o l e c u l a r  8  presented  responds  showed  Ni(4mepy) (H 0) (EFg)  The  method  the cobalt(II)  to the ligand  The  water-4-methylpyridine  by t h e i n f r a r e d  data  component  properties of  t h e two  s p e c t r a and magnetic  the magnetic  o f Co(4mepy)g-  are consistent.  anions,  and the  about  symmetry  are  EFg  indicated  the electronic  addition,  compounds  2  o f 4mepy m o l e c u l e s ,  interaction  by  2  determination  an  component  energy  an  <3  and t h e cor-  the calculated o f t h e v-^ b a n d indication to the ligand  field. The  effective  magnetic  moments  o f these  compounds  -97-  TABLE ELECTRONIC  SPECTRAL  III-8  DATA  FOR N i ( 4 m e p y ) g ( H 0 ) ( E F ) 2  BAND P O S I T I O N Ni(4mepy) (H 0) (PF )  COMPOUND  8  2  (b)  (a) 3  A A  + T 3  2g  {  2g  L  2  5  ig  T  l g  (P)  27.4s  Dq (cm- ) 1  B  (cm  )  (a)  mull  spectrum  (b)  diffuse  reflectance  2  (kK)  Ni(4mepy) (H 0) (AsF ) g  2  2  (b)  (a)  1 3 . 3w  16.7s  3  2  g  10.3m  9.53m 11.1m n.o.  + T  g  2  16.7s  16.8s  16.7s  26. 8s  27.4s  26.9s  1055  1050  790  805  g  2  -98-  are of  essentially 3.15  and  temperature  3.14  B.M.  fluorophosphate  and  consistent  a  with  at  (-6  sibly  of  A  spin-triplet  second  2  2  w  form. of  The  The  nickel(II)  of  are  moments  f o r the  compound,  hexa-  respectively,  nondegenerate  by  Dr.  and  Weiss  observed, to  coupling  s t r u c t u r e , as cations  Non-zero  a  the  consequence  ligand  8 pos-  field  structure of  S.  Rettig  i s presented i n the  (due  to  and  here  Ni(4mepy) R  Prof.  anions.  Figure  and  some b o n d by  3.9  consists the  i n the  nitrogens  Trotter  abbreviated  shows  distances four  J.  i n an  c o b a l t ( I I ) case,  and  i s coordinated  constants,  effects).  molecular  solved  s  arrangement  oxygens  and  results)  discrete  ular  a  2  (unpublished  observed  orbitally  components  spin-orbit  crystal  (H 0) (PFg)  lg^*  f o r E=As)  symmetry  order The  B 2 g  +1  low  are  Magnetic  3  term,  f o r E=P,  300K  hexafluoroarsenate  3 ground  independent.  molec-  cation.  and  two  as  i n the  analogous  c o b a l t ( I I ) compound.  The  molecules,  again,  appear  be  4-methyl-  pyridine 2.10  to  molecules. 2.12  adjacent 90°.  bond  These  trans-NiN 0 4  the  2,  4  2  the  ligands 2  bond  bond  distances  about thus  the  form  to  are  are  to  range 2.12  from  %,  a l l close  and  the  to  a  fairly  "regular octahedral"  This  should  be  contrasted  c o b a l t c a t i o n s where  compressed  is interesting  distances  nickel(II)  analogous  had  hydrogen-bonded  Ni-N  chromophore.  chromophore It  Ni-0  angles  structure of  CoN 0  The  to  water  tetragonal  speculate  on  the  with the  geometry. differences  -99-  -100-  in  the coordination  pounds ion.  because We  will  achieved  the only compare  be  the crystal of a  In a tetragonal split  into  observed  With the  2.5  e  the energy relative  shows-this  i s the  octahedral" the t  2/3<5  the  e  .  set lies  g  pression,  lower  t h e b^  situation  for axial  1/36  The  result  distortion  lies  coordination  elongation.).  defined  as  and b  6,  orbital z y  i n energy  orbital  energies  X  a r e ; e,. s e t , +  I f the tetragonal  metal(II)  orbitals  2  g  +  com-  (d ,d ) a n d b „(d ) xz yz 2g Y  d i f f e r e n c e o f t h e two s e t s  energies  4mepy  stabilization  distortion,  two s e t s ;  (p., 4 8 )  field  "regular  g (Figure  i n these  difference present  by d i s t o r t i o n  geometry. would  geometry  i s an a x i a l  elongation,  and i f i t i s an a x i a l lower.in  of the calculation  com-  energy.  of the stabilization 7  energies  shows  energetically octahedral  that  f o r octahedral  favorable  nickel(II)(d  occupancy  of the t  For  elongation  axial  energy  of  for a distortion 8  (  b  ))=-l/36  For  high  spin  and  there  symmetry  d  2 g  )  ^ g)  gives  e  should  spin  symmetry)  an energy  of  to the octahedral  i s no s t a b i l i z a t i o n  It  In high  whereas f o r d  7  , the  i s (t-^g)  5  4 1 (e ) (b ) g i v e s an g 2 -g -2/36 a n d f o r a x i a l compression,  , the occupancy  compared  to'occur  3  relative 8  ) , i ti s  the occupancy  (4(-1/36)+1(2/36))  occupancy  3(1/36  ) , i t i s not.  s e t ( i noctahedral  2  2 the  cobalt(II)(d  of the t  energy  to the octahedral be noted  that  gain  2  (2 (-2/36) +  stereochemistry. 6 set i s ( t ) 2  g  i n tetragonal  symmetry.  axial  elongation  i s favored  7 over the  axial above  compression arguments  f o r the d  configuration according  but the cobalt(II)  complex  has an  to  axially  -101-  compressed steric and  t e t r a g o n a l symmetry.  requirements  water.  The  approximately  in  the  ligands, 2.75  &  the  angle  is  water  of  the  oxygen  with  nitrogen  h e t e r o c y c l e bonded  attached  to  carbons  factors  would  pulsions  with  than  water  the  the  in  of As  the  lead  to  of  CFSE  and  we  shall  evidenced (section  by  2  the  2  We  distorted  crystal  2  to  i t is  are  close  to  have  the  In  2  2  the  hydrogens  to  120°.  steric metal  rationalized  the  3.4.2.2.4).  re-  ion the  (M=Co,  have  expected  considered  the  Ni)  when  structures, 2  properties of we  g  cobalt(II)  of  a  the  to  characterized  g  chromo-  arguments,  compounds.  It  discussed for  the  CoNg  2  (section  2  CFSE  2  Co(3mepy)g-  have  Ni(py) (PFg)  according  to  as  Ni(3mepy)g(H 0) (PFg)  arguments  applied  i n terms  the  r e g u l a r o c t a h e d r a l MN  f o r the CFSE  sections,  However,  and  would  chromophore  of  magnetic  3.2)  two  these  structure  having  noted 'that  next  exhibit  both  chromophores be  water  linear.  there  (N-C-H)  (H-O-H)  the  greater inter-ligand  as  CoN 0  should  metal  angle  i n the  (section  be  2  and  (section  should 4  the  system  2  also  the  compounds  phores.  angle  In  M(4mepy)g(H 0) (EFg)  see  2  Co(py)g(EFg)  3.3)  a  2  O-H-N  T h u s we  the  2  3.4.2.2.3)  (H 0) (PFg)  the  ligand  steric considerations.  M(3mepy) (H 0) (EFg) 2  to  with  molecules.  structure  6  pyridine  107°.  methylpyridines closer  observed terms  the  the  4-methylpyridine  n i t r o g e n i n the  i s approximately  reflects  n i t r o g e n h e t e r o c y c l e hydrogen-bonded  from  These  species,  ( a n g l e C-N-C) w h e r e a s  molecule  the  ligand  around  120°  This probably  chromophores  Jahn-Teller distortion  1  -102-  ( s e c t i o n 2.3.3, p. 47) o f the t energy i s s m a l l .  2  s e t where the s t a b i l i z a t i o n  T h i s i s because the  d i r e c t e d towards the metal as the e y  o r b i t a l s a r e not (0, : n  d 2 2 and d 2) x ~~ y z  are and t h e r e f o r e a r e l e s s a f f e c t e d by the l i g a n d s . m o l e c u l a r o r b i t a l theory, (and these e  the t  2  e l e c t r o n s are non-bonding  e l e c t r o n s , anti-bonding) e l e c t r o n s .  l i g a n d s around the metal i o n are e q u i v a l e n t favorable  pyridine and  When the  . i t i s not  (with r e s p e c t t o i n t e r - l i g a n d s t e r i c  f o r the d i s t o r t i o n t o be present.  In  repulsions)  A p p a r e n t l y , i n the methyl-  ( d e r i v a t i v e s ) o f c o b a l t ( I I ) , t h e CFSE c o n s i d e r a t i o n  s t e r i c f a c t o r s are complementary such t h a t they g i v e  to a d i s t o r t i o n .  rise  -103-  3.4.2.2.3  Ni(3mepy) (H 0) (EF ) g  Table these on  III-9  complexes.  the basis  2  2  6  2  gives the electronic  The  spectra  of octahedral nickel(II),  were  calculated  Consistent  with  octahedral nickel(II),  moments  for  Ni(3mepy) (H 0) (PF ) ,  and  f o r N i (3mepy) (H" 0) ( A s F )  2  2  6  g  9=-15.  These  2  g  2  f f  8  nature  , y  are very  2  g  The (H 0) (PF ) 2  g  confirms crystal  2  2  was  2  temperature:  ( 3 0 0 K ) =3 .16  similar  g  2  and m o l e c u l a r  determined  d i s c u s s e d i n more  of  the M(4mepy)g(H 0) (PF )  are  of  mag-  B.M.  to those  and observed  suggesting that  similar.  the  The m o l e c u l a r  , determined  by  X-ray  this.  be  and d e t a i l s  2  g  than 2  o f how  described i n section  structure  as p a r t  detail  2  procedures  2.4.2.2.2.  the effective  complexes  g  o f N i (3mepy) ( H 0 ) ( P F )  diffraction,  2  ff  o f the chromophore i s v e r y  structure  field  ( 3 0 0 K ) = 3 . 1 7 ' B . M . a n d 6=-6K;  the Ni(4mepy) (H 0)2(EF )2  for  the ligand  independent  y  2  2  properties  assigned  as d e s c r i b e d i n s e c t i o n  are essentially 6  data f o r  are satisfactorily  parameters  netic  spectral  of this  Ni(3mepy) g  work  the molecular  (M=Co,Ni)  was  The a t o m i c  and  will  structures  complexes.  the structure  6.5.3.  of  Experimental determined  positional  -104-  TABLE  III-9  ELECTRONIC SPECTRAL DATA FOR N i ( 3 m e p y ) ( H 0 ) ( E F g ) g  2  2  2  BAND POSITION (kK) E=p  ASSIGNMENT  (a) V  l  V  2  (  3 2q A  ( 3 A  T  2g^  3 2g)  3  T  lg  (  F  )  ^  3  B  (b)  10.80m-w 16.67m  16.95m  16.67m  27.07m  26.81m  17.07m  26.81m  1 080 xuou  . - 1 , (cm )  780  1 O K J  (a) m u l l spectrum (b) d i f f u s e  (a)  16.95m  / - I) N Dq(cm _  (b)  10.8m-w  v „ ( A + T., (P) ) 3 2g l g 3  E=As  reflectance  1080 7  8  0  -105-  and thermal parameters  are a l s o g i v e n t h e r e .  The bond d i s t a n c e s  and angles p r e s e n t i n the molecular s t r u c t u r e are shown i n Table I I I - 10 . The s t r u c t u r e c o n s i s t s of e s s e n t i a l l y N i (3mepy) £(OH ) ( 3mepy)] 4  2  2 + 2  c a t i o n s and P F  t h e r e i s some evidence f o r anion - H 0 2  distinct  anions  g  although  interaction.  The bond  d i s t a n c e s and angles found i n the 3-methylpyridine r i n g are s i m i l a r to those d e r i v e d f o r p y r i d i n e from a microwave study (90)•  The  3-methylpyridine m o i e t i e s are a l l p l a n a r w i t h i n  experimental e r r o r .  The P-F bond d i s t a n c e s o f two  l o g r a p h i c d i s t i n c t PFg~  crystal-  groups vary from 1.509(11) t o 1.577(9)5  i n one group and 1.513(11) t o 1.579(9) A* i n the o t h e r and bond angles f o r adjacent P-F bonds from 85.8 and from  87.1° and  are moderately  94.7° r e s p e c t i v e l y .  ° to  the  91.4°  The thermal  parameters  l a r g e and there are apparent d i s t o r t i o n s i n the  anion as i s u s u a l l y observed f o r t h i s n e a r l y s p h e r i c a l anion (9,1). F i g u r e 3.10 non-coordinated are not equal  shows a view of the c a t i o n with the  3mepy l i g a n d s shown.  The Ni-N d i s t a n c e s  (Table 111-10); N i - N ( l ) and Ni-N(4) are adjacent  and equal a t 2.094 IR whereas the Ni-N d i s t a n c e s o p p o s i t e these are s i g n i f i c a n t l y l o n g e r . a t 2.090 (7) and 2.128(7)2.  The Ni-0 d i s t a n c e s are a l s o The atoms N i , N.(l), N(3),  unequal 0(1),  0(2), and N i , N(2), N(4), 0(1), 0(2) are p l a n a r w i t h i n experimental e r r o r .  But n e i t h e r N i , N ( l ) , N(2), N(3),  nor N ( l ) , N(2), N(3), N(4) error.  N(4)  d e f i n e a plane w i t h i n experimental  The d e v i a t i o n from the l e a s t squares plane  through  -106-  TABLE III-10 BOND .DISTANCES AND ANGLES IN N i ( 3 m e p y ) ( H j O ) ( P F g ) g  2  2  (estimated standard d e v i a t i o n s i n brackets)  (i) BOND DISTANCES (X) N i - N ( l ) = 2.094 (8)!  N i - O ( l ) = 2.090 (7)  Ni-N(2) = 2.153(8)  Ni-0(2) = 2.128(7)  Ni-N(3) = 2.156(8)  0(1)-N(5) =2.716(11)  Ni-N(4) = 2.094 (8)  0(2)-N(6) =2.718(11)  RING 1  RING 3  RING 2  RING 4  N-C(l)  1. 349 (12)  1.336(12)  1.335(13)  1.354(13)  C(l)-C(2)  1.372(14)  1.343(14)  1.387(14)  1.376(14)  C(2)-C(3)  1.399 (16)  1.412(16)  1.402(17)  1.395(18)  C(3)-C(4)'  1.389 (18)  1.396 (18)  1.414 (18)  1.414 (19)  C(4)-C(5)  1.425(15)  1.403(15)  1.368(15)  1.363(16)  C(5)-N  1.373 (13)  1.530(16)  1.361(13)  1.355(13)  C(2)-C(6)  1.503 (16)  1.530(16)  1.521(18)  1.525(18)  RING 5  RING 6  N-C (1)  1.356(16)  1.358(16)  C(l)-C(2)  1.397(17)  1.401(17)  C(2)-C(3)  1.400(18)  1.358(18)  C(.3)-C(4)  1.347(18)  1.393(18)  C(4)-C(5)  1.435(18)  1.403(17)  1.324(15)  1.306(15)  1.486(19)  1.500(19)  . C(5)-NC(2)-C(6)  -107-  TABLE 111-10 (cont'd)  (i) BOND DISTANCES (ft)  ANION 1  ANION 2  P-F(l)  1.552(11)  1.556(11)  P-F(2)  1.565( 9)  1.517(12)  P-F(3)  1.577 ( 9)  1.513(11)  P-F(4)  1.562 (11)  1.579( 9)  P-F(5)  1.509 (12)  1.564 ( 9)  P-F(6)  1.526(12)  1.568(10)  ( i i ) BOND ANGLES (deg)  N(l)-Ni-N(2)  89.1(3)  N(l)-Ni-N(3)  177 .3(4)  N(l)-Ni-N(4)  92.3 (3)  N(l)-Ni-0(1)  92. 3(3)  N(l)-Ni-0(2)  88.5 (3)  N(2)-Ni-N(3)  89.7 (3)  N (2)-Ni-N (4)  178.4(4)  N(2)-Ni-0(1)  87.7 (3)  N(2)-Ni-0(2)  90.2 (3)  N(3)-Ni-N(4)  88. 9(3)  N(3)-Ni-0(1)  90.0(3)  N(3)-Ni-0(2)  89.1(3)  N(4)-Ni-0(1)  91.5 (3)  N(4)-Ni-0(2)  90. 6(3)  0(l)-Ni-0(2)  177.7(3)  RING 1  RING 2  RING 3  RING 4  RING 5  RING 6  C(5)-N-C(l)  120(1)  119(1)  119(1)  119(1)  121(1)  120(1)  N-C(l)-C(2)  124(1)  124(1)  124(1)  123(1)  123(1)  122(1)  C(l)-C(2)-C(3)  119(1)  119(1)  116(1)  118(1)  116(1)  117(1)  -108-  TABLE 111-10  (ii)  BOND ANGLES  (cont'd)  (deg)  RING 1  RING 2  RING 3  RING 4  RING 5  RING 6  C(2)-C(3)-C(4)  118(1)  118(1)  121(1)  119(1) . 121(1)  122(1)  C(3)-C(4)-C(5)  122(1)  119(1)  117(1)  120(1)  120 (1)  118(1)  C(4)-C(5)-N  118(1)  121(1)  123(1)  122(1)  119(1)  122(1)  C ( l ) - C ( 2 ) - C ( 6 ) 120(1)  121(1)  120(1)  120(1)  120(1)  119(1)  121(1)  120(1)  123(1)  122(1)  124(1)  124(1)  C(3).-C(2)-C(6)  ANION 1*  ANION  F(l)-P-F(2)  89.7 (7)  174.1(10)  F(l)-P-F(3)  90.9(7)  90.8(10)  F ( l ) - P - F (4)  87.1 (8)  87.1(6)  F(l)-P-F(5)  88.9(10)  91.8 (7)  F(l)-P-F(6)  176.3(11)  85.8 (7)  F(2)-P-F(3)  178.3(7)  94.8 (11)  F(2)-P-F(4)  91.1(7)  91.2 (7)  F.(2)-P-F(5)  89.7 (7)  89.8(7)  F(2)-P-F(6)  90.6 (7)  88.6(10)  F(3)-P-F(4)  87.3 (6)  89.4 (7)  F(3)-P-F(5)  92.0 (7)  91.4(7)  F (3)-P-F(6)  88.8 (7)  176.5(10)  F(4)-P-F(5)  175.9 (10)  178.6 (6)  F (4)-P-F(6)  89.3 (10)  89.7 (6)  F ( 5 ) - P - F (6)  94.7 (11)  89.3 (7)  *  the  numbering  system  of  the  2*  anions  is  arbitrary  -110-  t h e n i c k e l atom r e v e a l s t h a t a d j a c e n t and  (0.032)  below t h e plane  are both  n i t r o g e n s a r e above  and t h e r e f o r e o p p o s i t e  above o r below t h e p l a n e .  I f t h e Ni-N  nitrogens  distances  w e r e a l l t h e same, t h e a p p r o x i m a t e s y m m e t r y a b o u t n i c k e l 4 with respect t o thenitrogen coordinated  to it.  But the  d i s t o r t i o n o f t h e chromophore from t h e 4 - f o l d proper a x i s a n d t h e two 2 - f o l d axes p e r p e n d i c u l a r  6  2  d e s c r i b e d a s 422 o r  * 2  2  The 0 ( l - ) - N ( 5 ) a n d 0 ( 2 ) - N ( 6 ) d i s t a n c e s a r e  unit.  2 . 7 1 6 ( 1 1 ) a n d 2.718  (11)2. r e s p e c t i v e l y , c o m p a r a b l e t o t h e  0-N d i s t a n c e s o f t h e 0 H M(4mepy) (H 0) (PFg) 2  g  about t h e n i c k e l  3.11 shows a v i e w o f t h e N i ( 3 m e p y ) g ( H 0 ) ~  Figure (PF )  rotation  t o i t are not very  g r e a t , a n d t h e symmetry o f t h e l i g a n d f i e l d ion can reasonably.be  would  2  bonding i s l i k e l y  2  (4mepy)  molecular  2  2  axial  species  structure.  i n the  Again  involved i ntheinteraction.  hydrogen  I ti s inter-  e s t i n g t o n o t e t h a t o n l y one o f t h e h y d r o g e n atoms i s f o u n d t o b e H-bonded t o a n i t r o g e n h e t e r o c y c l e i n t h e 3mepy c a s e w h e r e a s t w o 0 — H — N b o n d s a r e s e e n i n t h e 4mepy c a s e . is  o b v i o u s l y t h e reason  bands, one sharp  t h a t t h e r e were two t y p e s  one  o f (0-H)  a n d one b r o a d , seen i n t h e i n f r a r e d  ( S e c t i o n 3.4.1) o f t h e 3mepy c o m p l e x e s .  This  spectra  Significantly,  only  v e r y b r o a d v(O-H) b a n d i s s e e n i n t h e M ( 4 m e p y ) ( H 0 ) ( E F g ) g  compounds where, b o t h  2  2  hydrogens on each water molecule a r e  i n v o l v e d i n hydrogen-bonding. The  c l o s e s t f l u o r i n e - o x y g e n d i s t a n c e s , i n the!  Ni(3mepy) (H 0) (PFg) 6  2  2  2  compound a r e 2 . 9 6 2 ( 1 1 ) 2 b e t w e e n 0 ( 1 )  2  -111-  FIGURE 3.11  VIEW OF  Ni(3mepy) (H 0) (PFg) g  2  2  2  -112-  and  P(2)  and  2.957(12)8 between  interesting from  this  groups very  to  note  that  molecular  are  there  i s no  infrared  spectra.  the  infrared  and  3.4.2.2.4  of  bonding  to  1^0  evidence  of  this  f o r such  6  magnetic  ion  i n an  octahedral  was  found  t o be  2  not  be  data The  and  a  on  6  r  e  ligand as  magnetic  performed  this  1040  and  are  9.19,  of  860  Dq cm  20.87  and  The  and  19.57  reasonable  f i t to  calculated  is The  the  the  PF, 6  (albeit,  interaction weak t o the  from  be  seen  in  limitations  of  the  a powder  2  spectra  a cobalt(II) 2  are  and  therefore  electronic  given  i n Table  the  values  of  respectively  experimental  mull  data.  v-^,  could  spectral III-ll.  s p e c t r a were v^,  and  and  represent  The  value  of  v  temperature  2  a A  1.40. effective  magnetic  moment o f  Co(3mepy)g(H^O)^ 4  is  2  electronic  measurements  The  from  calculated kK  electronic  (Co(3mepy)g(H 0)2(AsFg)  field.  calculated  \  evidence  molecules  susceptibility  2  B  very  2  compound.)  2  that  consistent with  for Co(3mepy)g(H 0) (PFg) values  i s clear  too  p r o p e r t i e s and  unstable  It is  purposes.  2  Co(3mepy)g(H2O)2(PFg)2  spectroscopy  F ( l ) .  i n turn points out  Co(3mepy) (H 0) (EF )  The  there  It is clearly  this  criteria  and  structure determination  the  infrared  although  involved in H  weak),  0(2)  dependent  consistent with  the  nominal  T^  g  (  p F  5  -113-  TABLE  III-ll  ELECTRONIC SPECTRAL DATA FOR  Co(3mepy) (H 0) (PFg)  BAND P O S I T I O N ( k K ) * ASSIGNMENT  V  ( T 4  3  -> T 4  l g  Dq  (cm" )  B  (cm  l g  (P))  1  22.82s  1  0  4  0  • r l  * mull  )  spectrum  860  g  2  2  2  -114-  ground  state  retical that  of  octahedral  curves  the  to  the  electronic  value  of  A  experimental  structure  that ofa.tetragonally The  i s very  A  is  750  3.4.1  2  cm  1  The  indicated  the  aquo  ligand  chromophore  to  complexes  g  similar with  present  (and  Co(3mepy)g(H2O)2( g)2 as  (axially This  the  compressed)  steric The  phore  could  diffraction crystals  are  compound  at  of  the  presence  be  available, the  time  fact,  However, cobalt  cell the  have  to  this  2  same) as  be  the  this  not the  to  the in  a  of  that  the  chromodistorted  3.4.2.2. CoN^C^  single  chromo-  crystal  Although  been  done The  on  6.5.4) do  this  examination  indicate  pattern  observed  for  mean  that  structure  X-ray  good  photographs  that  those  MN^C^  considerations.of  precession  the  of  the  assume  section  not  diffraction  same a s  nature  chromophores.  written.  section  and  the  compressed  had  was  and  section  Co(3mepy)g-  determination.  study  where  same t y p e  r e s u l t s of  thesis  (see  parameters  t h i s does  axially  Weissenberg  2  (in  by  from  presented  the  the  showed  trans-CoN^C^  structure  Co(3mepy)g(H 0)2(PFg) unit  of  verified  molecular  as  in  cobalt(II).  i.e. tetragonally  expected  factors  preliminary  the  be  to  3.4.2.3  the  for  and  complex i s  cm  3.4.2.1  2  regards  have  octahedral  chromophore would  CFSE's and  2  Co(4mepy)g(H2O)2(EFg)2  shows  observed  i s reasonable  complexes  E F  phore  It  111-12)  presented  section  present).  theo-  ( A = 465  section  2  the  3-methylpyridine  those of  f i t of  (Table  Ni(3mepy) (H 0) (PFg)  very  be  this  infrared evidence  that  (H20)2(PFg)2 a r e  data  s i m i l a r to  2  .  of  The  distorted octahedral  Co(4mepy) (H 0) (EFg)2 8  cobalt(II).  are  pn  that  very  similar  Ni(3mepy)g(H 0) (PFg) •  observed  2  parameters  around  2  2  around  nickel(II)  -115-  TABLE  111-12  MAGNETIC PROPERTIES OF Co (3mepy) (H^O) (PFg) g  TTYPVRTMFNTAL EXPERlMjilN 1B.J-1  TEMPERATURE  (  in Kelvin  2  )  V  1 e  f  f  <  -i n  i n  B  '  R  M  2  THEORETICAL  *  M)  ^  U  U  eff  A=1.40,  (i  n  B.M.)  k'=0.95  v = 3 , : X = - 1 5 5 :cm  296.2 272.8 251.3 226.5 203.0 177.9 149.6 139.8 104.0 84. 8  4.93  4.92  4.88  4.90  4.82  4.90  4.85 4.83 4.78 4.70  4.88 4.85 4.82 4.75  4.72  4.73  4.64  4.61  4.52  4.50  -116-  (see  section  metry  to  because  i t would  molecular provide  CoN^G^  be  structure  of the cobalt(II)  evidence  2  6  magnetic  e.s.r.  The  electronic spectra  single  data  band  centered 1  absorption  Never-  obtain  in  order  compressed  Given,  2  properties,  electronic spectral  compounds  of these  i n this  a t approximately (Figure  2.6  section,  Whatever  the nature  symmetry  i s i n d i c a t e d by spectrum  line  shapes  expected  (cf.  Figure  2.8,  or tetragonal  ions  which  be o f a C u N 0 4  splittings compounds  p F  g) 2  Figure a n <  dilute.  that  instead. axial  3J.2  shows  ^ shows t h e (D  properties  information  are magnetically  to expect  (CuN^G^ o r C u N g ) ,  i n an a x i a l  The magnetic  CuNg  chromophore  spectra.  f o r copper(II)  any o t h e r  2  according  octahedral  of the other  the e.s.r.  111-13.  be due t o t h e  of well-defined  o f Cu (3mepy) g ( ^ 0 ) 2 (  do n o t p r o v i d e  copper(II)  600 nm  o f t h e chromophore  p. 5 5 ) .  i n Table  i t i s not unreasonable  would  data  consist of a  p . 51) w o u l d  t h e absence  electronic spectra  e.s.r.  a r e shown  compounds  i n the e l e c t r o n i c spectra  described  compounds  g  o f e i t h e r a rhombic  chromophore. observed  2  f o r these  Hathaway s scale  the  to  complex  f o r the a x i a l l y  Cu(3mepy) (H 0) (EF )  and  the  6.5.3).  chromophore.  The  the  (see s e c t i o n  g  i n t e r e s t i n g and i n f o r m a t i v e  supporting  3.4.2.2.5  to  o f t h e l o w c r y s t a l l o g r a p h i c sym-  of the cationic species,C  theless, the  3.4.2.3)  4 h  )  of  except The  symmetry these that  conclusion  -117-  TABLE I I I - 1 3 ELECTRONIC PROPERTIES OF Cu ( 3mepy) (HjO) ( E F ) g  Cu(3mepy) (H 0) (PF ) g  V  B.M.)  g  2  g  2  Cu(3mepy) (H 0) (AsF ) g  1.88  (b)  _ 16.67  -11 16.81  (c)  16.67  16.67  t >  2.222  2.231  _  2.061  2.061  2.115  2,118  198  174  (kK)i  max  5  d  g  2  1-82  ( a )  err 9 (in Kelvins) E  2  2  gj  a  o A  (e)  y  ( i n gauss)  (a) a t 294K (b) m u l l  spectra  (c) d i f f u s e r e f l e c t a n c e (d) e . s . r .  spectra  s p e c t r a on powders  (e) c a l c u l a t e d b y u s e o f e q u a t i o n 2.5, p.23  2  2  g  2  -118-  FIGURE  3.12  E.S.R.  SPECTRUM  ( powder  OF  Cu(3mepy) (H 0) (PF ) g  a t room t e m p e r a t u r e )  2  2  g  2  -119-  th at  c a n be  copper(II)  CuNg  although  mentioned  (4000-2000 ferences  we  cm  from  ^)  6  contour  2  2  general  shape  copper(II)  3.13  of the spectra  two  sharp  and.one broad  the  other  3-methylpyridine  complexes,  t h e bands  complexes. ligands  This  CuN^C^  infrared  appear  4  single  would  available  crystal  provide  (although  evidence  chromophore. data  determined/  structure determination  Comparing  a  r  3-methyl-  The  This  study  energy  than  copper(II)  that  the  t o those  axial  of the  compounds. 2  2  as t o t h e nature good  crystals  of are  the preliminary.X-raythe data  have  i n  Cu(3mepy)g(H 0) ~  Although  from  bands;  i s consistent with  i n these on  spectra  as i n the other  suggest  similar  e  2  the  that the  i n nature.  separated  chromophore X-ray  .  In the  does  of  spectra o f the  at higher  complexes).  dif-  compounds  t o b e made u p o f t h r e e  conclusive proof  and t h e c e l l  graphs-have been  2  - 1  some  of the other  similar  complexes.  of a CuN 0  cm  spectra  show  i t i s seen  a r e not as w e l l  3-methylpyridine  metal-ligand  time.  p.88),  2  A  compounds  to those  i s  band  the infrared  t o 2000  i n Cu(3mepy)g(^0) (EFg)  presence  ular  4000  ( F i g u r e 3.6  2  the  i t i s a  the infrared  bands  Cu(3mepy)g(H 0)2(EFg)2  (PFg)2  i s that the  tetragonal "octahedral"  3-methylpyridine  shows  from  2  spectral  complexes  3.4.1,  of the other  Figure  o f these  pyridine  the  111-13  do n o t know w h e t h e r  of these  those  section.  other  of Table  elongated  i n section  Cu(3mepy) (H 0) (EFg)  of  the data  chromophore. As  this  from  ion i s i n axially  environment or  reached  collection  n o t been:completed  and at  photomolecthis  -120-  II  A B  S 0 R P T I 0 N +  ENERGY ( cm FIGURE 3.13  2000  3000  4000 )  INFRARED SPECTRA  (H 0)  (EF ). 6  2  (  (4000-200001*" ) o f C u ( 3 m e p y ) 6  s p e c t r u m I , E=P and s p e c t r u m I I ,  E=As) * N u j o l band)  -121-  3.4.3.  RELATION TO  The described and  OTHER WORK  4 - m e t h y l p y r i d i n e and  in earlier  parts  esting  i n sections  constant) a  into  and  s e c t i o n have  of  s e t s around the  the m e t a l - l i g a n d  different ligand When a n a l y z i n g  temperature studies nificant  t o + 20  cm  1  .  of  be  A  (octahedral)  same l i g a n d  This  held set  taken  of  the  section  ligands  the will  a l s o attempt to r a t i o n a l i z e  i n the  d i f f e r e n t compounds  parameters, i t  absence of  values  values be  of  Dq  two  are and  considered  f o r the  same g e n e r a l f o r the  careful  probably  structures of  in preparation  i s observed  (metal i o n  l i g a n d s e t , and  to the  Therefore  n i c k e l complexes,- t h e  obtained  respect  properties  ligand f i e l d  ) , the  summary o f t h e  considered  the  the  range i n these comparisons w i l l  equivalent.  parameters  inter-  species.  that,  (67  are  will  the  important to r e a l i z e  It is  w h i c h have t o be  chromophore.  rise  complexes  chapter.  metal ion  Factors  c o m p a r i s o n and  stoichiometries  pyridine  to e f f e c t of the  stereochemistry  c h e m i s t r y which g i v e s  w i t h the  this  complexes  t h e s e complexes w i t h  account f o r t h i s d i s c u s s i o n  attempt t h i s  will  of  range of metal i o n s .  nature of  this  3.2  the  calculated ligand f i e l d  with respect  themselves, the  the  and  electronic spectra  to d i f f e r e n t ligand  to  3.1  t o compare t h e  from the  the  this  s t r u c t u r e s d i f f e r e n t from those of  described  is  of  3-methylpyridine  the  low  only B  sig-  within  to  be  chromophores  discussion.  For  stereochemistry  chromophores  (NiN  g  and  -122-  NiN^C^) ; w h e r e a s , f o r t h e c o b a l t ( I I ) c o m p l e x e s , t h e s t e r e o chemistries are different  f o r t h e two c h r o m o p h o r e s  " o c t a h e d r a l " v s . CoN^C^ c o m p r e s s e d Finally, of  the s u b t l e concepts  average  will  initially  from  expected  be  (D^) octahedral.  of the application  environment" w i l l  be r e c o u n t e d .  assume t h a t t h i s r u l e behavior  of the ligand  d e a l t w i t h as an e x c e p t i o n t o t h i s  ment r u l e means t h a t a l t h o u g h types o f ligands surrounding s t r u c t u r e o f the metal rather  (CoNg  The d i s c u s s i o n s  i s upheld; field rule  of the "rule  any d e v i a t i o n  p a r a m e t e r s may (the average  t h e r e may be two v e r y a metal  may r e f l e c t  environ-  different  ion, the e l e c t r o n i c  t h e average  than the anisotropy of the l i g a n d  environment  distribution).  F o r t h e compound, N i (py) g (EFg) , t h e v a l u e s o f Dq 2  and  B a r e 1000 a n d 800 c m  - 1  4mepy c o m p l e x e s o f n i c k e l and  of B approximately  are  cm ^ ) .  (1050 cm "*")  t h e same and i n t h e 3mepy c o m p l e x e s , still  The Dq v a l u e s  significantly  In t h e analogous  t h e v a l u e o f Dq i s h i g h e r  t h e v a l u e o f Dq i s h i g h e r (780  respectively.  f o r t h e 3mepy and 4mepy  higher than  the B values a r e probably  (1080 cm ^) and o f B  lower  complexes  t h a t o f t h e p y c o m p l e x e s whereas  approximately  equivalent.  How do  t h e s e p a r a m e t e r s r e l a t e t o t h e s t r u c t u r e and b o n d i n g  i n the  c o m p l e x e s and t h e p r o p e r t i e s o f t h e l i g a n d s i n t h e two c h r o m o p h o r e s ? W a t e r i s a weaker f i e l d ?+  ligand  -1  (Dq f o r N i ( H 0 ) g  =910 cm  3-methylpyridine  a r e stronger bases  2  than p y r i d i n e  (16)) whereas 4 - m e t h y l p y r i d i n e and (and t h u s  probably  -123-  stronger would  field  ligands) than  be expected  to reduce  pyridine the value  (16). Water  as a  ligand  of B  less  than  from  B  Q  2+ pyridine  as l i g a n d  the  with  case  (B(Ni(H 0^  Given  this  (assuming  approximately  complexes  w i t h NiN^C^  same v a l u e  complexes case.  o f Dq  with  The o b s e r v e d  argument  ion  i n t h e NiN^G^  larger  six in  average  complexes  i s related  in  Dq a n d a d e c r e a s e  ligand the  The  case,  data  i n B  complexes,  involving  the metal  chromophores.  g  This  four molecules  lengths  may  by  result  i n t h e 4mepy a n d  complexes.  Thus,  would  to the pyridine  since  be an i n c r e a s e  expected  metal-  complexes,  as  indicate. among  the cobalt(II)  complexes  brings i n the complication of  complexes  of the ligand with  show t h e s e  the value  situation  effect  by  i s surrounded  (due t o g r e a t e r t h a n  compared  comparison  ligands  the nickel(II)  (1/a ) t h e o v e r a l l  The comparison  same  by  around  i n the NiN  i n the pyridine  factors.  the  rings  ligands.  previously,  cobalt(II)  than  i s not the  a n d two s m a l l e r , w a t e r  mentioned  the  this  aromatic  interaction),  experimental  the pyridine  i o n i s surrounded  than  to  However,  m e t a l - l i g a n d bond  Dq  approximately  o f B than  repulsions  that  a n d 3mepy  the nickel(II)  heterocyclic  shorter  3mepy  inter-ligand  in- the l a t t e r  large  value  expect  t h e 4mepy  have  be  electron  c a n be r a t i o n a l i z e d  chromophores  case,  also  of less  lengths)  chromophore.  parameters  heterocyclic  whereas  bond  and a l a r g e r  of less  the.former  equal  g  would  i n f o r m a t i o n , one would  chromophores would  the NiN  the  In  this  t h e m e t h y l p y r i d i n e s because  delocalization.  the  )=890);  2  o f Dq,  those  field  anisotropic  parameters  of nickel(II)  as  of  containing  effects.  For the Co(py) (EF )^  9 8 5 cm  i s very  g  similar  g  to  that  -124-  o b s e r v e d , 1000 cm of  f o r the Ni(py)g(EFg)  1  g=(B/B ) f o r t h e c o b a l t ( I I ) Q  the  c o m p l e x e s i s 0.84 w h e r e a s f o r  n i c k e l . ( I I ) c o m p l e x e s , i t i s 0.74.  (H 0) (EFg) 2  2  complexes. is  5%.  complexes  2  i s 2% h i g h e r  there  isa  fact that  are  b e i n g compared i n t h e c o b a l t  In  then f o r the Co(py)g(EFg)  smaller  increase  octahedral  structures  and t e t r a g o n a l  octahedral  2  are closer  i n the n i c k e l  t o the metal i o n than t h e stronger  It pyridine  ligands, field  appears t h a t  regular  pyridine  make any f u r t h e r the  aquated It  which gives pyridine, are  c o m p l e x e s c a n be o f these ligand  complexes.  B u t i t w o u l d be d i f f i c u l t  to  r a t i o n a l i z a t i o n s on t h e s e systems w i t h o u t analogous  c o m p l e x e s t o compare them t o .  i s i n t e r e s t i n g to speculate rise  moieties  o f t h e c o m p l e x e s i n r e l a t i o n t o t h e more  X-ray c r y s t a l l o g r a p h i c r e s u l t s and w i t h o u t  pyridine  both  t h e Dq and B v a l u e s o f t h e 3 - m e t h y l -  i n terms o f t h e p r o p e r t i e s  the structures  ligand  distance.  and 4 - m e t h y l p y r d i n e aquated  explained and  a r e a t t h e same  octa-  complexes.  4mepy, w h e r e a s i n t h e a n a l o g o u s n i c k e l ( I I ) c o m p l e x e s , types o f ligands  reflects  structures  t h e c o b a l t ( I I ) - 4 m e p y complexes, t h e weaker f i e l d  H 0,  complexe  complexes whereas o n l y  a r e b e i n g compared  2  i n Dq f o r t h e  complexes than f o r t h e n i c k e l ( I I ) complexes  the  hedral  The Dq f o r t h e Co(4mepy)g  The d i f f e r e n c e between t h e a n a l o g o u s n i c k e l  The f a c t t h a t  cobalt(II)  complexes; t h e v a l u e  2  to the differences  on t h e c h e m i s t r y  i n t h e p r o d u c t s when  4 - m e t h y l p y r i d i n e , and 3 - m e t h y l p y r i d i n e  p r e p a r e d u n d e r t h e same c o n d i t i o n s .  complexes  O t h e r s have  found  -125-  that metal(II) and  3-methylpyridine  When N i ( C 1 0 ) 4  in  perchlorates with pyridine,  2  form a s i m i l a r  hydrate  aqueous s o l u t i o n ,  Ni(4mepy) (H 0) (C10 ) , 4  It  2  2  array of d i f f e r e n t  i s reacted with  the products 4  and  2  4-methylpyridine, compounds.  these n e u t r a l l i g a n d s  formed a r e  Ni(py) (C10 ) , 4  Ni(3mepy) (H 0) (C10 ) . 4  2  2  4  2  4  (15,  seems t h a t w h e t h e r o r n o t w a t e r c o o r d i n a t e s does n o t  upon t h e  anion present,but  heterocyclic will  be  acids in  ligand .  bases  (92)  and  the  theory  16).  depend  of the n e u t r a l  o f these  systems  o f s o f t and  hard  e q u i l i b r i a which are  present  solution.  metal  t o SHAB t h e o r y ,  ions are a c i d s .  hard  or intermediate  this  theory  T h e s e a c i d s and i n character.  are  l i g a n d s under study hard  l i g a n d s a r e b a s e s and  An  b a s e and  similar  here  ( i g n o r i n g the  p y r i d i n e i s an  p y r i d i n e s c a n be  harder  than p y r i d i n e .  considered  o f the e l e c t r o n i c  soft,  more n u c l e o p h i l i c  Of  of  and  a n i o n s ) water i s a ;  acids. t o be  The  the c o b a l t ( I I )  methylsub-  intermediate  This i s because if ;  i s considered  the  i s harder)  bases  electronic  as a p e r t u r b a t i o n  s u b s t i t u t e n t makes t h e  ( i . e . the l i g a n d  and  the metal  s t r u c t u r e of p y r i d i n e , the p r i n c i p a l  i s t h a t the methyl  the  concept  i n t e r m e d i a t e b a s e and  s t r u c t u r e of the m e t h y l p y r i d i n e s  clusion  important  i n character.  n i c k e l (II) i o n s are i n t e r m e d i a t e  stituted  b a s e s c a n be  i s t h a t t h e b e s t e n e r g y m a t c h between a c i d s  b a s e s i s when t h e y  but  r e s p e c t to the  (SHAB)  According  and  This chemistry  examined w i t h  and  o n l y upon t h e n a t u r e  2  and  con-  nitrogen makes  the  -126-  ligand  a p o o r e r TT a c c e p t o r  because o f l e s s a b i l i t y  ( i . e . the ligand  i n these  soft  a s a IT a c c e p t o r l i g a n d ) .  Before considering theory  i s less  t h e a p p l i c a t i o n o f t h e SHAB  systems, t h e r e a c t i o n  understood.  Using  our  reaction  conditions)  the  pyridine  o r substituted  conditions  the hydrated metal(II)  ions  i n aqueous s o l u t i o n pyridine  have t o be ( n i t r a t e s under  means t h a t  before  a r e added t h e p r e d o m i n a n t 2+  species  i n s o l u t i o n a r e t h e hexaquo i o n s ,  the p y r i d i n e l i g a n d s b e l o w i s s e t up:  are present  (  H  2  0  )  (6-x) x L  Since the pyridine ions  (they  ligands,  to  the metal.  When  i n solution, the equilibrium  +  +  x+i i  L  ligands  M ( H  displace  2  0 )  (5-x) (x l)  are a better  are a l l intermediate  L, w i l l  .  2  v  K  M  M(H 0)g  L  +  +  V  match f o r t h e m e t a l  i n character),  the neutral  t h e w a t e r m o l e c u l e s and  When t h e r e a c t i o n p r o d u c e s ML^ (H 0) 2  coordinate 2+ 2  , there  a p p e a r s t o be d i f f e r e n c e s . i n b e h a v i o r , d e p e n d i n g upon w h e t h e r L  i s a substituted  pyridine  or pyridine i t s e l f . If L i sa 2+ substituted p y r i d i n e , the M L ( H 0 ) i s t h e end p r o d u c t a n d p r e c i p i t a t e s (or c r y s t a l l i z e s ) out of s o l u t i o n . If Li s 2+ 2+ p y r i d i n e , t h e p r o d u c t s formed a r e N i ( p y ) (C10 ) o r N i ( p y ) 4  2  2  4  (PF,~) where t h e w a t e r l i g a n d s  a r e no l o n g e r  4  g  coordinated.  6  These o b s e r v a t i o n s symbiosis  (9'3a) • The  inherent by  c a n be r a t i o n a l i z e d by t h e c o n c e p t o f  hardness o f an a c i d i c o r b a s i c  property  the other  site  o f a p a r t i c u l a r atom b u t c a n be  substituents  present;  i s n o t an influenced  this effect i s called  -127-  symbiosis.  The r e l a t i o n d f t h i s c o n c e p t t o t h e p r e s e n t  d i s c u s s i o n i s t h a t a s more p y r i d i n e l i g a n d s a r e c o o r d i n a t e d t o t h e m e t a l i o n (K^ t o K^) t h e c o m p l e x becomes s o f t e r i n n a t u r e and t h u s w a t e r a b l e as a l i g a n d be d i s p l a c e d .  as a h a r d e r bases  become l e s s  compati-  a n d t h e w a t e r s become more l a b i l e a n d c a n However, t h e m e t h y l p y r i d i n e bases  t h a n p y r i d i n e a n d when more o f them a r e added  are harder  (K^ t o K^)  2+ the complex N i L ( H 0 ) 4  2  2  i s harder than the corresponding  p y r i d i n e complex and a p p a r e n t l y water  l i g a n d s , hard  bases,  are r e t a i n e d i n t h e f i r s t c o o r d i n a t i o n sphere o f t h e m e t a l ( I I ) ion.  -128-  3.5  TETRAHEDRAL OF  P Y R I D I N E AND  COBALT(II);  Co(py) (EF ) , 4  Co(4mepy) (EF ) 4  3.5.1  g  g  COMPLEXES  Co(3mepy) (EF )  2  4  g  and  2  2  INTRODUCTION  This CoL (EF ) 4  g  These  section  m a t e r i a l s were  cussed  from  them  compounds  of the  obtained, by h e a t i n g  type,  and As.  o r vacuum  drying  t h e o c t a h e d r a l c o b a l t ( I I ) complexes  usual  i n complexes  distorted  with  4 m e p y , a n d 3mepy a n d E=P  i n the previous The  state  deals  where L=py,  2  techniques,  ion  METHYLPYRIDINE  sections of this  chapter.  c o o r d i n a t i o n geometry  of the type,  octahedron  with  Co(py) A 4  coordinated  structures of the CoL (EF ) 4  g  to contain non-coordinated  2  about  i s a  anions.  anions  the cobalt(II)  tetragonally The  complexes,  2  dis-  solid  however,  show  and t e t r a h e d r a l  2+ "CoL  " complex  4  complexes CoL (EF ) 4  from  g  cations.  t o be d i s c u s s e d 2  those  compounds  show  of similar  Unlike  the nickel(II)  i n the next a radical  compounds  with  chapter,  departure other  and  copper(II)  these i n structure  weakly  basic  anions. This  section  characterization spectra be  spectra.  of these  and magnetic  discussed  discusses  first,  the results  compounds.  The  properties o f these followed  The m o l e c u l a r  by  o f the  electronic compounds  a d i s c u s s i o n of the  structure determination  of  will infrared  -129-  Co(4mepy)^(PFg)2, techniques^will compared  relation  of  confirms  be p r e s e n t e d ;  to other  homoligand  with  which  of this  work  weakly  RESULTS  to previous  complexes  of  electronic  AND  spectral  15. mull  details  i n Chapter  6.  PROPERTIES.  f o r the  111-14 '.•  CoL^tEFg^  In" t h e - m u l l  spin-allowed  The  (especially  spectra are too large  and a r e c o n s i s t e n t w i t h  the  for a the  spectra,  transitions  are observed.  o f t h e bands  determined  Dq  and B v a l u e s  These were c a l c u l a t e d spectrum  i n the diffuse  L=3mepy,  18.20 kK  by C o t t o n  from  and t h e c e n t e r  observed  noted  The  visible  centrosym-  proposed  chromophore.  The III-  complexes  4  data  f o r a l l three  i n the solution  tetrahedral  be  the  on C o ( p y ) A 2  MAGNETIC  i n Table  coefficients  chromophore  Finally,  are given  a tetrahedral cobalt(II) species  metric  compound w i l l  be d i s c u s s e d .  compounds  SPECTRA  a b s o r p t i o n bands  band)  these  DISCUSSION  are presented  extinction  the  AND  of  with tetrahedral  work  basic anionswill  ELECTRONIC  The  the  this  c o b a l t ( I I ) compounds  the synthesis of these  3.5.2.1  then,  o r h e t e r o l i g a n d chromophores.  other  3.5.2  the findings  (94) , t h e r e  the v  of the  spectrum  a n d 18.30  kK  i n Table  determined  2  of gravity  reflectance  f o r L=py,  are given  from band  (18.10 kK f o r  f o r L=4mepy).  a r e some w e a k b a n d s  due t o  As spin  2 forbidden  transitions  (excited  s t a t e s from  the  D  free ion  -130-  TABLE ELECTRONIC  SPECTRAL  111-14 DATA FOR C o L ( E F ) 4  g  2  BAND P O S I T I O N ( k K )  ASSIGNMENT 4 A.  T (F)  "T.  i  (d)  T (P) 1  X  COMPOUND Co(py)  4  (PF ) 6  (a)  2  5.33w,br  9.26m  5.4 6 w , b r  9.26m  5.56w,br  9.43m  (bj Co(py)  4  (AsF ) g  (a)  2  (b) Co(4mepy) (PF ) 4  g  (a)  2  (b) n.o.'  (c)  5.48w,br  Co(4mepy) (AsFg) (a) 4  {  2  9.17(83) 10.5sh 9.43m  (b)  n.o.  (c) Co(3mepy) (PFg) 4  5.21w,br 9.30m  (a)  2  9.09(64)  (b)  ^n.o.  (c)  5.26w,br 9.30m  Co(3mepy) (AsFg) (a) 4  8.51(79)  2  (b) n.o.  8.70 (77)  (b) d i f f u s e  reflectance  (c) ;  (a)mull  spectrum  spectrum brackets,  (CH C1 ); 2  2  (d) s p i n  molar  17.7s 22.7w 19.1sh 26.Ow 17-.9s • 22.7w { 19.4sh 17 .7s 23.Ow { 19.5sh 17.7s 2 3 . Ow { 19.5sh 18.2s { 19.0sh 17 .7s { 18.9sh 17.9(611) { 18.9sh 18.25s { 18.9sh 17.7s 22.7w { 18.9sh 25.3w 17.7 (489) { 18.9sh 17.5s 22.7w { 19.6sh 25.6w 17.7s 22.7w { 18.9sh 25.6w  {  ;  rl7.98 (490)  ^18.86sh 17.4s 23.3 19.0sh 17.7s 22.7w 19.2sh 26. Ow ,17 .86 (233) H s . e s h (c) s o l u t i o n  extinction coefficents i n  forbidden  transitions  -131-  TABLE 111-15 LIGAND F I E L D PARAMETERS FOR C o L ( E F g ) 4  COMPOUND  Dq(cm ) 1  Co(py) (PF ) 4  g  Co(py) ( A s F ) 4  Co(4mepy)  g  2  2  Co(4mepy) (AsFg) 4  Co(3mepy) (PFg) 4  1  546  740  555  735  550  730  g  2  2  Co(3mepy) (AsF ) 4  (cm )  2  (PFg)  4  B  2  2  -132-  term) n e a r v^.  Because o f t h i s ,  t o be v i s u a l l y  estimated.  The are  band p o s i t i o n s o b s e r v e d  slightly  state  the center  different  spectra.  from those  i n the s o l u t i o n spectra  observed i n t h e s o l i d  T h i s may be a c o n s e q u e n c e o f a s l i g h t l y  cobalt(II)  environment  or angles)  i n s o l u t i o n than i n the s o l i d The  as  values  lODq) i n e a c h  this  o f g r a v i t y had  (with r e s p e c t  t o Co-N bond state.  o f lODq a n d t h e p o s i t i o n o f V-^ ( d e f i n e d  s p e c t r u m do n o t a g r e e e x a c t l y .  Also  However,  i t i s s u b j e c t t o i n t e r f e r e n c e s from 4  Therefore,  T  the center It  Co(py)  2 + 4  4  o v e r t o n e s a n d o v e r l a p w i t h v ^ ( &2~* i ( ) ) •  vibrational  - 1  distances  i s p e r h a p s n o t t o o s u r p r i s i n g s i n c e t h e V-^ band i s v e r y  weak a n d b r o a d .  cm  ,  o f g r a v i t y was d i f f i c u l t  i s interesting  546 c m  - 1  ,  ( s e c t i o n 3.2).  F  t o determine.  t o n o t e t h a t t h e Dq v a l u e f o r  i s about h a l f t h a t o f C o ( p y ) In f a c t ,  2 + g  same m e t a l - l i g a n d  should  ,  985  c a l c u l a t i o n s b a s e d on a p u r e l y  i o n i c model p r e d i c t f o r t h e same l i g a n d s a n d m e t a l the  different  distances,  i o n with  t h e Dq o f t h e o c t a h e d r a l  complex  be  (9/4) t h a t o f t h e t e t r a h e d r a l complex. Multiplying 2+ t h e Dq o b t a i n e d f o r C o ( p y ) b y (9/4) l e a d s t o t h e p r e d i c t i o n 2+ -1 t h a t Dq f o r C o ( p y ) s h o u l d be 1229 cm o r some 25% l a r g e r 4  6  than observed.  The d i s c r e p a n c y  i s likely  i n p a r t due t o t h e  limitations  of using  a purely  i o n i c model.  However, t h e  discrepancy  i s also  probably  due t o d i f f e r e n c e s i n s t e r i c  r e p u l s i o n s between t h e l i g a n d s i n t h e two complex T h a t i s , t h e Co-N bond d i s t a n c e s  are probably  species.  longer  i n the  -133-  C o ( p y ) g 2+  species  than  i n the sterically  less  crowded  2+ Co(py) in  species.  4  F o r example,  C o (4mepy) ( H 0 ) R  2  2  3.4.1.1) w h e r e a s (section  (PFg)  2  t h e Co-N (and 0) d i s t a n c e s  are greater  t h e Co-N d i s t a n c e s  3.5.2.2)  a r e 2.01A*.  Since  than  2.102.  (section  i n Co(4mepy) (PFg) 4  2  Dq i s p r o p o r t i o n a l t o  5 1/a  , t h e 5% i n c r e a s e i n b o n d  hedral a  cm  from  tetra-  to octahedral  s t e r e o c h e m i s t r y may b e u s e d t o c a l c u l a t e -1 2+ o f 9 6 0 cm f o r Co(py)g . T h e o b s e r v e d Dq o f  Dq v a l u e  985  length on going  1  i s i n remarkably - good  agreement w i t h  this  calculated  Dq. A the  crystal  Simply, be  o f coordination chemistry  f i e l d model  4  i n order 4  2  a Dq v a l u e 2  o f Dq c a l c u l a t e d  agreement  2  with  by t h i s  2  complexes,  4  One a p p r o p r i a t e 2+  2  i s 5 0 0 cm  value  o f 54 6 cm  would  4  3 9 0 (9"5/).  method  the experimental  should  2  for Co(py)  2 8 0 (9.4.") a n d D q (Co ( p y ) B r ) ,  Dq(CoBr ~),  value  4  environment".  CoX Y  and CoY  4  Dq(CoY )=Dq(CoX Y ).  to calculate  utilizing  o f average  o f t h e Dq's o f t h e C o X  1/2 D q ( C o X ) + l / 2  choice  i s the "rule  t h e Dq o f a h y p o t h e t i c a l c o m p l e x ,  t h e average  ie.  be  concept  The i n good  obtained  1  here. The  values  dependent  upon  which  -  EFg  are  L and t h e f a c t  anion  coordinated 546(py),  o f Dq o b t a i n e d  i s present  anions.  4  2  are  t h a t Dq i s n o t d e p e n d e n t  i s further  The v a l u e s  550 (3mepy),  for CoL (EFg)  evidence  upon  f o r non-  o f Dq a s a f u n c t i o n o f L  and 555(4mepy).  The d i f f e r e n c e s  -134-  observed  i n t h e Dq v a l u e  basicities >3mepy  follow  o f the three  >py)•  the trend  ligands  (96)  But i t i s probably  2+ CoL^  these  in  t h e c a l c u l a t i o n due t o b r e a d t h The  pounds  species  t o b e 550+5  magnetic  a r e summarized  cm  from t h e  strength:  4mepy  to consider  -1  because  of these  t h e Dq  of the error  of the spectral  properties i n Table  (base  better  of  expected  bands.  CoL (EFg) 4  111-16 a n d a r e  com-  2  consistent  4 with of  a  A  these  The  ground  2  state.  compounds a r e t e m p e r a t u r e  6 values  determined  zero  f o r the pyridine  This  suggests  that  from  the pyridine  arrangement  substituted  pyridine  crystal  around  ligands  X-ray  shows t h e C o ( 4 m e p y )  2 +  properties  i n the other have  the cobalt  i n the other  cation  moments  independent.  ligands  diffraction 4  magnetic  the magnetic  and non-zero  tetrahedral  single  The e f f e c t i v e  study  t o have  on a  are  complexes.  a more  than  regular  the methyl-  complexes.  The  Co(4mepy) (PF^) 4  slightly  2  distorted  t e t r a h e d r a l ^ chromophore. 3.5.2.2  MOLECULAR  The determination structure anions,  STRUCTURE OF  details  4  of the crystal  are presented  consists  Co(4mepy) (PF )  PF ~, a n d t h e c l o s e s t 6  6.5.1.1.  cations, contact  2  and m o l e c u l a r  i n section  of distinct  g  The m o l e c u l a r  Co(4mepy)  between  structure  them  2+ 4  , and  i s 3.28(3)2  -135-  TABLE 111-16 SUMMMARY OF MAGNETIC PROPERTIES OF C o L ^ ( E F ) g  COMPOUND  y « ( 295K)  y  " ( l i n B.M.)  ( i n B.M.)  o  f  f  ( 80K)1  0(1  4.30  4.29  0  4.33  4.31  0  4.33  4.26  -7  Co (4mepy) ( A s F ) _  4. 35  4.24  -5  Co(3mepy) (PF )  4.28  4.28  1  4.42  4.40  2  Co(py) (PF ) 4  Co(py)  4  6  2  (AsF ) 6  2  Co(4mepy) (PF ) 4  4  6  2  g  4  6  2  Co(3mepy) (AsSF ) 4  g  2  2  -136-  between F ( 2 )  C(6).  8  P angles  and  P  Co  d e f i n e d by one and of  and  129.35(4)°.  two  closest  a cation.  angles are l i s t e d  The  crystallographic  symmetry a b o u t from  cobalt  T^  the r i n g s .  N-Co-N a n g l e s g e n e r a t e d  a x i s and  atom l i e s  between t h e  axis  tetrahedral  of  pyridine  pyridine of for  this  motion,  ( 90  ( r e f . 97  t h e PF  by one  b  and  113.8°,  109.47°.  t o be  i s planar w i t h i n experimental  error  0. 2 8 8 o u t o f t h i s p l a n e ; t h e  angle  the plane of the r i n g  angles of the  observed  f o r example).  as h a s  The  T^  The  i s 2 8°; t o be  0° o r 4 5 ° .  4-methylpyridine study  f o r c o o r d i n a t e d 4-methylThe  bond l e n g t h s and  ~ anion are consistent with those normally  anion.  of  respectively  angles  t o those d e r i v e d i n a microwave ) and  by  two  a x i s because  b o n d l e n g t h s and  are s i m i l a r  and  4  symmetry w o u l d r e q u i r e t h e a n g l e  The ring  and  i s S (4)  along the  symmetry w o u l d r e q u i r e b o t h  but the cobalt  111-17.  the o r i e n t a t i o n  o p e r a t i o n s a r e 1 0 1 . 2 ( 9 ) ° and  4-methylpyridine moiety  P  symmetry i s shown  along the  r e p r e s e n t a compression  packing  cation.  i n Table  the compression  and  100.54(2°)  A l l o t h e r Co  shows a s t e r e o v i e w o f t h e  the d e v i a t i o n o f the c a t i o n  P)  88.  b o n d l e n g t h s and  successive  closest  operations are  The  The  and  shows a s t e r e o v i e w o f t h e  around  are g r e a t e r than 3.15  P d i s t a n c e i s 5.499(4)  successive  anions  Figure  Co  (between t h e Co  F i g u r e 3.14  these c l o s e s t  distances  The  thermal  been observed  parameters by  indicate  other authors  found  large  (91,  angles  thermal  98-103).  -137-  FIGURE  3.14  STEREOVIEW SHOWING THE PACKING  CATION. for  FIGURE  (The atoms o f t h e a n i o n and c a t i o n  20% and 50% p r o b a b i l i t i e s ,  3.15 are  OF ANIONS ABOUT A  respectively)  STEREOVIEW OF THE C o ( 4 m e p y ) drawn f o r 50%  a r e drawn  probability)  4  CATION.  ( A l l atoms  -138-  TABLE I I I - 1 7 BOND DISTANCES AND ANGLES IN C o ( 4 m e p y ) (estimated (i)  standard deviations  4  (PF ) g  2  i nbrackets)  BOND DISTANCES (8) Co-N  = 2. 01(1)  '  = 1. 39 (2)  C(3)-C(6)  = 1. 52(2)  N-C(l)  1. 39 (2)  N-C(5)  = 1. 37 (2)  P-F (1)  = 1. 54 (2)  C(l)-C(2)  = 1. 40(2)  P-F(2)  = 1. 51(2)  C(2)-C(3)  = 1. 40(3)  P-F (3)  = 1. 45(2)  C( 3)-C(4)  = 1. 38 (2)  ;  (ii)  C(4)-C(5)  BOND ANGLES  (deg)*  N-Co--N'  =113.8(5)  F ( 3 ) - -P- F ( 3 ) '  = 180 (2)  N-Co--N"  =101.2(9)  F ( 3 ) - -P- F ( 2 ) '  = 91(1)  C(5)- - N - C ( l )  =119 (2)  F ( 3 ) -P-• F ( l ) '  = 91(1)  N - C ( l ) - C ( 2 ) -'•= 121(2.)  F ( 3 ) -P-•F(2)  = 89(1)  C ( l ) - C ( 2 ) - C ( 3 ) =120(2)  F ( 3 ) -P-- F ( l )  = 89(1)  C(3) - C ( 4 ) - C ( 5 ) =121(2)  F ( 2 ) -P--F(3) '  = 91(1)  F ( 2 ) -P--F(2)  = 91(2)  =121(2)  C(4) - C ( 5 ) - N  C(2) - C ( 3 ) - C ( 6 ) = 117 (2)  F ( 2 ) -P-- F ( l ) '  =177(1)  C(4) - C ( 3 ) - C ( 6 ) =123(2)  F ( 2 ) -P-- F ( l )  = 92(1)  F ( l ) _p.- F ( 3 ) '  = 91(1)  F(l) -P-F(1)'  * atoms marked but  1  = 86(2)  (' o r ") a r e n o t c r y s t a l l o g r a p h i c a l l y  unique  g e n e r a t e d b y t h e symmetry o p e r a t i o n s o f t h e s p a c e  group.  -139-  This  a n i o n w o u l d be  and  show c o n s i d e r a b l e  nearly  spherical The  expected  t o have l a r g e  apparent  distortion  temperature due  factors  to i t having  symmetry.  CO-N  distance  of  2.01  7A f o u n d  i n our c a t i o n i c  2+ species, CoN^  Co(4mepy)  tetrahedral  examples.  The  4  , i s i n t h e r a n g e .normally o b s e r v e d  c h r o m o p h o r e s as shown by  tetrahedral  CoN^  following  chromophore has  c r y s t a l l o g r a p h i c a l l y withthe anionic complexes,  the  for  been  l i g a n d , NCS  examined  i n the  tetrakis(thiourea)mercury(II)tetrakis(isothiocyanato)  cobaltate(II) trihydrate  (104), p o t a s s i u m t e t r a k i s ( i s o t h i o c y a n a t o ) c o b a l t a t e ( I I )  ( 1 0 5 ) , t r i s (ethylenediamLne) c o b a l t ( I I I ) t e t r a k i s  (isothiocyanato)cobaltate(II)nitrate  ( 1 0 6 ) , and  1,4-diphenyl-  3 - p h e n y l a m i n o - l , 2 , 4- t r i a z o l i u m t e t r a k i s ( i s o t h i o c y a n a t o ) c o b a l t a t e (II)  (107)-  The  Co-N  distances  found  i n t h e s e compounds  2.01 ( 2 ) , 1.949 ( 7 ) , 1.928 (12)-1.966 ( 1 5 ) , and Examples o f complexes : c o n t a i n i n g which a l s o  give  this  CoN^  a n i o n i c . <bidentate  (1-pyrazolyl) borato) c o b a l t (II)  1  distortion 8.  (108)  and  s t r u c t u r a l parameter  from  tetrahedral  3 i s defined  with the  axis  value observed  ligands  bis(dihydrobis  (109); t h e Co-N  t h e s e compounds a r e 1.981 (7)-2 . 066 (8) and respectively. The  respectively.  chromophores a r e b i s ( N - t e r t - b u t y l -  pyrrole-2-carboxyaldimino)cobalt(II)  in A,  2.052 ( 5 ) ,  are  (T )  usually  to D  d  as t h e a n g l e t h a t and  2  distances  1.967  used  to  symmetry,is  the metal  (average)  indicate the  angle,  l i g a n d bond makes  i n t e t r a h e d r a l symmetry i t i s 5 4 . 7 ° . The 2+ f o r the Co(4mepy) c a t i o n i n t h i s study i s 4  -140-  56.8°. and  The  effects  electronic  of t h i s  distortion  on  the magnetic p r o p e r t i e s  s p e c t r a f o r the Co(4mepy)^(EFg)  2  complexes  were d i s c u s s e d e a r l i e r .  3.5.2.3  VIBRATIONAL  The  SPECTRA  characterization  as b e i n g t e t r a h e d r a l a n i o n s , EF, , from b  of these C o L ( E F g ) 4  complexes o f c o b a l t ( I I )  the  first  c o n f i r m the assignments The  infrared  spectra  be  e x a m i n e d now  The  evidence  bands o f  the  1,  of the  techniques.  the other p h y s i c a l  the s t e r e o c h e m i c a l l y  the observed  anion vibrations)  assigned  and  4mepy f o r t h e s e c o m p l e x e s .  f o r non-coordinated  Table  spectrum  show  of  ( 2g)  positions well  o t h e r compounds d e s c r i b e d i n t h i s the c h a r a c t e r i s t i c  and  the  (A^ )  symmetry, a r e s e e n  g  and  (0^)  from infrared  i s no  t h e compounds have  anion spectra. transitions,  v (E ) 2  There  2  g e n e r a l l y (as f o r t h e  chapter)  "non-coordinated"  formally allowed  s t r o n g bands and  removed  111-19 shows t h e b a n d s i n t h e  vibration  T  5  expected,  Co(3mepy)^(EFg)  f o r the  v  As  p y r i d i n e o r 4mepy.  evidence  i n 0^  will  structure.  assigned t o the v i b a t i o n s of the anions.  the  molecular  on  spectra  v^,  anions  section,  ( w i t h e m p h a s i s on  Table Al-3)  f r e e base v a l u e s .  and  The  described i n the l a s t  3mepy i n t h e i n f r a r e d  (see A p p e n d i x  details  the  111-18 g i v e s t h e p o s i t i o n s o f t h e s t e r e o c h e m i c a l l y  s e n s i t i v e bands o f py i s no  The  with respect to t h i s  Table  there  2  based  s i g n i f i c a n t bands o f L and  excludes  c o o r d i n a t i o n sphere.  are, t h e r e f o r e , non-coordinated. s t r u c t u r e of Co(4mepy)^(PFg)  compounds  2  g  Specifically,  are seen  as  bands, f o r m a l l y f o r b i d d e n  i n t h e s p e c t r a o f t h e PFg  and  AsFg  -141-  TABLE I I 1 - 1 8 NEUTRAL LIGAND BANDS I N THE INFRARED SPECTRA OF C o L ( E F ) 4  (L=py a n d 4mepyj E=As  E=P ( i ) PYRIDINE 8a  415m  419m  6a  643m  646m  1613m  1613m  16b  (ii)  4-METHYLPYRIDINE 560m  6a  810s  816s  10b+12  (b)  1 9a  1240m  1240w  19a  1512m  1512m  8a  1622s  1622s  (a) o b s c u r e d b y v  3  (b) o b s c u r e d b y p  C  of PF H  g  a t 1040 cm  1  6  2  -142-  TABLE  III-19  ANION BANDS I N THE INFRARED SPECTRA OF  ( i ) E=P  848  V lu T  4  V  lu  ( T  V  840vs,br  554s  557s  555s  740w  7 4 2w  710 }vs 685  697vs  690vs,br  395s  392s  395s  572w  n.o.  n.o.  (a)  E=As 3  (  T  lu  }  , .(b) v  l  v  2  2  J  W (ii)  }vs  g  840vs  836  }  4  L=3mepy  L=4mepy  L=py  CoL (EF )  (  A  ( E  l g g  )  y  n.o,  (a) p o s s i b l y o b s c u r e d b y v  4  of PF  (b) p o s s i b l y o b s c u r e d b y v  3  of AsF  6  g  -143-  compounds, r e s p e c t i v e l y ; a s weak b a n d s .  That  at  symmetry e f f e c t s .  a l l i s probably The  a consequence o f s i t e  d e t a i l e d appearance o f t h e a n i o n bands, i s  d i f f e r e n t depending on t h e n e u t r a l the  v  3( j ) T  u  t h e y a r e seen  band a p p e a r s  ligand present.  F o r L=py,  t o be made up o f two components.  T h i s may be due t o v e r y l o w s i t e  symmetry o r t o f a c t o r g r o u p  splitting,  anions  i e . two t y p e s  o f EFg  F o r L=3mepy t h e r e i s no e v i d e n c e the  v  2( g) E  v  A  F o r L=4mepy, t h e " n o r m a l "  t h e a n i o n bands a r e o b s e r v e d  than  f o r e i t h e r the ^ ( ^ g )  o  r  v i b r a t i o n , p e r h a p s i n d i c a t i v e o f 0^ symmetry  environment f o r the anions. of  i n the l a t t i c e .  0^ s i t e It  consistent  with  behavior  slightly  lower  symmetry. i s i n t e r e s t i n g t o note  the r e c i p r o c a l r e l a t i o n 2+  s h i p between t h e symmetry o f t h e CoL^ by e  c a t i o n as i n d i c a t e d  ( T a b l e 111-16) a n d t h e symmetry o f t h e E F g  as d i s c u s s e d i n t h e l a s t  paragraph.  environment  The p y r i d i n e  complexes  w h i c h h a v e t h e h i g h e s t symmetry c a t i o n s  (6=0) have t h e two  inequivalent  symmetry  EFg  anions  o r lowest  site  anions;  w h e r e a s , t h e 3mepy a n d 4mepy w h i c h have t h e more d i s t o r t e d cations  (6^0)' h a v e h i g h e r symmetry e n v i r o n m e n t s  f o r the anions.  -144-  3.5.3  RELATION TO OTHER WORK  As  mentioned  i n s e c t i o n 3.5.1, most  (tetrakis)-  p y r i d i n e complexes o f c o b a l t ( I I ) c o n t a i n i n g weakly b a s i c have b e e n a s s i g n e d  p s e u d o - o c t a h e d r a l chromophores.  compounds C o ( p y ) ^ A 2 , where A i s p e r c h l o r a t e fluoroborate CH S0 ~ 3  3  (no)/  (113),  trifluoroacetate  The  (110),  (111),  tetra-  methylsulphate  and t r i f l u o r o m e t h y l s u l p h a t e C F S 0 ~ 3  have b e e n c h a r a c t e r i z e d as t h i s  anions  (112),  3  t y p e o f complex.  The .  C o L ( E F g ) 2 compounds c h a r a c t e r i z e d h e r e have b e e n  assigned  4  2+ t e t r a h e d r a l CoN^  chromophores.  weak c o o r d i n a t i n g fluoroarsenate  abilities  T h i s must be due t o t h e  o f h e x a f l u o r o p h o s p h a t e and hexa-  compared t o t h e f o r m e r  Many compounds c o n t a i n i n g cobalt(II)  a r e known  (60); Table  anions.  tetrahedrally  coordinated  111-20 l i s t s some o f t h e s e  compounds w i t h t h e l i g a n d f i e l d p a r a m e t e r s d e r i v e d f r o m t h e analysis of their electronic spectra. The v a l u e o f Dq o b s e r v e d i n o u r C o L ( E F g ) 2 compounds 4  of  the values-  listed  (550-5 cm "*") i s l a r g e r t h a n a l l  i n Table  a consequence o f the l i g a t i n g spectrochemical  now d i s c u s s  o f complexes c o n s i d e r e d (where L i s a p y r i d i n e a f t e r our i n i t i a l 12 p . 937  species  .  This  being  i s presumably  lower i n the  s e r i e s than the p y r i d i n e ligands  We w i l l  (Vol.  111-20  some r e c e n t  studied  literature  t o have t h e t e t r a h e d r a l CoL^ ligand).  report  (1976)).  A l lthese reports  i n Inorg.  and N u c l .  The compound  here.  reports 2+ species  appeared  Chem. L e t t e r s  (Co(py) ) (Zn(NCSe) ) 4  4  -145-  TABLE  III-20  LIGAND F I E L D PARAMETERS OF SOME TETRAHEDRAL COMPLEXES OF COBALT(II)  ( a )  1 0 D q ( c m }.)  COMPLEX  B(cm  2  "  3125  710  2  "  2800  695  Co(NCS) "  4550  691  Co(NCSe) ~  4710  653  Co(N0 )  4660  755  A7 4 2<-C\ 50  600  3920  658  CoCl  4  CoBr  4  2  4  2  4  2  3  Co(tu)  (a)  2  _  2  "  4  Co(N ) 3  4  4  " n~\ (b)  from r e f e r e n c e  (b) t u = t h i o u r e a  33  1  )  -146-  has  been a s s i g n e d  a  structure  containing  2+ Co(py) '  tetrahedral  4  2cations of  Dq  and  and  tetrahedral  B calculated  s p e c t r u m were 4 89 are  and  Zn(NCSe) f o r the  608  anions  4  cation  cm " " r e s p e c t i v e l y . -  species  values  electronic These  1  v a l u e i s much c l o s e r t o t h a t  and  The  from the  i n disagreement w i t h those determined  f o r m e r Dq  (84).  parameters  i n t h i s work.  reported  f o r Co(NCSe)  i s , i n f a c t , i n e x c e l l e n t agreement w i t h the  calculated  by  using  Co (NCSe) ^ (py)  the  r u l e of  average environment  ( c a l c u l a t e d Dq=492 cm  some s c r a m b l i n g  "*") .  The 2-  This  4  value  f o r the  perhaps  speci  indicates  of  t h e l i g a n d s , py and NCSe , between t h e 2 + 2 + . two m e t a l i o n s , Co and Zn i n t h e compound o f stoichiometry, CoZn(py) (NCSe) . 4  4  Some compounds have been r e p o r t e d  and  where L  is a substituted  have been a s s i g n e d  pyridine  a structure  containing  2+ the  tetrahedral  CoL  species.  4  T h e s e compounds  ( C o L ) ( C u ( S C N ) ) 2 where L = 2 - m e t h y l p y r i d i n e , 4  and  2  3-aminopyridine  from the 379  and  (86).  e l e c t r o n i c spectra 630  reported. s h o u l d be  cm  Dq  are:  4-aminopyridine,  and  B values  464  and  673  calculated cm  (L=2mepy);  1  f o r L=3ampy i s n o t 2+ A s s u m i n g t h a t t h e Dq v a l u e f o r t h e C o L species 2+ s i m i l a r t o t h e Dq f o r C o ( p y ) , t h e v a l u e o f Dq 1  The s p e c t r u m  4  4  for CoL (NCS) 2  (L=4ampy) .  The  are  2  from the  a v e r a g e r u l e w o u l d be  456  cm  1  .  This 2+  is  s i m i l a r to the  species. analysis.  Again  o b s e r v e d Dq  some l i g a n d  values assigned  scrambling  to  the  CoL  i s s u g g e s t e d by  4  this  -147-  .These two CoL^ 2 + s p e c i e s calculated observed  from  electronic  i n t h i s work.  (Cu(SCN) ) , 2  15.39  kK  This corresponds  4  2  s t u d i e d by  max  from  at  Co(3ampy) (Cu(SCN) ) i 4  4  54 9 nm  o t h e r w o r k e r s and  2  2  compounds.  2  f o r the  pyridine  s t u d i e d here,  a  discrepancy. The  thfe s o l i d  last  4  described  section w i l l  are exposed to p y r i d i n e vapor.  2  exposure,  formed.  discussion of t h i s  focus  on  s t a t e t r a n s f o r m a t i o n s w h i c h t a k e p l a c e when s a m p l e s  of Co(py) (EFg)  The  homogeneous C o ( p y ) g ( E F g )  characterization  i n section  between t h e two  3.2.2  different  of these  and  As  a  compounds  2  latter  t h e means o f  because  chromophore  t o o c t a h e d r a l CoNg u n d e r t h e m i l d e s t  4  Co(py)g(EFg)  converts quickly  was  t y p e s o f compounds i n 3.2.3.  of conditions (vaporized p y r i d i n e ) . reversible;  are  differentiating  o f t h e i n s t a n t a n e o u s change i n t h e c o b a l t ( I I ) t e t r a h e d r a l CoN  result  compounds  These t r a n f o r m a t i o n s are r a t h e r i n t e r e s t i n g  from  15.55, 4  f o r the C o ( p y ) ( E F g )  o f 64 3 and  were  Co(2mepy) ~  4  and  2  Dq's  those  f o r Co(py) Zn (NCSe) ,  observed  to a i  L  this  kK  The  bands were o b s e r v e d  4  compared t o 18.20  of  spectra different  The  tetrahedral  erroneous.  Co(4ampy) (Cu(SCN) ) ,  2  complexes  the i s o l a t i o n o f  (84,86) a p p e a r t o . b e  16.14, 14.29, and  sizable  r e p o r t s on  2  The  when h e a t e d  to Co(py) (EFg) . 4  process  t o 80°C " i n v a c u o "  T h e s e two  2  i s also  transformations  are r e p r e s e n t e d below: Co(py)  4  (EFg)  Co (py) g (EFg)  2  2  ("in vacuo" c o n d i t i o n s ) RT + 2py -> Co (py) ( E F ) g  £ o 0  c  Co(py) (EFg) 4  2  g  + 2py  2  (3.1) (3.2)  -148-  If  the  long  pink  compound, Co (py)  period  to the  o f time  (1-2  (EF ) , i s l e f t  g  g  2  years),  p r e s e n c e o f Co (py)  (EF )  4  g  This  take place  a t room t e m p e r a t u r e and  may  really  be  an  Co(py) (EF ) 4  And  thus  (3.1)  and  to r a p i d l y s h i f t for  the  desired If  it  g  the  + 2py  2  are  these  t Co(py) (EF ) 6  species t h a t we  stabilization  considerations.  the  CoN^  g  just  are should  The  thermodynamics i n c o o r d i n a t i o n  4 Co-N  (3.2)  energy  CFSE and  (3.3)  2  the  conditions  direction  chromophore  chemistry  are  the  overall  bond e n e r g y  the  formation  enough N  octahedral  EF  the  smaller  ~ a n i o n ) and  of  the  ligands  are  complex i s u n s t a b l e  lattice 2+  Co ( p y ) steric  energy  considerations  room t e m p e r a t u r e l o s i n g p y r i d i n e t o f o r m t h e O t h e r f a c t o r s s u c h as  4  with  crystal  bond  at  the  the  (provided  in equilibrium,  t r y t o examine some  (CFSE) and  favor  truly  s p i t e of t h i s ,  with  needed  appropriate  parameters a s s o c i a t e d  overall  bonds) w i l l  perhaps favor  can  transformation  In  complex.  be  below.  e q u i l i b r i u m i n the  thermodynamic p a r a m e t e r s .  (6 v s  compound c a n  therefore  really  due  product.  seems r e a s o n a b l e  field  pink  for a  tinge  transformation  e q u i l i b r i u m as  (3.2)  the  red-purple  i n the  2  observed.  (3.1)  suggests t h a t  the  standing  CoN  provided). even  tetrahedral  energy e f f e c t s  cation in  over  g  (which  combination  effects clearly  play  an  import  D  r o l e i n d e t e r m i n i n g t h e r e l a t i v e t h e r m o d y n a m i c s t a b i l i t i e s .of 2+ 2+ the C o ( p y ) and C o ( p y ) species. 4  g  -149-  CHAPTER 4  COMPOUNDS CONTAINING COORDINATED HEXAFLUOROPHOSPHATE AND  HEXAFLUOROARSENATE  This on  d i s c u s s the r e s u l t s o f our  t h e compounds N i L ( E F g ) ( L = p y , 4 m e p y , E = P , As 4  E=As) and  with  4  infrared  differing reason, ML^A  g  magnetic p r o p e r t i e s of these spectral  degrees  Included  be  of metal-anion o f and  complexes w i l l  characterization cussed.  d a t a may  be  interaction.  criteria  thermal  CuL,(EF,)~ these  2  the  the  4  X-ray  unusual  4  Finally,  compounds.  2  s t u d i e s t h a t the N i L ( E F g ) this  chapter w i l l  the  dis-  p r o p e r t i e s o f N i ( p y ) ( A s F g ) , and  decomposition  were s u b j e c t e d t o .  this  t h e n be  a r e r e p o r t s on 4  temperature  of  D e t a i l s of  s t r u c t u r e determination of Ni(4mepy) (PFg) , variable  along  i n terms For  complexes w i l l  section  electronic  for anionic coordination  discussed f i r s t .  of the n i c k e l in this  compounds  interpreted  studies  L=3mepy,  The  2  the concept 2  and  2  CuL (EF ) (L=py,4mepy,3mepy, E=P,As).  s p e c t r a l and  in  chapter w i l l  2  the  compounds  consider  the  D e t a i l s o f t h e methods o f p r e p a r i n g  complexes a r e g i v e n i n Chapter  6.  -150-  4.1  CRITERIA FOR COORDINATION  Whether o r n o t a n a n i o n i o n depends on many f a c t o r s : present, the  lattice  anion,  the b a s i c i t y  sufficiently  requirements o f the metal.  This  o f compounds N i ( X - p y ) ^ ( C l O ^ )  2  pyridine) (pK  where i f t h e b a s i c i t y  • of the corresponding  perchlorate there  a r e no o t h e r  It  MA , 2  the coordination  i s seen i n t h e s e r i e s  (where X-py i s a s u b s t i t u t e d o f X-py i s o v e r a c e r t a i n  (6.6).  salts,  >6.00) t h e  On t h e o t h e r  hand, i f  6  D  ability  t h a n most o t h e r  I f t h e PFg  anions  and A s F g  2  compounds  2  compounds  because o f t h e l a r g e d i f f e r e n c e s i n t h e c o o r d i n a t i n g  it  complexes.  to very  then,  strengths  tetragonally  I n d e e d i t may l e a d t o c o m p l e x e s where  i s n o t c e r t a i n even t h a t t h e anions  coordinated.  presented  anions are i n t i m a t e l y  the metal i o n i n M(py)^(EFg)  o f p y r i d i n e a n d EFg , t h i s may l e a d  such  (as e v i d e n c e d b y t h e 4  s e c t i o n 3.5.3).  coordinated. and A s F ,  comparison o f t h e s t r u c t u r e s o f the C o ( p y ) A  distorted  level  e s t a b l i s h e d t h a t the anions PF,  and t e t r a f l u o r o b o r a t e  associated with  than the a n i o n i c  f o r example) t h e a n i o n s must be  have l e s s c o o r d i n a t i n g  in  ligands  l i g a n d s p r e s e n t ( i e . a compound o f t h e  i s well  perchlorate  effect  pyridinium  i s not coordinated  stoichiometry  as  greater  s u c h t h a t t h e s e l i g a n d s may s a t i s f y  ligands  and s i z e o f  ( 1 7 ) . F o r example, t h e o t h e r  may h a v e a L e w i s b a s i c i t y species  t o a metal  the nature of the other  energy e f f e c t s ,  and o t h e r s  coordinates  I t i s important,  should  be  then, t o develop  w h i c h may be u s e d a s e v i d e n c e f o r o r a g a i n s t  considered criteria  anion  coordination.  -151-  The electronic  spectral  under study, (iii)  criteria and  (ii)  infrared  f o r c o o r d i n a t i o n may  involve  magnetic p r o p e r t i e s of the  (i) the complex  X-ray c r y s t a l l o g r a p h i c evidence,  spectral  evidence  ( i f the  anion  and  i s polyatomic).  Specifically: (i)  The  the e l e c t r o n i c the  spectral  stereochemistry,  must i n c l u d e t h e of  a n i o n may  be  and  given  anions  considered  coordinated i f  magnetic p r o p e r t i e s i n d i c a t e that the  s t o i c h i o m e t r y of the  i n the  first  compound,  c o o r d i n a t i o n sphere  the metal i o n . (ii)  The  anion  may  be  X-ray c r y s t a l l o g r a p h i c evidence  considered  i s a v a i l a b l e and  bond d i s t a n c e s w h i c h l i e w i t h i n t h e radii and  and  the  sum  the  van  the  anion  2  the anion  isotropic  rotational disordering).  anion  2  the  be  considered  i n d i c a t e t h a t the  i s g r e a t l y reduced  consistent with  structure with  a n i o n may  s p e c t r a l data  ionic  ion  no  ion (for tetragonal  evidence  for  coordinated i f symmetry  below i t s " f r e e i o n "  l o w e r symmetry e x p e c t e d  a structure  definite  anion would occupy d e f i n i t e  in trans-Ni(py)^A  The  t o occupy  respect to the metal  positions  (iii)  the  distortions  s t r u c t u r e f r o m i t ' s " f r e e i o n " s h a p e and  example i n M ( p y ) ^ A , t h e  the  of  of. t h e m e t a l  c o n c l u s i v e would i n c l u d e l a r g e  coordination positions with  infrared  sum  M-A  Other c r y s t a l l o g r a p h i c evidence  w h i c h shows t h e d o n o r atoms o f  the  shows  range o f the  d e r Waals r a d i i  d o n o r atom o f t h e a n i o n .  w h i c h w o u l d be of  of  coordinated i f  for a  of  symmetry coordinated  -152-  anion.  F o r example,  "ionic"  salts  tion,  this  i f t h e symmetry o f t h e a n i o n  and C . j i n t h e monodentate be r e f l e c t e d  bands i n t h e i n f r a r e d  in  coordinated  v  should  is  situa-  i n t h e number a n d i n t e n s i t y o f  spectra.  An example o f t h e u s e o f t h e a b o v e c r i t e r i a c o o r d i n a t i o n compounds o f w e a k l y b a s i c a n i o n s earlier and  4  2  2  infrared  The e l e c t r o n i c  spectral  s p e c t r a , and s i n g l e c r y s t a l  have been p u b l i s h e d .  diffraction spectral  o f pseudo-octahedral  bands i n t h e v i s i b l e to c r i t e r i o n  coordinated (II)  The and  p e r c h l o r a t e anions  B.M.). and  (I) and compound  confirm  i s a five  This  this.  atom s p e c i e s  (=3N-6) d e g r e e s o f v i b r a t i o n a l  T h e r e a r e f o u r f u n d a m e n t a l modes o f v i b r a t i o n ;  2  modes b o t h  salts.  f o r compound  The i n f r a r e d d a t a  2 T ' s which a r e both  bands  =  e  ( i ) , implies non-coordinated  t h e r e f o r e there are nine  freedom.  nickel(II)  r e g i o n and ^ f f 3 ' 2 7  p e r c h l o r a t e anions  respectively.  behavior  ( I I ) shows t h e  =  e  according  and m a g n e t i c  (one s t r o n g band i n t h e e l e c t r o n i c  s p e c t r u m a n d y f f 0 ) /' w h e r e a s , compound behavior  studies  (I) show t h e c h a r a c t e r i s t i c  square p l a n a r n i c k e l ( I I )  characteristic  dimethyl-  and m a g n e t i c p r o p e r t i e s ,  The e l e c t r o n i c  p r o p e r t i e s o f compound  (two  i n t h e (114)  work on t h e compounds, N i (3, 4 - l u t i d i n e ) (ClO^) (I) /  pyridine).  E  i s found  N i ( 3 , 5 - l u t i d i n e ) (ClO^,) ( I I ) , (where l u t i d i n e =  for  with  infrared  a n d Raman a c t i v e and A  o f w h i c h a r e Raman a c t i v e  expected  i n the infrared  The i n f r a r e d  only.  and  So, t h e r e , a r e two  spectrum o f simple  s p e c t r u m o f KCIO^ (89b)., shows  perchlorate three  -153-  b a n d s , two and  one  strong  weak  (v (T ) 3  I  cm  s t r o n g b a n d a t 1108  hand, t h e region  "*") t h e cm  spectrum of  1  molecular  nickel  and  neighbour than and  of the  the  of  o x y g e n and  perchlorate indicative  t h e van thus  anions of the  interaction.  The  too  and  typical  of nickel(II) (trans)  this  symmetry,  3 v  the  assignment o f  of  square  perchlorate anions.  d i s t a n c e i s 3.343 2 , d e r Waals r a d i i long  compound planar  around The  nearest  a value  greater  (3.1-3.2 7A(93b)) f o r n i c k e l  f o r a chemical  linkage.  The  perhaps  structural  parameters of the c a t i o n  the  of  other  strong d i r e c t i o n a l  and  the  angle  3,4-dimethylpyridine  planar  molecular  by  very  absence o f  f o r square  consistent with  C  a r e , moreover, d i s o r d e r e d ,  the p l a n a r  The  the  I I shows t h r e e bands i n  structure determination  ( N i - N d i s t a n c e i s 1.897(3) 2 plane  .  coordinated perchlorate.  non-coordinated  sum  the  substituted pyridine ligand  nickel-oxygen  cm  report  On  when i t p o s s e s s e s  I(T15)' i s c o n s i s t e n t with coordination  -1  indicative  perchlorate.  compound  of unidentate  cm )  v-^(A^) 935  a s s i g n a b l e to ClO^  a s s i g n a b l e to ClO^  The  (T^)  630  2  s p e c t r u m shows o n l y one  (non-coordinated)  indicative  4  (the p r e v i o u s workers d i d not  s p e c t r a b e l o w 700  "ionic"  ^ (T )  - 1  (the f o r m a l l y f o r b i d d e n  F o r compound  an  1050-1170 c m ,  2  cation-anion  between the ring  i s 90°)  NiN^ are  nickel(II).  s t r u c t u r e o f compound  II  (116) i s  assignment of pseudo-octahedral  four 3,5-dimethylpyridine  perchlorate anions.  The  coordination  l i g a n d s and  nickel-oxygen  two  distance i s  -154-  2.187(2) 2 , distance The  the  and  effect  nitrogen  considerably c l o s e to the  sum  of p e r c h l o r a t e  bond d i s t a n c e  a v e r a g e NiN^  These are  shorter of  ionic  van  radii  coordination  p l a n e and  der  Waals  (2.10  2).  i s seen i n  2.093(2) R and  of  t y p i c a l values  than the  the  angle  3,5-dimethylpyridine  for octahedral  range  from  nickelbetween  plane of  n i c k e l ( I I ) complexes.  The  -N-Ni-0 a n g l e s  81.3(2) t o  the  p e r c h l o r a t e .anions o c c u p y d e f i n i t e . . a x i a l p o s i t i o n s . Compound I I f u l f i l l s  97.7(3)° i n d i c a t i n g  a l l criteria  f o r anionic,  c o o r d i n a t i o n w h e r e a s compound I d o e s n ' t f u l f i l l But be  s e v e r a l s i t u a t i o n s can  be  envisioned  such c l e a r evidence r e g a r d i n g a n i o n  example, c r i t e r i o n quite different chemistries.  Nickel(II) satisfies  any  coordination. metal  this  of  does not  stereochemistry  and  ( i ) more d i f f i c u l t  complex c o u l d be criterion  Also there  may  not  t h i s makes t h e  in  and the  a  when other  function  a p p l i c a t i o n of  criterion  Even i n the n i c k e l ( I I )  t h u s making t h e  questionable  considering X-ray  stereo-  that a tetragonally distorted  anions are  be  case.  spin-paired  (i> o n l y , a  whether o r not  change s p i n s t a t e as  in this  case i t i s conceivable  On  not  has  requirement,  or t e t r a h e d r a l , i t i s s p i n - f r e e .  hand c o p p e r ( I I )  these.  For  ion  in different  t h a t when i t i s s q u a r e p l a n a r , i t i s s p i n - p a i r e d octahedral  of  where t h e r e may  ( i ) w o r k s b e s t when t h e  electronic properties  46.6°.  procedure  octahedral  a p p l i c a t i o n of for  determining  coordinated. the  other  criteria  ( i i and  c r y s t a l l o g r a p h i c evidence or  iii),  the  -155-  i n f r a r e d s p e c t r a l e v i d e n c e may to the  latter,  n o t be d e f i n i t i v e .  In  regard  the metal-anion i n t e r a c t i o n , though  definite,  may  o n l y cause a s m a l l p e r t u r b a t i o n of the anion's  structure  and  hence the  coordinated  intrinsically  may  n o t be m a n i f e s t e d  I n c o n c l u s i o n we whether or not  l o w e r symmetry o f t h e a n i o n  feel that  i n the  infrared  when  spectrum.  i n addressing  the question  of  the anions are coordinated  i n complexes  of  the type s t u d i e d here, i t i s necessary to apply  as many  criteria  h a v e done i n  our  f o r c o o r d i n a t i o n as p o s s i b l e .  r a t h e r d e t a i l e d s t u d i e s on  t o be  described  T h i s we  the N i L ^ f E F g ^  i n the next s e c t i o n .  compounds  -156-  4 .2  COMPLEXES OF NICKEL (II) ; N i L ^ ('EFg)  2  4.2.1  INTRODUCTION  As  noted  i n t h e i n t r o d u c t i o n ( s e c t i o n 1.1.2), t h e  compound N i ( p y ) ( P F g ) 4  to  2  was f o u n d  by M a y f i e l d and B u l l  have an anomalous m a g n e t i c moment o f 1.98 B.M.,  because i t i s i n d i c a t i v e o f a s p i n - d o u b l e t whereas, i n m a g n e t i c a l l y a singlet  or t r i p l e t  was p r e p a r e d 100°C this on  this  nickel(II)  systems  state i s possible.  degradation  The compound  of Ni(py)g(PFg)  authors.  this  the formation  have been h e a t e d  Our work  o f a white  sublimate  Ni(py)g(PFg)  a t t e m p e r a t u r e s o f 100°C  S e c t i o n 4.2.2.4.3 d e s c r i b e s t h e c h a r a c t e r i z a t i o n  subliminate  the r e s i d u e l e f t Ni(py) (PFg) . 4  at  2  results.  t h e c o o l e r p o r t i o n s o f t h e vacuum f l a s k when  or higher.  only  No f u r t h e r p h y s i c a l c h a r a c t e r i z a t i o n o f  have o b s e r v e d  2  anomalous  ground s t a t e ,  compound h a s y i e l d e d v e r y d i f f e r e n t  or N i ( p y ) ^ ( P F g )  of  d  compound h a s b e e n r e p o r t e d by t h e s e  We on  ground  by t h e r m a l  " i n vacuo".  dilute  (14)  2  a s t h e compound, .-py'PFg.  behind  cannot s t i l l  This behavior  Clearly,  be f o r m u l a t e d  then,  as  i s g e n e r a l l y observed  s e r i e s o f compounds N i L ^ ( E F g ) ,  when t h e y  100°C.  measurements o n t h e r e s i d u e  2  left for  Magnetic  over  after  susceptibility varying periods  of heating  t h e compound N i ( 4 m e p y ) ( P F g ) 4  2  a r e heated  f o r the above  are described  i n s e c t i o n 4.2.2.4.1.  2  -157-  The  results  show t h a t  the molar  magnetic  a f u n c t i o n o f the h e a t i n g time that  the decomposition  pure  NiL (EFg)2 4  susceptibility i s  and t e m p e r a t u r e  and  product i s paramagnetic.  c o m p l e x e s we c o n c l u d e d  that  indicate  To o b t a i n  i t was  necessary  t o a v o i d h e a t i n g where p o s s i b l e , a n d where n o t p o s s i b l e , t o carefully  purify  t h e p r o d u c t by  recrystallization.  N i ( p y ) ^ ( E F g ) 2 c o m p l e x e s were p r e p a r e d  The  i n the  p r e s e n t work f r o m t h e N i ( p y ) g ( E F g ) ^ c o m p l e x e s a t room by  stirring  i n dichloromethane.  of  the v o l a t i l i t y  of pyridine  and  avoids the p o s s i b i l i t y  The  Ni(4mepy) (EFg)2  N i(4mepy) (H 0)2(EFg)2 2  i n t h e N i (py)g ( E F g ) ^ compounds  of s i g n i f i c a n t  formed  by room t e m p e r a t u r e  of Ni(3mepy)g(H 0)2(AsFg)2 2  disappeared)  4.2.2.  4.2.2.1  recrystallization The  Ni(3mepy) (AsFg) 4  " i n vacuo"  drying  t h e w a t e r band i n t h e i n f r a r e d i n chloroform.  ELECTRONIC SPECTRAL  PROPERTIES  the exception of N i ( p y ) ( A s F g )  4.2.2.4), t h e magnetic  NiL^(EFg)2  decomposition.  DISCUSSION  MAGNETIC AND  With in  (till  f o l l o w e d by s t i r r i n g  RESULTS AND  thermal  compounds f o l l o w e d by  from a d i c h l o r o m e t h a n e - c h l o r o f o r m s o l v e n t . compound was  advantage  were p r e p a r e d by h e a t i n g o f t h e  4  R  T h i s method t a k e s  temperature  4  2  (discussed  and s p e c t r a l p r o p e r t i e s o f t h e s e  compounds a r e a l l s i m i l a r  i n nature.  The  electronic  2  -158-  s p e c t r a o f t h e s e compounds c o n s i s t  (Table IV-1).  band i n t h e v i s i b l e  region  spectrum  f o r square  and in  is typical  the e x t i n c t i o n 4  g  Ni(3,5-lutidine) (C10 ) , 4  4  o f 80-90 M  complexes  2  2  kK,  spectrum been  (e=ll)  i s also  e=110M~ cm~ 1  a weaker band i s sometimes n o t e d 16.55  cm  1  4  typical  4  no  shows t h e d i f f u s e of the N i L ( A s F )  here.  The  o f the center of g r a v i t y  , appears  4mepy>py. position  4  to s h i f t  v m  a  x  g  vs.  22.9  anion  cio " 4  kK  i n the  2  studied  o f t h e band,  i n the s e r i e s : 4  i s independent  of E  for Ni(4mepy) (C10 ) 4  indicative  complexes  electronic  3mepy>  t h e compounds N i L ( E F g ) , t h e  to note t h a t the p o s i t i o n o f v ^ max compounds and  2  t o h i g h e r energy  However, w i t h i n of  (eg.  reflectance  (350-740 nm)  nicix  Although  such bands have  specta  v  (eg.  study.  4.1  position  observed  (19)).  1  band  complexes  1  for Ni(3,5-lutidine) (C10 ) )  in this Figure  single  a t lower energies  of square p l a n a r n i c k e l ( I I ) ,  found  This  planar nickel(II)  coefficient  the N i ( 4 m e p y ) ( E F )  of a single absorption  perhaps  i n t e r a c t i o n w i t h t h e two  4  .  2  It i s interesting  f o r the  Ni(4mepy).(EF,)« 4 6 2 r  j  (19) a r e d i f f e r e n t  2  of a d i f f e r e n t types of anions  degree (EF  (22.1  of metalvs.  g  ). The m a g n e t i c  them t o be  essentially  properties  o f the N i L ( E F ) , 4  g  compounds  diamagnetic a l t h o u g h t h e r e appears —6  some r e s i d u a l p a r a m a g n e t i s m p r e s e n t (see A p p e n d i x  2)).  This residual  (^300  x 10  —1 mole  to  show be  3 cm  a t 295K,  paramagnetism i s b a s i c a l l y  -159-  TABLE IV-1 ELECTRONIC  SPECTRAL  DATA FOR  NiL (EF )  BAND POSITION  4  g  2  (kK)  COMPOUND Ni(py) (PF ) 4  6  2  Ni(py) (AsF ) 4  6  2  Ni(4mepy) (PFg) 2 4  Ni(4mepy) (AsF ) 4  g  Ni(3mepy) (AsF ) 4  (a) m u l l  g  spectra  2  2  (a)  21.51  (b)  21.41s  (a)  21.51  (b)  21.41s  (a)  22.5s  (b)  22.1s  (c)  22.0(90)  (a)  22.2s  (b)  22.1s  (c)  22.1 (82)  (a)  23.26  (b)  22.47s  (c)  22.32(85)  (b) d i f f u s e r e f l e c t a n c e  (c) s o l u t i o n s p e c t r a ( C H C 1 ) 2  (M  _ 1  cm  _ 1  )  i n brackets.  2  spectra  ; molar e x t i n c t i o n c o e f f i c e n t s  -160-  -161-  temperature its  independent  origin.  states effect  but  T h e r e may  be  i n t o the ground (section  behavior  some m i x i n g  term, through  2.2.2).  seems t o be  some u n c e r t a i n i t y  e x i s t s as  of excited a second  a characteristic  paramagnetic  order  Whatever t h e cause,  to  this  Zeeman  magnetic  property of  these  compounds. The are  c o n s i s t e n t w i t h the  square of  electronic  p l a n a r NiN^.  Ni(4mepy)^(PFg)  this  but  also  be  4.2.2.2  IV-2,  8a v i b r a t i o n  This  i n the  anion  infrared  inter-  spectra  VIBRATIONAL- SPECTRA  Ni(3mepy)^(AsFg)2  of  confirms  o f v e r y weak a x i a l  o f which a r e seen  or  t h e s e compounds.  Table  4.2.2.3  next.  4-methylpridine,  in  as  structure determination  discussed i n section  T h e r e i s - no  of  molecular  i n d i c a t e s presence  discussed  magnetic p r o p e r t i e s  f o r m u l a t i o n o f the chromophore  The  2  a c t i o n , the e f f e c t s to  s p e c t r a and  evidence  3-methylpyridine For  compounds and  in•the infrared  see A p p e n d i x - 1 ( T a b l e :  t h e r e i s no  the  16b  spectra  t h i s b e h a v i o r may The  be  As  shown  assigned to  vibration  compared t o t h e  than observed  when v e r y s t r o n g l y bound.  Al-3).  band w h i c h c a n be  o f p y r i d i n e and  i s larger  pyridine,  t h e p o s i t i o n s o f t h e bands o f  7 0 cm~^~ t o h i g h e r e n e r g y shift  f o r non-coordinated  has  free  a  the  shift  ligand  i n most p y r i d i n e c o o r d i n a t i o n characteristic  of p y r i d i n e  corresponding stereochemically  -162-  TABLE I V - 2 SELECTED NEUTRAL LIGAND BANDS I N THE INFRARED SPECTRA OF N i L ( E F g ) 4  NiL (PFg) 4  (i)  NiL (AsFg)  2  4  2  L=PY 8a  1612s  1612s  6a  n.o.  n.o.  16b  470w  469w  8a  1620m  1620m  19a  1513m  1513m  9a  1250vw,1240vw  1  1054w  1053w  10b+12  817s  820s  6a  ---( )  (ii)  L=4mepy  (a) p o s s i b l y o b s c u r e d b y v  1250w, 1240vw  a  4  (T ) l u  5  of PF  g  7  5  m  2  -163-  s e n s i t i v e bands o f 4 - m e t h y l p y r i d i n e show some features; the is  t h e 6a band  i s shifted  by +50  cm  interesting  r e l a t i v e to  1  f r e e b a s e , and t h e l a band a p p e a r s a s a weak band when i t usually  a moderately strong  band.  T a b l e IV-3 shows t h e i n f r a r e d the  EFg  anions.  -  The g e n e r a l  bands a s s i g n e d  feature of the anion  to  spectra,  along w i t h the appearance o f the f o r m a l l y allowed  and  bands, i s t h e p r e s e n c e o f b o t h t h e v, (A,-,) and v? (E^)  bands,  which are formally band o f P F g  -  forbidden  i n 0^  symmetry.  and t h e v ( E g ) bands o f A s F g i n the i n f r a r e d  a p p e a r a s bands o f medium i n t e n s i t y . AsF  and t h e v» (E„) band o f PF,z g b  -  b  anion v i b r a t i o n s . ( i n 0^  symmetry)  anionic The  splitting are  formally  do n o t .  Figure of  4.2  spectra Bull  4  2  complexes.  T  t o show some  o f PFg-.  bands  interference  account f o r the  spectra 4  (1000-350 2  above.  t h e band a t 470 cm  the 5 ( 2 g ) v i b r a t i o n  of the  and N i ( p y ) ( A s F g ) .  show t h e f e a t u r e s d i s c u s s e d  (14) had a s s i g n e d v  (PFg)  other  bands.  shows t h e i n f r a r e d  t h e compounds N i (py)  to  and t h i s may  of these  they  forbidden  However, t h e s e  q u i t e b r o a d and i n some c a s e s s u b j e c t  splitting  separated  a r e o f t e n maslced by  b a n d s , s u g g e s t s t h a t t h e symmetry  ligand vibrations  A  (A^g) band o f  The a p p e a r a n c e o f t h e s e  i n l o w e r symmetry  lack of resolved  to  The  v i b r a t i o n s w h i c h w o u l d be e x p e c t e d  by n e u t r a l  ^( ig)  s p e c t r a and  e n v i r o n m e n t i s l o w e r t h a n 0^ i n t h e s e and  v  are well  2  from o t h e r anion v i b r a t i o n s  The  1  Mayfield  These and  i n Ni (py) (PFg)  However, t h i s  cm  4  2  band a p p e a r s  1  )  -164-  TABLE I V - I  ANION BANDS IN THE INFRARED SPECTRA OF  ASSIGNMENT  BAND POSITION Ni(py) (EF ) 4  g  4  g  2  (cm" )  Ni(4mepy) (EFg) 4  NiL (EF )  1  2  Ni(3mepy) (EF ) 4  ( i ) E=P  Vlu> T  4  v  v v  (ii)  ( T  lu  l )  iV (  2 g (E  )  847vs,834vs  558m  558m  740m  7 4 4m  ___( )  ___•(*)  700vs  700vs  7 00vs  395s  397s  392s  67 2m-w  672m  665s  565m  565m  555m-s  a  E=As  3 lu>  v  843vs,br  (T  V lu T  W W  }  (a) may be h i d d e n by t h e v ( T 4  l u  )  band e n v e l o p e  g  2  -J.OO-  1000  800  -  ENERGY FIGURE 4.2  INFRARED 4  spectrum  2  400  (cm ) - 1  SPECTRA  Ni(py) (EFg) .  600  (1000-350 cm" )  ( spectrum  I I i s E=As)  1  OF  I i s E=P and  -166-  in  the spectrum o f N i ( p y ) ( A s F g ) 4  have any b a n d s i n t h i s  vibration of pyridine.  and  Bull's  observed We  the other  2  authors  sample o f N i ( p y ) g ( P F g )  4.2.2.3  observed  t h e band i n t h e i r  of N i ( p y ) (PFg) 4  (section  2  impurity i n  2  3.2.2).  MOLECULAR STRUCTURE OF N i ( 4 m e p y ) ( P F g ) 4  The determination 6.5.2.  b u t was n o t  2  s p e c t r a o f N i (py) g (EFg) (E=R and A s ) .  s p e c t r u m due t o t h e p r e s e n c e their  details  of the c r y s t a l  of Ni(4mepy) (PFg) 4  2  4  The  nickel  2  structure  are described i n section  t o the observed  properties of the N i L ( E F g )  2  and m o l e c u l a r  This s e c t i o n discusses the molecular  how i t c a n be r e l a t e d  to the  T h i s band a l s o a p p e a r e d i n M a y f i e l d  spectrum o f N i ( p y ) g ( P F g )  i n our i n f r a r e d  conclude  doesn't  r e g i o n , i t must be a s s i g n e d  16b  infrared  and s i n c e AsFg  2  s t r u c t u r e and  m a g n e t i c and s p e c t r a l  compounds i n g e n e r a l .  atom i s s i t u a t e d  on a c r y s t a l l o g r a p h i c  c e n t e r o f i n v e r s i o n a n d t h e two c r y s t a l l o g r a p h i c a l l y 4-methylpyridine  m o i e t i e s d e f i n e a square  of n i t r o g e n s around t h e n i c k e l . distinct PFg  planar  distinct  environment  T h e r e i s one c r y s t a l l o g r a p h i c a l l y  PFg g r o u p and, b e c a u s e o f i n v e r s i o n symmetry, t h e  g r o u p s o c c u p y p o s i t i o n s a b o v e and b e l o w t h e n i c k e l -  nitrogen  square  planar unit.  v i e w and s t e r e o v i e w Ni(4mepy) (PF ) 4  g  2  F i g u r e s 4.3- and 4..4.- show a  r e s p e c t i v e l y o f the formula  unit  Ni(C H N) .(P(^) 6  FIGURE  4.3  7  4  VIEW OF N i ( 4 m e p y ) ( P F g ) . 4  f o r 50% p r o b a b i l i t y )  2  2  ( A l l atoms a r e d r a w n  -168-  FIGURE 4.4  STEREOVIEW OF N i ( 4 m e p y ) ( P F ) 4  d r a w n f o r 50%  probabilty)  g  2  ( A l l atoms a  -169-  The IV-4.  The  bond d i s t a n c e s and  bond d i s t a n c e s and  p y r i d i n e molecules  are t y p i c a l  as i n C o ( 4 m e p y ) ^ ( P F g ) and in P-F  angles  i n t h e PFg  a n g l e s a r e shown i n T a b l e  angles w i t h i n the for coordinated  (section  2  3.5.2).  group are s i m i l a r  to those  observed (when  d i s t a n c e s are not c o r r e c t e d f o r thermal motions) 86.2  t o 92.3°,  opposite  apparent  distortions  may  indicate  a small disordering  commonly o b s e r v e d The  F-P-F 175.7° to  large thermal o f t h e PFg  nearly spherical  i s 91.6(4)°.  The  i s 3.031(9) 2 between N i and  a n g l e s a r e 89.2  and  crystallographic  inversion)  but  symmetry a b o u t  the approximate  N(2)  nickel  symmetry  the NiN^  nickel  p l a n e and  97.3°, whereas  0°(90°) o r  parameters groups anion  are close  the  to 90°.  The  4-methylpyridine  The  which are  (91 ) . 1.919(10) anion  F(l)-Ni-N  respectively. is I  is  d i s t a n c e s a r e t h e same w i t h i n e x p e r i m e n t a l a n g l e s around  adjacent  nearest nickel  F(l).  9 2 . 6 ° f o r N ( l ) and  the  177.8°.  ;  bond d i s t a n c e s a r e 1.916(9) and  angle  1  and  for this  Ni-N  t h e N^-Ni-N  contact  and  bond d i s t a n c e s  ;  The  The  4-methylpyridine  c o n t a i n i n g PFg,- ,P-F 1.466-1.593 2  simple s a l t s  F-P-F,  and  The  4-methyl-  (center of since  error  and  angles  plane  are  symmetry w o u l d r e q u i r e an  Ni-N a l l the  between 102.1°  angle  of  45°. The  Ni-N  commonly o b s e r v e d  d i s t a n c e s observed i n square  here  p l a n a r NiN^  tetrakis(4-methylpyridine)nickel(II)  are i n the  range  chromophores; .  p e r c h l o r a t e ( 2 3 )Ni-N i s  1.8 95 (5)-1.900 (5)., t e t r a k i s (3 , 4 - l u t i d i n e ) n i c k e l ( I I )  2  -170-  TABLE I V - 4 BOND DISTANCES AND ANGLES I N N i ( 4 m e p y ) ( P F g ) 4  (estimated standard d e v i a t i o n i n brackets)  BOND DISTANCES ( 2 ) Ni-N(l)  Ni-N(2)  =1.916(9)  =1.919(10)  P - F ( l ) =1. 588 (8)  P - F ( 2 ) =1.556 (9)  P - F ( 3 ) =1.567(11)  P - F ( 4 ) =1.466(12)  P - F ( 5 ) =1.593 (13)  P - F ( 6 ) =1.543 (9)  Ni-F(l)  =3.031(8)  RING 1  RING 2  N-C(l)  1.337 (.14)  1.322 (17)  C(l)-C(2)  1. 368 (16)  1.393 (19)  C(2)-C(3)  1.362(18)  1.385(19)  C(3)-C(4)  1.383 (18)  1.353(19)  C(4)-C(5)  1.386(18)  1.380 (22)  C(5)-N  1.340(16)  1.360 (16)  C(3)-C(6)  1.554 (17)  1.548 (20)  BOND ANGLES (deg) N ( l ) - N i - N ( 2 ) =91.6 (4)  N ( l ) - N i - F ( l ) = 89. 2(4)  N ( 2 ) - N i - F ( l ) = 92.6 (4)  F ( l ) - P - F ( 2 ) = 90. 7 ( 5 )  F ( l ) - P - F (3) =88.3(5)  F ( l ) - P - F ( 4 ) = 92. 0 ( 7 )  F(l)-P-F(5)  =86.2(6)  F ( 2 ) - P - F (3) =176.7(9)  F ( l ) - P - F ( 6 ) = 175 .7(7) F ( 2 ) - P - F ( 4 ) ='92. 2 ( 9 )  F(2)-P-F(5)  = 89.1 (8)  F ( 2 ) - P - F ( 6 ) == 89.1 ( 6 )  F(3)-P-F(4)  = 91.0 (10)  F ( 3 ) - P - F ( 5 ) == 87.7 (9)  -171-  TABLE IV-4  (ii)  (cont'd)  BOND ANGLES (deg)  F(3)-P- F(6)  91.7(6)  F ( 4 ) -P-F (5) 177.8  F ( 4 ) - P - F(6)  92.3(9)  F(5) -P-F(6)  89.6  RING 1  RING 2  C(5)-N-C(l)  117. 8 (11)  117. 6(13)  N-  121. 6 (12)  123. 4(14)  C(l)-C(2)-C(3)  120. 7 (12)  119. 3(14)  C(2)-C(3)-C(4)  118. 8(12)  116. 5(16)  C(3)-C(4)-C(5)  117. 5(14)  122. 7 (16)  C(4)-C(5)-N  123. 3(13)  120. 5 U 4 )  C(2)-C(3)-C(6)  122. 3(13)  119. 0(16)  C(4)-C(3)-C(6)  118. 8(14)  124..5(15)  C(l)-C(2)  -172-  perchlorate  (115)  borato)nickel(II) bis  8  i s 1.89  the  coordination  90°)  (C10 ) 4  The  (substituted)  planar is  (117)  Ni-N  8  i s 1.88  (mesostilbenediammine)nickel(II)  Ni-N of  i s 1.897(3) 8 , b i s ( d i e t h y l b i s ( 1 - p y r a z o l y l ) -  Ni-N  and  45°  angle.is  pyridine  square  NiN  i s usually 4  angle  i s 4 6 . 6 ° and  closest nickel-anion  is  3.290(8) 8 w i t h a d i s o r d e r e d  it  i s 3.031(9) 8 w i t h no  of  the  The  sum  so  i t appears t h a t  whereas the meters of suggesting metal  Ni-0  o f van  structures of w i t h the  two  the  2  i s useful anion  former  whereas i n o u r  compound  compound  for isotropic disordering  same r a n g e  i s greater.  l e s s than those of  i t i s constrained  tetrakis-  i n the  der Waals r a d i i  i n the  tetrakis-  i s i n the  contact  Ni-F(l) distance  distance  F ( l ) are that  the  angle  4  anion,  evidence  f l u o r i n e with n i c k e l are  square  ).  d i f f e r e n c e between t h e  anion.  planes  i n Ni(4mepy) (NCS) ,  hexafluorophosphate  The  the  4  (4-methylpyridine)nickel(II)  present.  )  c o o r d i n a t i o n •( i n N i ( 3 , 5 - l u t i d i n e ) ~  comparison of molecular  only  in  , the  4  perchlorate  the  (25  90°  (4-methylpyridine)nickel(II)  since  planar  p l a n e and  4  ( in Ni(3,4-lutidine) (C10 )  49.7-5.9.5° (118) The  rings  the  dichloracetate  a n g l e between t h e  in octahedral  (116), the  2  and  by  f o r oxygen  (3.1-3.2 8  and  (93(b)))  i s l e s s than t h i s Also,  the  the  other  thermal  sum para-  fluorines  i n t e r a c t i o n with  the  ion. The  c l o s e s t contacts  that  the  the  4-methylpyridine r i n g s are F(l)-C(.l)  3.7  and  3.19  8  f o r two  PF, 6  a n i o n makes w i t h  which, have l e n g t h s  crystallographically distinct  of  moieties.  -173-  Clearly,  the observed magnetic  and s p e c t r a l  o f t h e N i L ^ ( E F g ) ^ compounds c a n be r e l a t e d structure The  similar  magnetic  pounds a r e p r i m a r i l y ation  of nickel  infrared metric of  ring  spectral  the r e s u l t  spectra observed  It 4  f o r them; t h a t  cause  PFg  some  stronger  4  The low temperature  t o t h e argument t h a t  structure  is  f o r square  typical  i n which  (,<17 0K)  ••• M a k i  the nickel-anion and  also  of the nickel(II)  (119) p o i n t s  suggest  i s present i nthe  significantly  gives  t h e EFg~ a n i o n s a r e weakly  coordination  different.  4  0  as  parameters,  (section  isomerization of Ni(py) (AsFg)  the N i L . ( E F , ) compounds g e n e r a l l y . 4 b £  electronic  symmetry.  spectra of  are different  2  i s weak a t room t e m p e r a t u r e  a t low temperatures  a n asym-  of the anions are also  section,  The  a n d the. weak, a n i o n  the e l e c t r o n i c  4  i n the next  interaction  For  indicate  type o f metal-anion i n t e r a c t i o n  compound.  planar coordin-  lowering of anion  and N i ( 4 m e p y ) ( C 1 0 )  2  o f t h e s e com-  (py, 4mepy, 3mepy).  a l o n g w i t h t h e PFg - N i s t r u c t u r a l  discussed  in  that  4  i s , the metal-anion contact  a significant  4.2.2.1) a n d t h e p o s i t i o n i n g  that  ligand  f o r the anions  s h o u l d be n o t e d  Ni(4mepy) (PFg)  Ni(4mepy) (PFg)2•  square  t h a n t h e sum o f v a n d e r W a a l s r a d i i  interaction  This,  properties  of strong  by t h e n e u t r a l  environment  less  to a general  t o the molecular structure of  and e l e c t r o n i c  properties  The f a c t  credibility coordinated that the  i o n i n these  c a n be  complexes  rationalised.  o u t i n h i s weak f i e l d  calculation,  2  -174-  there  i s no d i s t i n c t i o n  square p l a n a r  and v e r y  i n electronic  s t r u c t u r e between  tetragonally distorted  octahedral  coordination.  4.2.2.4  LOW  TEMPERATURE ISOMERIZATION OF  This  section describes cryogenic  Ni(PY)4(AsFg)2• vibrational ferent  The m a g n e t i c , e l e c t r o n i c  s p e c t r a l properties of t h i s  at liquid  temperature.  We  n i t r o g e n temperature  Ni(py) (AsFg) 4  s t u d i e s on s p e c t r a l and  compound a r e d i f -  (77K) a n d room  a s c r i b e t h e changes i n t h e s e p r o p e r t i e s  t o a i n c r e a s e i n m e t a l - a n i o n i n t e r a c t i o n as t h i s undergoes  2  compound  a change i n s t r u c t u r e o n c o o l i n g .  4.2.2.4.1  MAGNETIC AND ELECTRONIC SPECTRAL PROPERTIES  The compound N i ( p y ) ( A s F g ) 4  6.2.1.8(a)  ("stir"  preparation)  2  prepared according to  has some u n u s u a l m a g n e t i c  p r o p e r t i e s a t t e m p e r a t u r e s l o w e r t h a n 200K but!has.-the p r o p e r t i e s of the other N i L ( E F g ) 4  300-220K. plotted and  2  compounds i n t h e r a n g e  F i g u r e 4.5 shows t h e m o l a r m a g n e t i c  a g a i n s t temperature f o r N i ( p y ) ( P F g ) 4  illustrates  normal  t h e d i s c o n t i n u i t y around  F i g u r e 4.6 shows t h e m o l a r  2  susceptibility and N i ( p y ) ( A s F g ) 4  200 K f o r N i ( p y ) ( A s F g ) 4  s u s c e p t i b i l i t y and  m a g n e t i c moment p l o t t e d a s a f u n c t i o n o f t e m p e r a t u r e o v e r the  range  300-77 K.  2  From 300 t o 220K, t h i s  susceptibility  2  -175-  loXwmor1)  FIGURE 4.5  MAGNETIC S U S C E P T I B I L I T I E S (The  shaded and u n s h a d e d  points  f o r E=P and E=As,  OF N i ( p y ) ( E F ) 4  circles  g  .  are the data  respectively)  -176-  T(K) FIGURE 4.6  MAGNETIC S U S P E C T I B I L I T Y  OF  Ni(py) (AsF ) 4  g  2  is  temperature  independent  a n d smal], c o r r e s p o n d i n g  —6 paramagnetism  3  o f 300 x 1 0  —1  cm  mol  220  t o 170 K, t h e s u s c e p t i b i l i t y  and  below  (i.e. is  l / x  1 7 0 K,  close  and  a T ) .  m  t o 0.65 B.M.,  below  This to  temperature  above  (since  ground  tetrahedral spectrum distorted  80 K  typical  electrons  4  from  constant  behavior  300-220  K,  rapidly,  a t 2.85  may b e  B.M.  related  g  i s close  2  about  spectrum  of nickel(II) 2  band  octahedral  of a tetragonally  4  next. g  The s p e c t r u m  i n a square compounds  spectrum  or  electronic  of Ni(py) (AsF )  a t 80 K a p p e a r s  single  spectrum  g  moment  spin-triplet  i o n as discussed  4.7 .  f o r the N i L ( E F )  spin-triplet  The  a t 80 K i s t h a t  i n Figure  The spectrum  The  nickel.  spectrum  planar  to the spin only  of distorted  nickel(II)  4  o f square  170 K i t i s a  i s shown  3 0 0 K a n d a new  moment,  (2.83 B.M.)).  electronic  two s p e c t r a J t h e  C u r i e law  indicative  be i n d i c a t i v e  octahedral  rapidly  state of the nickel(II) i o n  below  of Ni(py) (AsF )  as seen  4.3.2.1). of  whereas,  stereochemistry  The  ment  t h e ground  e  s t a t e may  very  From  of the nickel(II) i o n .  a U f f o f 2 . 8 5 B.M.  2 unpaired  and  magnetic  220 K i s a s p i n - s i n g l e t  stereochemistry,  for  magnetic  essentially  dependent  the stereochemistry  obeys  units).  220 t o 1 7 0 K i t i n c r e a s e s  170 K i t r e m a i n s  Clearly,  a  from  (c.g.s.  increases  the susceptibility The e f f e c t i v e  to a  a t 300  2  a t 300 K i s  planar  environ-  generally  (section  t o be t h e which  consisting of five  superimposit  i s observed a t  bands.  This  -178-  FIGURE 4.7  ELECTRONIC SPECTRUM OF N i ( p y ) ( A s F ) 4  (sample a s a powder)  g  2  (300 and 80  -179-  new s p e c t r u m  i s similar  t o t h a t observed  ( F i g u r e 4.8) where a n a x i a l l y chromophore i s p r e s e n t . and  ligand  section  field  4  2  bands may be a s s i g n e d This  i s done i n  4.2.2.4.2.  indicates  electronic  spectrum  which  t h e presence o f a mixture o f the square p l a n a r  tetragonal  tibility  five  calculated.  But, i s t h e o b s e r v e d  and  4  elongated d i s t o r t e d octahedral  These  parameters  for Ni(py) (C10 )  species,  c o n s i s t e n t w i t h the magnetic  measurements?  suscep-  The v a l u e o f y f f o b s e r v e d a t 80 K, e  0  2.85  B.M.,  i s l o w compared t o t h a t observed": f o r a n a l o g o u s  tetragonally  distorted  o c t a h e d r a l complexes  t e t r a g o n a l p y r i d i n e complex, N i ( p y ) ( B F ) 4  3.2 B.M.). and  Assuming t h a t  4  2  4  2  i s 3.2.B.M. and t h e  o f "square p l a n a r " N i ( p y ) ( A s F g ) 4  300 x 1 0 ^ m o l e  of  2.85 B.M. c o r r e s p o n d s t o an 75:25% m i x t u r e o f t h e two. Having  is for  relative  3 :  t h e next step i s t o attempt intensities  considered.  c o e f f i c i e n t s of the v i s i b l e  The e x t i n c t i o n  bands o f t h e d i s t o r t e d  forms  t o account  o f t h e " s q u a r e p l a n a r " and  " o c t a h e d r a l " b a n d s i n t h e 80 K e l e c t r o n i c the e x t i n c t i o n  moment  concluded that a mixture of s t r u c t u r a l  p r e s e n t a t 7 7K, the  1  , t h e e x p e r i m e n t a l magnetic  2  is  -  cm  where y g r r i s  a t 80 K and t h e m a g n e t i c  moment o f " o c t a h e d r a l " N i ( p y ) ( A s F g ) susceptibility  2  there i s a mixture o f "octahedral"  "square p l a n a r " N i ( p y ) ( A s F g )  magnetic  4  ( f o r example t h e  spectrum.  Here,  b a n d s w i l l be  c o e f f i c i e n t s bf the v i s i b l e  "octahedral"  and " s q u a r e p l a n a r "  -180-  1500 FIGURE 4.8  1000 X (nm)  500  ELECTRONIC SPECTRA OF N i ( p y ) ( A s F ) 4  Ni(py) (C10 ) 4  and  4  2  g  (80K) AND  2  (300K). ( N i ( p y ) ( A s F )  Ni(py).(CIO.)„  4  as a m u l l e d  6  2  sample)  as a powder  -181-  complexes are d i f f e r e n t , probably  e f o r the square p l a n a r band i s  c l o s e 100 M c m ( c f N i ( 4 m e p y ) ( P F ) - 1  4  whereas f o r the d i s t o r t e d -1 c l o s e to 5M cm e=5). and  The  3 (cf  B  g  2  where £=90)  " o c t a h e d r a l " complex, i t i s probably, 3  ig+  E  9  o  f  Ni(4mepy) (C10 ) 4  4  2  where  r e l a t i v e i n t e n s i t i e s of these d i s t o r t e d  square planar bands i n a 75:25% mixture  absorption  due  octahedral  would be 1:7;  the  t o the square p l a n a r complex would appear  as the s t r o n g e s t band i n the spectrum. We  have accounted f o r the observed  and e l e c t r o n i c s p e c t r a of N i ( p y ) ( A s F ) 4  chemical  2  i n terms of a s t e r e o -  change around n i c k e l ( I I ) which i s incomplete.  i s unusual two  g  magnetic p r o p e r t i e s  but not unknown f o r n i c k e l ( I I ) compounds to have  types of chromophore e x i s t i n g i n the same l a t t i c e .  mentioned i n the i n t r o d u c t o r y chapter  s t r u c t u r e of b i s ( m e s o - s t i l b e n e )  dichloroacetate  revealed three  ( 26)  f o u r - c o o r d i n a t e with c o o r d i n a t e d and respectively.  nickel(II)  crystallographically  d i s t i n c t n i c k e l c e n t e r s ; two were s i x - c o o r d i n a t e and  d i c h l o r o a c e t a t e anions  As  ( s e c t i o n 1.1.2), the  c r y s t a l and molecular  was  It  one  non-coordinated  Some o t h e r systems  a l s o show t h i s s t r u c t u r a l f e a t u r e which Sacconi  (60)  has  r e f e r r e d t o by the term, i n t e r a l l o g o n y . An important  q u e s t i o n remains t o be answered, "What  t r a n s f o r m a t i o n takes p l a c e i n the temperature range 220 170  to  K as i n d i c a t e d by the magnetic s u s c e p t i b i l i t y measure-  ments?".  The  e l e c t r o n i c s p e c t r a l data i n d i c a t e t h a t most  -182-  of the n i c k e l ( I I )  c e n t e r s undergo a s t e r e o c h e m i c a l change  from  square  planar to distorted  The  magnetic  ing  change i n t h e - g r o u n d  susceptibility  t r a n s f o r m a t i o n as an  measurements i n d i c a t e  spin  K and  state.  correspond-  have r e f e r r e d  non-coordinated  b e l o w 17 0 K,  to  and  attempt  that  coordinated  at understanding  t a k i n g p l a c e , the parameter K i s used. that  i s ,K  The  the  definition  of K i s given i n equation  4.1;  nickel(II)  high s p i n c h a r a c t e r to those  centers having  this  respectively.  I n o r d e r t o make an process  We  a  i s o m e r i z a t i o n s i n c e i t i s apparent  the anions are predominantly a b o v e 220  octahedral coordination.  i s the r a t i o  of having  low.spin character. T  . mole f r a c t i o n  K=—T  of h i g h s p i n  T~-  2  3 — T —  mole f r a c t i o n o f low Assuming the h i g h - s p i n f r a c t i o n U  e f  £  = 3.20  isomer,  x^'  B.M., c  a  n  the molar  . N,  ... /N-,  T  T-—=  spin  hs'  ,„ , > ...(4.1)  Is  i s a C u r i e paramagnet w i t h  suspectibility  of the h i g h - s p i n  be d e t e r m i n e d from: X =(3.20/2.828) (1/T)  ...(4.2)  2  h  The  molar s u s c e p t i b i l i t y —6  t o be and by (X  300  of the low-spin isomer,  —1  x 10  the  mole  cm  .  and  simultaneous  The N,  ls*l  N  l s  +  + N  N  hs*h  h s  mole f r a c t i o n of h i g h - s p i n r e s p e c t i v e l y , may  equations  i s the experimental molar N  i s assumed  3  l o w - s p i n i s o m e r s , N, solving  X]_#  =  = 1  4.3  and  be  determined  4.4.. b e l o w  susceptibility): X  ex  ...(4.3) ...(4.4)  -183-  Thus K c a n  be  c a l c u l a t e d by  Since will  undergo t h i s  and go  we  N^  values  s  process,  s u c h as  only  was  c o n s t a n t K* and  (4.1). of  the  Ni(py) (AsF ) 4  to normalize  the  done by  v a l u e s o f N, , N, , N* , K, hs Is' Is'  25%  as  (  K*  are  N  as  / J. )• s  not  under-  (N^ ~0.25) s  The  N  h s  2  the  that w i l l  defining  g  calculated  shown i n T a b l e  A4-1  371). This  equilibrium  p a r a m e t e r , K*,  constant  since  can  i t  be  4  the  equilibrium this  6  equation  i s an  a  quasi-  equilibrium,  In  are  K*  (AH)  in  can  and  6  be  ...(4.5]  2  equilibrium. r e l a t e d to  entropy  the  (AS), by  use  4.6. In  Figure  4  constant i f these species  process  t o be  f* Ni(py) (AsF ) (h.s.)  2  thermodynamic parameters, e n t h a l p y of  considered  represents  Ni(py) (AsF ) (l.ss.)  If  75%  i t i s best  to disregard  This  the e q u i l i b r i u m  (p.  of equation  have seen t h a t  isomerization.  and  use  4.9  K =  shows t h e  the  In K p l o t , the  4.6  (217K) t o  4.6(217K) t o  (-AH/R) (1/T) p l o t of  I n K*  plot is linear  5.5  ( 1 8 2 K ) and  6.5  (174K).  +  (AS/R) against  i n the  f o r the  The  In  ...(4.6) 1/T.  For 3  range of K*  values of  10  /T  from  p l o t , i n the  AH(in  cm ) -1  range  and  AS  x  10  3 (in  cal/(mole-K)) derived  from the  and  -44.8, r e s p e c t i v e l y , and  In  f o r the  K p l o t are In  K*  -2.52  p l o t , they  are  3 -2.58  x 10  parameters at  and  -38.9, r e s p e c t i v e l y .  i s that  200K s i n c e  the  i t i s an  The  spin equilibrium  meaning o f  process  e x o t h e r m i c p r o c e s s and  is  can  the  enthalpy  favorable overcome  -184-  (From t h e m a g n e t i c d a t a  of  Ni(py) (AsF ) ) 4  g  2  -185-  t h e t h e r m a l r a n d o m i z a t i o n p r o c e s s e s w h i c h would oppose i t (kT=^14 0 cm ~~) .  The e n t r o p y v a l u e s i n d i c a t e t h a t t h e e n t r o p y  aspects of the "equilibrium" are unfavorable.  S i n c e we  have  seen t h a t t h e b i n d i n g o f t h e h e x a f l u o r o a r s e n a t e t o t h e m e t a l ion i s greater i n the lower temperature  isomer, the d i s -  order of the hexafluoroarsenate anion decreases. temperature  Thus a s t h e  i s l o w e r e d , t h e d i s o r d e r p r e s e n t d e c r e a s e s and  gives r i s e to the unfavorable entropy  this  term.  The p h y s i c a l i n t e r p r e t i o n o f t h i s m o d e l i s t h a t o f e q u a t i o n 4.7; w h e r e t h e AH p a r a m e t e r d e r i v e d Ni(py)  2 + 4  (4  coordinate)+2AsF ~ j N i ( p y ) ( A s F g ) 6  4  2  (six coordinate)...(4.7) 3 -1 (^2.7 x 10 cm / m o l e ( 3 0 . 9 k J / m o l e ) ) i n c l u d e s t h e b o n d e n e r g i e s o f r i g h t hand s i d e m o l e c u l e s compared t o t h o s e o f . t h e l e f t , hand s i d e molecules p l u s t h e c o n t r i b u t i o n from t h e c r y s t a l t r a n s f o r m a t i o n energy. based  on t h e p r e m i s e  entirely distinct  T h i s model  lattice  ( r e f e r r e d t o as m o d e l ( I ) ) i s  t h a t t h e t r a n s f o r m a t i o n i s b e t w e e n two  s p i n systems;  "N^ " m o l e c u l e s h a v e a  state singlet without a thermally accessible t r i p l e t  ground  s t a t e and  "N, " m o l e c u l e s h a v e t h i s s i t u a t i o n r e v e r s e d , hs A n o t h e r model  ( m o d e l ( I I ) ) c a n be a s s e m b l e d  where t h e  s p i n - s i n g l e t a n d s p i n - t r i p l e t a r e i n same s p i n s y s t e m , i . e . the e l e c t r o n i c s t r u c t u r e of the n i c k e l ( I I )  i o n ( 7 5 % o f them)  i n v o l v e s a ground  state singlet with a thermally accessible  term  The e q u a t i o n w h i c h d e s c r i b e s t h e  ( a t ^215K).  Boltzmann  triplet  -186-  d i s t r i b u t i o n o f molecules  i n the singlet  is  A E i s the separation  equation  (4.8) (where  I n K* = - A E / R T of the s i n g l e t lower-and  compared  o f equation  culated  a r e g i v e n i n T a b l e A4-2 4.10. -250  f o r the spin  the l a r g e r  state).  spin entropy of  (4.9), a l l o w s A E t o b e c a l -  r a n g e 215 t o 160 K.  The c a l c u l a t e d  3-lnK)  (p.37 2)  singlet  Use o f t h e r e a r r a n g e d  ...(4.9) and i l l u s t r a t e d  The A E v a l u e s v a r y between +707 cm  i n Figure  ( a t 215K) and  1  cm " " ( a t 160K) , where t h e l a t t e r v a l u e i n d i c a t e s t h a t t h e -  1  spin-triplet at  from  (4.8), equation  A E = RT(In  ...(4.8)  and i s p o s i t i v e  to singlet  i n the temperature  states  + In 3  t h e l n 3 terms a r i s e s  the t r i p l e t form  and t r i p l e t  and t r i p l e t  160 K.  i s 250 cm  lower  1  The o v e r a l l  i n energy  temperature  then  the spin-singlet  dependence o f A E i n t h i s  model i s s p i n - c r o s s o v e r b e h a v i o r . To K*  (and t h u s  summarize, m o d e l (I).'has a n a l y z e d t h e temperature  o f two s e p a r a t e  spin  and in  spin-triplet  Q V  ~4-)  x  n  terms  a n d t h e s p i n - t r i p l e t has  anions.  M o d e l ( I I ) , on t h e o t h e r  t h e p a r a m e t e r K* i n t e r m s o f t h e s p i n - s i n g l e t  energy  each n i c k e l ( I I )  would  anions  c o o r d i n a t e d AsFg  hand, h a s a n a l y z e d  X  systems, where t h e s p i n - s i n g l e t h a s v e r y  weakly c o o r d i n a t e d AsFg "classical"  dependence o f  t h e parameter  ion.  t h e n be v a r i a b l e  s t a t e s b e i n g p r e s e n t and a c c e s s i b l e The c o o r d i n a t i o n o f t h e AsFg through  t h e temperature  range,  anions varying  -187-  600  400 200 AE (in  0  cm ) 1  -200 -400  |  , , •  170  190  .  210  TEMPERATURE ( i n K e l v i n ) FIGURE 4.10  PLOT OF AE AGAINST TEMPERATURE ( from t h e magnetic d a t a o f N i ( p y ) ^ ( A s F ) ) g  2  -188-  from weakly  coordinating  Magnetic  to " c l a s s i c a l l y "  s u s c e p t i b i l i t y measurements a r e a b u l k  property of the m a t e r i a l as t o t h e l i k e l y behavior, this  models.  The  (I) w o u l d due  (I) and  range would  electronic  consist  state.  c a n o n l y make  The  (II). Electronic  d i f f e r e n t i a t e between the  state,  s p e c t r a would  temperature i s v a r i e d .  v a r i e d with temperature.  the t r a n s f o r m a t i o n  understand  B u t we  s y s t e m w h i c h does  4  2  intensity spectra  spectrum  not  undergo  ions).  on t h e b a s i s o f t h e m a g n e t i c  suscep-  and m o d e l ( I I ) c a n n o t be  dif-  h a v e c o n s i d e r e d b o t h i n an a t t e m p t  complex.  the  would  the e l e c t r o n i c  t h e p r o c e s s t a k i n g p l a c e b e t w e e n 220  the N i ( p y ) ( A s F g )  as  as  on b o t h t y p e s o f  (25% o f t h e n i c k e l ( I I )  measurements,model(I)  ferentiated.  be  as w e l l  one  spin-triplet  vary i n i n t e n s i t y  Superimposed  nickel(II)  In c o n c l u s i o n , tibility  two  spectra,  A s y s t e m b a s e d on m o d e l ( I I )  and m o d e l ( I I ) ) w o u l d  of the s p i n - s i n g l e t  o f two  the o t h e r to  have a spectrum i n w h i c h band p o s i t i o n s  (of model(I)  spectra i n  s p e c t r u m o f a s y s t e m b a s e d on m o d e l  ground  two  assumptions  t o the observed  of the s u p e r i m p o s i t i o n  to a s p i n - s i n g l e t  ground  and t h u s we  systems which g i v e r i s e  i . e . models  temperature  coordinated.  and  160K  to in  -189-  4.2.2.4.2  ELECTRONIC  Table  STRUCTURE AND  IV-5 l i s t s  STEREOCHEMISTRY  the t r a n s i t i o n  energies  ments f o r t h e 80K s p e c t r u m o f N i ( p y ) ( A s F ) . 4  in  g  be o b t a i n e d  f r o m t h e 80K s p e c t r u m .  parameters f o r N i ( p y ) ( A s F ) 4  pyridine for data  complexes w i t h  the other to  g  2  other  Table  Ni(py) (AsF ) 4  IV-6 l i s t s  and some t e t r a g o n a l anionic  assign-  As o u t l i n e d  2  s e c t i o n 2.3.2.1, t h e t e t r a g o n a l p a r a m e t e r s o f  can  and  species(  g  these  nickel-  the parameters  c o m p l e x e s were r e c a l c u l a t e d f r o m t h e p u b l i s h e d  include configuration interaction (section  2.3.2.1)  TABLE IV-5 ELECTRONIC  SPECTRUM OF  BAND POSITION  (kK)  Ni(py) (AsF ) 4  g  2  ASSIGNMENT  ( a )  6.92  3  B  l g  ->  3  (b)  E ( F) 3  g  13.0  ->  3  14.3  -  3  B  2 g  ( F)  A  2 g  ( F)  3  3  \  17.5  (  3  F  )  (c)  22.2 28.2  3  *  *  A„ 3 3  (a) powder a t 80K (c) s q u a r e p l a n a r  (b) s e e s e c t i o n band,  ^^ig^^iq  ( P) 3  3  Eg  ( P) 3  2.3.2.1  2  -190-  TABLE I V - 6 TETRAGONAL PARAMETERS OF SOME N i ( p y ) f a COMPOUNDS PARAMETER VALUE (cm ) 1  COMPOUND Ni(py) (AsF ) 4  g  Ni(py) (BF ) 4  4  2  Ni(py) (cio ) 4  Ni(py)  4  2  (FS0 )  4  3  The o f N i (py)  2  4  2  Dq ^xy  Dt  Ds  B  REFERENCE  1300  568  1588  887  T h i s work  1300  540  1240  890  (120)  1290  500  930  930  (120)  1180  359  342  900  (121)  tetragonal.parameters (AsF ) „ a r every b z c  o f the low temperature  s i m i l a r t o those  t e t r a f l u o r o b o r a t e and p e r c h l o r a t e l i s t e d o f Dq  arev i r t u a l l y  Dt a r e l a r g e r ligand  than those  o f t h e compounds o f  above.  The v a l u e s  i d e n t i c a l w h e r e a s t h e v a l u e s o f Ds a n d  f o r o u r compound.  field  isomer  This suggests  that the axial  strength of thehexafluoroarsenate  of' t h e s e o t h e r a n i o n s .  A s expected,-  anion i s l e s s t h e complex  w i t h c o o r d i n a t e d hexaf l u o r o a r s e n a t e i s - a very-.distorted species The  cryogenic electronic  s p e c t r a l and magnetic  properties of Ni(py) (AsFg)^ indicate that this 4  has  an e s s e n t i a l l y  compound  s q u a r e p l a n a r s t e r e o c h e m i s t r y a t room  t e m p e r a t u r e and a p r e d o m i n a n t l y  axially  elongated t e t r a g o n a l l y  d i s t o r t e d o c t a h e d r a l stereochemistry a t temperatures  below  170  anions,  K.  Using  t h e c r i t e r i a o f s e c t i o n 4.1,  the A s F  g  m u s t become c o o r d i n a t e d b e l o w 17 0 K b e c a u s e t h e s e p r o p e r t i e s are t y p i c a l  for six-coordinate nickel(II).  T h u s , t h e room  temperature form, t e t r a k i s ( p y r i d i n e ) n i c k e l ( I I )  hexafluoro-  -191-  arsenate  becomes, a t t e m p e r a t u r e s b e l o w 170 K,  arsenato)tetrakis(pyridine)nickel(II). w h i c h must be t a k i n g p l a c e is  The  bis(hexafluoro-  isomerization  i n t h e t e m p e r a t u r e r a n g e 220-170 K  t h a t t h e a n i o n s a r e moving c l o s e r t o t h e n i c k e l and,  per-  h a p s , t h e p y r i d i n e r i n g s a r e moving f a r t h e r away. The Ni(PY)4(AsFg) spectroscopy  other  cryogenic  e x p e r i m e n t s performed on  were t h e v a r i a b l e t e m p e r a t u r e v i b r a t i o n a l  2  s t u d i e s and t h e s e a r e d i s c u s s e d  i n the next  section.  4.2.2.4.3  VIBRATIONAL  One o b j e c t of d i f f e r i n g spectra the  o f EFg  anion  metric  chemical  SPECTROSCOPY  of this  thesis i s t o c o r r e l a t e the e f f e c t s  e n v i r o n m e n t s on t h e o b s e r v e d i n f r a r e d  anions.  As was d i s c u s s e d  environment i n N i L ^ E F g ^  and a s i s shown i n S e c t i o n  partially  i n section  compounds i s v e r y  4.2.2.3, t h i s  due t o weak c a t i o n - a n i o n ,  4.2.2.2, asym-  i s probably  nickel(II)-EFg, inter-  action.  In the N i ( p y ) ^ ( A s F g ) 2  section,  t h e d i f f e r e n c e s i n t h e i n f r a r e d s p e c t r a between a  weakly c o o r d i n a t e d arsenate  low  species  case  t o be d i s c u s s e d  a n d more s t r o n g l y c o o r d i n a t e d  in this  hexafluoro-  c a n be e x a m i n e d .  Since  we have shown i n s e c t i o n 4.2.2.4.1 t h a t t h e  temperature  i s o m e r i z a t i o n o f N i (py) ^ (AsFg) ^ ' i s no't 100%  efficient  we w o u l d e x p e c t t o s e e i n b o t h t h e i n f r a r e d and  -192-  Raman s p e c t r a t h e s p e c t r a a t u r e spectrum.  o f b o t h i s o m e r s i n t h e low  The d i f f e r e n c e  and  t h e low t e m p e r a t u r e  the  low t e m p e r a t u r e  tabulated  data w i l l will  be  isomer. spectral data f o r N i ( p y ) ( A s F g ) 4  i n T a b l e IV-7.  The r a t h e r b o u n t i f u l  be c o n s i d e r e d f i r s t  and t h e n t h e Raman  and b e c a u s e  (900-300  cm )  s p e c t r a were o b t a i n e d o n  of Christiansen cm  1  scattering .  spectra  4  4.7.  the spectra spectra  i n the observed anion v i b r a t i o n s  v i b r a t i o n s o f t h e two The band a t 5-66 v 2  (  are p a r t i c u l a r l y  E g  cm  1  )  a n <  scans a r e p e r f o r m e d sample i s c o o l i n g  i n the v ( E ) A s F g 2  i n t h e room ^  and 16b  g  i s o m e r s show some i n t e r e s t i n g  x  n  and a l s o a new  t  n  e  80K  temperature spectrum  i n t h e 500-600 -cm f r o m room  1  features.  spectrum i s  t h i s band  band a p p e a r s a t 533  pyridine  cm  1  .  is still I f successive  r e g i o n when t h e  temperature  t o 80K,  in intensity.  temperature  S i n c e t h e sample i s c o o l i n g ,  l e s s o f the h i g h temperature  isomer as t h e temperature  mu;i s t t h e r e f o r e be  v  2  o r a component  2  cm  cm 1  1  band  t h e r e must  and more o f t h e low  i s lowered;  of v  solid  t h e 566  band i s f o u n d t o d e c r e a s e i n i n t e n s i t y w h i l e t h e 533  be r e l a t i v e l y  notice-  spectra.  The d i f f e r e n c e s  increases  show  2  Differences  i n t h e two  assigned to  powdered  The i n f r a r e d  i n t h e 16 b v i b r a t i o n o f p y r i d i n e  present  infrared  o f N i ( p y ) ( A s F g ) a t 300 and 80 K a r e shown  -1  in Figure  able  2  discussed.  good r e s o l u t i o n o n l y b e l o w 1000  and  termperature 2  The i n f r a r e d samples  t h e room  s p e c t r u m o f N i ( p y ) ^ ( A s F g ) i s due t o  The v i b r a t i o n a l are  between  temper-  t h i s new  band  of the coordinated  -193-  TABLE I V - 7 VIBRATIONAL  SPECTRAL  DATA FOR N i ( p y ) ( A s F g ) 4  2  (b)  ASSIGNMENTS INFRARED 300K  RAMAN  80K  300K  80K  (i)ANION \) (A. ) 1 lg  — ( a )  — ( a )  680(3) 703 (1) 678(1)  v 2  (E ) g  566m  562w  n.o.  n.o.  533m v 3  (T, ) lu  695 v s , L 7 0 5 s h b  r  685vs br 660sh v,(T, ) 4 lu  398vs  390vs 370(2)  V  5  (ii)  ( T  2g  367(1)  )  PYRIDINE  9a  1218m  1212m  15  1155m  1145m  18a  1068m  1060m  4  762s  6a  1030(10)  755s  (a) 632m  16b  1023(10)  471m  654(3)  653(1)  465w 432w  (a) p o s s i b l y brackets  o b s c u r e d by 3 ( v  T l u  indicate relative  )  o  f  A  s  F  g  intensity;  (k) numbers i n t h e low t e m p e r a t u r e  Raman s p e c t r u m hasu'more. i n t e n s e bands t h a n t h e h i g h e r temperature  spectrum.  -194-  FIGURE 4.11  INFRARED (300  SPECTRA  and 80K)  (800-350 cm"  ) OF  Ni(py) (AsFg) 4  2  -195-  AsF  species.  g  sensitive in  to d i f f e r e n t  t h e two  t h e 470  V 2 ( E ^ ) band o f A s F  The  cm  vibration  isomers.  The  ^ and  cm  432  of pyridine  respectively. temperature  The  that AsF  same t y p e o f b e h a v i o r i s o b s e r v e d f o r ~~ b a n d s w h i c h  are a s s i g n e d t o the  i n t h e h i g h and  low t e m p e r a t u r e  isomer i s s i g n i f i c a n t because  p i t c h of the r i n g s  particularly  must e x p e r i e n c e  g  l o w e r i n g of energy o f t h i s  pyridine-nickel(II)  Either  environments  appears  g  interaction  or b o t h o f t h e s e f a c t o r s would  be  e x p e c t e d f o r a change  s p e c i e s w i t h weakly c o o r d i n a t e d  u  l u  ) /  appears  species  n  d  v  2 ^  E  g ^  when A s F  t  *  i  e  f  o  r  m  e  r  t  w  o  p o s s e s s e s 0^  g  temperature a  r  e  symmetry,  I n t h e low t e m p e r a t u r e at slightly  and  a t 8OK  a new may  v  2  formally whereas,  infrared  lower energy,  v  band a p p e a r s .  4  is  Another  be a s s i g n e d t o t h e 16b  vibra-  pyridine. Normally,  temperature  i f  t h e r e i s no  i s lowered, the i n f r a r e d  s e e n by c o m p a r i n g (Figure  a  lower energy,  band w h i c h of  T  i s b r o a d e r and  slightly  tion  (  i s not allowed.  spectrum,  new  4  i n the i n f r a r e d  the l a t t e r  at  a n i o n v i b r a t i o n s o b s e r v e d a t room  (T^ ) / v  allowed  isomer.  coordinated anions. The  are  less  a change i n t h e  anions to a tetragonal pseudo-octahedral n i c k e l ( I I ) fully  low  indicate  ( t o w a r d s 4 5°) i n t h e low t e m p e r a t u r e  from a square p l a n a r n i c k e l ( I I )  with  isomers  band i n the  i t may  or at l e a s t  16b  4.12).  t h e 80K  and  In c o n t r a s t ,  s t r u c t u r a l change when t h e bands sharpen; t h i s i s  300K s p e c t r a o f the  Ni(py) (PF ) 4  g  2  v i b r a t i o n o f N i (py) ('AsF^) 4  2  -196-  -197-  in  the low temperature  s p e c t r u m i s much b r o a d e r t h a n i n t h e  room t e m p e r a t u r e s p e c t r u m . some s t r u c t u r e .  T h i s band  o f n o n - c o o r d i n a t e d AsFg in  this  In a d d i t i o n ;  o f AsFg  vibration  (recall  25% o f t h e complex  c o o r d i n a t e d AsFg  shows  remains  plus the  and t h e 6a v i b r a t i o n o f p y r i d i n e .  (A-^)  The  i s n o t c o m p l i c a t e d b y o t h e r v i b r a t i o n s a n d shows  a s l i g h t b r o a d e n i n g and s h i f t Neither  band  i s p r o b a b l y composed o f t h e " ^ ' s  f o r m e v e n a t 80K)and  vibrations  this  the  nor the  t o l o w e r e n e r g y on  cooling.  bands show r e a l l y  significant  because o f t h e s i m i l a r i t y  o f the vibrations  f o r t h e two t y p e s  o f AsFg  o f t h e poor r e s o l u t i o n  and a l s o b e c a u s e  the s o l i d  state The  in  afforded  by  spectrum.  Raman s p e c t r a l d a t a f o r N i ( p y ) ^ ( A s F g )  T a b l e IV-7  changes  do n o t show any l a r g e  shifts  i n band  2  recorded position  b u t t h e i n t e n s i t y o f t h e b a n d s i n t h e 80K s p e c t r u m i s g r e a t e r and  the baseline behavior i s d i f f e r e n t  spectrum.  f r o m t h a t o f t h e 3 00K  T h i s b e h a v i o r i s n o t o b s e r v e d i n t h e 3 00 and 8OK  Raman s p e c t r a o f t h e n o n - i s o m e r i z i n g compound N i ( p y ) ( P F g ) . 4  2  The phenomenon o b s e r v e d i s p r o b a b l y due t o t h e d i f f e r e n c e s i n the e l e c t r o n i c  s t r u c t u r e s o f t h e low t e m p e r a t u r e isomer o f  Ni(py) (AsFg)  compared t o t h a t o f t h e N i L ^ ( E F g )  4  generally.  2  The N i L ^ ( E F g )  2  compounds do n o t g e n e r a l l y  a c c e p t a b l e Raman s p e c t r a w i t h t h e 540 nm e x c i t i n g due  to the f a c t  length.  that  complexes  2  give  l i n e , probably  t h e s e compounds a b s o r b e n e r g y o f t h i s  The l o w t e m p e r a t u r e  form o f N i ( p y ) ( A s F g ) 4  2  wave-  does n o t  -198-  absorb very therefore The  strongly  a t t h i s wavelength  scatters well  observed  and g i v e s  isomer o f  ) and  a r e a s o n a b l e Raman s p e c t r u i  Raman s p e c t r u m c a n be c o n s i d e r e d  t o t h e low t e m p e r a t u r e  4.7  (Figure  t o be due o n l y  Ni(py) (AsF ) . 4  g  2  -199-  4.2.2.5  THERMAL STUDIES  We NiL (EFg)2 4  tion.  d e s c r i b e h e r e some s t u d i e s made on samples o f  compounds w h i c h were p r e p a r e d  Previous  Ni(py) (PFg) 4  precursors of  this  that  4  by h e a t i n g  this  of  different  type.  evidence  The v a r i a b l e , t e m p e r a t u r e 4  preparation)  temperatures  will  f o r m e d by h e a t i n g  f o r pure  4  f o r comparison)  2  (each  temperature of  t h i s m a t e r i a l was  cobalt  temperatures  2  by thermal  sidelight, means  f o u n d hot. t o • e x h i b i t  t h e low  i s o m e r i z a t i o n which c h a r a c t e r i z e s the behavior  pure N i ( p y ) ( A s F g ) 2 4  4.2.2.5.1  products  as an i n t e r e s t i n g  4  be d i s c u s s e d ;  time i n t h e i r  (and r e l a t e d  the p r e p a r a t i o n o f samples o f N i ( p y ) ( A s F g ) will  compounds  involving dif-  at elevated  Finally,  results  susceptibilities  The d e c o m p o s i t i o n  samples o f N i L ( E F g )  a l s o be d i s c u s s e d h e r e .  2  as d e s c r i b e d  THERMAL PREPARATIONS  i n s e c t i o n 4.2.2.4.  OF N i ( 4 m e p y ) ( P F g ) 4  2  AND  MAGNETIC PROPERTIES OF PRODUCTS  The of  the t i t l e  from  f o r our contention  and l e n g t h o f h e a t i n g  be e x a m i n e d .  copper complexes  The  magnetic  samples o f N i ( 4 m e p y ) ( P F g )  ferent heating  will  supporting  (14) .  conditions are not s a t i s f a c t o r y  of  and  compounds i n v o l v e d i s o l a t i o n  2  t o 100°C " i n v a c u o "  section provide  these  decomposi-  work p u b l i s h e d b y o t h e r w o r k e r s on t h e  and N i ( 4 m e p y ) ( P F g )  2  by t h e r m a l  v a r i a b l e temperature magnetic  susceptibility  compound h a s b e e n s t u d i e d as a f u n c t i o n o f h e a t i n g  -200-  t i m e and  temperature used i n i t s . p r e p a r a t i o n . -  tibilities lized" pure  The-magnetic  o f t h e s e " t h e r m a l " p r e p a r a t i o n s and o f  Ni(4mepy)^(PFg)2  are i l l u s t r a t e d  ( " r e c r y s t a l l i z e d " ) sample.has  i n Figure  "recrvstal4.13.  what i s b a s i c a l l y —6  independent paramagnetism whereas, t h e "impure" sample have t h i s susceptibility magnetic  e  t.i.p.  as 0.05,  B.M.)  0.13,  gives  and  c, r e s p e c t i v e l y , It  diamagnetic  plus  a spin-free  f o r three  t o be  properties.  the l i m i t e d  account.  bridging  fluorides  studies,  section  —1 mole  -  ;  Ni(4mepy)^(PFg)2 paramagnetic  an i m p u r i t y  this  contribution  species with  o f paramagnetic  samples  labelled  impurity  a, b,  and  ).  certain The  3 cm  nickel(II)  the f r a c t i o n  about the  limited  assignment  temperature  range  a c c u r a c y o f f o r c e methods f o r m e a s u r i n g  susceptibilities  taken i n t o  netically  0.15  t.i.p.  The  a.temperature  An a n a l y s i s o f  i n T a b l e VI-4,(p.275  of these magnetic  be  p l u s a superimposed  is difficult  (300-77K) and  60 x l O  a t lower temperatures.  assumed t o be  o f 3.0  of  (thermal preparations)  b e h a v i o r assuming  (impurity u ££  (t.i.p.)  suscep-  are sources o f e r r o r which s h o u l d  I f the impurity  (as i s i n d i c a t e d  4.2.2.5.2) t h e r e  by  Regardless, i t i s clear  present  i n t h e samples  the thermal degradation  i s the p o s s i b i l i t y  c o n c e n t r a t e d system p r o v i d i n g  ution .  i s a complex w i t h  that  the impurity  o f a magcontrib-  some t y p e o f i m p u r i t y i s  when h e a t i s u s e d i n t h e i r  preparations.  -201-  I  Q  ,P  ,  , TEMPERATURE  FIGURE 4.13  MAGNETIC  ( i n Kelvins)  SUSCEPTIBILITY OF THE THERMAL PREPARATIONS  OF Ni(4mepy)^(PFg)2  ( The p r e p a r a t i v e  o f a,b,and c a r e g i v e n method  ,  of d i s given  i n Table  i n section  IV-4  method  , the preparative  6.2.3.8)  -202-  4.2.2.5.2  THERMAL DECOMPOSITION STUDIES OF  As m e n t i o n e d or Ni(4mepy) (PFg) 4  greater  then  i n section  i s heated  2  100°C, a w h i t e  4.2.1,  found  g  around  sublimate i s observed  4  g  sublimes.  2  4  a t temperatures  f o r each N i L ( E F )  amounts o f w h i t e m a t e r i a l  4  when'Ni(py) (PF )  t h e c o o l e r p o r t i o n s o f t h e vacuum f l a s k . a t u r e c o u l d be  ML (EF )  g  and  t o form  a t temperatures  the white m a t e r i a l but  i s formed  2  compound where  T h i s temperature  as a d e c o m p o s i t i o n  The  is  evidence  suggest  form:  infrared that  4  6  2  ->•  c o n d i t i o n s and  g  decomposition  a n a l y s e s do n o t a g r e e (see s e c t i o n  sublimates  of the N i L ( E F ) 4  spectral,  g  and mass i s of  N i L ( E F ) F + L" E F ^ x  6  2  specthe  the white  +(3-x)L  s u b l i m a t e i s LEF,..  T h i s w o u l d seem t o r e p r e s e n t a somewhat s i m p l i f i e d overall  complex  •  r e s i d u e i s N i L ( E F ) F and x  that  :  the decomposition  NiL (EF )  itself  This indicates  (C,H,N) f r o m t h e r e s i d u e s and  analytical,  copious  product.  from the t h e r m a l d e c o m p o s i t i o n  a r e shown.  The  100°C.;  6.2.5, t h e d e c o m p o s i t i o n  the elemental analyses  trometric  than  i s not a c o n s t i t u e n t p a r t of the  In s e c t i o n  resulting  less  on  A h e a t i n g temper-  g r e a t e r t h a n 100°C whereas the i s o l a t e d w h i t e m a t e r i a l sublimes  2  reaction,  however, as t h e  e x a c t l y w i t h the i n d i c a t e d  6.2.5). S u p p o r t i n g e v i d e n c e  view  of  elemental products  f o r these  proposed  the  -203-  products on  o f r e a c t i o n comes f r o m  the sublimates  the  the i n f r a r e d  and r e s i d u e s and f r o m  t h e mass s p e c t r a o f  infrared  s p e c t r a o f N i L (EF,)F X  the presence  of a L moiety  environment from presence those and  observed  which i s i n a d i f f e r e n t  that o f the precursor  o f an " i o n i c "  EFg  since  ( N i L ( E F g ) ) ; the 4  ( i . e . t h e bands a r e s i m i l a r t o  presence  400 cm ^ .  from  infrared  spectra of the sublimates  o f bands w h i c h a r e s i m i l a r  vibration  e v i d e n c e , w h i c h must  v i b r a t i o n s o f t h e LEF,- s p e c i e s .  bands t h a t a r e a s s i g n e d t o t h e L m o i e t y those  sublimate  from N i ( p y ) ( P F g ) 4  are represented  respectively. assigned  are d i f f e r e n t  o f t h e p r e c u r s o r and t h e r e s i d u e ; T a b l e  2  heated  i n Tables  t o 154°C " i n vacuo". p y P F ^ , pyAsF,., and I V - 9 , I V - 1 0 , and I V - 1 1 ,  The peak w i t h t h e h i g h e s t  t o t h e s p e c i e s LEF,- . +  IV-8 g i v e s  s p e c t r a o f t h e r e s i d u e and  mass s p e c t r a o f t h e s u b l i m a t e s 5  show t h e  t o those expected f o r  b u t , b e c a u s e o f t h e mass s p e c t r a l  4mepyPF  to v(Ni-F)  r e g i o n has been a s s i g n e d t o t h i s  the assignments o f t h e i n f r a r e d  The  band c e n t e r e d a t  T h i s b a n d c a n be a s s i g n e d  assigned to the skeletal  The  3 )';  (122) .  3  The  EF~ b  2  o f a new t y p e o f compound i s i n d i c a t e d  a band i n t h i s  KNiF  chemical  i n t h e compounds d e s c r i b e d i n C h a p t e r  the presence  approximately  indicate:  D  b e c a u s e o f t h e o b s e r v a t i o n o f a weak, b r o a d  be  data  sublimates. The  in  spectral  Other  (m/e) r a t i o may be  p e a k s may be a s s i g n e d  -204-  TABLE IV-8 INFRARED SPECTRAL DATA FOR N i (py) .(PF )  SUBLIMATE AND RESIDUE  ASSIGNMENT **  SUBLIMATE  8a  1625s  1610m  8b  1580w  n.o.  9a  1231m  1230m  15  1168m  1160m  18a  1090s  1080m-s  12  RESIDUE  1050m-s 1020w  V,(NPF ) 3 5 C  ?  870vs,br 810vs,br  V lu T  }  P F  850vs  6  4_  715s  760s  11  715s  700s  6a  685s  640s  v . ( T , ) PF ~ 4 lu 6 v.fNPF..)? 4 o 16b  560s 540vs,br,asy 420vw  431m  + 420 w , v b r  v (Ni-F) ** p y r i d i n e  assignment  unless otherwise  indicated  -205-  TABLE I V - 9 MASS SPECTRAL DATA FOR p y P F  m/e  RELATIVE  m/e  RELATIVE  RATIO  HEIGHT*  RATIO  HEIGHT*  187 186 185 107 104  7 60(pyPF ) +  4  3 100(PF ) +  4  10  69  4  53  14  52  60  51  30  88  6(PF )  50  10  85  7  49  6  80  13  45  3  39  14  79  +  3  100(py ) +  78  17  38  6  77  3  37  3  76  4  32  15  75  5  31  3  * A s s i g n m e n t when a p p l i c a b l e i s  i n brackets  -206-  TABLE I V - 10 MASS SPECTRAL DATA FOR  pyAsF  m/e  RELATIVE  m/e  RELATIVE  RATIO  HEIGHT*  RATIO  HEIGHT*  231  6  230  89(pyAsF ) +  5  76  2  75  2  71  2  69  2  153  2  151  7(AsF  149  2  57  1  147  2  56  1  135  3  55  1  132  2(AsF  53  5  131  2  52  33  113  4(AsF  51  19  106  2  50  9  103  2  49  2  101  3  44  2  87  2  43  2  85  4  42  2  80  6  39  14  38  . 2  32  16  79  + c  + 4  + 3  )  )  )  100(py ) +  78  9  77  2 * A s s i g n m e n t when a p p l i c a b l e  i n brackets  -207-  TABLE I V - 1 1 MASS SPECTRAL DATA FOR 4mepyPF . r  m/e  RELATIVE  m/e  RELATIVE  RATIO  HEIGHT*  RATIO  HEIGHT*  201  1  200  13(4mepyPF )  64  3  107  50(PF )  63  5  +  4  +  4  104  1  62  2  95  1  61  1  94  12  54  6  53  5  93  100(4mepy ) +  92  1  52  4  91  2  51  6  88  5(PF  50  4  78  2 '  41  1  69  1  40  1  67  20  39  1  66  14  38  1  65  12  37  1  + 3  )  * A s s i g n m e n t when a p p l i c a b l e i s i n b r a c k e t s  -208-  to  EF^  ,  In  conclusion this  of  the white  is  a material  +  EF^" ", and  the fragmentation p a t t e r n o f the L  1  evidence  suggest  s u b l i m a t e from  these  that  thermal  LEFp. compounds, a d d u c t s  decomposition  of  p e n t a f l u o r o a r s e n i c (V) , a r e n o t unknown  crystal  and  bling  PF^  pyridine,  (g) t h r o u g h has We  precursors of  structure  have known t h a t  complexes.  4  The  o f py'PFj-, p r e p a r e d by  bub-  solution  of  4  g  2  studied  grams a r e s i m i l a r (PF ) g  are  2  The  same q u a l i f i c a t i o n  (where M=N,  Co  t o be  below the c r i t i c a l cobalt(II) The  is  and  light  not  samples been  c o p p e r ( I I ) complexes,  are i n the and  thermo-  M(py)^-  shown i n F i g u r e 4.14,  significant  from  there  products  i n the f a c t  amount o f  temperatures  that  decomposition  f o r the c o p p e r ( I I )  complexes. work on  a t 145°C  t h e s e compounds i s n o t be  " i n vacuo",  pink residue i s l e f t  mass s p e c t r u m  has  the d i f f e r e n t i a l  temperature  decomposition  some o b s e r v a t i o n s w i l l heated  and  These d i f f e r e n c e s  any  heating  f o r a l l these complexes,  Cu) , as  at the decomposition  t h e r e appears n o t  but  Even though  i n nature  some d i f f e r e n c e s .  formed  and  here.  " i n vacuo"  f o r the p r e p a r a t i o n o f pure  made f o r t h e p r e p a r a t i o n o f c o b a l t ( I I ) ML (EF ) ,  containing  0-24). t h e use  i s unsatisfactory  NiL (EFg)2  (12 3 ) .  an a c e t o n i t r i l e  been d e t e r m i n e d  reactions  pentafluorophosphorus  (V) and  molecular  component  LEFr..  of the composition  The  t h e main  moiety.  indicates  reported. a white  comprehensive  When C o ( p y ) ^ ( P F ) g  sublimate  i n the r e a c t i o n f l a s k .  the white m a t e r i a l  forms and  2  a  The  i s pyPFj.'., b u t  the  -209-  FIGURE  4.14  DIFFERENTIAL  THERMOGRAMS  OF M  1  (py) . (PF )  -210-  infrared  spectrum  py o r PFg cm  1  of the residue i n d i c a t e s  species present; i n fact  i s observed, The  C0F2.  overall  decomposition  4  When C u ( p y ) ( P F g ) 4  not look "clean". and  o n l y a b r o a d band ^  suggesting the r e s i d u e to  Co(py) (PFg)  of white  t h a t t h e r e i s no  2  2  £ CoF  2  reaction  + 2py'PF  5  400  be  i s presented +  below  2py  was  heated  t o 156°C, the decomposition  The  m a t e r i a l w h i c h s u b l i m e d was  b l u e - p u r p l e components and  a  did  mixture  t h e r e s i d u e was  a  non-  homogeneous m i x t u r e o f brown, b l a c k , and y e l l o w m a t e r i a l s . I m p o r t a n t f r o m t h e p o i n t o f v i e w o f t h e s y n t h e t i c work, t h e r e was  no  and  CuL.(EF )  used  evidence to suggest 4  r  0  n  z  that  t o 8 0 - 9 0 ° C and  the h e a t i n g of the  40°C, r e s p e c t i v e l y ,  t o p r e p a r e t h e s e compounds) r e s u l t e d  amount o f  i n an  CoL (EFg) 4  2  (the c o n d i t i o n s  significant  decomposition. T h u s , by c o m p a r i s o n w i t h o u r t h e r m a l  studies  the n i c k e l ( I I ) c o m p l e x e s , the chemistry of the thermal r e a c t i o n s of the c o b a l t ( I I ) t o be q u i t e d i f f e r e n t .  and  products of these thermal  decomposition  c o p p e r ( I I ) complexes a r e  More work on  the i d e n t i f i c a t i o n  decomposition  reactions  on  seen of  should  the  be  done. 4.2.2.5.3  THERMAL PREPARATION OF PROPERTIES OF  The revealed  Ni(py) (AsFg)^ 4  AND  THIS MATERIAL  characterization  of N i ( p y ) ( A s F g ) ^ (section 4  some r a t h e r n o v e l l o w t e m p e r a t u r e  properties.  4.2.2.4)  This  -211-  compound  ( h e r e a f t e r r e f e r r e d t o a s t h e a form) was  f r o m N i ( p y ) g ( A s F g ) 2 by c r y s t a l l i z a t i o n  by s t i r r i n g  f o u n d , however, t h a t when N i ( p y )  2  24 h o u r s , a new does  (3)  this  magnetic  (AsFg)2  described  i n s e c t i o n 4.2.2.4, b u t  Figure  4.15  properties  shows t h e v a r i a b l e  o f t h e s e two  f o r 24 h o u r s  described  temperature  forms. 3 forms  o f t h e s e a and  " i n vacuo"  compounds  of  Ni(py)^-  When t h e a f o r m i s ( c o n d i t i o n s used  o f t h e 3 form) i t r e t a i n s t h e p r o p e r t i e s  preparation  We  i s h e a t e d a t 60°C f o r  show some i n t e r e s t i n g f e a t u r e s .  h e a t e d t o 60°C  i n the  of the a  I n an a t t e m p t t o i n v e s t i g a t e f u r t h e r t h e s t r u c t u r a l  differences  o f t h e a and  photographs  f o r t h e two  related in  g  the o t h e r N i L ^ f E F g ^  susceptibilities The  form.  much l i k e  chapter.  (AsF )  i n CHCl^-  o f N i ( p y ) ^ ( A s F g ) 2 , i s o b t a i n e d which  n o t have t h e p r o p e r t i e s  r a t h e r behaves in  form  f i  prepared  complex,  T a b l e IV-12  .  3 forms we f o r m s and,  Ni(4mepy) (PFg) • 4  2  o b t a i n e d X-ray f o r comparison,  powder f o r the  The d - s p a c i n g s a r e shown  The d i f f r a c t i o n p a t t e r n s o f t h e a  and 3  forms  of N i ( p y ) ( A s F g ) 2 are very s i m i l a r i n nature although there 4  are  some d i f f e r e n c e s  use t h i s  i n the d-spacings.  It is difficult  technique f o r a -quantitative discussion of  s t r u c t u r e because N i ( p y ) ^ ( A s F g ) 2 p r o b a b l y has symmetry.  I t seems t h e s t r u c t u r e s Some i n t e r e s t i n g f e a t u r e s  the  to  lattice  t o o low a  are s i m i l a r but not  lattice identical.  of the i s o m e r i z a t i o n  of  a f o r m emerge when t h e low t e m p e r a t u r e i n f r a r e d and e l e c t r o n i c  spectra  a r e o b t a i n e d on m u l l e d s a m p l e s .  T h e r e i s no  c h a n g e i n t h e e l e c t r o n i c s p e c t r u m o f a m u l l e d sample  noticeable on  cooling  -212-  10% (cm mol"') 3  2^  1 6 0  FIGURE 4.15  T(K)  MAGNETIC S U S C E P T I B I L I T Y Ni(py) (AsFg) 4  for  2  300  2 6 0  OF THE  ( The c i r c l e s  a AND  are the data  t h e a f o r m and t h e t r i a n g l e s  form)  3 FORMS OF  those  points  of the 6  -213-  TABLE IV-12 D-SPACINGS OF N i ( p y ) ( A s F g ) 4  Ni(py) (AsFg) 4  2  2  ( a and g f o r m s ) AND  Ni ( p y ) ( A s F g ) 4  4  Ni(4mepy)  4  B  a  1  2  Ni(4mepy) (PFg)  1  8.66  m-s  8.64  m-s  9.62  m-s  2  7.62  s  7.60  s  8.79  s  3  7.11  s  7.10  s  8.09  vs  4  6.39  vs  6.16  vs,br  7.4 6 w  5  5.96  vs  5.95  vs,br  6.91  s  6  5.45  vw  5.45  w  6.26  w  7  4.98  s  4 . 95m  5.67  vs  8  4.69  m-s  4.65m  5.40  vs  9  4.39  vs,br  4.48  s  4.79  s  10  4.19  vs  4.15  s  4.57  w  11  4.00  m  3.98  m  4.38  s  12  3.53  w  3.53  w  4 .16 v s  13  3.31  m  3.28m  4.02  vw  14  2.97  w  3.13  w  3.65  w-m  2.98  w  3.54  s  3.26  w  3.12  w  15 16 17  2  -214-  to l i q u i d infrared mulled  nitrogen  s p e c t r u m on c o o l i n g  sample  spectrum).  Moreover,  cm  i n the  (although the v~(E ) z g 4.2.3.3) d o e s a p p e a r i n t h e  ~~ ( s e c t i o n  T h e s e two  t h e change  i s n o t as n o t i c e a b l e w i t h t h e  as w i t h t h e powdered  o f A s F ~ a t 570 b  ization  temperatures.  sample  observations  suggest that  o f t h e a f o r m d o e s n ' t go a s e f f i c i e n t l y  the isomeri n the mulled  s t a t e a s i n t h e powder. How  a r e t h e m u l l e d f o r m s o f a and  i s o m e r i z a t i o n o f a must be a s o l i d o f w h i c h must be r e l a t e d tice.  The m u l l i n g  state effect,  to r e g u l a r i t y  the  The  efficiency  of the c r y s t a l l i n e  i n an i n e r t m a t r i x w h i c h  cooperativity effects.  It is likely  lessens  that  ( w h i c h was  t o be a c r y s t a l l i z a t i o n lattice,  obtained  process).  the B form, whether isomerization.  latter  lattice  which i s present only  process  lattice  considered  because o f i t s d i s o r d e r e d  as a powder o r m u l l e d w i l l  undergo  powder.  The  by what c a n be Hence,  any  t h e 3 form,  w h i c h i s f o r m e d by t h e r m a l means, h a s a more d i s o r d e r e d than the a form  lat-  o f t h e a f o r m must r e s u l t i n  Ni(PY)A (AsF,)- c l u s t e r s 4 b Z lattice  B related?  requires  i n the m i c r o c r y s t a l l i n e  a  not regular  a  -215-  4.2.3  FACTORS DETERMINING ANION COORDINATION  IN N i L A 4  2  COMPOUNDS  In t h e p r e c e d i n g 4.2.2.2 we p r o v i d e d Ni ( p y ) ( P F ) , 4  6  4  4  the anions  ever.  t h a t t h e s t r u c t u r e s o f t h e complexes 6  N i ( 4 m e p y ) ( A s F ) , and  2  4  i n v o l v e square p l a n a r  o u t t h a t they  c o u l d be c o n s i d e r e d complexes.  4  as f o r t h e o t h e r  lower temperatures,  g  2  are only  4  g  The  very  weakly  i n which the anions  I t seems a p p r o p r i a t e a t  review the l i t e r a t u r e o f the r e l a t e d  determine whether o r n o t t h e a n i o n  to identify  i s coordinated  factors that  i n such  com-  T h i s p o i n t was a l l u d e d t o i n s e c t i o n 4.1. A review of the l i t e r a t u r e  of the types, pyridine  structures  compounds w h i l e a t  2  c o m p l e x e s g e n e r a l l y i n an e f f o r t  plexes.  These  i s q u i t e u n i q u e , how-  a n o t h e r isomer i s formed  this point to b r i e f l y  and  2  NiL (EF )  become more s t r o n g l y c o o r d i n a t e d .  4  as s t r o n g l y  o v e r t h e t e m p e r a t u r e r a n g e 80 t o 300 K.  A t room t e m p e r a t u r e , t h e a n i o n s  NiL A  2  i n axial positions.  r e l a t e d complex, N i ( p y ) ( A s F ) ,  coordinated  g  n i c k e l ( I I ) species  weakly c o o r d i n a t e d  distorted octahedral  are maintained closely  2  very  We a l s o p o i n t e d tetragonally  evidence  Ni(4mepy) (PF ) ,  2  Ni(3mepy) (AsFg) with  d i s c u s s i o n s o f s e c t i o n s 4.2.2.1 and  N i L A-,  shows t h a t s e v e r a l compounds  (where L i s a p y r i d i n e o r s u b s t i t u t e d  and A i s a n a n i o n i c s p e c i e s )  have b e e n c h a r a c t e r i z e d  show a v a r i e t y o f s t e r e o c h e m i s t r i e s  upon L a n d A  (and s t o i c h i o m e t r y ,  x).  around n i c k e l  We w i l l  consider  depending only  -216-  t h o s e c a s e s when x i s 4 b e c a u s e t h e s e a r e a p p r o p r i a t e discussion.  Here t h e p s e u d o - o c t a h e d r a l and square  stereochemistries  anions  BF^  -  2  4  3  (127).  coordination NiN^A ; the  (16 ) , C 1 0 ~ (16 ) , R e 0 ~  (126) , NCO~ (126) , F S 0 ~ Br  planar  compounds i n w h i c h L i s p y r i d i n e h a v e  2  a trans-"octahedral"  (A) b e i n g  this  a r e predominant.  Some N i L ^ A been a s s i g n e d  for  ( 1 2 5 ) , NCS~  4  (121) , CF^.COO" (128) ,,"l"(127) , C l " (127)-,  Other p y r i d i n e complexes have square p l a n a r c o -  o r d i n a t i o n geometries about n i c k e l ( I I ) only very weakly coordinated  anions;  a r e when t h e a n i o n i c s p e c i e s p r e s e n t (130), and E F g The  -  (studied  nature  and n o n - c o o r d i n a t e d o r  some e x a m p l e s o f t h e s e i sI^  (129),  Sn(NCS)g  here).  o f L a l s o has an e f f e c t on t h e s t r u c t u r e  of t h e complex, w i t h t h i s e f f e c t most w i d e l y n i c k e l ( I I ) p e r c h l o r a t e complexes, N i L ( C l 0 ) 4  4  studied i n the 2  (19 - 2 2 ) .  When L i s p y r i d i n e , 3 - b r o m o p y r i d i n e , 4 - i s o p r o p y l p y r i d i n e , a n d 3,5-dimethylpyridine are coordinated.  (see s e c t i o n 4.1),  When L i s 4 - m e t h y l p y r i d i n e ,  or 3,4-dimethylpyridine are not coordinated. perchlorate  the perchlorate  ( s e c t i o n 4.1),  4-aminopyridine,  the perchlorate  When L i s 3 - m e t h y l p y r i d i n e  a n i o n s may o r may n o t be c o o r d i n a t e d  upon t h e method o f p r e p a r a t i o n ;  refluxing  i n a benzene-2,2-dimethoxypropane mixture with coordinated  anions'  anions  (21 ) , t h e depending  Ni(3mepy) (H 0) (C10 ) 4  gives  2  2  4  t h e compound  p e r c h l o r a t e a n d vacuum d r y i n g o f N i ( 3 m e p y ) ~ 4  2  -217-  ( H 0 ) 2 ( C 1 0 ) 2 g i v e s t h e compound w i t h n o n - c o o r d i n a t e d 2  The  anions.  4  basicities  o f these L moieties  in order of increasing b a s i c i t y 3-Brpy(2.84)<  ( 1 3 1 , 96) a r e a r r a n g e d  (pKa's i n b r a c k e t s ) b e l o w :  py(5.12)<3mepy(5.68)<4-isopropylpy(6.02)  Mmepy (6 . 02l<3 ,5-dimepy (6 .15) <3 ,4-dimepy (6 . 46) < 4aminopy(8.96) The  basicities  o f t h e L m o i e t i e s appear t o determine  cases whether t h e a n i o n c o o r d i n a t e s t o t h e metal when t h e b a s e s t r e n g t h o f L i s l e s s anions  than  i n most  ion.  t h a t o f 3mepy, t h e  a r e c o o r d i n a t e d and when more t h e n t h a t o f 3mepy, t h e  a n i o n s a r e n o t c o o r d i n a t e d i n t h e NiL^A2 c o m p l e x e s . is  3mepy, t h e s o l i d  structure  L i s 3,5-dimethylpyridine.  rule  is  form o f N i ( 3 m e p y ) ( C 1 0 ) 4  methane, an i d e n t i c a l m i x t u r e forms i s o b t a i n e d .  4  of a square  o f t h e square 4  basicity  planar nickel(II)  solid  chemistry.  i n dichloro-  complex.  2  i s dissolved i n  indicates These  the presence  NiL (Cl0 ) 4  4  properties i n the s o l i d  2  state  The s o l u t i o n p r o p e r t i e s o f t h e s e two c o m p l e x e s ,  i n t o account  conform  o f L and t h e o v e r a l l But  where  p l a n a r and o c t a h e d r a l 4  state,  spectrum  complexes, then, have d i f f e r e n t  when t a k e n  -  When N i (3 , i 5 - d i m e p y ) ( C 1 0 ) i w h i c h h a s  the electronic  i n solution.  solution  i s dissolved  2  octahedral coordination i n the s o l i d dichloromethane  when  T h i s c a s e a l o n g w i t h t h e one  L i s 3 - m e t h y l p y r i d i n e have some i n t e r e s t i n g When e i t h e r  When L  i s variable.  One o f t h e e x c e p t i o n s t o t h i s  than  Generally  the fact  well with the correlation of  s t e r e o c h e m i s t r y o f t h e complex.  t h a t t h e s t r u c t u r e s i n s o l u t i o n and  s t a t e a r e d i f f e r e n t when L i s 3 - m e t h y l p y r i d i n e a n d  -218-  3,5-dimethylpyridine  does s u g g e s t t h a t  lattice  h a v e some e f f e c t on t h e s t r u c t u r e p r e s e n t . authors  (115) who r e p o r t e d  the molecular  energies  may  In f a c t , the structure of  N i ( 3 , 5 d i m e p y ) ^ ( C l O ^ ) 2 were s e a r c h i n g  f o r s t r u c t u r a l clues f o r  anomalous o c t a h e d r a l  ( b a s e d on b a s e  of  stereochemistry  3 , 5 - d i m e t h y l p y r i d i n e ) by c o m p a r i s o n  Ni(3,4-dimepy)^(ClO^)2 of the neutral there  ligand).  (which f o l l o w s  to the structure of the trend  T h e y were f o r c e d  was n o t any s i m p l e e x p l a n a t i o n  strength  inbasicity  to conclude  that  b u t t h a t t h e anomalous  s t r u c t u r e must be due t o " s e c o n d a r y " v a l e n c e  forces  or"lattice  energy e f f e c t s . " It  i s i n t e r e s t i n g to speculate  on t h e r e a s o n s  N i ( P Y ) 4 ( A s F g ) 2 u n d e r g o e s t h e low t e m p e r a t u r e whereas o t h e r ligands fore,  NiL^fEFg^  c o m p l e x e s do n o t .  (py, 3mepy, 4mepy) p y r i d i n e  from t h e s t u d i e s  c o m p l e x e s w o u l d be most l i k e l y  isomerization Of a l l t h e t h r e e  i s the least basic,  on t h e p e r c h l o r a t e  complexes,  t o have c o o r d i n a t e d  one w o u l d e x p e c t t h e b a s e s t r e n g t h  since  and  A s F ~ t o be a p p r o x i m a t e l y e q u a l one w o u l d e x p e c t b complexes  form whereas o n l y the  AsFg"  quite  4  2  one d o e s .  there-  the pyridine  o f b o t h PFg both  t o have a p a r a m a g n e t i c  Comparing t h e s e p y r i d i n e  complexes,  (As-F=1.80 2 ( 5 ) ) a n i o n s a r e l a r g e r t h a n t h e PFg  (P-F=^l.50°0 involve  (Ni(py) (EFg) )  neutral  anions.  But  pyridine  that  a n i o n s b u t any c o n s i d e r a t i o n  lattice  subtle  energy e f f e c t s .  (cfN i L ( C 1 0 ) , 4  4  2  of anion  s i z e would  T h e s e e f f e c t s a p p e a r t o be  L=3,4dimepy a n d 3 , 5 - d i m e p y ) .  -219-  O t h e r f a c t o r s w h i c h may o f E-F  b o n d s and  be  important are  the p o l a r i z i b i l i t y  the  intrinsic  o f t h e EFg  anion.  f o r e , i t i s d i f f i c u l t to a s c e r t a i n the o r i g i n of the perature  i s o m e r i z a t i o n of N i ( p y ) ( A s F g ) . 4  i s t h a t i t does t a k e p l a c e are u s e f u l i n assigning  the  and  There-  low  However, t h e  2  the  strength  r e s u l t s of the  tempoint  characterization  s t r u c t u r e of the N i L ( E F g ) 4  2  complexes  generally. Further would i n c l u d e the  w o r k w h i c h c o u l d be d o n e on s y n t h e s i s , and  Work on  base s t r e n g t h  NiL^(EFg)  c h a r a c t e r i z a t i o n of  where L i s a s u b s t i t u t e d p y r i d i n e o f pyridine.  the  complexes  lower base s t r e n g t h  t h e s e s y s t e m s w o u l d show w h e t h e r t h e  of L could  f o r c e t h e EFg  anions to o  2  than lower  coordinate.  -220-  4.3  COMPLEXES OF C O P P E R ( I I ) ;  4.3.1  4  g  2  INTRODUCTION  The previously (15).  CuL (EF )  compound, C u ( p y ) ( P F g ) , 4  by M a y f i e l d and B u l l  2  has been s t u d i e d  (14) and by McWhinnie e t a l  The i n t e r p r e t i o n o f t h e e l e c t r o n i c  p r o p e r t i e s o f the  compound b y t h e s e a u t h o r s was t h a t  the copper(II) i o n i s i n  a distorted  with semi-coordinated  PFg  o c t a h e d r a l environment  anions. It  i s interesting  d a t a on C u ( p y ) ( P F g ) . 4  407  and 391 cm . 1  in  spectrum  They s t a t e  state  i n section  403 cm , i n d i c a t e 1  the l a t t i c e  4  that  t h e 429 cm  2.2.4, t h e p r e s e n c e  the presence  and t h u s ,  as t o t h e p u r i t y  of this  1  2  infrared there are  a t 600, 429,  band c a n p r o b a b l y (14 ) .  As we  o f bands a t  of non-coordinated  ^604 and  pyridine  i t appears  that  compound.  McWhinnie e t a l (15) do  n o t r e p o r t t h e p r e p a r a t i v e method u s e d spectrum  that  of Cu(py) (PFg)  a s s i g n e d t o t h e 16b v i b r a t i o n o f p y r i d i n e  have n o t e d ^  t o examine t h e p u b l i s h e d  M a y f i e l d and B u l l  2  bands, i n t h e i n f r a r e d  be  (27 )  t h e r e i s some d o u b t  nor t h e f u l l  infrared  a n d , m o r e o v e r , t h e r e i s some d i s a g r e e m e n t i n t h e a s s i g n -  ment o f t h e PFg  vibrations  i n t h e two r e p o r t s .  We have s y n t h e s i z e d t h e s e r i e s  o f compounds  where L i s p y , 4mepy, and 3mepy and E i s P and A s .  CuL (EFg) 4  With-these  2  -221-  combinations  of n e u t r a l  to o b t a i n  unambiguous a s s i g n m e n t o f  As  the  an  d e s c r i p t i o n of  complexes  the  the  anions,  preparations  and  necessry  the of  ^400  cm  t o remove l a t t i c e  ^ i n the  t o be  anion the  bands.  Cu(py)^(EFg)  ( s e c t i o n 6.2.2.8-.9).  at  pyridine  2  40°C (bands  disappear).  used i n the  C u ( 4 m e p y ) ^ ( E F g ) 2 compounds i n o r d e r  materials  i t is possible  i n f r a r e d spectrum  A l s o , more d i l u t e s o l u t i o n s had of  and  ( s e c t i o n 6.2.1.8-.9) i n d i c a t e , h e a t i n g  " i n v a c u o " was a t ^600  ligands  preparati  to obtain  "pure"  -222-  4.3.2  RESULTS AND  This on  the  DISCUSSION  section w i l l  CuL (EFg) 4  2  d i s c u s s the  complexes.  First  susceptibility  measurements w i l l  the  spectral  electronic  be  presented  on  other  data  will  obtained with  and  complexes.  presented  and  f o r the N i L ( E F ) 4  reference  t o the  g  low  o f our  studies  the r e s u l t s  of the  magnetic  be d i s c u s s e d  briefly.  Then,  e l e c t r o n s p i n resonance data  discussed with  copper(II) be  and  results  reference Finally,  discussed 2  the  work  infrared  in relation  compounds o f  temperature  to previous  spectral  to the  s e c t i o n 4.2  isomer  will  data  (particularly  (Ni(py) (AsF ) ) 4  g  2  spectrum, s e c t i o n 4.2.2.4.3).  4.3.2.1  MAGNETIC PROPERTIES  All  of these  CuL (EFg) 4  2  compounds have m a g n e t i c  moments i n t h e r a n g e o f 1.8-2.0 B.M. of  magnetically  dilute  copper(II)  (see A p p e n d i x  systems.  2)  indicative  -223-  4.3.2.2  ELECTRONIC SPECTRAL PROPERTIES  Table the  title  metric  IV-131ists  compounds.  i n the v i s i b l e  correlation  absorption  s p e c t r a l data f o r  The s p e c t r a c o n s i s t o f a b r o a d ,  band c e n t e r e d  Hathaways  the e l e c t r o n i c  diagram  region.  ( F i g u r e 2.7  maxima a r e c o n s i s t e n t w i t h  tetragonal octahedral  chromophore.  asym-  According  p . 53  to  ), the  an a x i a l l y  elongated  The e x t i n c t i o n c o e f f i c i e n t s -1  of  the  bands o b t a i n e d  are  consistent with  are  similar  where  i n the s o l u t i o n spectra  this  to the value  t e t r a g o n a l chromophore (e=52) o b s e r v e d 4  2  The band maxima o b s e r v e d  around copper(II)  The s q u a r e p l a n a r  this is  evidence  propensity  supports  chiometry o f these coordinated (14,  15) h a s  distorted  g  of ligands  the  ligating  (70 ) .  anions  work on t h e  t h e same . c o n c l u s i o n . .  h a s done  octahedral  X-ray d i f f r a c t i o n  f o r ir-bonding  e n v i r o n m e n t and, g i v e n  The p r e v i o u s  l e d to-much  Hathaway  chromophore  stereochemistry  c o m p l e x e s , has E F  to i t .  has  A l l of  the c o n c l u s i o n t h a t the copper(II)  i n a pseudo-octahedral  a great  2  f o r o u r compounds  i s u s u a l l y not observed unless  s p e c i e s have a g r e a t  )  they  chromophore  4  2.7).  since  cm  4  r u l e o u t t h e p r e s e n c e o f a t e t r a h e d r a l "CuN " (cf F i g u r e  M  for Cu(py) (SO^F)  a (trans-octahedral) tetragonal CuN 0  been p o s t u l a t e d .  ('WO  -1  the  stoi-  at least  weakly  Cu(py) (PF ) 4  :  ion  g  2  •-  d e a l o f work on t e t r a g o n a l l y  complexes o f c o p p e r ( I I ) .  and o f s i n g l e c r y s t a l  The r e s u l t s o f  polarized  electronic  -224-  TABLE I V - 13 ELECTRONIC SPECTRAL DATA FOR CuL„(EF,)„ 4 6 2 BAND POSITION (kK) COMPOUND Cu(py)  4  (PF ) 6  2  C u ( p y ) (AsF ) 4  6  6  4  4  g  (PF ) 6  Cu (3mepy) ( A s F ) 4  (a) m u l l  (b)  18.35  (a)  18.70  (b)  18.18  (a)  19. 61  (b)  19.15  (c)  19.01(69)  (a)  19.61  (b)  18.87 -  (c)  18.87(71)  (a)  19.42  (b)  18. 87  (c)  19.01 (77)  (a)  19.42  (b)  18.87  (c)  18.90 (73)  2  Cu(4mepy) (AsF )  Cu(3mepy)  18 .70  2  Cu(4mepy) (PF ) 4  (a)  g  2  2  2  spectrum  .(b) d i f f u s e r e f l e c t a n c e  (c) s o l u t i o n s p e c t r u m ; m o l a r e x t i n c t i o n (in M^cm" ) i n b r a c k e t s . 1  spectrum  coefficents  -225-  spectroscopy and  have b e e n c o r r e l a t e d  f o r tetraammines  b i s ( e t h y l e n e d i a m i n e ) , Cu (en) X 2  (where X i s an  anion with  an a n i o n w i t h a  2  ,(133 ) c o m p l e x e s o f c o p p e r ( I I )  2  a single  (-2) c h a r g e ) .  Cu(NH^)^X ,(132)  negative  charge or X  is  2  The d o r b i t a l o r d e r i n g s and  the p o l a r i z a t i o n p r o p e r t i e s o f t h e p o s s i b l e - t r a n s i t i o n s been used t o e x p l a i n t h e c o r r e l a t i o n s p e c t r a ) a b s o r p t i o n maxima w i t h  have  o f observed(powder  t h e chromophore  tetragonality  present. The  d orbital  o c t a h e d r a l geometry these  orbitals  has  and  in axially  tetragonality 2  are:  e  g ' 2g <  3  These o r b i t a l  energy l e v e l E^;  < a  lg ' <  2  2  >  B  >  A  E  r  e  s  2  e  c  t  : ,  lg'  2  l  v  e  as  < a  lg k2g klg' <  <  to the  2  2  2  l  increase i n tetragonal distortion  g e o m e t r y t o w a r d s -a s q u a r e  g  ; B . > B „ > A, > g' lg 2g lg  Hathaway h a s s t a t e d f o u r c r i t e r i a the  e  i n order of  orderings correspond  orderings: B,> A , > B_ > E ^ lg lg 2g 2 2 2 2 and ig 2g l g ^ g' P Y• B  The o r d e r i n g o f  levels  y j r  2  tetragonal  t h e d e g r e e of- t e t r a g o n a l d i s t o r t i o n •  The o r d e r i n g o f t h e s e  e^a^g<b g<b^g.  elongated  b e e n shown ( p.48) .  can vary with  f r o m 0^ symmetry. increasing  splitting  f o r measuring  from t e t r a g o n a l o c t a h e d r a l  p l a n a r c o n f i g u r a t i o n and t h e y are,,  the t e t r a g o n a l i t y " i n c r e a s e s : (i)  the higher  i s the energy o f the d 2+d 2 z  x  2  2 2 . . ( B, -> A, ) t r a n s i t i o n lg lg' v  (ii)  the higher  i s the energy of the d  2 2 -*-d 2 2 ( B, -> E ) t r a n s i t i o n ; x -y lg g' extent than i n ( i )  although  , d to a  lesser  -226-  (iii)  the shorter  i s the in-plane  l i g a n d bond l e n g t h , (iv)  the smaller  parameter, T correction atom  R  copper-  g  i s the t e t r a g o n a l i t y  ( = R / R , where P^ i n v o l v e s g  L  f o r the  (axial) tetragonal  ligand  present.  From t h e i r p o l a r i z e d e l e c t r o n i c s p e c t r a l r e s u l t s , coworkers 2  of the is  (133) h a v e f o u n d t h a t  also the  intense  transition  t h e band w i t h  conclusion  i s t h a t as the  a  s p e c t r a l data This  last  regard  x  i s necessary  crystal  studies  been s t u d i e d  2  since there  but only  have c o m p i l e d t h e  recently  t o powder e l e c t r o n i c f o r t h e band  i s a definite  anions.  Thompson and  (powder) e l e c t r o n i c s p e c t r a l d a t a  t h a t as v  decreases. ability  the c o o r d i n a t i n g  This  gives  o f the anions  diffuse reflectance):  2  has  Alleyne f o r a number weakly  of the v i s i b l e max  J  band i n c r e a s e s ,  structure.  (only Cu(py)^(CF^CC^)  (134)).  They have assumed  rise  /  absence o f s i n g l e  t e t r a k i s ( p y r i d i n e ) c o p p e r ( I I ) complexes c o n t a i n i n g  basic  envelope  to c o r r e l a t e the e l e c t r o n i c  complexes t o m o l e c u l a r  on t h e s e c o m p l e x e s  The  increases.  r u l e has been used  of the Cu(py)^A  e n e r g y o f any o f  increases  v m  (it is  b a n d s a r e much w e a k e r .  t e t r a g o n a l i t y o f t h e chromophore This  of  The o t h e r  2 2 B, -> E „ band lg g  The  i n the spectrum  transition  t h a t c a n be r e a c h e d w i t h  spectroscopy the  present  the highest  d-*-d t r a n s i t i o n s ) .  Hathaway and  t h e band e n v e l o p e i s made up  2 2 B, -»- Btransitions. lg 2g  B, -*-E and lg g  t h e most  a  ability  of the a n i o n i c  to the scale of  (s tronger-> weaker;  v  species  coordinating (kK) i n b r a c k e t s ,  -227-  CF C0 ~(15.5)>p-CH CgH S0 "(16.5)>S0 F~(17.0) 3  2  3  >BF ~(17.7)> value  4  3  s t r o n g band a t 19.1  is  u n l i k e our  kK  results  fluoroarsenate  and  i n the  resolution  et  al  of  a m a i n b a n d a t 18.3  kK. It  We  r e p o r t the  spectrum  (section and  noted  of  spectrum kK  and  a low  aquated  Bull  (15)  and  g  2  "has ; the.  energy  as  2  consisting  shoulder at  intensity 2  2  certain  i n the  t h e ambiguous v i b r a t i o n a l  o f Thompson and  g  compounds  2  in this  range  similar structure  about the  4.3.1).  Alleyne  report of data  purity  •(-pyridine) c;Qpp.er"-(II) . c o m p l e x e s .  the v  The" o t h e r C u L  and  the  of Cu(py)  A  (PF,)  the" T t e t r a k i s (PFg-)  4  .'(where^'L'.is-- 3 m e p y a n d -'4mepy) 'have, e v e n l a r g e r - v a l u e s :  :  comparisons o f the v  compounds show some i n t e r e s t i n g  McWhinnie  Nevertheless, given  (120),  of  of M a y f i e l d  l a r g e s t v a l u e • (18!.3..kK, here')' o f ' a l l ' . " o f  The  16.2  shoulder.  p y r i d i n e complex o f t o be  McWhinnie  compounds p r e v i o u s l y s t u d i e d b e c a u s e  (presented i n s e c t i o n  results  g  111-13 p.117) a b s o r b  It is difficult  the C u ( p y ) ( P F )  al  observed;  shoulder.  4  a low  hexa-  a t 7 7K-which m i g h t  of C u ( p y ) ( P F )  the absence o f p r e p a r a t i v e d e t a i l s et  energy  g  p r e s u m a b l y an  4  low  run  (14),  This  and  t h a t the C u ( 3 m e p y ) ( H 0 ) ( E F )  3.4.2.2.5, T a b l e  would a l s o .  kK) .  b a n d was  was  Bull  observed  a s h o u l d e r at. 16.2  of the  have n o t observed  s h o u l d be  bands were  c o m p l e x e s where o n l y one 1  (15)  two  f o r the hexafluorophosphate  however, M a y f i e l d a n d ' B u l l s result  g  i s t h a t o f M a y f i e l d and  2  the o t h e r complexes,  (a  3  4  for Cu(py) (PFg)  whereas f o r  3  C10 "(17.8)>N0 "(18.1)>PF ~(19.1)  4  The  2  2  0  '/."  complexes  °f.-  v m a x  '  v a l u e s w i t h i n t h e CuL. (EF,) max 4 b z f e a t u r e s . The °f v  m  a  x  -228-  Cu(py)^(AsFg)  2  i s lower  Cu(py)^(PFg)2• anion  T h i s may  i n energy indicate  (.2kK)  in  X i s small  is  a significant ^  anion  i n these  still  to t e l l  max  py<3mepy<4mepy; t h i s  series  weakly) than  present  whether  this  v a l u e s do :. '  i n the series:  follows the b a s i c i t y  of the neutral  L, w i t h t h e more b a s i c l i g a n d b e i n g more s t r o n g l y  bound.- F i g u r e 4 . 1 6 CuL„(PF ) C  0  shows t h e d i f f u s e  .1  c o m p l e x e s . The d i f f e r e n c e - -  However, t h e v  seem t o i n c r e a s e w i t h t h e L m o i e t y  ligand,  (though  (^5nm) and i t i s d i f f i c u l t difference.  that of  that the hexafluoroarsenate  i s more s t r o n g l y c o o r d i n a t e d  the hexaf luorophosphate  than  reflectance  f o r the three neutral ligands.  s p e c t r a of'  350  450  550 WAVELENGTH  FIGURE 4.16  750  ( i n nm)  V I S I B L E ELECTRONIC SPECTRA OF ( Spectrum  650  CuL I.EF ) 4  g  2  I L i s 4mepy, s p e c t r u m I I L i s 3mepy,  and S p e c t r u m I I I .L i s py)  -230-  4.3.2.3  ELECTRON SPIN RESONANCE SPECTROSCOPY  Figures Cu (py)  4  (PFg)  as  2  The  solution  4.18  show t h e  (300K) and  powder and 77K  shape e x p e c t e d  environment  and  a powder  respectively. line  4.17  e.s.r.  i n s o l u t i o n .(300  for copper(II)  in - an  (see s e c t i o n 2 . 3 . 3 . 2 ) .  copper(II)  than the  complexes can  time s c a l e of the  observed g value (equation have t h e  2.5,  i s an  p.23).  general  of  and  s o l u t i o n s p e c t r a have  The  axial  line  tumble  (  D 4 n  )  77K) the  "octahedral"  shape o f t h e  s p e c t r u m i s t h a t o f c o p p e r ( I I ) i n an  ment; t h e  spectra  isotropic  environ-  in solution faster  e . s . r . measurement s u c h t h a t  average o f the A l l o f the  f e a t u r e s of the  300K  axial  values  the  gjj and  gj.  e.s.r.  s p e c t r a of the  CuL^tEFg^  spectra  shown i n t h e s e  two  illustrations. Table constants  (A and  compounds. the  B)  are  4  g values  from the  noted t h a t the  reported  here;  than the  g g  g  values value  obtained  indicative  the  parameters  to those  the  4  complexes  of c o p p e r ( I I )  tetragonally distorted octahedral  equations  2.12-.15 p.  of only obtained  obtained  Cu(py) (EFg)^  f o r these  coupling  title  compounds a r e  the  elongated  52).  hyperfine  solution, spectra  these  powder s p e c t r u m i n d i c a t i v e o f The  and  s p e c t r a of  s o l u t i o n s p e c t r a were s i m i l a r  solution.  greater  be  the  s o l u b l e i n dichloromethane but  from t h e s e from the  lists  derived  I t should  Cu(py) (EFg)2  sparingly  in  IV- 14  i n an  environment  species are axially (see  FIGURE 4.17  E.S.R. SPECTRUM OF C u ( p y ) ( P F ) 4  g  2  AS A POWDER AT 8OK  "•( * A r e f e r s t o a b s o r b a n c e and H r e f e r s  t o magnetic  field)  -232-  dA/dHl  FIGURE 4.18 E.S.R.  SPECTRA OF Cu (py)  (PF )  METHANE SOLUTION AT 300 AND ( * see F i g .  4.17  p.231)  g  2  8OK  IN DICHLORO-  -233-  TABLE I V - 14 E.S.R. DATA FOR  CuL.(EF,)  COMPOUND 5(1 Cu(py) (PF ) 4  6  2  Cu(py) (AsF ) 4  6  2  Cu(4mepy) (PF ) 4  6  2  , (b) 2 .256  2 .068  2,.128  193  (a) 2 .239  2 .064  --  185 -  (b) 2 .224  2 .062  2..116  160  (a) 2 .239  2 .064  (b) 2 .296  2 .026  (a) 2 .231  2 .061  (b) 2 .294  2 .030  2 .228  2 .041  (b) 2 .235  2 .058  (a) 2 .228  2 ,055  (b) 2 .223  2 .058  (CH C1 ) 2  s p e c t r u m and g | and  B  (  2.17 (c)  o  2,.054  (a) powder s p e c t r u m a t room (b) s o l u t i o n  g  (a) 2..249  (a)  6'2  g_L.  2  85  84  45  83  82  25  85  84  40  85  84  32  86  85  27  83  82  n  X / U  205  2 .116  1 QK iy j  175  2 .118  185 • 195  2 .117  185 • 195  2 .113  temperature  spectra: g  Q  and A  g^and A f r o m l i q u i d  calculated  (p 5 4 ) ,  T "7  31  N  2  Q  from  room-temperature  temperature  by u s e o f e q u a t i o n s 2.5 (p23)  respectively  i n gauss  (d) i n 1 0 c m : A ( c m ) = A ( g a u s s ) . ( g / g ) 9 . 3 4 8 4 x l 0 ~ 4  - 1  spectrum  - 1  g  5  and  -234-  Inspection o f equation function  2.13 r e v e a l s t h a t gj_ i s a  (via s p i n - o r b i t coupling) ^  separation.  ^  This  of the d 2  ^  2r-d , d  x -y  xy' yz  separation corresponds t o the e l e c t r o n i c  2 B, E w h i c h a c c o r d i n g t o c r i t e r i o n ( i i ) (p.225) j_g g increases i n energy w i t h i n c r e a s i n g t e t r a g o n a l d i s t o r t i o n . Thus, t h e v a l u e o f g ^ s h o u l d d e c r e a s e w i t h i n c r e a s i n g t e t r a g o n a l  transition  distortion  2  (assuming X stays'xeasonably 2  The  gjj v a l u e v a r i e s w i t h t h e  and  should  constant  i n a series).  2 ^g"*" 2 g t r a n s i t i o n  (eg.  B  increase with increasing tetragonal  2.12)  distortion.  The v a l u e o f g s h o u l d d e c r e a s e w i t h i n c r e a s i n g t e t r a g o n a l d i s t o r t i o n s i n c e i t i s more d e p e n d e n t o n g_j_ t h a n gj|. The Q  i n s p e c t i o n o f t h e gj_ v a l u e s that they a r e q u i t e constant  obtained  f o r the CuL (EF )2 4  through the s e r i e s  g  shows  but the  2 2 E ( B, E ) t r a n s i t i o n v a r i e s d e p e n d i n g upon L ( s e c t i o n 4.3.2.2). xg g The  g  Q  a n d gj| v a l u e s  fore, the value  a l s o a p p e a r more o r l e s s . c o n s i s t e n t . T h e r e -  o f A must c h a n g e a l s o  so > t h a t i t  b a l a n c e s t h e s e changes i n t h e d o r b i t a l c o m p l e x e s ; X must be g r e a t e r f o r L:  counter-  separation.  (in absolute  value)  For these  i n the series  =4mepy>=3mepy>=py. Thompson a n d A l l e y n e  (121) h a v e r e p o r t e d  p a r a m e t e r s f o r a number o f C u ( p y ) ^ A 2 c o m p l e x e s .  the e.s.r.  They h a v e  found t h a t as t h e c o o r d i n a t i n g a b i l i t y o f t h e a n i o n i c  species  decreases (as judged by t h e energy o f t h e v i s i b l e band), t h e g v a l u e d e c r e a s e s and t h e A v a l u e i n c r e a s e s . The g and o o o 3  -235-  -4 A  Q  values  -1  ( i n 10  cm  ) f o r the 9  A  complexes a r e l i s t e d A  0  o  C10 "  2.114  77  BF "  2.114  78  S0 F~  2.121  73  2.128  65  4  4  3  pCH C H S0 ~ 3  6  The  5  3  comparison o f the v a l u e s o f g  the C u ( p y ) ( E F g ) 2  below:  and A  Q  Q  observed f o r  a b o v e shows t h a t g values o (2.128 and 2.116) do n o t f o l l o w t h e t r e n d e x p e c t e d f r o m t h e 4  s t u d i e d here t o those  3  electronic  spectral  r e s u l t s whereas t h e A  values  Q  This correlation with the coordinating a b i l i t y s p e c i e s c o u l d be e x p e c t e d is  less  A=C10  4  than  since the decrease  of the anionic  i n the value of g  1% f o r t h e complex w i t h A = p C H C H S 0 3  whereas t h e d e c r e a s e  the d i f f e r e n c e s  in g  Q  g  i n the value o f A  a r e n o t always  d e t e c t e d whereas t h e v a r i a t i o n  (84 and 82) do.  4  Q  3  compared t o  i s ^20%.  l a r g e enough  i n A_ i s . o  t h e o t h e r C u L ( E F g ) 2 complexes a r e comparable t o those  in  the Cu(py) (EFg)^ 4  complexes.  Thus t o be  The v a l u e s o f A „ o  in  4  Q  observed observed  -236  4.3.2.4  VIBRATIONAL SPECTROSCOPY  T a b l e IV-15 chemically in  the  of  s e n s i t i v e v i b r a t i o n s of p y r i d i n e  infrared  evidence  g i v e s the p o s i t i o n s of the  spectra of t h e i r  f o r non-coordinated  the v i b r a t i o n  compounds.  neutral  4  g  IV-16  400  cm )  spectra  4  2  for  -1  and :  asymmetry.  The  formally  v i b r a t i o n appears and  symmetry.  4  4  g  2  (1000-  shows t h e  infrared  (where L i s p y ,  2  v  4  The  i n t o two  The  compounds, t h e  ) and  v  4  of s p l i t t i n g ,  f o r b i d d e n ( i n O^  bands c a n be (T  l u  )  (T^ )  a  ^  s  u  broadening,  The  or  appearance  e x p l a i n e d i n terms o f  band o f Cu ( p y ) ( P F ) 4  infrared  symmetry) v-^(A-^g)  as a s t r o n g , s h a r p b a n d .  g  2  appears  lower to  be  components w h e r e a s t h e s e b a n d s i n t h e o t h e r  hexafluorophosphate bands.  . CuL (AsFg)  CuL (EF )  spectra  F i g u r e 4.20  t o v.j (T  s t r o n g bands w i t h i n d i c a t i o n s  split  of  infrared  species i n the  g  hexafluorophosphate  show t h e b a n d s due  of the  infrared  3mepy). For the  spectra  positions  s e p a r a t e d from those  shows t h e i n f r a r e d  CuL (PFg)  (900-300 c m )  4mepy, and  The  g i v e s the p o s i t i o n s of the  F i g u r e 4.19 of  -1  i s no  )•  s p e c t r a l bands a s s i g n e d t o t h e E F compounds.  There  ligand.  are well  2  ( T a b l e A l - 3 , p.317  Table  4-methylpyridine  of the 3-methylpyridine i n the  spectra of Cu(3mepy) (EF ) the f r e e base  and  stereo-  fact  complexes appear  as.only rather  t h a t the bands o f the l a t t e r  n o t show s p l i t t i n g  i s because  of the presence  broad  complexes o f 4mepy  do and  -237-  TABLECIV-15 SELECTED INFRARED SPECTRAL DATA FOR  CuL (PF ) 4  (i)  6  CuL (EF ) 4  6  CuL (AsF )  2  4  6  L=py 8a  1609s  1611s  6a  642m  650m,642m  16b  440s,430w  440s,  8a  1620s  1620s  19a  1512m  1512m  9a  1241m  1241m  (ii)  L=4mepy  1  n.o.  n.o.  10b+12  (a)  810s  6a  (b)  n.o.  (a) p o s s i b l y  o b s c u r e d by v  (b) p o s s i b l y  o b s c u r e d by v ( T  3  4  (T ) l u  l u  )  of PF  g  of PF  g  430w  2  2  -238-  TABLE IV-1-6 ANION BANDS I N THE INFRARED SPECTRA OF C u L ( E F ) 4  ASSIGNMENT  •(C)  BAND POSITION Cu(py) -(EF ) 4  (i)  6  2  2  (cm ) 1  Cu(4mepy) ( E F ) 4  g  6  2  Cu (3mepy) ( E F ) 4  E=P 852s,828s 4  V  •  l  V  lu)  ( T  (  A  2  l g  }  (a)  850s,br  830s,br  g  2  (a)  551s,asy  555s,asy  553s,asy  7 4 2m-s  7 4 0m-s  740s  705s,br  705s,br  705s,br  395s,br  399s,395s  395s,br  67 5m-s  670s  669s  579w,552s  578w,549s  (b)  g  (ii)  E=As  V  v  l u  T  l  (  A  l g  }  )  579w,556s  W  (a)  may c o n t a i n n e u t r a l l i g a n d b a n d s i n t h e b a n d e n v e l o p e  (b) may be h i d d e n i n t h e v ( T 4  (c)  1 u  a s s i g n m e n t s a r e based on O  ) band e n v e l o p e symmetry  f o r the anion  -239-  -240-  r- L=3mepy  L=4mepy A  B S  0 R P T I  0  N +  L=py  900  700 ENERGY (cm ) 1  FIGURE 4.20  INFRARED SPECTRA (900-350cm ) OF C u L ( A s F ) _1  4  g  2  -241-  3mepy bands i n t h i s  region  (see F i g u r e  4.19 i n t h e r e g i o n  800-830 cm ~~) w h i c h c a u s e t h e s p l i t t i n g s The  vibrations  asymmetric  bands.  due t o u n r e s o l v e d the  i n the infrared  activation  -. \  n o t t o be r e s o l v e d .  s p e c t r a appear as s t r o n g ,  T h i s a s y m m e t r i c a p p e a r a n c e may be  splitting  of the  and s p l i t t i n g  (T  x u  ) v i b r a t i o n and t o  of the formally  forbidden (0^  symmetry) v „ ( E ) v i b r a t i o n . /. g The i n f r a r e d not  much d i f f e r e n t  for  the s p l i t t i n g  of  the  bands o f P F ~ i n t h e C u L ( E F ) g  from those observed of  g  f o rN i L ( E F ) 4  g  I t i s interesting  t o note  However, t h e band a t 885 c m has been a s s i g n e d  p.  880 em  usually  example,  a1, have a s s i g n e d  to  t h e a s y m m e t r i c band  however,  g  band  (see F i g u r e  4.2  g  even  s p e c t r u m o f Co ( p y ) ( P F ) g  I t i s also  the s p l i t  have c o n c l u d e d  band o f P F  a n i o n h a s n e a r l y 0^ symmetry  see t h e i n f r a r e d  et  g  c o m p l e x e s i t a p p e a r s a s medium t o  g  3.2, p . 7 3 ) ) .  here) .  the pyridine  o c c u r s a s a weak band  c o m p l e x e s where t h e P F  Figure  that  4  to a pyridine vibration;  165) b u t i n t h e P F  (for  except  i n .our s p e c t r u m o f C u ( p y ) ( P F )  - 1  s t r o n g on t h e h i g h e n e r g y s i d e o f t h e in  2  are  e t a l . have a s s i g n e d t h r e e bands a s components o f  (a band a t 885 cm ~~ and t h e two b a n d s o b s e r v e d  at  2  ( i n one c a s e ) and t h e c h a r a c t e r i s t i c s  band c o n t o u r .  McWhinnie  4  v  interesting  ^ g^ E  2  a  n  d  v  that  4^ lu^ T  g  McWhinnie  vibrations  (and s h o u l d e r s ) a r o u n d 560 cm that  t h e a s y m m e t r i c shape o f v  g i v e s an i n d i c a t i o n o f s p l i t t i n g  2  We, 4  just  of degenerate v i b r a t i o n s .  2  -242-  For spectral and  the hexafluoroarsenate  results  are very  (or t h e i r  AsFg (0^)  complexes, t h e i n f r a r e d  interesting  because  as w e l l separated  bands.  v i b r a t i o n s appear as s t r o n g , broad  than V 4 , though) bands. v  A  a n  2  l o w symmetry e q u i v a l e n t s ) v i b r a t i o n s o f  are present  metry) ^ ( ^ g )  , v , v^,  &  (  a  The f o r m a l l y  ( v ^ i s much  The f o r m a l l y f o r b i d d e n  component o f ) v ( E ) 2  allowed  broader  ( i n 0 ^ sym-  appear as s t r o n g  g  bands.  P e r h a p s , most s i g n i f i c a n t l y ,  the v^Eg ) which i s a  doubly  d e g e n e r a t e v i b r a t i o n when A s F g  i s i n 0 ^ symmetry  appears t o s p l i t of  into  the CuL (AsFg) 4  2  1  two components  complexes.  i n the i n f r a r e d  spectra  . T h i s a s s i g n m e n t i s b a s e d on  the  fact  t h a t p y r i d i n e d o e s n o t have any. bands between 500 and  600  cm  (cf Cu(py) (PFg) ,  - 1  4  F i g u r e 4.19) and t h u s  2  bands i n C u ( p y ) ( A s F g ) t 5 7 9 4  t o components o f t h e and  energies  G  ( 0  H  vibration;  )  i n the i n f r a r e d  arsenate—copper(II) as  E  complexes a r e s i m i l a r  i n t h e p y r i d i n e complex  this  (although,  infrared  the CuL (EFg) 4  2  complexes.  spectral  have p r o v i d e d  weak, t h o u g h d e f i n i t e , these  hexafluoro-  and a r e a s s i g n e d  t h e r e may be  inter-  or 3-methylpyridine v i b r a t i o n s  region) . The  of  t h e band s t r u c t u r e  spectra of other  f e r e n c e s due t o 4 - m e t h y l p y r i d i n e in  if must be a s s i g n e d  and 556 cm  2  t h e two  •  data  (the EFg  vibrations)  supporting evidence  c o o r d i n a t i o n o f t h e EFg •._' - . '•  ;  _ * '•  f o r the  anions i n  -243-  4.3.3, RELATION TO  4.3.3.1  Cu(py) (PF ) 4  This  g  Our  Mayfield  Bull  and  that this pyridine There are  been p r e p a r e d by  i n f r a r e d data  differ  ( 1 4 ) ; however, we  i s doubtless i n the  obtained  2  compound has  of workers.  We  OTHER WORK  are not  previous  McWhinnie e t a l d i d n o t analytical  data  on  report  their  COMPARISON OF  sample o f  ML (EF ) 4  g  2  A c o n s i d e r a t i o n of the CuL (EF ) 4  itself  g  2  p  4  e l e c t r o n i c "spectrum  preparative "Cu(py)  in  s e c t i o n 4.1  on  the  (p. 1 5 1 ) .  the  material.  method  nor  g  2  COMPLEXES  i n f r a r e d s t u d i e s on 4  coordination  for  (PF ) ".  4  s y s t e m compared t o t h e N i L ( E F )  o f h e x a f l u o r o p h o s p h a t e and  we  s e c t i o n 4.2.2)  d i f f e r e n c e except  g  system  2  to a d i s c u s s i o n of anionic c o o r d i n a t i o n  for anionic  "free"  previously studied  the  by  ( s e c t i o n 4.3.1)  by .McWhinnie e t a l . ( see  to account f o r the  groups  "Cu(py) ( Fg)2"•  w o r k e r s ' sample o f  p o s s i b i l i t y o f i m p u r i t i e s i n the  4.3.3.2  have shown  a r e s u l t o f the presence of  that reported  able  other  from t h o s e r e p o r t e d  some d i f f e r e n c e s between t h e and  two  Criteria  ( i ) and  lends  i n compounds  hexafluoroarsenate.  i n compounds o f t h i s  the  The  criteria  t y p e were  (iii)  e l e c t r o n i c s t r u c t u r e o f t h e m e t a l i o n and  are on  advanced  based the i n f r a r e d  -244-  spectra observed Criterion  f o r the a n i o n i c s p e c i e s ,  respectively.  ( i i ) deals w i t h X-ray c r y s t a l l o g r a p h i c  evidence  which i s not a v a i l a b l e f o r t h i s d i s c u s s i o n . Thus, i n o r d e r t o d i s c u s s a n i o n i c c o o r d i n a t i o n i n the C u L ( E F g ) 4  and N i L ( E F g )  2  4  2  c o m p l e x e s , we  c o n c l u s i o n s r e g a r d i n g the metal m a g n e t i c and We  i o n s t e r e o c h e m i s t r y from  e l e c t r o n i c s p e c t r a l p r o p e r t i e s of the  h a v e s e e n t h a t .the N i L ( E F g ) 4  been a s s i g n e d  2  by t h e m o l e c u l a r  Ni(py) (AsFg) ,  anions weakly  T h i s s t r u c t u r e has  One  o f the. N i L ( E F g ) 4  ( s e c t i o n 4.2.2.4) h a s ,  2  coordinated anions  been  2  ( s e c t i o n 4.2.2.4.2) c a n be  coordinated  confirmed  Ni(4mepy) (PFg) 4  according to  criterion  form.  We  s t r e n g t h o f the AsFg  have anion  compared t o t h o s e o f t h e a x i a l  anions  compounds w i t h c o o r d i n a t e d a n i o n s b e c a u s e o f  2  s i m i l a r e l e c t r o n i c s t r u c t u r e s of the n i c k e l ( I I ) a p p l i c a t i o n of c r i t e r i o n  c u t as n i c k e l ( I I )  ( i ) f o r c o p p e r ( I I ) i s n o t as  I t does appear however t h a t t h e  are coordinated i n the C u ( p y ) ( E F g ) 4  2  clear-  anions  complexes and,moreover,  f r o m t h e e l e c t r o n i c s p e c t r a i t a p p e a r s t h a t c t h e EFg  anions  a r e more w e a k l y c o o r d i n a t e d t h a n t h e a n i o n i c s p e c i e s , A, 2  complexes  (section  4.3.2.2).  the  ions involved.  '."(i.e. c o p p e r d o e s n o t c h a n g e s p i n s t a t e on  anion c o o r d i n a t i o n ) .  other Cu(py)^A  2  compounds, n a m e l y  i n the low temperature  shown t h a t t h e a x i a l l i g a n d f i e l d  in other NiL^A  two  s t r u c t u r e d e t e r m i n a t i o n of  ( s e c t i o n 4.2.2.3).  The  complexes.  s t r u c t u r e s w i t h f o u r n e u t r a l l i g a n d s (L) s t r o n g l y  i n the a x i a l p o s i t i o n s .  (i),  the  compounds g e n e r a l l y h a v e  b o n d e d i n t h e e q u a t o r i a l p l a n e and  4  s h o u l d d r a w some  in  -245-  When t h e quantitatively and  the  to  to  observed  ordinating  anions other  of  these  EF '  a ML^fEFg^  anions  properties  ability  classify  in  in  a  c a n be  EF,  series  as  of  assigned  anions,.it  anions  compound c a n  does  being  the  seem  compared  compounds  KL^A^  to  be  weak  co-  reasonable  coordinated  anions.  b  Thus,  the  (EFg)2 be  A  F  and  g  anion  the  EF^  considered  anions. hand, This  In  is  so  of  some  be,  in  the  structure  form of  different  to  4  is  with  CoL (EFg) 4  around the  the  other  from t h a t  CoN^)  In  than  are  indicate  how-  CoL (EFg)2  the  that  4  ion  (D^)  anions.  clearly  observed  anions.  cobalt(II)  coordinated  complexes  2  can  coordinated  coordinated  interaction.  (tetrahedral  on  g ) 2 does  p F  4  electronic  "classical" 4  Ni(py) ~  present .  different  Ni(4mepy) (  of  not  that'the  ion  fully  generally is  of  complexes  2  sense,  anions  fact  with  complexes  the  CuL (EFg)  isomer  is observed  The E F  .not  g  coordinated  cobalt(II).  (AsF ) 6  the  have the  the  stereochemistry  Co(py)4A2  To  On  the  metal-anion  completely  in  the  compounds  by  compounds  temperature  classical  nickel(II)  the  anions  the  4  of  low  in  NiL (EFg)2  complexes,  for  the  anions  because  crystal  ever  in  coordination  Ni(py)4A2  The  to  the  full  structure in  s  2  and the other  very limits  (EFg)2  summarize,  CuL (EFg) 4  hand,  weakly of  the  complexes  the 2  low  temperature  complexes  have  isomer  coordinated  the , N i L . ( E F , ) „ compounds,  coordinated concept have  of  sense  in  anionic  coordination. anions.  Ni(py) ~ 4  anions,  generally,  anions,  non-coordinated  a  of  stretching The  CoL ~ 4  -246-  We h a v e c o n c l u d e d ordinated  anions  study based  exist  be d e v e l o p e d  the infrared  "How c a n t h e i n f r a r e d from  structure.  (i) of section  "What c r i t e r i a  from  differentiated  ionelectronic  criterion  questions remain.  f o r " c l a s s i c a l l y " co-  i n t h e some o f t h e compounds o f t h i s  on t h e m e t a l  compounds f u l f i l l  that cases  data  for EF  spectrum  4.1.  of these  f o r coordinated EF,  o r d i n a t e d anions and n o n - c o o r d i n a t e d  Important  c o o r d i n a t i o n may  g  the spectra observed  These  compounds?", a n i o n s be  f o r v e r y weakly c o -  EF,  anions."  spectra o f the hexafluoroarsenate anions  The i n f r a r e d  i n t h e M'L^tAsFg),, *  (M'=Co,Ni, and Cu) c o m p l e x e s p r o v i d e t h e most e a s i l y spectra  and w i l l  be c o n s i d e r e d  interpreted  first.  When t h e A s F , a n i o n i s i n a n o n - c o o r d i n a t e d , b coordinated, and  or f u l l y  coordinated situation,  positions o f the  (T^ ) a n d  bands do n o t v a r y a p p r e c i a b l y . the p o s i t i o n s o f the  v  formally on  infrared  a n c x  570  However, t h e s t r u c t u r e s and  ^ 2^ g^ v  b  E  a  n  When AsF,, b 0^ symmetry) t h e  1  coordinated  d  (which a r e b o t h  s  t o a metal  spectrum.  (A^ ) band i s n o t a s a weak band a t  When A s F  i s v e r y weakly  g  i o n (i.e; the N i L ^ ( A s F ) g  t h e i ( A ^ g ) band i s o b s e r v e d  depending  i s a non-coordinated  a n d t h e v ~ ( E ) band i s o b s e r v e d g  cm " - i n t h e i n f r a r e d -  spectral  f o r b i d d e n i n 0^ symmetry) do change  ( i n approximate  observed  the structures  (T-^ ) i n f r a r e d  t h e form o f c o o r d i n a t i o n .  anion  weakly  2  compounds),  a s a s h a r p , medium i n t e n s i t y  v  band sars  on  t h e low energy  side of 3 ( i ) ' v  :  T  u  a  n  d  t  n  e  v (E ) 2  g  band appe<  -247-  as  a sharp,  the of  infrared  as 2  spectrum  coordinated  i n t e n s i t y band a t ^57 0 cm ^ i n  ( F i g u r e 4.21  t h e NiL.tAsF/) ~ c o m p l e x e s , 4 6 2  fully  v  medium t o s t r o n g  shows t h e i n f r a r e d  900-300 cm ) . 1  t o a metal i o n , the  (Eg)  cm  band  When A s F , i s b  (A-^g) band  i t does i n t h e weakly c o o r d i n a t i n g case;  appears  whereas, t h e  .(of O^) a p p e a r s a s two b a n d s , one weak a t ^580  a n d one s t r o n g a t ^560 cm ^ i n t h e i n f r a r e d  F i g u r e 4.22 compares t h e i n f r a r e d and  spectrum  Ni(py) (AsFg) 4  spectra  (room t e m p e r a t u r e  2  of  spectra.  Cu(py) (AsFg) 4  2  form) and shows t h e d i f -  f e r e n c e s mentioned above; t h e comparison o f F i g u r e  4.22 t o  F i g u r e 4.11 (p. 194) shows t h a t t h e s p e c t r u m o f t h e l o w t e m p e r ature  isomer o f N i ( p y ) ( A s F g ) 4  2  and t h a t o f  Cu(py) (AsFg) 4  have s i m i l a r d i f f e r e n c e s f r o m t h e s p e c t r u m o f t h e room ature  isomer o f N i ( p y ) ( A s F g ) . 4  \>2 ( g )  band o f A s F g  E  different  anion  a p p e a r s t o be d i a g n o s t i c i n d i f f e r e n t i a t i n g  e n v i r o n m e n t s ; a weak p e r t u r b a t i o n  of  interaction  the degenerate The  (PFg)  2  (site  sym-  weak c o o r d i n -  and a f u l l c o -  gives a strong a c t i v a t i o n  and a  splitting  vibration.  infrared  s p e c t r a o f t h e PFg  anions  i n t h e M'L^-  compounds do n o t g i v e a s d i a g n o s t i c a p a t t e r n o f b a n d  character. PF  a very  perturbation gives a strong activation  ordinative  temper-  Thus, t h e appearance o f t h e  2  m e t r y e f f e c t s ) , g i v e s a weak a c t i v a t i o n , ative  2  The d i f f e r e n c e between t h e i n f r a r e d  ~ i n the non-coordinated  spectra of  s i t u a t i o n and t h e very  weakly  D  coordinated the  case i s i n t h a t the ^ ( ^ g )  former s i t u a t i o n .  v  A  When t h e PF,. b  band i s  weaker i n  i s i n a fully  coordinated  -248-  -249-  Ni(py) (AsF ) 300K 4  A B S O R P T  6 2  Cu(py) (AsF|) 300K 4  2  I  O N +  800 FIGURE 4.22  600  400  INFRARED SPECTRA  t/(crrr ) 1  ( 8 0 0 - 350 cm" ) 1  of Ni(py),(AsF,)_ 4  AND C u ( p y )  (AsF ) g  (mulled  i n Nujol)  6  2  -250-  situation  as i n t h e C u L ( P F g ) 4  differences  from  Figure  gives the i n f r a r e d  4.23  from  1000-400 cm  4.19  (CuL (PFg) 4  c o m p l e x e s , t h e r e a r e n o t many  2  the v e r y weakly c o o r d i n a t e d  1  ;  situation.  spectra o f the N i L  comparison  of t h i s  4  illustration  s p e c t r a ) shows t h e r e a r e n o t many  2  (PFg )  to Figure differences.  The  qualitative  d i f f e r e n c e s a r e t h e g r e a t e r asymmetry  and  a splitting  of the  (whereas The  no  V  3( ^ ) T  splitting  i n the spectrum  of  t n  3( i )' T  u  e  4  f o r the N i L ( E F g ) 4  )  T  4  l  u  v  u  complexes).  2  The  splitting  band c o n t o u r ,  of the  (A^ )  to p r o v i d e  criteria  f o r c o o r d i n a t i o n of the  anion. of  infrared  vibration  and  the strong a c t i v a t i o n  g  T h e s e f e a t u r e s h a v e t o be  seen  the v ( T ) band has b e e n o b s e r v e d 3 lu 0  Co(py) (PFg) 4  2  ( T a b l e I I I - l 9 p. 1 4 2 ) ,  anions are non-coordinated. spectrum and  of C o ( p y ) ( P F g ) 4  2  The  was  thus the anion i n f r a r e d  i n terms of s i t e  splittings.  The  of AsFg  -  splitting  of the v ( E ) 2  g  from  a complex i n w h i c h  the  infrared  as a v e r y weak band  of Co(py) (PFg) 4  2  can  be  or f a c t o r  group  feature regarding coordination o f the v  vibration  compounds i s n o t o b s e r v e d  splitting of  c  symmetry e f f e c t s  anions i s the s p l i t t i n g  PFg  together since  observed  most d i a g n o s t i c  seen  v , ( A , ) band i n t h e 1 lg  spectrum  rationalized  c a n be  i n the spectrum  n  T  intensity,  of both complexes.  asymmetry o f t h e v (  °f 4( i )  spectra  2  a s a medium t o s t r o n g  sharp band v  the C u L ( P F g )  n  i s observed  (A-^g) band a p p e a r s ;  i  U  compounds  2  but t h i s  (E ) v i b r a t i o n .  2  The  g  of the PFg"  i n the  CuL (PFg) 4  2  c o u l d r e s u l t from.'.interference  t h e s t r o n g band a s s i g n e d t o t h e  v 4  (  T x  u  )  vibration.  The  -251-  FIGURE 4.23  INFRARED  SPECTRA  (1000- 400 cm" ) 1  of N i L ( P F ) 4  g  2  -252-  question arises, of  the  ^(Eg)  shown by of  the  "Why  do  vibration  Table III-2  imply  (p.  the  When t h e  EF  b  symmetry o f vibration  species  the  their infrared  infrared  and  Thus we to  -1  -1  metry.  The  to  the  the  to  (  the  can  the  assign  the  vibrations  the  site  a n c  ^  *~2v  highest  A^  be  s  y  m  m  of  the the  g  v(B- ) v i b r a t i o n L  symmetry e f f e c t s  t  A^  vibration  the  e  r  Y • u  v~(E  in  is  is  both  only band  w e a k e r band i n the  C  sym-  4 v  i s seen a t a l l are  is C , 4 v  )  and  higher intensity and  sym-  possible  explained  of AsF ~  g r o s s symmetry ).  vibration  B.^ v i b r a t i o n  L  v(B-^  i s probably G  '4v'  i n t e n s i t y pattern of spectra  As  bands when t h e  splitting  v(A- ) v i b r a t i o n  i s , although the  symmetry  two  whereas the  can  fact that  p r o b a b l y means t h a t  into  pattern  anions?"  g  (degenerate) E  activities;  Raman a c t i v e  (560-550 c m )  and  infrared  terms of  cm )  splits  The  intensity  coordinated EF the  a n i o n i s C.  i n the  and  monodentate, the  i s expected.  Raman a c t i v e .  splitting  i s lowered  ~ anions are  B-^ v i b r a t i o n s  (that  29),  octahedral species  metry of  ( 580  the  present the  also  precise  -253-  CHAPTER 5  SUGGESTIONS FOR FURTHER STUDY  This chapter w i l l further  summarize t h e s u g g e s t i o n s f o r  s t u d y w h i c h were p r o p o s e d  chapters.  In a d d i t i o n ,  fluorophosphate  i tw i l l  i n t h e p r e c e d i n g two  suggest  and h e x a f l u o r o a r s e n a t e  m i g h t be a t t e m p t e d  i n the future.  o t h e r work on h e x a complexes  which  -254-  5.1  SUGGESTIONS FOR  FURTHER STUDY  Suggestions  f o r f u r t h e r study  3 i n c l u d e d the d e t e r m i n a t i o n (H 0) (PF ) 2  2  6  (section  of molecular  ( s e c t i o n 3.4.2.2.4) and  2  3.4.2.2.5).  the  stereochemistry  and  spectral  presented  was  g  2  assigned  on  2  disprove  the b a s i s of  magnetic  studies.  proposed  to.the  i n s e c t i o n 4.2.3.  the b a s i c i t y  isolation  of the  o f a complex w i t h  low  temperature  compounds, where  2  L  thermal  degradation  i s Co,  N i , and  i d e n t i f y more f u l l y p o s s i b l e , as  products  One  should  area of  complexes.  a l s o suggested  similar  the M ' L ( E F g ) 4  done.  2  t h a t more  detailed  complexes  (where  F u r t h e r work c o u l d sublimates  and  i t might  o f t h i s work, t o e x p l a i n t h e initial  different  studies.  f u r t h e r work w h i c h c o u l d be s t u d i e s of the  i n t e r a c t i o n s and  comparison of r e l a t e d  the  2  T h i s work w o u l d g i v e more d e t a i l e d  regarding metal-anion fruitful  4  be  i n v o l v e s the X-ray d i f f r a c t i o n compounds.  in  the  Ni(py) (AsFg) .  t h e r e s i d u e s and  i n the  result  room t e m p e r a t u r e p r o p e r t i e s  i t was  a result  obtained  n e u t r a l l i g a n d can  s t u d i e s on  Cu)  T h i s would d e t e r m i n e whether  isomer of  I n C h a p t e r 4,  be  2  Such s t u d i e s would c o n f i r m o r w h i c h was  Co(3mepy)g-  a s u b s t i t u t e d p y r i d i n e o f weaker b a s e s t r e n g t h t h e n p y r i d i n e , -  lowering  M'  structures of  Cu(3mepy) (H 0) (PFg)  F u r t h e r r e s e a r c h on N i L ^ ( E F g ) is  i n Chapter  pursued  CuL (EFg) 4  information  would permit  copper(II)  and  2  a more  nickel(II)  -255-  The s y n t h e s i s a n d c h a r a c t e r i z a t i o n o f h e x a f l u o r o p h o s p h a t e and h e x a f l u o r o a r s e n a t e covered  i n t h e p r e s e n t work  compounds o f m e t a l s  not  ( s u c h a s i r o n a n d manganese)  and  w i t h d i f f e r e n t n e u t r a l l i g a n d s p e c i e s w o u l d l e a d t o new a n d p o s s i b l y novel complexes. the M(EFg) present.  compounds  2  As m e n t i o n e d i n s e c t i o n 1.1.2,  are poorly characterized materials a t  F u r t h e r work o f t h e t y p e r e c o u n t e d  i n this thesis  o n s u c h compounds w o u l d p r o v i d e u s e f u l d a t a o n t h e v i b r a t i o n a l modes o f c o o r d i n a t e d EF,.  anions,  s i n c e , as mentioned i n  b  s e c t i o n 4.1, t h e b i s ( h e x a f l u o r o p h o s p h a t o ) -  and b i s ( h e x a f l u o r o -  a r s e n a t o ) - m e t a l ( I I ) anhydrous s a l t s would most c o n t a i n coordinated EF,  certainly  anions.  6  A n o t h e r s y s t e m o f c o m p l e x e s w h i c h w o u l d be to  e x p l o r e i n v o l v e s p y r a z i n e and s u b s t i t u t e d p y r a z i n e l i g a n d s .  Pyrazine i s a aromatic except'there and  interesting  h e t e r o c y c l i c molecule  similar to pyridine  a r e two n i t r o g e n atoms i n " t r a n s " p o s i t i o n s (1  4 p o s i t i o n s ) and hence t h e m o l e c u l e  being a b r i d g i n g l i g a n d .  has t h e p o t e n t i a l o f  T r a n s i t i o n metal  containing hexafluorophosphate  pyrazine  or hexafluoroarsenate  may e x h i b i t s i g n i f i c a n t l y d i f f e r e n t p r o p e r t i e s f r o m complexes c o n t a i n i n g o t h e r anions.  be b r i e f l y d i s c u s s e d  2  c a n be i s o l a t e d .  pyrazine  i s PF  g  and  next.  The i n i t a l w o r k on t h i s (PFg)  anions  Some i n i t i a l w o r k h a s b e e n  done by u s on t h e s y s t e m w h e r e M i s Cu and EF.g this will  complexes  system i n d i c a t e s t h a t  P r e l i m i n a r y data  Cu(pyz)^-  suggest the hexafluoro-  -256-  phosphate anions a r e not coordinated contains  complex  meric arrays may  cations  therefore point  ligands.  These  cations  (Cu-Cu) i n t e r a c t i o n .and w o u l d  be p a r t i c u l a r l y  of view.  complex  which a r e p r o b a b l y l i n k e d i n poly-  by b r i d g i n g p y r a z i n e  e x h i b i t magnetic  and h e n c e t h e  i n t e r e s t i n g t o study from  this  -257-  CHAPTER 6  EXPERIMENTAL  This chapter t h i s work. studied,  the experimental  details of  The m a t e r i a l s u s e d , t h e s y n t h e s i s o f t h e compounds  the d e t a i l s  degradations, techniques  describes  of unsuccessful preparations  the d e t a i l s  thermal  on t h e a p p l i c a t i o n o f t h e p h y s i c a l  of investigation,  g a t i o n s by s i n g l e c r y s t a l  and  and t h e d e t a i l s  of the i n v e s t i -  X-ray d i f f r a c t i o n w i l l  be o u t l i n e d .  -258-  6.1  MATERIALS  The m a t e r i a l s u s e d i n t h i s w o r k w e r e o f  reagent  g r a d e and were used w i t h o u t f u r t h e r p u r i f i c a t i o n otherwise stated. were:  The c o m m e r c i a l  Ni(H 0) (N0 ) , 2  g  3  AnalaR  2  unless  sources of the reagents  (BDH);  Co(H 0) (N0 ) , 2  g  3  2  M a l l i n c k r o d t ; C u ( H 0 ) ( N 0 ) , F i s c h e r S c i e n t i f i c ; NH^PF^, 2  Alfa  g  Products. 3-methylpyridine,  4 - m e t h y l p y r i d i n e , w e r e r e c e i v e d as amber l i q u i d s .  atmospheric  of  2  reagents, p y r i d i n e ,  r e f l u x e d over barium  and  3  P r o d u c t s ; and K A s F , A l f a The BDH  and  3  o x i d e f o r 24 h o u r s  and d i s t i l l e d  p r e s s u r e , t h e y became c l e a r l i q u i d s .  t u r n e d an amber  w i t h i n a month o f t h e d i s t i l l a t i o n .  at  Pyridine  3-methylpyridine remained c l e a r f o r a reasonable t i m e , whereas 4 - m e t h y l p y r i d i n e  When  period  color  -259-  6.2  PREPARATIONS  Unless otherwise mentioned, a l l m a n i p u l a t i o n s t h e compounds a f t e r performed  i n an  being  inert  " i n vacuo"  (a d y n a m i c vacuum) were  a t m o s p h e r e p r o v i d e d by  C o r p o r a t i o n D r i - L a b M o d e l HE-43 e q u i p p e d M o d e l 93. and  was  L- o r K-  circulated  the dry t r a i n s . the  grade  use  N  2  where M I I  M  I : E  the system  (N0 ) 3  t o prepare  and  the  xH 0+4yL+2M (EFg) I  2  2  this  was  I  2  pyridine  —>  L - ( H 0 ) (EFg) + 2 M N 0 (aq) + (x-z) H 0 + z  2  3  2  i s Co I I , N i I I o r Cu I I , L i s p y r i d i n e ,  3 - m e t h y l p y r i d i n e and  The  d e s i r e d p r o d u c t M L^,A , p r e c i p i t a t e s  M (EFg) I  2  2  a l l t h e . o t h e r s p e c i e s remain  the hexafluoro-phosphate  and  3yL 4-methylpyridine  r e f e r s t o NH^PFg o r  II  and  sieves i n  by:  and  solution  atmosphere  (monthly).  complexes i s g i v e n I 3 :  Train  1  g e n e r a l method u s e d  M  Herring  s i e v e s were r e g e n e r a t e d ..by  o f an o v e n i n c o r p o r a t e d i n t o  The  w i t h a Dry  L i n d e 4A m o l e c u l a r  These m o l e c u l a r  done p e r i o d i c a l l y  a D.L.  p r o v i d e d the i n e r t  through  of  from  the  KAsFg.  aqueous  i n solution.  Since  -arsenate are g e n e r a l l y stable  to hydrolysis  i n basic  aqueous s o l u t i o n  (1 ) , t h i s method i s  appropriate.  With these p o o r l y c o o r d i n a t i n g anions  the  ratio  II of p y r i d i n e  to metal, M  , i s g e n e r a l l y g r e a t e r than  four.  -260-r  In  t h e r e a c t i o n s where L = p y r i d i n e , t h e compounds  precipitated for  Co  1 1  from  and N i  1  1  aqueous s o l u t i o n and y=4 f o r C u  freshly precipitated The  initial  product  product  the of  infrared lattice  "in  or  "Ly(EFg)  spectra of the i n i t i a l  In the l a t t e r  the .  a n d t u r n s mauve o n d r y i n g .  products  showed t h e p r e s e n c e  t o eliminate these.  t h e p r e p a r a t i v e r e a c t i o n s where L i s 4 - m e t h y l p y r i d i n e  3-methylpyridine,  t h e s o l u t i o n c h e m i s t r y was q u i t e  consisting  t o g e t h e r , a two p h a s e  o f an " o i l y "  strongly colored  p h a s e a n d a n aqueous w e a k l y c o l o r e d u p p e r p h a s e . the s e p a r a t i o n and slow e v a p o r a t i o n o f t h e lower materials of the stoichiometry M L ^ ( H 0 ) ( E F ) 2  a n d L=4-me t h y l p y r i d i n e ,  3-methylpyridine, Cu  case,  w a t e r and p y r i d i n e a n d t h e d r y i n g  When t h e r e a g e n t s were s t i r r e d  Ni  have y=6  2  In g e n e r a l , w i t h these p y r i d i n e complexes,  v a c u o " was n e c e s s a r y  developed  i:i  h a d y>4 b u t was u n s t a b l e t o t h e  (non-coordinated)  In  .  i s blue  probably  drying conditions.  1 1  as M  y=6.  2  g  2  different.  system lower  Generally, phase  where:  gave ( i ) M=Co,  y=8 a n d ( i i ) -M=Cb, Ni*->eu<afid  L=  The o n l y e x c e p t i o n was where M i s  and L = 4 - m e t h y l p y r i d i n e ,  i n this  case, the r e a c t i o n  yields  Cu(4mepy) (EF ) . 4  The  6  2  compounds c o n t a i n i n g p y r i d i n e ,  3-methyl-pyridine for  h a v i n g y>4 were u s e d  t h e p r e p a r a t i o n o r attempted  w i t h y<4.  4-methyl- and  as t h e s t a r t i n g m a t e r i a l s  preparation of derivatives  -261-  Details next  o f the preparative  and a r e c l a s s i f i e d  pyridine,  the three sections,  in  a table.  ligand,  L,  the a n a l y t i c a l  involved:  A t t h e end  data are compiled  PYRIDINE COMPLEXES  The in  as t o t h e n e u t r a l  4 - m e t h y l p y r i d i n e and 3 - m e t h y l p y r i d i n e .  of  6.2.1  procedures are given  Table  6.2.1.1  a n a l y t i c a l data  VI-I.  HEXAKIS(PYRIDINE)COBALT(II) Co(py) (PF ) 6  Cobalt(II) was d i s s o l v e d  magnetically, phosphate  HEXAFLUOROPHOSPHATE  2  n i t r a t e hexahydrate  (17 m l . ) .  a filtered  consisting While  solution  The m i x t u r e was s t i r r e d  (Co(N0 ) 3  2  6H 0,2.9g) 2  o f 50 m l . o f d i s t i l l e d  t h i s s o l u t i o n was  o f ammonium  (NH^PFg, 3.2g) i n d i s t i l l e d  (10-15 m i n u t e s ) . filtered  6  i n a solution  water and p y r i d i n e  added.  f o r t h e s e complexes a r e p r e s e n t e d  until  water  stirred  hexafluoro-  (125 ml.) was  precipitation  occurred  The o r a n g e p r e c i p i t a t e w h i c h f o r m e d was  and washed w i t h a s o l u t i o n  and  pyridine  (5 m l . ) .  This  for  about 1 day.  the  product a t t h i s point  material  consisting was d r i e d  D e p e n d i n g upon t h e d r y i n g varied  i n color  o f 50 m l . H 0 2  " i n vacuo"  conditions  used,  f r o m mauve t o v i o l e t  -262-  and  had  a c o m p o s i t i o n i n t e r m e d i a t e between t h e h e x a k i s ( p y r i d i n e )  and  tetrakis(pyridine)  pink Co(py)g(PFg)2  complexes.  compound was  mauve-violet material  minutes  was  usually  sufficient  6  Cobalt(II) w a t e r was  significant  g)  i n 125  The  initial  nitrate  nil. water  few  decomposition.  HEXAFLUOROARSENATE  (2.9 g)  i n 50  hexafluoroarsenate  i n t h e same manner as  Co(py)g(AsFg)2  was  ml. (KAsFg,  i n 6.2.7.2.  p r o d u c t o b t a i n e d i n t h e r e a c t i o n was equilibrating  orange.  w i t h p y r i d i n e .-vapor and. d r y i n g A  o b t a i n e d as a p i n k powder.  T E T R A K I S ( P Y R I D I N E ) C O B A L T ( I I ) HEXAFLUOROPHOSPHATE Co(py) (PFg) 4  6.2.1.4  t o a vacuum f o r a  hexahydrate  A f t e r washing,  6.2.1.3  for  2  reacted with potassium  4.6  vapor  t o remove s u r f a c e p y r i d i n e  HEXAKIS(PYRIDINE)COBALT(II) Co(py) (AsFg)  the  a l l o w i n g the  a vacuum) a t room t e m p e r a t u r e  Exposing the product  f r o m t h e sample w i t h o u t  6.2.1.2  o b t a i n e d by  to e q u i l i b r a t e with pyridine  (pyridine vaporized into s e v e r a l hours.  Complete c o n v e r s i o n t o  2  TETRAKIS(PYRIDINE)COBALT(II) Co(py) (AsFg) 4  The  HEXAFLUOROARSENATE  2  Co(py)g(EFg)  2  compound was  heated  at  80-90°C  -263-  "in  vacuo"  f o r 3 t o 4 hours t o y i e l d  Co(py)^(EFg)  ' fy  2.1.5  2  a s an i n t e n s e  the corresponding product,  red purple  HEXAKIS (PYRIDINE) NICKEL ( I I ) Ni(py) .(PF ) 6  6.2.1.6  6  Ni(py) (AsF )  Nickel(II) was d i s s o l v e d pyridine  6  HEXAFLUOROPHOSPHATE  2  HEXAKIS(PYRIDINE)NICKEL(II) g  powder.  HEXAFLUOROARSENATE  2  n i t r a t e hexahydrate  i n a solution  and was r e a c t e d  (Ni(N0 ) *6H 0,2.9g) 3  2  2  o f 50 m l . w a t e r and 16 m l . o f  w i t h >a-' f i l t e r e d . , agueous ^ s o l u t i o n o f  ammonium h e x a f l u o r o p h o s p h a t e (NH^PF^, 3.2 g) o r ; p o t a s s i u m hexafluoroarsenate  (KAsEg, 4 . 7 g ) .  was f o r m e d i m m e d i a t e l y .  After  A light  -.."the d e s i r e d  precipitate  a h a l f hour o f s t i r r i n g , t h e  p r e c i p i t a t e was f i l t e r e d , washed, a n d d r i e d yielding  blue  material,  i n vacuo  as a "robins  f o r 1 day  egg" b l u e  powder. T h e s e compounds when d r i e d periods color  (4 o r 5 d a y s ) w o u l d  produce t r a c e s  i n d i c a t i v e of the corresponding  compounds. this  " i n vacuo" f o r p r o l o n g e d  color  The p y r i d i n e to disappear.  o f an o r a n g e  yellow  tetrakis(pyridine)nickel(II)  v a p o r t r e a t m e n t o f 6.2.1.1 w o u l d  cause  -264-  6.2.1.7  TETRAKIS(PYRIDINE)NICKEL(II) Ni(py) (PF ) 4  6  HEXAFLUOROPHOSPHATE  2  T h i s compound o r a compound s i m i l a r prepared found  (14) by t h e r m a l means  this  from N i ( p y ) ( P F ) . g  are not very soluble (nitromethane,  The  g  We  2  t o be an u n s a t i s f a c t o r y , method,; g i v i n g - a  compound due t o d e c o m p o s i t i o n .  carbon  t o i t was  tried,  compounds  is a stir  acetone,  i n order to prevent  p r e p a r a t i o n which takes  of pyridine  of N i ( p y ) ( P F ) 6  g  benzene,  r e c r y s t a l l i z a t i o n was n o t p o s s i b l e .  method o f p r e p a r a t i o n u s e d ,  instability  2  thermal  advantage  i n dichloromethane  and t h e  (3.3.2) t o dynamic p y r i d i n e  I n t h e d r y box, a sample o f N i ( p y ) ( P F ) was g  ferred  t o an E r l e n m e y e r  added.  present  largely  yellow  sparingly  had  a faint  filtered  stirred  light  for•1.day,  orange  the i n i t i a l l y  as an i n s o l u b l e  " r o b i n s egg" b l u e solid,  s o l u b l e compound.  a fluted  was  transformed  compound, t o an  The s u p e r n a t a n t  orange  liquid  The c o n t e n t s o f t h e f l a s k were  filter  yellow i n color.  an o r a n g e  trans-  m a g n e t i c a l l y f o r 1 hour,  paper  p r o d u c t was washed w i t h d i c h l o r o m e t h a n e was  2  f  blue-green color.  through  g  removal.  f l a s k ,and 50. ml, o f d i c h l o r o m e t h a n e  T h i s m i x t u r e was  d u r i n g which time,  impure  i n any o f t h e common o r g a n i c s o l v e n t s  tetrachloride)  of the s o l u b i l i t y  have  rather  Since these p y r i d i n e  chloroform, dichloromethane,  decomposition,  previously  and t h e o r a n g e - y e l l o w until  the f i l t r a t e  After being dried  y e l l o w powder-was o b t a i n e d .  " i n vacuo"  -265-  6.2.1.8 T E T R A K I S ( P Y R I D I N E ) N I C K E L ( I I ) HEXAFLUOROPHOSPHATE Ni(py)  (AsF )  4  6  2  (a) " S t i r " p r e p a r a t i o n This orange-yellow  compound was  6.1.2.7) u s i n g N i ( p y ) ( A s F ) g  g  2  prepared  as t h e s t a r t i n g  as above  (section  material.  (b) "Heat" p r e p a r a t i o n As m e n t i o n e d not  satisfactory  in section  6.1.2.7, t h e t h e r m a l method i s  f o r hexafluorophosphate  derivatives.  h e x a f l u o r o a r s e n a t e compound c a n be p r e p a r e d f o r m by t h e r m a l means, however. Ni(py)  r  6  (AsF,)„ was b 2.  yielding  heated  an o r a n g e - y e l l o w  A  The  i n reasonably  pure  sample o f " r o b i n s egg"  blue  a t 60°C " i n v a c u o "  f o r 24  hours  powder.  6.2.1.9 TETRAKIS(PYRIDINE)COPPER(II) HEXAFLUOROPHOSPHATE Cu(py)  (PF )  4  6  2  6.2.1.10 TETRAKIS(PYRIDINE)COPPER(II) Cu(py) (AsF ) 4  g  2  T h e s e compounds were p r e p a r e d t h a t d e s c r i b e d i n r e f e r e n d e 14. (Cu (N0 ) 3  2  • 3 H 0 , 4.8g) 2  was  of  pyridine.'  A filtered  or  KAsF ;(9 . 2g, 250ml) was g  and  5 ml  indicated  i n a manner s i m i l a r  Cupric nitrate  dissolved  i n 50 ml  H 0  and  2  4  added.  filtered,  p y r i d i n e ) and d r i e d  Precipitation A f t e r one  washed  " i n vacuo".  t h a t n o n - c o o r d i n a t e d p y r i d i n e was  g  16; ml (6.5g, 150ml)  o f a blue-mauve  half-hour of  ( solution The  to  trihydrate  aqueous s o l u t i o n o f N H P F  m a t e r i a l occurred immediately. t h e p r e c i p i t a t e was  HEXAFLUOROARSENATE  o f 50 ml infrared  stirring, water spectra  present. This  was  -266-  TABLE V I - 1 ANALYTICAL COMPOUND  DATA-FOR. P Y R I D I N E %  -  *  i  C Co(py)  (PFg)  6  2  Co(py)g(AsFg Co(py) (PFg)  2  4  Co(py) (AsF 4  6  Ni(py) (PFg) 6  Ni(py) (AsFg 6  Ni(py) (PFg) 4  Ni(py) (AsFg 4  >2 2 }  2  2 }  2  a  \  3 • • Cu(py) (PF ) 4  g  Cu(py) (AsF 4  £  2  i>2  ,  COMPLEXES a FOUND "5  EXPECTED H  N  C  H  N  4 3 . 76  3. 67  10 .21  43 . 36  3 .50  10 .26  3 9 . 54  3. 34  9. 22  39. 3 0  3. 21  9. 12  3 6 . 11  3 .03  8. 42  3 5 . 97  3. 10  8. 22  31. .90 2. 68  7. 44  3 1 . 81  2 .73  7. 42  43. , 77 3 .67  10 .21  4 3 . 69  3. 5  10 . 0  39. .54  3. 34  9. 22  3 9 . 20  3. 3  8. 95  36. .16  3. 03  8. 43  3 6 . 12  2. 99  8. 49  31, .90  2. 68  7 .44  3 1 . 70  2. 74  7. 31  31 .90  2. 68  7. 44  31, .98  2. 83  7 . 15  35 . 86 3..01 8. 36  35. ,68  3., 02  8. 45  2 . .66 7 . .39  31. ,51  2.,57  ,27 7 .  31 .70  -267-  con  f i r m e d b y m i c r o a n a l y s i s , y>4.  40°C " i n v a c u o "  6.2.2  H e a t i n g o f t h e compound a t  g a v e t h e d e s i r e d mauve•• . p o w d e r Cu (py) (EFg)  4-METHYLPYRIDINE  4  2  COMPLEXES  The a n a l y t i c a l d a t a f o r t h e s e c o m p l e x e s a r e g i v e n i n Table VI-2.  6.2.2.1  OCTAKIS(4-METHYLPYRIDINE)DIAQUOCOBALT(II) HEXAFLUOROPHOSPHATE C o ( 4 m e p y ) ( H Q ) ( P F ) Q  6.2.2.2  2  2  g  2  OCTAKIS(4-METHYLPYRIDINE)DIAQUOCOBALT(II) HEXAFLUOROARSENATE C o ( 4 m e p y ) ( H 0 ) ) A s F ) Q  6.2.2.3  2  g  OCTAKIS (4-METHYLPYRIDINE) •DIAQUONICKEL(II-) HEXAFLUOROPHOSPHATE  6.2.2.4  2  Ni(4mepy) (H 0) (PFg) g  2  2  2  OCTAKIS(4-METHYLPYRIDINE)DIAQUONICKEL(II) HEXAFLUOROARSENATE N i ( 4 m e p y ) ( H 0 ) ( A s F ) g  All  2  2  g  2  f o u r compounds w e r e p r e p a r e d b y t h e same p r o c e d u r e .  The a p p r o p r i a t e m e t a l ( I I ) n i t r a t e h e x a h y d r a t e  (0.002 m o l e )  was d i s s o l v e d i n 100 m l . o f d i s t i l l e d w a t e r c o n t a i n i n g 39 m l . of  4-methylpyridine.  a filtered  To t h i s s o l u t i o n was a d d e d w i t h  stirring,  s o l u t i o n o f 0.04 m o l e s o f ammonium h e x a f l u o r o p h o s p h a t e  -268-  in  50 m l . w a t e r  ( o r 0.04 m o l e s o f p o t a s s i u m h e x a f l u o r o a r s e n a t e  in  250 m l . w a t e r ) .  S t i r r i n g was  w h i c h t i m e a two p h a s e an u p p e r w e a k l y lower  "oily"  nickel. funnel  colored  f o r 1 hour  or c o l o r l e s s  l a y e r , w h i c h was  aqueous  layer,  red f o r cobalt  transferred with a  i n a vacuum d e s i c c a t o r .  3 weeks, o r a n g e - r e d c r y s t a l s of the nickel  were washed w i t h a s o l u t i o n ml. water.  After  separatory over  phosphorous  a period of 2 to  o f the c o b a l t complexes  and a  and b l u e f o r  t o an e v a p o r a t i n g d i s h w h i c h was p l a c e d  crystals  during  system developed which c o n s i s t e d o f  The l o w e r l a y e r was  pentoxide  blue  continued  complexes  formed.  The  and  crystals  o f 5 m l . 4 - m e t h y l p y r i d i n e i n 50  Since the c r y s t a l s  tend to lose  4-methylpyridine  on e x p o s u r e t o t h e a t m o s p h e r e  o r t o a vacuum, t h e y were  outside  t h e d r y box i n s e a l e d  vials  washing  liquid.  "in  Just prior  still  stored  "wet" w i t h t h e  t o u s e , t h e c r y s t a l s were  dried  v a c u o " f o r a b o u t 15 m i n u t e s .  6.2.2.5  TETRAKIS(4-METHYLPYRIDINE)COBALT(II) HEXAFLUOROPHOSPHATE-Co(4mepy) (PFg) 4  6.2.2.6  2  TETRAKIS(4-METHYLPYRIDINE)COBALT(II) HEXAFLUOROARSENATE-Co(4 epy) (AsFg) m  The was at  corresponding dried  4  2  Co(4mepy)g(H 0) (EFg) 2  2  2  complex  g r o u n d t o a f i n e powder i n t h e d r y box and t h e n h e a t e d 8 0 - 9 0 ° C f o r 3-4  hours  " i n vacuo".  This treatment y i e l d e d  -269-  the d e s i r e d  6.2.2.7  intensely colored  red-purple  TETRAKIS(4-METHYLPYRIDINE)NICKEL(II) •! HEXAFLUOROPHOSPHATE  6.2.2.8  Ni(4mepy) (PFg) 4  2  TETRAKIS(4-METHYLPYRIDINE)NICKEL(II) HEXAFLUOROARSENATE  The ground  complexes.  Ni(4mepy) (AsFg) 4  corresponding Ni(4mepy)g(H 0) A 2  2  2  c o m p l e x e s was  2  t o a f i n e powder i n t h e d r y box and t h e n h e a t e d a t -8 0°C f o r  3-4 h o u r s  in a  t h e s e compounds unlike  vacuum y i e l d i n g were m o d e r a t e l y  the analogous p y r i d i n e  from t h i s  6.2.2.9  soluble  i n dichloromethane,  complexes,  t h e y were  recrystallized  solvent.  TETRAKIS(4-METHYLPYRIDINE)COPPER(II) HEXAFLUOROPHOSPHATE  6.2.2.10  a yellow-orange product. Since  Cu(4mepy) (PFg) 4  2  TETRAKIS(4-METHYLPYRIDINE)COPPER(II) HEXAFLUOROARSENATE  Cu(4mepy) (AsFg) 4  2  In these p r e p a r a t i o n s , t h e c o n d i t i o n s used gave p r o d u c t s w i t h h i g h p e r c e n t a g e s o f N, p e r h a p s t h e p r e s e n c e o f N0~ i m p u r i t i e s . o b t a i n e d by u s i n g more d i l u t e  Reasonable  conditions  i n 6.2.2.1  indicating  analysis  were  i n the reaction.  -270-  The c o n d i t i o n s were o b t a i n e d by u s i n g t h e same v o l u m e s o f w a t e r as i n 6.2.2.1 b u t u s i n g 1/4 prescribed  i n 6.2.2.1.  gave a n i m m e d i a t e  6.2.3  w h i c h was t r e a t e d  reagents  i n t h e same  i n 2.2.1.9.  3-METHYLPYRIDINE  The a n a l y t i c a l in  S t i r r i n g o f t h e s e combined  precipitate,  manner as d e s c r i b e d  o f t h e amount o f r e a g e n t s  COMPLEXES  data  f o r t h e s e complexes  are complied  Table VI-3. *  6.2.3.1  HEXAKIS  (3-METHYLPYRIDINE)DIAQUOCOBALT(II)  HEXAFLUOROPHOSPHATE  6.2.3.2  HEXAKIS  HEXAKIS  g  2  g  Co(3mepy) (H 0) (AsFg) g  2  2  6  HEXAKIS  2  (3-METHYLPYRIDINE)DIAQUONICKEL(II)  HEXAFLUOROPHOSPHATE Ni(3mepy) ( H 0 ) (PFg)  6.2.3.4  2  (3-METHYLPYRIDINE)DIAQUOCOBALT(II)  HEXAFLUOROARSENATE  6.2.3.3  Co(3mepy) (HgO) (PF )  2  2  2  (3-METHYLPYRIDINE)DIAQUONICKEL(II)  HEXAFLUOROARSENATE N i ( 3 m e p y ) ( H 0 ) ( A s F ) g  6.2.3.5  HEXAKIS  2  2  g  2  (3-METHYLPYRIDINE)DIAQUOCOPPER(II)  HEXAFLUOROPHOSPHATE  Cu(3mepy) (H 0) (PF ) g  2  2  g  2  -271-  TABLE VI-.2 ANALYTICAL DATA FOR THE 4-METHYLPYRIDINE COMPLEXES % EXPECTED COMPOUND (i)  C  H  N  M(4raepy) (H 0) (EF ) 8  2  2  6  % FOUND C  H  N  2  5. 35 9.,92  51.,00 5. 20  9.,89  47..50 4.,80  9 .10 ,  M=Co, E=P  51.02  M=Co, E=As  47.34 4. 97 9., 20  M=Ni, E=P  51.03  5. 35 9..92  51,.30  5.,42 10,.10  M=Ni, E=As  47.35 4 .96 9,.20  47 ,.00  4 ,. 99 9..00  ( i i ) :M(4mepy) 4  ( E F  6 2 )  M=Co, E=P  39.96 3. 91 7 .77  39 .70  3,.91  7 .87  M=Co, E=As  35.62 3. 49 6 .92  35 .60  3..66  7 .17  M=Ni, E=P  39.97 3.,91 7 .77  39 . 80 3 .71  7 .88  M=Ni , E=As  35.63 3.,49  6 .93  35 .50  3 .53  7 .10  M=Cu, E=P  39.71  3 .89 .  7 .72  39 .68  3 .88  7 .91  M=Cu, E=As  35.42 3,.47  6 .88  35 .57  3 .47  7 .00  -272-  6.2.3.6  HEXAKIS  (3-METHYLPYRIDINE)DIAQUOCOPPER(II)  HEXAFLUOROARSENATE  Cu(3mepy) (H 0) (AsF ) g  T h e s e c o m p l e x e s were p r e p a r e d to  6.2.2.1-4 e x c e p t t h a t  or  -arsenate  salt  s a l t was  improved  added.  1-2 weeks o f p r e p a r a t i o n . were f i l t e r e d a n d washed again l e f t  in  a desiccator  6.2.3.7  2  2  i n a similar  manner  The a d d i t i o n o f t h e e x c e s s  After  which took p l a c e crystallization,  within the c r y s t a l s  (50 m l . w a t e r - 5 m l . 3 - m e t h y l p y r i d i n e )  "wet" w i t h t h e w a s h i n g l i q u i d  i n sealed  vials  (not i n t h e d r y b o x ) .  TETRAKIS(3-METHYLPYRIDINE)COBALT(II) HEXAFLUOROPHOSPHATE C o ( 3 m e p y ) ( P F ) 4  6.2.3.8  2  Co(3mepy) (AsF ) 4  T h e s e compounds were p r e p a r e d Co(3mepy) (H 0) A g  2  2  2  g  2  from t h e c o r r e s p o n d i n g  c o m p l e x e s , by g r i n d i n g t o a  powder a n d pumping " i n v a c u o " required.  g  TETRAKIS(3-METHYLPYRIDINE)COBALT(II) HEXAFLUOROARSENATE  dried  g  2 grams more o f t h e h e x a f l u o r o - p h o s p h a t e  the c r y s t a l l i z a t i o n  and  2  f o r 24  hours.  fine  No h e a t i n g  was  -273-  6.2.3. 9.  TETRAKIS (3-METHYLPYRIDINE) NICKEL (II)' HEXAFLUOROARSENATE N i ( 3 m e p y ) ( A s F g ) 4  2  The t r e a t m e n t o f N i ( 3 m e p y ) g ( H 0 ) A v i a t h e method 2  2  2  o f 6.2.3.7-.8 g a v e a l i g h t b l u e - y e l l o w p o w d e r . s p e c t r a i n d i c a t e d the absence o f water. o f t h e s e compounds  The  infrared  The m i c r o a n a l y s e s  gave m o l e r a t i o s o f m e t a l t o 3 - m e t h y l p y r i d i n e  o f 1:»' w h e r e 4< x< 6 .  The a p p l i c a t i o n o f a 3 - m e t h y l p y r i d i n e  a t m o s p h e r e a s i n 6.2.1.1 g a v e x=5.5. The t e t r a k i s ( 3 - m e t h y l p y r i d i n e ) compounds w e r e p r e p a r e d by t r e a t i n g t h e d r i e d p r o d u c t above as i n 6.2.1.8(a) u s i n g c h l o r o f o r m as t h e i n e r t  6.2.3 .10  solvent.  TETRAKIS(3-METHYLPYRIDINE)COPPER(II) HEXAFLUOROPHOSPHATE C u ( 3 m e p y ) ( P F g ) 4  6.2.3 J.1  2  TETRAKIS (3-METHYLPYRIDINE) C O P P E R ( I I ) HEXAFLUOROARSENATE C u ( 3 m e p y ) ( A s F g ) 4  2  T h e s e compounds w e r e p r e p a r e d f r o m t h e c o r r e s p o n d i n g Cu(3mepy)g(H 0) A 2  2  2  c o m p l e x e s by d r y i n g " i n v a c u o " f o r 24 h o u r s .  T h e s e compounds w e r e mauve p o w d e r s .  -274-  . TABLE V I - 3 ANALYTICAL DATA FOR THE 3-METHYLPYRIDINE COMPLEXES  % FOUND  % EXPECTED H  C (i)  C  N  H  N  M(3mepy) ( H 0 ) ( E F ) 2 6  2  2  6  45.5 5.15  8. 90  4.77  8.,99  8.15  41.9 4.49  8..12  8.86  45.4  5.00  8..67  4.47  8.11  42.0 4.44  8..15  M=Co, E=P  39.96 3.91  7.77  40.00 4.00  7 .79  M=Co, E=As  35.62  3.49  6.92  35.69 3.51  6 .98  M=Ni  35.63 3.49  6.93  35. 38, 3.50  6 :74  M=Cu, E=P  39.71 3.89  7.72  39.38  3.91  7 .67  M=Cu, E=As  35.42  3.47  6.88  35.31 3.46  6 .86  45.8 4.91  8.91  41.9 .4.49  8.15  M=Ni, E=P  45.8 4.91  8. 91  45.8  M=Ni, E=As  41.9 4.50  M=Cu, E=P  45.6 4. 89  M=Cu, E=As  41.7  M=Co, E=P M=Co,  (ii)  E=As  ( a )  M(3mepy) 4  f  ( E F  6 2  E=As  (a) no a n a l y t i c a l  )  data arereported  however t h e C o ( 3 m e p y ) ( A s F g ) 4  from i t , w a s o b t a i n e d  2  i n a pure  f o r Co(3mepy) (H 0) (AsFg) g  2  2  compound,which was p r e p a r e d form.  2  -275-  6.2.4  THERMAL  6.2.4.1  STUDIES  TETRAKIS(4-METHYLPYRIDINE)NICKEL(II) HEXAFLUOROPHOSPHATE Ni(4mepy) (PF ) 4  6  >  2  A white m a t e r i a l subliming of  t h e vacuum t a k e - o f f a d a p t e r  (^100°C) o f t h i s prompted t h i s and  Table  the duration o f t h i s 4  2  preparation  observation  VI-4 g i v e s t h e h e a t i n g  heating  i n s e c t i o n 4.2.2.5.1.  of  samples a r e compiled  that  temperature  f o r the preparation of the  m a t e r i a l w h i c h was a n a l y z e d  impurity these  a thermal  complex was t h e i n i t i a l  study.  Ni(4mepy) (PFg)  during  on t h e c o o l e r - p o r t i o n s  The m a g n e t i c  f o r paramagnetic susceptibilities  i n A p p e n d i x 4, T a b l e A4-3.  TABLE VI-4 THERMAL PREPARATIONS OF N i ( 4 m e p y ) ( P F ) 4  SAMPLE  TEMPERATURE(°C)  g  2  DURATION ( h r )  a  72  45  b  110  32  r.  112  23  -276-  6.2.4.2  THERMAL DEGRADATION STUDIES  As m e n t i o n e d  i n section  6.2.4.1, when t h e  (PF^)„ 6 2  i s heated  a t 100°C a w h i t e  formirig  .... When t h e NiL„ (EF,.) _ compounds a r e h e a t e d 4  temperatures, der of t h i s  section w i l l  t a k e s p l a c e . The  N i ( 4 m e p y ) . ( P F , ) „ and 4  of white m a t e r i a l color.  The  29.2 9%,;. 2.4 6%,  C:H:N  C,  and  their  critical  2  de-  H,  a t 170°C c o p i o u s  and  the r e s i d u e i s a  f o r pyPF  the values of  which i n d i c a t e s  t h a t t h e r e was  of the p y r i d i n e moiety.  g  3.20%, and  (and N i ( p y ) F ( P F ) 2  g  4.64%( and  31.5%, 2.65%,and 7 . 3 5 % ) .  agreement  of'  these  the r e s i d u e ; a l s o  5.1:6:1 w h i c h may pyridine moieties.  be  pastel  N analyses f o r the sublimate  6.66%. E v e n t h o u g h  t h e r e s i d u e i s 28.7 0%,  amounts  2  6.83%; t h e v a l u e s e x p e c t e d  i s 5:5:1  for Ni(py)F(PF )  in  g  n i t r o g e n a r e 2% o f f t h e v a l u e s e x p e c t e d ,  decomposition for  b  s u b l i m e s o f f and  28.66%, 2.36%, and  ratio  o f N i (py) ^ ( P F ) ,  temperatures. 4  and  remain-  2  b  When N i (py) . (PF,.) _ i s h e a t e d  carbon  at higher  present the a n a l y t i c a l data f o r the  2.  b  composition  green  i s observed  sublimates of the decomposition  N i (py) . ( A s F , ) ~ , and  4  2  noticeable decomposition  r e s i d u e s and  4  D  sublimate  Ni(4mepy) ~  )  The  C,  H,  indicative  are  the the mole not  and  N  any analyses  6.62%; t h e v a l u e s  expected  a r e 19.90%, 1.67%, There  C:H:N  and  i s n o t v e r y good  s t o i c h i o m e t r i e s w i t h the v a l u e s t h e mole r a t i o  5  are  observed  i n the r e s i d u e i s  o f some d e c o m p o s i t i o n  of  the  -277-  When N i ( p y ) ( A s F g ) 4  i s sublimed  i s heated  2  a t 180°C " i n v a c u o " ,  a white  material  o f f and t h e r e s i d u e i s a p a s t e l  green.  The C, H, a n d N a n a l y s e s f o r t h e s u b l i m a t e were 2 3.53%,  1.91% a n d 5.43%, r e s p e c t i v e l y ; are  the values expected  24.12%, 2.02%,and 5.63%. A g a i n ,  case,  the observed  as i n t h e N i ( p y )  v a l u e s a r e 2% d i f f e r e n t  i s 5:4.9:1, w h i c h i n d i c a t e s  unit  i n the sublimate.  intact  molecules  good a g r e e m e n t .  4  a white m a t e r i a l  r e s i d u e remains.  The C:H:N r a t i o  is  g  2  i s heated  of pyridine  s u b l i m e s o f f and a p a s t e l  yellow  The 6, H, and N a n a l y s e s f o r t h e s u b l i m a t e these values f o r  a r e 32.17%, 3.22%, and 6.39%. The observed" G:H:N  6.0:7.0:1.0  present;  found  a t 162-172°C " i n  33.17%, 3.22%, and 6.29%, r e s p e c t i v e l y ; 5  and t h e  has o c c u r r e d . When N i ( 4 m e p y ) ( P F )  4mepyPF  the pyridine  the values  o f expected  (5.6:8.7:1),however, shows t h a t d e c o m p o s i t i o n  are  values;  f o r a compound o f t h e s t o i c h i o m e t r y N i ( p y ) F ( A s F g ) a r e  shows a f a i r l y  vacuo",  2  These a n a l y s e s f o r t h e  17 . 37 %, 1.46% , a n d 4.05%. The c o m p a r i s o n found  g  that  r e s i d u e a r e 19.57%, 2.53%, and 4.05%, r e s p e c t i v e l y ; expected  (PF )  from t h e e x p e c t e d  t h e C:H:N mole r a t i o isstill  f o r pyAsFj-  w h i c h i s c o n s i s t e n t w i t h a 4mepy m o i e t y  but the observed  of approximately  2% f r o m  v a l u e s o f t h e elements the expected  values.  ratio  being  show a d e v i a t i o n  The C, H, and N  analyses  f o r t h e r e s i d u e a r e 22.83%, 2.50, and 5.00%; t h e v a l u e s  expected  f o r N i ( 4 m e p y ) F ( P F g ) a r e 22.82%, 2.23%, and 4.44%. The  agreement o f found C:H:N r a t i o  and e x p e c t e d  a n a l y s e s i s n o t e x a c t and t h e  ( 5 . 3 : 6 . 9 : 1 . 0 ) i n d i c a t e s 4mepy d e c o m p o s i t i o n .  •  -278-  6.2.5  UNSUCCESSFUL  The  PREPARATIONS  o n l y compound w h i c h w o u l d  s e r i e s o f compounds Ni(3mepy)^(PFg) -  s t u d i e d h e r e w h i c h was n o t p r e p a r e d was I t s s y n t h e s i s was n o t c o m p l e t e d  2  of  time l i m i t a t i o n s .  Ni(3mepy)^(AsFg)  2  As m e n t i o n e d  compound  the Ni(3mepy)g(H 0) (AsFg)2 2  the i n f r a r e d  2  spectrum 2  spectrum  i n section  compound  till  2  6.2.3.9, t h e  t h e water  band i n  When t h i s was done w i t h  compound,  d i dnot disappear.  Ni(3mepy)g(H 0)2(PFg)2  because  i s p r e p a r e d b y vacuum d r y i n g o f  disappeared.  the Ni(3mepy)g(H 0)2(PFg)2 infrared  be a member o f t h e  the water  band i n t h e  When t h e " n o n - d r y "  compound was h e a t e d a t 66°C  " i n vacuo",  t h e e l e m e n t a l a n a l y s e s (C : 38.10%, H : 4.15%, a n d N : 7.74%) indicated  t h a t d e c o m p o s i t i o n had t a k e n p l a c e b e c a u s e  deviation  from t h e expected percentages  respectively)  and o f t h e mole r a t i o .  the expected values  (6:7:1).  with chloroform, thef i l t r a t e the f i l t e r  -  i s washed  As t h e sample was  t u r n e d more y e l l o w i n t i n g e  c o u l d n o t be removed.  c a n p r o b a b l y be s y n t h e s i z e d  reaction  conditions,  The N i ( 3 m e p y ) ^ ( P F g )  by t h e j u d i c i o u s  i . e . lower h e a t i n g  f o r the " s t i r "  from  was g r e e n a n d t h e m a t e r i a l o n  compound  solvent  4.15%, 7.74%  (5.7:7.5:1)  When t h i s m a t e r i a l  washed, t h e y e l l o w - g r e e n m a t e r i a l  ferent  C:H:N  paper,-a yellow-green s o l i d .  but t h e green c o l o r  (39.97%,  of the  use o f  temperature o r a d i f -  preparation.  2  -279-  6.3  ANALYTICAL DATA  Elemental a n a l y s e s f o r carbon, hydrogen, were done by Mr.  P e t e r Borda  of t h i s  department.  of  t h e d e t e r m i n a t i o n a r e c o n s i d e r e d t o be +.3%  of  an e l e m e n t ,  6.4  i . e . 35.2  +  The  accuracy  on t h e p e r c e n t a g e  .3.  MAGNETIC S U S C E P T I B I L I T Y MEASUREMENTS  The m a g n e t i c  susceptibilites  were d e t e r m i n e d - a t f i e l d  o f t h e compounds p r e p a r e d  s t r e n g t h s of, a p p r o x i m a t e l y '  8000 g a u s s , u s i n g a Gouy a p p a r a t u s p r e v i o u s l y temperature  t u b e and  range  s t u d i e d was  a p p a r a t u s was  calibrated  tetrathiocynatocobaltate  f r o m 305K  b a s e d on t h e known v a r i a b l e  was  The  c o r r e c t e d by a  compounds, t h e r e s u l t s  packings through the temperature tested  temperature  calibration  a r e f o r one  r a n g e and  for field  are  s u s c e p t i b i l i t i e s were f o u n d t o be  field  or  corrected  d e p e n d e n c e by m e a s u r e -  ments a t room t e m p e r a t u r e w i t h a F a r a d a y b a l a n c e .  studied.  sample  temperature behavior of the standard,  two  the complexes  (135).  4  a l l paramagnetic  and  t o 80K.  or  u s i n g HgCo(CNS) , m e r c u r i c  For  for packing errors  4000  described  (136), as t h e s t a n d a r d ; t h e  m o n i t e r e d by t h e t h e r m o c o u p l e ,  of  nitrogen  PHYSICAL EXPERIMENTAL TECHNIQUES  6.4.1  The  and  independent  The  magnetic  fora l l  -280-  The the  e f f e c t i v e m a g n e t i c moments w e r e c a l c u l a t e d  e x p r e s s i o n (41) y  e  f  f  = 2.828  (x -T)  J s  A  where T i s t h e a b s o l u t e t e m p e r a t u r e i n K e l v i n s and x A molar of  from  susceptibility  i s the  i n e g i s . u n i t s c o r r e c t e d f o r diamagnetism  a t o m i c m o i e t i e s p r e s e n t a n d , when a p p r o p r i a t e , f o r t e m p e r a t u r e  independent paramagnetism; The sources  X  = A  X -(diamagnetic corrections)-t.i.p.  d i a m a g n e t i c c o r r e c t i o n s were o b t a i n e d from s t a n d a r d  ( 4 0 , 4 1 , 1 3 7 ) . The c o r r e c t i o n s u s e d f o r t h e a t o m i c  s u s p e c t i b i l i t i e s of the metal ions are: il2;  Cu(II)=-13;  and C o ( I I ) = - 1 2 ; f o r t h e l i g a n d m o i e t i e s :  Ni(II)=  pyridine=-49;  m e t h y l p y r i d i n e a n d 3 - m e t h y l p y r i d i n e =-61, f o r t h e a n i o n s : — "67, A s F g = - 9 7 . units  A l l d i a m a g n e t i c c o r r e c t i o n s a r e 10  temperature independent paramagnetism  i n c l u d e d when t h e e l e c t r o n i c a n "A " o r "E" g r o u n d 2  t e r m was  s p e c t r a l data i n d i c a t e d the presence  state.  The c o r r e c t i o n f o r a n " A " 2  t.i.p.  = 8N8 /10Dq  t.i.p.  = 4N8 /10Dq  2  f o r "E" t e r m  6.4.2  =  e.g.s,  term i s :  and  g  —6 3 (10 cm mole). The  of  —6  PF  2  INFRARED SPECTROSCOPY  The were r e c  room t e m p e r a t u r e  (routine) infrared  o r d e d o n a P e r k i n E l m e r M o d e l 4 57 G r a t i n g  spectra Spectrometer  -281-  o v e r t h e range KRS-5 and  4 000  - 250 cm ~~.  The c e l l  windows" u s e d were  (Harshaw C h e m i c a l Co.) and were composed o f 42% T l B r  58% T i l .  The N u j o l m u l l s were p r e p a r e d i n t h e d r y b o x ,  s p r e a d on t h e p l a t e s , and e x a m i n e d a s s o o n  sealed w i t h tape to prevent as p o s s i b l e .  A l l s p e c t r a were  w i t h t h e p o l y s t y r e n e s t a n d a r d a t 1601 and 907 cm The  low t e m p e r a t u r e  E l m e r M o d e l 225 G r a t i n g (4000 - 250 c m described  - 1  ).  1  calibrated  .  s p e c t r a were r e c o r d e d o n a P e r k i n -  S p e c t r o m e t e r o v e r t h e same r e g i o n  The low t e m p e r a t u r e  elsewhere.  hydrolysis  cell  (138) h a s b e e n  The s a m p l i n g t e c h n i q u e i n v o l v e d  a m u l l o r powder sample between t h e KRS-5 p l a t e s w h i c h placed of  i n the c e l l  h o l d e r i n t h e d r y box, j o i n e d  t h e a p p a r a t u s , and q u i c k l y  A typical of  a room t e m p e r a t u r e  of  liquid  the  2  i n t o t h e dewar and c o o l i n g  (8OK was t h e t e m p e r a t u r e  ref.138),  temperature  allowing  consisted  introduction  1 t o ±h h o u r s  with  tion.  These  r e c o r d e d w i t h a- t h e r m o c o u p l e  t h e sample chamber t o warm up t o room  f o r 1 t o 1% h o u r s , a n d r e c o r d i n g  a g a i n t o check  for  h hour,  line.  sample beam c u t o f f , r e c o r d i n g o f t h e l o w t e m p e r a t u r e  spectrum in  N  o f a d y n a m i c vacuum  spectrum a f t e r  were  t o the rest  e v a c u a t e d on a vacuum  run, with application  using  reproducibility  and t h e a b s e n c e  s p e c t r a were c a l i b r a t e d  the routine  spectra.  t h e spectrum o f any  decomposi-  i n .the same manner a s  -282-  '6.. 4. 3  ELECTRONIC SPECTROSCOPY  The  visible  (650-2500 nm)  a Cary  solid  between s i l i c a  14  state  w i t h a N u j o l soaked  and  the absorbance l e v e l  1  cm  spectrum  Recording  glass plates,  filters.  and  light  filter was  infrared  of the  were r u n p e r i o d i c a l l y  The  as N u j o l  s c a t t e r i n g was  room mulls  compensated  p a p e r i n t h e r e f e r e n c e beam,  adjusted with  t h e use  S o l u t i o n s p e c t r a were r e c o r d e d  (CANLAB r e d l a b e l )  regions  compounds  Spectrometer.  s p e c t r a were r e c o r d e d  for  density  (350-650 nm)  o f the e l e c t r o n i c  were r e c o r d e d on temperature  region  and  5 cm  silica  of n e u t r a l  u s i n g matched  glass cells  t o c h e c k w h e t h e r t h e y were i n  (blanks  fact  matched.) The temperature was  the  cell  same as  2.4.2)jlight the  low  same as  temperature (138).  f o r the  The low  The  visible  procedure temperature  s c a t t e r i n g and f o r the mull  s p e c t r a were r u n u s i n g t h e  infrared  the  spectrum  (Section  a b s o r b a n c e l e v e l s were t r e a t e d  s p e c t r a above.  (350  - 741  were r e c o r d e d  on  meter w i t h  a  isible  Model SR.  Magnesium c a r b o n a t e  standard.  f o r running  low  a B a u s h and  nm)  diffuse  reflectance  Lomb S p e c t r o n i c 600  reflectance  a t t a c h m e n t and  was  used  as t h e  spectra  spectrophotoSargent  recorder  reflectance  -283-  6.4.4  ELECTRON SPIN RESONANCE  E.s.r.  (E.S.R.) SPECTROSCOPY  s p e c t r a were r e c o r d e d o n a V a r i a n A s s o c i a t e s  E-3 s p e c t r o m e t e r e q u i p p e d w i t h a 100 kHz The  X-band f r e q u e n c y was m o n i t o r e d  Hewlett-Packard Converter recorder of  1000  8-18  GHz,.  modulation.  during the spectra with a  C o u n t e r w i t h a 5256A  The m a g n e t i c  field  variation  i n d i c a t e d v a l u e was c a l i b r a t e d  Frequency  from t h e  f o r t h e sweep  width  gauss. The  at  5245L E l e c t r o n i c  field  ambient  capillary  e.s.r.  s p e c t r a on s o l i d  temperature tubes.  temperature  on powders s e a l e d  The s o l u t i o n  and l i q u i d  glass tubes.  state  i n 1.6 mm  were r u n (i.d.)  s p e c t r a were r e c o r d e d a t room  nitrogen  The a p p r o x i m a t e  samples  temperatures  i n 3mm  i.d.  silica  concentrations of the s o l u t i o n  -4 sample were  6.4.5  10  M.  SINGLE CRYSTAL X-RAY DIFFRACTION  The 0.3 o r 0.5 mm  crystals  selected  for this  Lindemann c a p i l l a r i e s .  under  a p o l a r i z i n g microscope  gross  features of n o n - c r y s t a l l i r i i t y .  rejected  at this  a  We-issenberg  The c r y s t a l s were  t o determine  with non-filtered  camera..  If a direct  observed  i f t h e r e were any  I f a c r y s t a l was n o t .  s t a g e , i t was mounted o n a g o n i o m e t e r  r o t a t i o n photographs on  s t u d y were s e a l e d i n  and  CuKa ( X = l . 5418A") were a x i s was  coincident  w i t h t h e r o t a t i o n a x i s o f t h e camera, t h e z e r o , f i r s t , and  taken  -284-  second l e v e l photgraphs were t a k e n as were t h e p r e c e s s i o n photograghs o f t h e two complementary  zones. •  The space group and u n i t c e l l parameters o f t h e c r y s t a l were d e t e r m i n e d from t h e s e p r e l i m i n a r y photographs.  The methods  o f d a t a c o l l e c t i o n and s t r u c t u r e s o l u t i o n f o r o u r s t u d i e s a r e g i v e n i n s e c t i o n 6.5.  6.4.6  RAMAN SPECTROSCOPY  Raman s p e c t r a were r e c o r d e d on a Spex Ramalog 5 s p e c t r o m e t e r e q u i p p e d w i t h a 514.5 nm argon i o n l a s e r . The s p e c t r a were performed on powdered samples s e a l e d i n 1.6mm capillaries.  The a p p a r a t u s used t o o b t a i n t h e l o w t e m p e r a t u r e  s p e c t r a has been d e s c r i b e d by Aubke and Lee (13 9 ) .  6.4.7  OTHER METHODS  The powder X-ray photographs were o b t a i n e d on powdered samples s e a l e d i n 0.5 mm Lindemann c a p i l l a r i e s .  The samples  were exposed t o N i - f i l t e r e d Cu Ka( =1.54 182) r a d i a t i o n f o r 12 h o u r s .  The d i f f r a c t i o n a n g l e , 8 , i s r e l a t e d t o S b y : 4 6= S/r  where S i s t h e d i s t a n c e between t h e two r e c o r d e d a r c s o f a g i v e n cone o f d i f f r a c t e d X - r a y s , r i s t h e r a d i u s o f t h e camera, and 8 i s i n r a d i a n s .  The r a d i u s o f t h e camera used  was 57.296 mm, and t h e e q u a t i o n above s i m p l i f i e s t o :  -2 85-  where 9 i s i n d e g r e e s related  and  S i s i n mm.  to the d i f f r a c t i o n 2dsin0= Differential  a n g l e by  The  d-spacings  the Bragg  equation:  nX  t h e r m a l a n a l y s e s were o b t a i n e d on  Series  C a l c i u m c a r b o n a t e was  300  QDTA o p e r a t i n g between 15  used  and  applied  500  t h e mass s p e c t r o m e t r y  lab of t h i s  resolution Department.  C.  During to  chamber.' Mass s p e c t r a were o b t a i n e d as low  from  Fisher O  as t h e r e f e r e n c e m a t e r i a l .  t h e h e a t i n g o f t h e sample, a d y n a m i c vacuum was sample  a  O  TM  Thermalizer  are  spectra  the  -286-  6.5-  SINGLE CRYSTAL  This  section w i l l  determination, structure for  describe  data c o l l e c t i o n ,  solution,  t h e compounds  6.5>1  X-RAY DIFFRACTION  the c r y s t a l  studied  structure  d a t a r e d u c t i o n , method a t  and t h e m o l e c u l a r i n this  structure  determination  manner.  TETRAKIS(4-METHYLPYRIDINE)COBALT(II) HEXAFLUOROPHOSPHATE  6.5.1.1  RESULTS  CRYSTAL  Co(4mepy) (PF ) 4  PREPARATION AND  A saturated,  filtered  g  DATA  2  COLLECTION  solution  o f t h e complex  in  a 1:1 m i x t u r e o f d i c h l o r o m e t h a n e and c h l o r o f o r m was  to  evaporate slowly  i n an i n e r t  a t m o s p h e r e chamber.  1-2 weeks, t h e deep r e d - p u r p l e s o l u t i o n g a v e l a r g e tetragonal  crystals  o f t h e same c o l o r .  h y g r o s c o p i c and were s t o r e d  i n the i n e r t  however, t h e s e a l i n g o f t h e c r y s t a l s was done q u i c k l y  allowed  After elongated,  The c r y s t a l s  were  a t m o s p h e r e chamber;  i n Lindemann  capillaries  i n a i r a n d no a p p a r e n t d e c o m p o s i t i o n o f t h e v  c r y s t a l s was o b s e r v e d . photographs i n d i c a t e d t e m a t i c absences  (6.2.3.5)  The p r e l i m i n a r y a tetragonal  Weiss.enber.g-and  precession  s p a c e g r o u p and t h e s y s -  (hkl:h+k+l=2n+l; hkO:h(k)=2n+l; O k l = l ( k ) = 2 n + l ; 20  hhl=l=2n+l,  3h+1^4n)gave t h e s p a c e g r o u p as I 4 / a c d  No. 142) ( 5 9 ) .  1  (D  4 h  ,  -287-  The  crystal  chosen  on a D a t e x - a u t o m a t e d  f o r d a t a c o l l e c t i o n was  GE XRD-6 t h r e e c i r c l e  e q u i p p e d w i t h a MoK^ ( =0.7107°i) and  X-ray  t h e i<f> ( p h i ) a x i s ' c o i n c i d e n t .  were d e t e r m i n e d by l e a s t centered  reflections.  tetragonal,  V=63952 , Z=8, '  p  3  r a n g e was  1.80  background  was  s c a n f o r 10  crystal  unit  cell  C  24 28 H  current  f o r 2°<2 0 < 4 O ° , t h e  reflections  were  and  the strong r e f l e c t i o n s ;  t h e s e c o n d c r y s t a l was  to  the f i r s t ,  crystals of  o f which  for  the c r y s t a l s .  was  (hkl:h< k,  and was  1/16  The  several  The  reflection  f o r the  measured a t  d e v i a t i o n s were c a l c u l a t e d  from a  were a p p l i e d 2  two  intervals  the r e f l e c t i o n data reflections  o f the t o t a l sphere o f r e f l e c t i o n s ) factors  second  similar,  t o t a l number o f i n d e p e n d e n t  L o r e n t z and p o l a r i z a t i o n  is  used t o s c a l e  each  t h e remeasurement  randomly  t h r o u g h t o u t d a t a c o l l e c t i o n , was  40 reflections  and  and o r i e n t a t i o n ) .  fluctuated  the  a  caused a d e l a y o f  of  the i n t e n s i t y  and  remeasured  data c o l l e c t i o n  shape,  scan  t h e end o f  and e x t r a z i r c o n i u m f i l t e r s  (instrumental d i f f i c u l t i e s  P  c=18.818(6)2,  months between t h e i n i t i a l  332,  N  w i t h a s p e e d o f 2°/min.,  strongest  i n size,  12 4 2'  1  c o u n t e d a t t h e b e g i n n i n g and The  G o F  manually  cm" .  - 3  were c o l l e c t e d  axis  parameters  , a=18.434(7)2,  g - c m , y=7.60 ^ '  + 0.8(tan6)  sec.  using lesser  source with the c  data are:  14^/acd  , =1.50 calc  Intensities  diffractometer  s q u a r e s r e f i n e m e n t on 12  Crystal  space group  The  mounted  and s t a n d a r d  (I)=S+B+(0.04S)  t h e s c a n c o u n t and B i s t h e b a c k g r o u n d  749.  count.  2  where S No a b s o r p t i o n  -288-  or  extinction  had  corrections  intensity(I)  were c o n s i d e r e d  6 .5-'. 1. 2  were made. A than 3a(I)  greater  the  gave t h e  function  solution. the  The  to  normalized  by  w i t h E>1.4  were u s e d i n t h e  from the  Since the  the  structure  assigned  for  more r e f l e c t i o n was  other r e f l e c t i o n s ,  two  such that  t h e y were n o t  reflections  a primitive  c e l l ( 59 ) ,  cell  invariants  unit  the  147  the  had  the had  primitive  to  had  be  reflections  be  cell.  and  phases  (the  phase  The  the  related  u s e d i n the' p h a s e d e t e r m i n i n g p r o c e s s a r e  to  eight  listed  of  parity of  parity  i s g i v e n i n terms  The  1^  origin.  to have a  p a r i t i e s of to  The  assigned  structure).  reflections so  f i x the  invariants  the  were  reflections.  determine the  reflections  indexed r e f l e c t i o n s b a s e d on  methods  factors(E)  five  needed to  c o u l d not  i s d e p e n d e n t on invariant  unit  •  use  relationships  these  structural  these s t r u c t u r a l  the  phase d e t e r m i n i n g p r o c e s s .  p r o g r a m TANS gave f i v e  these s i x r e f l e c t i o n s  by  direct  structure  s y m b o l i c phases. These t h r e e r e f l e c t i o n s  the  b a c k g r o u n d and  c o m p u t e r p r o g r a m SHNORM and  t h u s a p h a s e w o u l d be l e a s t one  solve  were u n s u c c e s s f u l ,  calculated  At  above t h e  reflections  STRUCTURE DETERMINATION  Patterson  listing  347  of  observed.  Although attempts of  total  body  of  of centered  these reflections  below:  -289-  phase  from:  2.45  0  origin  0  2.41  TT  E  l  -10  0  3.59  TT  Z  l  0  -16  0  3.17  0  E  l  0  -12  0  4.81  0  E  l  8  -12  0  1.93  0  S  l  1  -15  6  2.46  "a"  1  -2  17  2.25  "b"  h  k  1  2  -3  3  6  -14  0  E  The u s e o f t h e p h a s e s 0 andTr f o r t h e s y m b o l i c a  and b gave set  four # "  solutions  phase o f a c  TT  2  phase  of b  N, det(/131) 112  27  125  T  TT 0  77  below:  R. K 42  c  1  The  and t h e s e a r e l i s t e d  3  0  TT  24  131  4  0  0  39  117  f o r determining  the best  criteria  value of  (Karle r e s i d u a l )  Set#3 f i t s  the  criteria  solution  are the lowest  and t h e most d e t e r m i n e d p h a s e s .  b e s t and d o e s y i e l d ,  the  solution.  The E-map g e n e r a t e d f r o m t h i s p h a s e d s e t o f reflections and one  at  revealed  two  s t r o n g p e a k s ; one  at  131  (.50,.25,.125)  (.10,0.0,-25) w h i c h c o r r e s p o n d t o t h e 8a ( 4'?, and  16e  ( 2,C )  are  t h e p o s i t i o n s o f t h e c o b a l t and p h o s p h o r u s atoms  2  phases  positions  of the second s e t t i n g  o f 14^/acd.  These  respective  -290-  Successive Fourier from  these cobalt  parameters  difference  maps b a s e d  and p h o s p h o r u s  positions  by f u l l  parameters, cycles given the  and  anisotropic  and p h o s p h o r u s (14 0,141) ,*  Q  W=F*/F ; q  in  a weighting--scheme ;  F = a v e r a g e F =80) was e m p l o y e d , Q  f o r 346 r e f l e c t i o n s ( o n e  was c o n s i d e r e d p o o r l y  and phosphorus  shift  determined.  are  listed  cycle  o f 0.024a.  was  thermal parameters  4 -11 5,  ; F = 2 7.0 and q  o f r e f i n e m e n t gave a maximum The h y d r o g e n  The o b s e r v e d  i n Appendix  respectively.  reflection,  m e a s u r e d and i s o m i t t e d  A subsequent  not  and  three  The v a l u e s o f R a n d R were 0.072 and 0.092 w  respectively  parameter  For the f i n a l  (symmetry c o n s t r a i n e d  t h e anomolous s c a t t e r i n g o f c o b a l t  =2.0).  atoms were  r e f i n e m e n t , a l l o f t h e atoms were  thermal parameters  w=1.0; F > F * ,  included.  F  o f these twelve  t h e r e s i d u a l , R, was 0.12 3.  case o f c o b a l t  Q  atoms.  matrix l e a s t squares w i t h i s o t r o p i c thermal  o f l e a s t squares  (F <F*,  calculated  gave t h e p o s i t i o n a l  o f t h e r e m a i n i n g t e n non-hydrogen  When t h e p o s i t i o n p a r a m e t e r s refined  on t h e p h a s e s  atom p o s i t i o n s  and c a l c u l a t e d  3 ( T a b l e A3-3).  structure  were factors  The . f i n a l p o s i t i o n a l  a r e g i v e n i n T a b l e s ' A3-1 and, A3-2,  -291-  6.5.2  T E T R A K I S ( 4 - M E T H Y L P Y R I D I N E ) N I C K E L ( I I ) HEXAFLUOROPHOSPHATE Ni(4mepy) (PF ) 4  6.5.2.1  CRYSTAL  The  6  PREPARATION  crystals  Co(4mepy) (PFg)2•  were  Weisenburg  i n 0.3  prepared  small  group.  as  C2/c The  manually  l ( h ) = 2n+l, 6 (C No.  15)  2 h  c r y s t a l was  yellow crystals  OkO  mounted  the orientation  , No.  least  unit  squares  was  cell  The  were  study  preliminary  a monoclinic  i n a random o r i e n t a t i o n CAD4  controlled  space  four  diffractometer  (SEARCH)  matrix  and  refinement o f these  24 28 4 H  C2/c,  N  N i P  2 12 F  and  indexed  for a triclinic  found reflections  unit  triclinic  unit  determined  from  the pre-  were d e t e r m i n e d  from  the  done.  dimensions  (  F  W  =  7  2  1  re-indexed reflections.  •  1  e.  circle d i f -  c r y s t a l data are: C  group  9).  transformation of the d i r e c t  photographs, The  for this  indicated  to the C-centered monoclinic c e l l ,  liminary  The  4  or Cc(C  and  simple  produced  to  (k=2n+l) ) gave t h e s p a c e  The minicomputer  calculated  manner  of the systematic absences ( h k l :  i n reciprocal  cell  chosen  photographs  25 r e f l e c t i o n s  A  in a similar  centered i n the Enraf-Nonius  fractometer.  COLLECTION  Lindemann c a p i l l a r i e s .  Examination  hOl:  either  mm  and p r e c e s s i o n  h+k=2n+l,  cell.  DATA  h y d r o s c o p i c and t h e c r y s t a l s  sealed  space  AND  were  The  4  mildly  2  5  ) / monoclinic,  a=19.709(5), b=9.866(2),  c=16.515(9)8,  -292-  3=101.54 (4)°,  -3 Z=4, p •;.•=!. 52 3 g cm  1 , u=8.2:cm -  ,  A. (MoKa) =0 . 7107 3 8 The  d a t a c o l l e c t i o n was done i n t h e r a n g e  w i t h monochromated MoKa r a d i a t i o n The  i n an omega s c a n mode.  omega s c a n a n g l e was 0 . 9 0 + 0 . 4 5 ( t a n 6 ) , t h e h o r i z o n t a l  w i d t h was 2.75+tan0 a n d t h e s c a n s p e e d SIGRRE, unique  control  reflections  ( h k l , h k l ) were r e c o r d e d .  r e f l e c t i o n s were c h e c k e d  every  s o u r c e time and t h r e e o r i e n t a t i o n checked  calculated  i f the observed  by more t h a n  5000 s e c o n d s  intensity o f X-ray  c o n t r o l ' r e f l e c t i o n s were  scattering  0.18°.  mean o f t h e s c a t t e r i n g v a r i e d  were a p p l i e d .  v e c t o r d i f f e r e d from t h e  During data c o l l e c t i o n , the r a n d o m l y +1.5% and t h e o r i e n t a t i o n  m a t r i x d i d n o t need t o be r e c a l c u l a t e d .  each  Three  The  e v e r y 150 r e f l e c t i o n s ; t h e o r i e n t a t i o n m a t r i x was  recalculated  factors  aperture  parameters,  and SIGMA, were 0.500 and 0.333 r e s p e c t i v e l y .  control  LP.  A standard deviation  (Lorentz-polarization) was a s s i g n e d t o  r e f l e c t i o n by: q (l)=S+4(B +B )+(0.051) 2  1  where S=scan c o u n t Of  2°<20<45°  2  2  and B^ and B  2  a r e t h e background  t h e 2057 r e f l e c t i o n s c o l l e c t e d ,  were c o n s i d e r e d o b s e r v e d .  6.5.2.2  The t e r m  1002  count.  (49%) h a d I>3g(D  and  E g ( F ) / £ F was 0.057 7.  STRUCTURE DETERMINATION  The  Patterson function  was u s e d  to solve the structure.  -293-  The  two  s p a c e g r o u p s , Cc  s p a c e g r o u p , Cm. number o f must be  The  fact that  general positions  e i t h e r on  fore  I n Cc,  the  nickel  and  t h e s e two  two  w o u l d be  C2/c.  P a t t e r s o n map  between the the  Ni-P  eight,  vectors  ;  C2/c  2-fold  are  needed  i n order The  gave the  asymmetric  for  i n the  scheme  unit.  C2/c  absorption  positions  R  The  as  as  the  of  d i r e c t method Cc  corrections  were n o t  A  phos-  gave, the' same -  thermal  anomalous  the of  parameters scattering  employment „of a . w e i g h t i n g r e s i d u a l and  weighted  0.096 r e s p e c t i v e l y .  were n o t  determined.  4a)  solution  s y n t h e s e s gave  the  =,23.1), t h e and  in vectors  the  . . .  i n c l u s i o n of  were 0.071  of  (special position,  Fourier  the  one  principal  i n Cc  relative positions  p h o s p h o r u s , and  R and  there-  described  vectors  With a n i s o t r o p i c  ( s e c t i o n 6.5.1.2, F  residual, and  and  to  one  unit  r e m a i n i n g n o n - h y d r o g e n atoms, a t o t a l  a l l t h e s e atoms, t h e  o f .cobalt  and  i s 4 and  vectors  Ni-Ni  centers of  Successive difference  22  atoms  axis  v e r y different;,, the  s p l u t a o h as , t h e - P a t t e r s o n f u n c t i o n ,  the  the  P a t t e r s o n map  ( t h e method s i m i l a r t o 6.5.1.2) and  of  nickel  general positions  gave the  positions  i n C2/c  p h o s p h o r u s atoms i n t h e  p h o rus: a t o m s , a g e n e r a l p o s i t i o n . in  the  a  t w i c e as many N i - P  inversion  same P a t t e r s o n  says t h a t  phosphorus p o s i t i o n s .  difference  and  the  s i t u a t i o n s w o u l d be  The  Z=4  c e n t e r s or  number o f  3 general positions  have the  being  inversion  general position describes cell.  0.2/c,  and  applied  final  and  cycle of  the  Extinction  hydrogen  least  squares  -294-  r e f i n e m e n t d i d n o t show any s h i f t s tables final and  of F  o  and F  positional  T a b l e A3-5,  c  g r e a t e r than  a r e t a b u l a t e d i n Appendix  and t h e r m a l  parameters  respectively).  0.256.  The  3 as a r e t h e  ( i n T a b l e s A3-6, A3-4,  -295-  6.5.3  HEXAKIS(3-METHYLPYRIDINE)DIAQUONICKEL(II) HEXAFLUOROPHOSPHATE  6.5.3.1  Ni(3mepy) (HjO) (PF ) g  CRYSTAL PREPARATION AND  Small  crystals  berg and  and  2  DATA COLLECTION  g  the X-ray d i f f r a c t i o n  u s e d were s e a l e d  g  of N i ( 3 m e p y ) ( H 0 ) ( P F )  from the procedure o f s e c t i o n for  2  2  2  The  small  Lindemann c a p i l l a r i e s .  precession- photograghs  the s y s t e m a t i c absences  obtained e  2  6.2.3.3 were f o u n d t o be  investigations.  i n .3 mm  g  indicated  suitable  crystals  The  Weisseh-  a m o n o c l i n i c ispace  group  (hkl:  h+k+l=2n+l; h O l : l = 2 n ( h = 2 n ) ; . 6 as Cc ( C No.9) o r C 2 / C ( C ,  0k0:(k=2n)) g a v e t h e s p a c e g r o u p  s  2 h  No.15) . The in  crystal  chosen  a random o r i e n t a t i o n on  controlled  diffractometer  (A=0.71069 8 )  X-ray  in  s p a c e and  reciprocal  simple  t h e E n r a f - N o n i u s CAD4  s o u r c e ; 25  C  computer:  r e f l e c t i o n s were f o u n d  indexed to a t r i c l i n i c  transformation of the u n i t  crystal  mounted  e q u i p p e d w i t h monochromated Mo  C-centered monoclinic c e l l The  f o r d a t a c o l l e c t i o n was  cell  indicated  was  by  unit  needed  Ka  automatically  cell.  to give  the p r e l i m i n a r y  A the  photos.  data are: 3 6 4 8 1 2 i . 6 2 2 m o n o c l i n i c , space group H  F  N  N  0  P  a=10.497(1)8,  b=20.074(3)8,  c-21.836(5)8  3=103.93(2)°,  V=44658  p  3  Z=4,  Cc,  , =1.40, C3.1C  y=11.9 The  cm"  1  reflection  intensities  were c o l l e c t e d  2°<28<50°  -296-  parameters  (SIGPRE a n d SIGMA) w e r e 0.500 a n d 0.033.  scan angle  was  to provide  background counts,  (1.75  The omega  (1.10 +0.35 x t a n 0 ) , e x t e n d e d 2 5 % o n b o t h with a h o r i z o n t a l aperature  sides of  + t a n 0 ) mm and t h r e e o r i e n t a t i o n c o n t r o l r e f l e c t i o n s  were measured e v e r y  100 r e f l e c t i o n s a n d t h e o r i e n t a t i o n m a t r i x  r e c a l c u l a t e d i f t h e s c a t t e r i n g v e c t o r was 0.10° f r o m t h e c a l culated position. measured every data  Three i n t e n s i t y c o n t r o l r e f l e c t i o n s  3 600 s e c o n d s o f X - r a y e x p o s u r e t i m e ;  were  during the  c o l l e c t i o n , t h e mean o f t h e i r i n t e n s i t i e s v a r i e d r a n d o m l y  +1.3%.  I n the data  r e d u c t i o n , L o r e n t z - p o l a r i z a t i o n (LP) c o r -  r e c t i o n s were a p p l i e d and an e s t i m a t e d  standard  d e v i a t i o n was  assigned: a(I) = S+4(B +B ) + 1  2  w h e r e S = s c a n c o u n t a n d B^ a n d B 4179 r e f l e c t i o n d a t a were c o n s i d e r e d  6.5.3.2  collected,  2  (0.05I)  2  = background count. 2723  Of t h e  (65.2%) h a d I > 3 a ( I ) a n d  observed.  STRUCTURE SOLUTION  A t t e m p t s t o s o l v e t h e s t r u c t u r e by t h e use o f t h e Patterson  f u n c t i o n were u n s u c c e s s f u l .  Attempts t o solve the  s t r u c t u r e b y d i r e c t m e t h o d s i n a manner s i m i l a r t o t h a t by C o ( 4 m e p y ) ( P F g ) 4  2  ( s e c t i o n 6.5.1) w e r e a l s o  D i r e c t methods d i d n o t meet w i t h s u c c e s s  described  unsuccessful.  because o f t h e n o r m a l i z -  a t i o n procedures t o c a l c u l a t e the E values  i n SHNORM.  I fthe  -297-  K curve visually was true  (14 2)  was  plotted  and t h e c u r v e  the E values obtained  solved u s i n g the c e n t r i c s p a c e g r o u p was  baseline  estimated  gave t h e s o l u t i o n .  The  structure  s p a c e g r o u p C2/c g r o u p b u t t h e  the a c e n t r i c  one,  Cc. .  The t h r e e l a r g e s t p e a k s i n t h e E-map a r e shown ( R H O - r e l a t i v e peak  height) X  Peak - #;  0. 500  0.125  0.2500  560  2  0. 00  0.125  0.250  198  3  0. 350  0.307  0.410  145  4  0. 304  0.444  0.411  140  canv  (1/2, y , 1/4)  crystallographic  for  a trial  the  solution with  . be a s s i g n e d  i s t h e 2e p o s i t i o n  2 fold  c o o r d i n a t e s o f peak  ( C ) symmetry.  3 as t h e p o s i t i o n  structure  d i d not y i e l d  whereas  n i c k e l and phosphorus p o s i t i o n s Since  one more g e n e r a l p o s i t i o n  a solution.  are both  unit  This has  Z=8;  and  phosphorus  However, i n  t h e r e f o r e , the  general  of the t i t l e  above  positions the  compound,  f o r a phosphorus  4 were u s e d .  atom  Therefore,  a solution.  i n C2/c  i s needed  and t h e c o o r d i n a t e s o f peak solution.  of the phosphorus  t h e number o f p h o s p h o r u s atoms i s t w i c e  number o f n i c k e l i n t h e f o r m u l a  the  o f C2/c w h i c h  n i c k e l on a s p e c i a l p o s i t i o n  s p a c e g r o u p Cc Z=4,  Cc.  to n i c k e l .  Attempts t o use the  2  on a g e n e r a l p o s i t i o n d i d n o t y i e l d  in  RHO  1  i  the  C2/c): z  Y  Peak 1*- (1/2 , 1/8,1/4)position  (space g r o u p  below  atom;  This procedure yielded  -298-  W i t h t h e x and to define  z c o o r d i n a t e s o f t h e n i c k e l atom f i x e d  the o r i g i n i n the a c e n t r i c space group,  subsequent  c y c l e s o f f u l l m a t r i x l e a s t square refinement y i e l d e d p o s i t i o n o f t h e r e m a i n i n g 56 n o n - h y d r o g e n a t o m s .  With  i n c l u s i o n o f t h e a n o m a l o u s s c a t t e r i n g o f n i c k e l and the  final  R and R  w e r e 0.051  and  0.063  the the  phosphorus,  (the r e f l e c t i o n s were  w w e i g h t e d by t h e e r r o r s In the f i n a l was  0.30  a'.  from t h e i n t e n s i t y d a t a  collection).  c y c l e o f r e f i n e m e n t t h e maximum p a r a m e t e r The p o s i t i o n s o f h y d r o g e n s  were n o t  found nor were a b s o r p t i o n o r e x t i n c t i o n c o r r e c t i o n s The  f i n a l p o s i t i o n a l and t h e r m a l p a r a m e t e r s  Appendix  2, T a b l e s A3-7  and A3-8  Table  A3-9.  applied.  are tabulated  respectively.  and c a l c u l a t e d s t r u c t u r e f a c t o r s a r e l i s t e d  shift  The  in  observed  i n Appendix  3,  -299-  6.5.4  HEXAKIS(3-METHYLPYRIDINE)DIAQUOCOBALT(II) HEXAFLUOROPHOSPHATE  The determined -for  space group  for.this  Co(3mepy) (H 0) (PFg) g  and u n i t ' c e l l  6.2.3.1).  s i o n photographs similar  g  6.5.5  cell  of the monoclinic parameters  Weissenberg  i t s diffraction 2  2  b=20.o8,  been  suitable  and  group  C2/c o r C c .  see  preces-  pattern  The  2  from t h e p r e l i m i n a r y  i s very  systematic 0k0(k=2n+l);  The a p p r o x i m a t e  photographs a r e :  a n d c=21.7°i a n d 3 = 1 0 4 ° w i t h Z = 4 ) .  HEXAKIS(3-METHYLPYRIDINE)DIAQUOCOPPER(II) HEXAFLUOROPHOSPHATE  The preliminary  crystal  space group  Cu(3mepy) (HjO) (PFg) g  and p r e c e s s i o n The p h o t g r a p h s  and t h e e v a l u a t i o n  paramters b=9.588,  a s e i t h e r C2/c o r C c .  derived c=19.8l8  2  determined  photographs indicated a  of the systematic  : h+k=2n+l; h O l : l = 2 n ( h = 2 n ) ,  space group  2  s t r u c t u r e has been  Weissenberg  crystalline material.  (hkl  Crystals  a r e : h k l : h+k=2n+l; h O l , l=2n(h=2n) and  indicative  a=10.l8,  have  -from t h e r e a c t i o n m i x t u r e (  The p r e l i m i n a r y indicate that  2  parameters  to that of Ni(3mepy) (H 0) (PFg) .  absences  unit  2  crystalline material.  X - r a y s t u d i e s were o b t a i n e d  section  2  and OkO  a n d 3 = 1 1 5 ° w i t h Z=4.  of this monoclinic  absences  : (k=2n)) gave t h e  The a p p r o x i m a t e  from t h e p r e l i m i n a r y  from t h e .  photographs  unit are:  The u n i t c e l l  cell a=25. 088,  parameters  -300-  are  different  and  Co(3mepy) (H 0) (PF )  respectively).  from t h o s e o b s e r v e d 6  2  2  6  2  for Ni(3mepy) (H 0) (PF )  (sections  g  2  2  6.5.3.1 and 6.5.4,  g  2  -3 DE-  REFERENCES (1)  W. Lange i n F l u o r i n e C h e m i s t r y , A c a d e m i c P r e s s , New Y o r k .  (2)  L. K o l d i t z  1950 p .  i n Halogen Chemistry,  A c a d e m i c P r e s s , New Y o r k . (3)  J.H. Simons, e d . V o l . 1. 126  V. Gutmann, e d . V o l . 2.  1967 p .  115  R. S c h m u t z l e r  i n Advances i n F l u o r i n e Chemistry,  Butterworths,  London.  1965 p .  V o l . 5.  203.  (4)  H. Bonde and G. T u e f f e r . Z. a n o r g .  (5)  J.A. I b e r s . 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