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The synthesis, magnetic and mossbauer spectral properties of poly-[mu]-bis (di-n-octylphosphinato) iron(II)… Peers, James Richard Douglas 1989

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THE  SYNTHESIS, OF  MAGNETIC AND MOSSBAUER  SPECTRAL  POLY-^-BIS(DI-N-OCTYLPHOSPHINATO)IRON(II) ZINC(II)-DOPED  PROPERTIES AND  ANALOGUES  by  JAMES  B.Sc,  RICHARD  DOUGLAS  PEERS  The U n i v e r s i t y o f B r i t i s h Columbia,  A THESIS SUBMITTED IN PARTIAL FULFILLMENT THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  in  THE FACULTY OF GRADUATE STUDIES Department o f C h e m i s t r y  We a c c e p t t h i s t h e s i s as c o n f o r m i n g to the required  standard  The U n i v e r s i t y o f B r i t i s h Columbia October, 1989 ©  James R i c h a r d Douglas P e e r s ,  1989  1986  OF  ITS  In  presenting this  degree at the  thesis  in  partial  University of  fulfilment  of  of  department  this or  thesis for by  his  requirements  British Columbia, I agree that the  freely available for reference and study. I further copying  the  her  representatives.  an advanced  Library shall make it  agree that permission for extensive  scholarly purposes may be  or  for  It  is  granted  by the  understood  that  head of copying  my or  publication of this thesis for financial gain shall not be allowed without my written permission.  Department  of  CU^ilS  \C  The University of British Columbia Vancouver, Canada  Date  DE-6 (2/88)  13  OcM&C  ( W  ABSTRACT  The  inorganic  coordination  poly-u-bis(di-n-octylphosphinato)iron(II),  polymer,  (Fe[(n-C H  was  p r e p a r e d and  compound  were  vibrational, dependent  analyzed  magnetic  postulation  Form  II  in of  this  II.  compound  occurs  not  intermediate  ligands. in  chain  The  the  Heisenberg S=l  Lande s p l i t t i n g  on  triplet  as  of  suggested  pressure. that  the  and  i r o n ( I I ) centres  ground  state,  giving  to  the  2-80  K  model,  The  splitting  and  vs.  35 to  in an  the  properties  according  i r o n centres  a l s o t o have unexpectedly high  results, electronic structure ii  S=l  temperature data,  analyzed  showed the  of  g v a l u e was  to to  a be  large  presumed t o  r e s u l t of l a r g e o r b i t a l angular momentum c o n t r i b u t i o n s . these  this  chromophore.  a r e s u l t of a— donation  coupled and  f a c t o r , g.  a Form I to  Mossbauer s p e c t r o s c o p y a l s o showed  contribution  of  the  material,  four-coordinate  magnetic s u s c e p t i b i l i t y  range  antiferromagnetically  rare  system.  positive  for  to  this  metal-oxygen  suggested t h a t  i n the  s p i n S=l  this  temperature  leading of  n  induced over the temperature range  quadrupole doublet, p o s s i b l y  the  results  of  Evidence  application  compressed t e t r a h e d r a l  were  substantial  linear  the  Both forms were suggested t o be  material  collected  forms  calorimetry  Mossbauer s p e c t r a l s t u d i e s  of the  two  2  calorimetry,  seen s u g g e s t i n g t h a t  upon  thermally  studies. found,  2  properties  scanning  was  of  Evidence was  scanning  possess a h i g h l y  a  differential  existence  transition  t r a n s i t i o n was  this  physical  susceptibility  the  I and  Differential  to 300°C.  using  The  e l e c t r o n i c and Mossbauer spectroscopy and  polymorphism  labelled  characterized.  ) PO ] } , 17  8  be  Based  schemes were proposed  for  Forms I a n d I I . In {Fe  addition,  Zn [ (n-C H l-x  x  0.2.  8  These  appeared  11  2  2  dependent  to occur  also  2  proposal that  t o a more was  substantial  susceptibility  discussed  K  with  vs.  and  magnetic  compound,  x=0.05,  by  Mossbauer  of  S=2  of doping  forms  f o r t h e S=2  in a qualitative  from data  iron (II).  iii  this  l e d to the system  large  zinc  quadrupole a  result  Magnetic  collected  of these  i s to  to the  ligands. also  also  Mossbauer  again perhaps  the were  A  and  S=l c e n t r e s ,  centres adjacent  lines,  scanning  and  II.  This  into  the d e t a i l s  manner.  studies  o f i r o n (II)  configuration.  samples;  and  spectroscopy  I and  zinc(II)  of the iron  temperature  0.1  differential  susceptibility  cr-donation  f o r these  this  ,  analyzed  tetrahedral  observed  of  r e  were  the e f f e c t  centres  2-80  n  the presence  the geometries  range  prepared  i n the polymorphic  distort  of  samples  again suggested the presence  showed  splitting  were  vibrational  spectroscopy but  ) PO ] } ,  compounds  calorimetry, temperature  zinc(II)-doped  over  the  results  are  Table of Contents  Page  Abstract  i i  Table of Contents  iv  List  of Tables  vi  List  of Figures  List  o f A b b r e v i a t i o n s a n d Symbols  v i i ix  Acknowledgements  x  CHAPTER I INTRODUCTION  1  I.A. I.B. I . C.  Poly(metalphosphinates) T r a n s i t i o n Metal Di-n-octylphosphinates A i m o f t h e P r e s e n t Work a n d T h e s i s O u t l i n e Chapter I References  CHAPTER I I RESULTS AND DISCUSSION I : POLY-u-BIS(DI-N-OCTYLPHOSPHINATO)IRON(II) I I . A. II.B. II.C. II.D. II.E. I I . F.  Syntheses Infrared Spectra Thermal S t u d i e s Mossbauer Spectroscopy E l e c t r o n i c Spectroscopy Magnetic S u s c e p t i b i l i t y Chapter II References  Measurements  1 3 7 9  12 12 14 20 23 33 36 53  CHAPTER I I I RESULTS AND DISCUSSION I I : ZINC DOPED POLY-u-BIS(DI-N-OCTYLPHOSPHINATO)IRON(II)  56  I I I . A. S y n t h e s e s III.B. Infrared Spectra I I I . C . Thermal S t u d i e s I I I . D . Mossbauer Spectroscopy I I I . E . M a g n e t i c S u c e p t i b i l i t y Measurements Chapter I I I References  56 57 58 60 65 70  CHAPTER I V CONCLUSIONS AND  SUGGESTIONS FOR FURTHER WORK  CHAPTER V EXPERIMENTAL V.A. M a t e r i a l s and P r e p a r a t i v e Techniques V.B. Elemental Analyses V.C. I n f r a r e d Spectroscopy V.D. E l e c t r o n i c Spectroscopy V.E. M a g n e t i c S u s c e p t i b i l i t y Measurements V.F. Mossbauer Spectroscopy iv  71  74 74 74 74 74 74 76  V.G.  Syntheses Gl. Synthesis of Di-n-octylphosphinic Acid, (C H ) P0 H 8  G2.  1 7  2  2  1 7  2  2  G2.1  Fe[(CgH  G2.2  Fe[(C H  1 7  ) P 0 ] , sample 2  78  G2.3  Fe[(C H  1 7  ) P 0 ] , sample 3  78  g  g  )  1 7  P 0 2  2 2' ]  2  2  2  s  a  P  m  l  e  1  7  7  2  2  2  G2.4 Fe[(CgH ) 2 2' P Synthesis of B i s ( d i - n - o c t y l p h o s p h i n a t o ) z i n c (II), Zn[(CgH ) P0 ] 79 p 0  1 7  2  2  ]  s  a  m  l  e  4  7  9  2  2  P r e p a r a t i o n o f Mized-Metal Compounds, l-x x G4.1 F e  0 < 8  G4.2  Fe  0 > 9  G4.3  Fe ;  G4.4  Fe  Z n  F e  V.H.  77  2  1 7  G4.  76  2  S y n t h e s i s of B i s ( d i - n - o c t y l p h o s h i n a t o ) i r o n ( I I ) , Fe[(C H ) P0 ] 8  G3.  76  [ ( C  0  0 1  8 17>2 V2 Zn [(C H ) PO ] , P (  H  80  Z n ^ [ ( C g H ) P 0 ] , sample 6  80  8  1 7  0  9 5  Zn  0 9  2  1 7  Zn*  P 0  0 > 9  1 3  0 1  0  sample 5  0 > 2  # 0 5  8  [(CgH  1 7  2  2  [(C H  1 7  2  2  2  2  ) PO ] , 2  2  ) PO ]  Attempted Syntheses HI. F e [ ( C H ) 2 2 H2. F e Cd t(C H ) PO ] Chapter V References g  8  2  2  2  sample 7  81 81 82  ]  8  2  2  8  1 7  2  2  2  82 84  APPENDIX I Assignment o f I n f r a r e d Data APPENDIX I I Magnetic S u s c e p t i b i l i t y  Data  v  85 92  L i s t o f Tables 2.1  Frequencies  Page o f i>(P0 ) regions i n v a r i o u s 2  v a r i o u s metal(phosphinate)polymers  16  2.2  P0  20  2.3  Mossbauer parameters f o r compound 2  2.4  Comparison o f the F i s h e r , L i n e s and Weng  2  s t r e t c h i n g f r e q u e n c i e s , compounds 1-4  29  S=l models f o r compound 2  44  2.5  Magnetic parameters f o r compounds 1-4, F i s h e r model  45  3.1  I n f r a r e d s t r e t c h i n g f r e q u e n c i e s o f t h e v(P0 ) of doped samples Fe Zn [ (C H ) PO ]  57  2  ^  3.2  ^  l-X  X  8  17' 2  2  J  2  Mossbauer s p e c t r a l parameters f o r zinc-doped compounds  vi  regions  60  List 1.1  of Figures  Page  Structures of Cu[(CH  ) PO ]  2 5 2  and  2 2  Mn [ (CH ) PO ] -2H 0 3  2.1  2  Comparison untreated  2.2  2 2  2  2  o f P0  stretching  2  and ground  sample  Thermograms o f u n t r e a t e d of  regions of 1  and ground  19 samples  compounds 4  22  2.3  D e c a y scheme f o r C o  2.4  Mossbauer s p e c t r a o f u n t r e a t e d and ground forms o f compound 2 a t 77 K E l e c t r o n i c c o n f i g u r a t i o n s as a f u n c t i o n o f symmetry f o r F e ( I I ) c o m p l e x e s  2.5 2.6  24  57  Electronic region  spectrum  o f compound 1  34  Magnetically concentrated  2.8  M a g n e t i c s u s c e p t i b i l i t y vs. o f compound 1 , u n t r e a t e d M a g n e t i c s u s c e p t i b i l i t y vs. compound 2, u n t r e a t e d  2.10 2.11 2.12 2.13  2.14 2.15 2.16 2.17  30  i n the near-infrared  2.7  2.9  28  systems temperature  38 plot 39  temperature p l o t  of 39  M a g n e t i c s u s c e p t i b i l i t y vs. t e m p e r a t u r e p l o t compound 2, u n t r e a t e d , Weng model  of  M a g n e t i c s u s c e p t i b i l i t y vs. t e m p e r a t u r e p l o t compound 2, u n t r e a t e d , L i n e s model  of  Magnetic s u s c e p t i b i l i t y compound 1-4, u n t r e a t e d  vs.  temperature p l o t  43 43 of 46  Comparison o f magnetic s u s c e p t i b i l i t y vs. t e m p e r a t u r e o f u n t r e a t e d and ground samples compound 1 Magnetic s u s c e p t i b i l i t y 1, ground  vs.  Magnetic s u s c e p t i b i l i t y compound 3, u n t r e a t e d  vs.  Magnetic s u s c e p t i b i l i t y compound 4, u n t r e a t e d  vs.  temperature  of 47  o f compound 47  temperature f o r 49 temperature f o r 49  Comparison o f t h e magnetic s u s c e p t i b i l i t y vs. t e m p e r a t u r e b e h a v i o u r s o f u n t r e a t e d and ground s a m p l e s o f compound 3 vii  50  2.18  Magnetic s u s c e p t i b i l i t y of compound 3, ground  vs. temperature  plot 50  2.19  Magnetic s u s c e p t i b i l i t y vs. temperature p l o t s f o r compound 2, v a r y i n g g and J  52  3.1  Thermograms o f sample  59  3.2  Mossbauer  spectrum o f compound 5 (x=0.2) at 77 K  61  3.3  Mossbauer  spectrum o f compound 6 (x=0.1) at 77 K  61  3.4  Mossbauer  spectrum o f compound 7 (x=0.05) at 77 K  62  3.5  Magnetic s u s c e p t i b i l i t y vs. temperature p l o t s o f u n t r e a t e d and ground samples o f compound 5 (x=0.2)  66  3.6  Magnetic s u s c e p t i b i l i t y vs. temperature p l o t s o f u n t r e a t e d and ground samples of compound 6 (x=0.1)  66  3.7  Magnetic s u s c e p t i b i l i t y vs. temperature p l o t o f compound 7 (x=0.05), u n t r e a t e d  68  6 (x=0.1)  viii  L i s t o f A b b r e v i a t i o n s and Symbols NMR  n u c l e a r magnetic resonance  EPR  e l e c t r o n p a r a m a g n e t i c resonance i n f r a r e d s t r e t c h i n g frequency  v -l  cm IR DSC Me OH asy sym s  infrared differential  scanning calorimetry  methanol asymmetric symmetric strong medium  m  weak  w sh N  shoulder Avogadro's number Boltzmann's c o n s t a n t  k  isomer s h i f t  8  quadrupole s p l i t t i n g  AE Q  EFG  r g *  reciprocal centimeters  M  B.M.  electric  field  gradient  Mossbauer l i n e w i d t h Lande s p l i t t i n g  factor  molar magnetic  susceptibility  e f f e c t i v e magnetic moment Bohr magneton  ix  ACKNOWLEDGEMENTS  I  would  research  first  like  s u p e r v i s o r s , Dr. and  to  express  R.C.  my  sincere  Thompson and  J.R.  their  labs.  of my  l a b group f o r t h e i r t e c h n i c a l a s s i s t a n c e , companionship  good humour.  g r a t i t u d e and b e s t wishes  my  research i n  a l s o go t o t h e members  S p e c i a l t h a n k s a l s o t o M a r t i n E h l e r t , Tom for their  manuscript.  I am  assistance with  the  a l s o i n d e b t e d t o Mr.  p r o o f r e a d i n g of  Bill  Lake,  friends who  and  made my  and  Otieno  and this  f o r generously  a l l o w i n g me t o use t h e l a s e r p r i n t e r i n h i s o f f i c e , t h u s a major d i s a s t e r .  my  Sams, f o r  help  My  d u r a t i o n of  to  their  Mark A s t o n  patience during the  Dr.  thanks  averting  I would a l s o l i k e t o e x t e n d f o n d r e g a r d s t o  c o l l e a g u e s here  i n the  c h e m i s t r y department a t  my  UBC,  t i m e here v e r y e n j o y a b l e , humourous and even s l i g h t l y  t u n e f u l at t i m e s . Thanks a r e a l s o i n o r d e r t o t h e s t a f f o f t h e electronic Without  and  the  glassblowing  skill  of  these  shops  for  people,  the  t h e s i s would l i t e r a l l y be i m p o s s i b l e .  parents  for  I would their  like  support  i m p o r t a n t l y , I thank my mom  to  express  over  work  these  work.  described i n  this thank  services. my  special  past  for getting better.  x  excellent  I would a l s o l i k e t o  Mr. P e t e r Borda f o r h i s m i c r o a n a l y t i c a l Finally,  their  mechanical,  two  thanks years.  to  my  Most  I .  A.  INTRODUCTION  POLY(METALPHOSPHINATES)  Work on p o l y ( m e t a l p h o s p h i n a t e ) compounds has been from  a variety  polymeric r  of different  nature  of  2  4  1  2  2  J  was  .  on  the substituents  changing  metals .  1959 , 1  2  '  with  plastic  on phosphorus  conducted  and u s i n g  different 31  13  •  heat,  measurements  paramagnetic  resonance  and v a r i a b l e t e m p e r a t u r e has  demonstrated  the  has always  analysis, chain  been  although alkyl-  (EPR) s p e c t r o s c o p y ,  magnetic wealth  m i c r o s c o p i c p r o p e r t i e s o f t h e s e compounds.  shorter  in  A t t h a t t i m e , some work was a l s o b e i n g  N.M.R. ' , e l e c t r o n  X-ray  confirmed  Only r e c e n t l y , t h e employment o f such t e c h n i q u e s as P  1 1  research  A f t e r the  .  properties  specific  9  the years.  c e n t r e d on t h e f o r m u l a t i o n o f m a t e r i a l s 2-10  12  over  UO [ (n-C H ) PO ]  l  research  angles  approached  the i s o l a t i o n some s u c c e s s  susceptibility of  interesting  One d i f f i c u l t y of single  has been  and a r y l p h o s p h i n a t e s .  Two  1 4  i n this  crystals for  encountered f o r representative  s t r u c t u r e s a r e shown f o r t h i s c l a s s o f compound i n F i g u r e s I . l . a and  I.l.b.  I t can be seen  i n v o l v e d may be f o u r -  from  these  diagrams  or six-coordinate. 15  central  metal  atom  plays  a vital  t h e metal  F i v e - c o o r d i n a t e metal  p h o s p h i n a t e systems have a l s o been o b s e r v e d . the  that  role  The geometry  about  i n determining the  magnetic p r o p e r t i e s o f t r a n s i t i o n m e t a l complexes and t h e v a r i e t y of  d i f f e r e n t geometries a v a i l a b l e i n poly(metalphosphinates) g i v e s  us i n t e r e s t i n g model systems correlations. have  shown  causing  12  31  P NMR  electron  magnetic  f o r the study of magneto-structural  studies of several poly(metalphosphinates) delocalization  superexchange  onto  between 1  t h e phosphorus  adjacent  metal  atom, centres  Figure 1.1a.  Section of the  Figure 1.1b.  C u [ ( C H ) P 0 2 ] 2 chain (Ref. 16). 2  5  Section of the  M n [ ( C H ) P O ] . 2 H 0 chain (Ref. 17).  2  3  2  2  2  2  through  the bridging  mechanism  forms  magnetic  phosphinate  the basis  susceptibility  ligand.  f o r many  behaviour  J  •  superexchange  i n t e r e s t i n g studies  of these  compounds, and has been seen b e f o r e i  This  of the  phosphinate  with other  bridged  types of b r i d g i n g  1 8 , 1 9  ligands B.  TRANSITION  The  METAL  research  DI-N-OCTYLPHOSPHINATES  described  di-n-octylphosphinate analogues.  of  Some p r e v i o u s  di-n-octylphosphinate  2 0  Cr(II),  Mn(II),  characterized differential  thesis  iron(II)  and  research  polymers  r e v i e w e d . H.D. G i l l m a n ' of  i n this  2 1  its  of divalent  zinc(II)-doped  Ni(II),  metals  the  calorimetry.  will  now be  di-n-octylphosphinates  Co (II)  and  them by i n f r a r e d and U V / v i s i b l e scanning  on t h e  which has been c a r r i e d out on  synthesized  Fe(II),  concentrates  Room  Cu(II)  and  spectroscopy  and  temperature  magnetic  s u s c e p t i b i l i t y measurements were a l s o conducted by G i l l m a n i n t h i s study, not  although  magnetic s t u d i e s on t h e Fe and C r analogues were  i n c l u d e d due t o t h e a i r - s e n s i t i v e n a t u r e  Later Peers  studies 2 6  by B a n k s , 22  examined  Oliver et a l . ,  2 3  of these m a t e r i a l s .  Haynes e t al.  t h e N i , Co and Cu s p e c i e s  further,  2 4 , 2 5  and  including  v a r i a b l e t e m p e r a t u r e magnetic s u s c e p t i b i l i t y measurements. The  poly(di-n-octylphosphinate)  compounds  u s u a l l y i n v o l v e s r e a c t i n g t h e metal c h l o r i d e , acetate  or sulphate  with  synthesis  partially  of  neutralized di-n-octylphosphinic  where t h e m e t a l  sulphate  i s used as a s t a r t i n g  acid.  I n cases  reagent,  i t has  been found t h a t e x c e s s water s h o u l d be added a f t e r a d d i t i o n o f t h e metal sulphate Solubility  t o prevent the formation  studies  in a  wide  range  3  of a sulphate of  solvents  copolymer . 23  of  varying  dielectric polymers tested  constant  to  be  have  shown  insoluble  except  strong  Unfortunately,  there  or  as  metal  which yet  decompose  no  compounds  may  infrared X-ray  but  good  be  of  use  the  of  22-26  .  structures for  structures  such  of  the  metal  and EPR  of  these  diagnostic tools  atom  has  spectroscopy.  largely  some s h o r t c h a i n a l k y l - and crystals  f o r X-ray  The  precluded  c h a r a c t e r i z a t i o n of these compounds by NMR.  single  compounds  as  (IR) and U V / v i s i b l e spectroscopy, Mossbauer spectroscopy,  powder d i f f r a c t i o n ,  nature  the  the  a l l solvents  Characterization therefore i s  estimates  made by  in  known c r y s t a l  the d i - n - o c t y l p h o s p h i n a t e polymers. incomplete,  di-n-octylphosphinate  sparingly soluble  acids, are  the  paramagnetic  the  structural  As mentioned e a r l i e r ,  a r y l p h o s p h i n a t e s p e c i e s have p r o v i d e d a n a l y s i s and  the  spectral  data  from  those compounds with known s t r u c t u r e s can be compared to those f o r compounds  where  single  crystals  have  not  been  obtained,  p r o v i d i n g i n d i r e c t s t r u c t u r a l i n f o r m a t i o n on the l a t t e r The  Co ( I I )  and  2 6  ' .  C u ( I I ) d i - n - o c t y l p h o s p h i n a t e s have both  t  shown t o occur  23  thus  been  »  i n two  polymorphic  21  forms.  The  Co ( I I )  22  polymer '  o b t a i n e d from s o l u t i o n i s a l i g h t blue c o l o u r ; on h e a t i n g to about 80°C, i t undergoes an apparent  t r a n s i t i o n t o a navy b l u e m a t e r i a l .  U V / v i s i b l e spectroscopy data i n d i c a t e t h a t the l i g h t b l u e form i s pseudooctahedral  and  the  navy  blue  Infrared  s t u d i e s r e v e a l t h r e e P0  and  cm  at  1015 1130  -1  and  2  cm  -1  phosphinate  groups,  1140,  form.  1070 bands  The  form imply the presence  with two  three of  two  of the bands o v e r l a p p i n g .  A two-band v(PO ) r e g i o n i n d i c a t e s the presence 4  pseudotetrahedral.  compound and only two  f o r the p s e u d o t e t r a h e d r a l  bands seen f o r the pseudooctahedral different  is  s t r e t c h i n g bands at  f o r the pseudooctahedral 1050  form  of only one  type  of  phosphinate  occurred  ligand.  i n two  compressed  forms,  tetrahedral  Oliver  found  arbitrarily  labelled  a  form,  when  c o o l e d , underwent an i r r e v e r s i b l e form.  0 form had  The  but  UV/visible  compressed  data  2  suggest  tetrahedral  Cu [ (CgH^) P0 ] 2  a and 0.  melted  at  The  135°C  2  point  at around  and  98°C.  2  highly then  change t o the l e s s compressed  a melting  case, the IR data f o r the P0  that  In  p  this  s t r e t c h i n g r e g i o n were i n c o n c l u s i v e , a relaxation  chromophore  from  a more t o a  less  going from t h e a t o the 0  on  form. Variable  temperature  magnetic  susceptibility  have been performed on the Co, Cu and N i complexes mentioned e a r l i e r , Co[(C H 8  ) PO ] 17  2  2  both  Magnetic s u s c e p t i b i l i t y  Cu [ (C H ) P0 ] , i7  2  compressed exchange,  antiferromagnetic  workers  The two forms of  exchange;  however,  i s s t r o n g e r i n the case of the p s e u d o o c t a h e d r a l form  infra) . g  display  by the  2  the exchange (vide  yielding interesting results.  measurements  2  o b t a i n e d by  2  Haynes  data f o r the two  et  al.  show  2A  the  forms of a  (highly  t e t r a h e d r a l ) form t o e x h i b i t a n t i f e r r o m a g n e t i c magnetic w h i l e the 0 ( l e s s compressed  t e t r a h e d r a l ) form i s weakly  ferromagnetic. The unusual  Ni(II)  di-n-octylphosphinate  magnetic  polymorphism compound  susceptibility  over  the 2  an  2  transition  to  compound,  moreover,  consistent  with  behaviour,  temperature  Ni[(CgH^) P0 ]  2  exhibits  range  shows  26  but  no  studied.  state  at  field-dependent  f e r r o m a g n e t i c exchange.  The  around  6  with  a  K.  The  behaviour,  also  antiferromagnetic  become important at low thermal e n e r g i e s . 5  of  Instead, the  o r d e r i n g at low temperatures i s q u i t e p o s s i b l y i n t e r c h a i n which may  quite  evidence  f e r r o m a g n e t i c exchange,  antiferromagnetic shows  complex  coupling  A brief  d i s c u s s i o n o f what i s known about t h e i n f l u e n c e o f  geometry on magnetic exchange i n t h e s e compounds s h o u l d be u s e f u l here.  There a r e two pathways  f o r magnetic exchange, t h e <r and n 24  pathways.  I t has  been  argued  It  i s t h e pathway  has  also  ferromagnetic in  been  conducive  seen  that  a  consequence  quite  sensitive  magnitude changes  the  of  b a s i c a l l y t h a t o f two s p h e r e s . is  to antiferromagnetic  systems i s r e l a t i v e l y  geometry,  to  small  of antiferromagnetic  i n geometry.  magnitude insensitive  o—type  sake o f s i m p l i c i t y ,  coupling  i s sensitive  may  so t h e <r pathway Now,  between  t h e magnetic  orbital  cloud,  which  Cu(II)  exchange.  flattened  until  further,  will  Obviously,  once  will  model  orbital will  to subtle but the than  However,  be  there  be o n l y  copper i s  will  be b e t t e r  rise  symmetry  weak  about  there  to  and  the n  measurable  chromophore  is  i s achieved, the  because  t h e <r pathway  be more c o m p l i c a t e d 6  will  dominate, g i v i n g  i f the  ferromagnetic  leaving only will  I f t h e geometry  of the metal give  square p l a n a r  again  be z e r o ,  this  the  systems f o r t h e  i f t h e symmetry  i n turn  antiferromagnetic  overlap  overlap  o f g r e a t e r magnitude  a squashed t e t r a h e d r o n ,  overlap  will  being  thus  be a v a i l a b l e ,  We now c o n s i d e r  exchange.  to give  exchange  changes  overlap  i n geometry;  in  s i n c e t h e r e w i l l be o n l y one u n p a i r e d e l e c t r o n  weak jr o v e r l a p ,  flattened  exchange.  ir-type o r b i t a l  about t h e copper atom i s p u r e l y t e t r a h e d r a l ,  ferromagnetic  orbital  t o small  i n t h i s system, t h u s g i v i n g one. magnetic o r b i t a l .  very  overlap  exchange  changes  B o t h pathways  coupling.  of  orbital  Conversely,  antiferromagnetic coupling i s t y p i c a l l y ferromagnetic  orbital  exchange pathway, w h i l e ir-type  provides the ferromagnetic overlap  cr-type  that  the net n  f o r exchange.  i n systems  with  more  than  one  unpaired  considerations exchange  may  be  observed.  phosphinate  electron,  used  This  the  23  geometrical  type  with  of  magnetic  observations  of  25  are a v a i l a b l e t o e x p l a i n t h e  the l i g a n d f i e l d geometry about t h e m e t a l  extended H u c k e l approach ,  calculations  giving  30  treatments.  good  Experimental  these  treatments  ferromagnetic  3 1 - 3 5  exchange  towards  become  predict  same  systems made i n our g r o u p " .  o f changing  twisting  the  a n a l y s i s concurs  T h e o r e t i c a l treatments  of  to  but  atom u s i n g  as w e l l as a l i g a n d f i e l d  2 7 - 2 9  agreement  between  the  two  theory separate  r e s u l t s seem t o c o n f i r m t h e c o n c l u s i o n s  :  the  is  seen  observations in  square  t e t r a h e d r a l symmetry  antiferromagnetic,  tetrahedral.symmetry  effects  but  have  planar  causes  greater  been  that  chromophores;  the  exchange  distortion  causes the exchange t o become  to  towards  ferromagnetic  again.  C.  AIM  OF  The  THE  aim  PRESENT  WORK  AND  THESIS  of t h e work d e s c r i b e d i n t h i s t h e s i s was  t h e d i - n - o c t y l p h o s p h i n a t e of i r o n (II) known about  the  other  presents  a  to iron(III)  the  fact  that  anticipated insights  iron  that  into  57  Fe  the  Because  the study  synthetic challenge  not  study o f t h e C o ( I I ) , N i ( I I ) and C u ( I I ) a n a l o q u e s . synthetic d i f f i c u l t i e s  a  Mossbauer  Mossbauer  studies  structures  p o l y (metalphosphinates) .  active  and  would  magnetic  of  the  iron(II) in  the  Offsetting  the  compounds i s  nucleus.  To our knowledge, t h i s  7  of  present  inherent i n studying i r o n ( I I ) is  t o examine  i n l i g h t of the i n f o r m a t i o n  poly(metalphosphinates).  ease o f o x i d a t i o n of i r o n ( I I ) phosphinates  OUTLINE  It  provide  unique  properties study  was  of  represents  the  first  Mossbauer  poly(metalphosphinate) The  second  aim  spectral  characterization  of  a  system.  of  this  work  system, i n which a non-magnetic  was  to  create  a  mixed  metal  i o n ( z i n c ( I I ) ) i s doped i n t o  i r o n ( I I ) system i n s m a l l q u a n t i t i e s .  this  I t was a n t i c i p a t e d t h a t z i n c  d o p i n g would i n f l u e n c e t h e p h y s i c a l p r o p e r t i e s o f t h e s e m a t e r i a l s i n a i n t e r e s t i n g manner. In C h a p t e r I I t h e r e s u l t s and d i s c u s s i o n f o r our s t u d i e s F e [ ( C H ) PO ] a r e p r e s e n t e d , w h i l e i n C h a p t e r I I I t h e so 8 17 2 2 2 doped systems, Fe Zn [ (C H ) PO ] , a r e d i s c u s s e d . A ^ l-x x 8 17 2 2 2'  on  called  c  summary  J  and  suggestions f o r further  work  are  p r o v i d e d i n Chapter  E x p e r i m e n t a l d e t a i l s can be found i n Chapter V.  8  1  IV.  CHAPTER  1.  Healy,  T.V.; Kennedy,  2.  Nannelli, Sprout,  Nannelli,  P.;  B.P.;  Peschko,  J.P.; Saraceno, A . J . ;  Dahl,  G . J . J.  Polym.  Sci.,  H.D.;  Block,  B.P.  Polym.  Sci.,  J.  13, 2849.  S.H.; Schaumann, C.W.;  Roth,  V.; G i a n c o t t i , V.; R i p a m o n t i , A. J. Am. Chem. Soc.  87, 391.  6.  Rose,  S.H.; B l o c k , B.P. J. Am. Chem. Soc. 1965,  7.  Rose,  S.H.; B l o c k , B.P. J. Polym.  8.  Rose,  S.H.; B l o c k , B.P., ibid,  9.  Delman,  10.  A.D.; K e l l y ,  A-l 1966,  Pitts,  11.  Pitts,  12.  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RESULTS  ANDDISCUSSION  I :  POLY-u-BIS(DI-N-OCTYLPHOSPHINATO)IRON(II)  A .  SYNTHESES  As i s t h e case w i t h almost  a l l F e ( I I ) work, t h e p r e p a r a t i o n  of p o l y - u - b i s ( d i - n - o c t y l p h o s p h i n a t o ) i r o n ( I I ) standard taken  vacuum  to  line  remove  freeze-pump-thaw  and  gas  drybox  from  cycles.  techniques.  the  Upon  i n v o l v e d t h e use of Precautions  solvents  leaving  used  by  glassware  were  several  with  small  amounts of l e f t - o v e r product out i n the l a b o r a t o r y atmosphere, i t was  found  that  air-sensitive,  the  Fe(II)  complexes  made  were  showing no s i g n s of an obvious  immediate  with the atmosphere, but over prolonged p e r i o d s they  would  turn  dark  brown.  This  not  is likely  reaction  (several  due  to  highly  hours),  oxidation.  Thus, every p r e c a u t i o n was taken t o p r o t e c t the compounds from the atmosphere as much as p o s s i b l e . Initial reactions and,  was  characterization  of  a c h i e v e d through  the use of i n f r a r e d  sometimes, d i f f e r e n t i a l  detecting hydrolysis removal.  the  products  scanning c a l o r i m e t r y ,  or incomplete  solvent  of  synthetic  spectroscopy  as a means of  (water and/or a l c o h o l )  In both cases, an OH s t r e t c h i n g v i b r a t i o n would show up  i n t h e i n f r a r e d spectrum  at around  appeared,  were  the products  then  3500 cm . -1  dried  I f such a v i b r a t i o n  further  and  rechecked.  Once no evidence o f h y d r o l y s i s or excess s o l v e n t was p r e s e n t , the samples were submitted f o r m i c r o a n a l y s i s . to pick glovebox, by  up water or other OH as evidenced by IR.  heating  at  temperatures  The samples d i d appear  c o n t a i n i n g compounds T h i s contaminant over  12  100°  C  for  s l o w l y i n the  c o u l d be removed several  hours.  Differential detecting  scanning  excess  calorimetry  water  or  solvent  was  sometimes  present,  by  giving  event at or near the known b o i l i n g p o i n t of the The slow  general  procedure t o  addition  of  synthesize  the  metal  these  2  2  Care was  8  17  2  to  the  chain  acid  Fe[(C H  2  lengths  solution  ) PO ] 17  8  in  the  as  2  a d d i t i o n of the  slow  product  However, the procedure was  not  as  2  +  2KC1  2  F e C l -4H 0 t o  possible,  polymers  standardized  i s r e f l e c t e d i n the magnetic s u s c e p t i b i l i t y  seen  later. reaction conditions  profound  effect  on  the  final  different  forms  of  Fe [ (C H 8  II.  The  physical  described Fe  l-x  x  8  in  2  phenomenon.  2  The  were  2'  i n Chapter V.  I t was  ratio  of  ) PO ~  to  would  give  Form  I  (C H 8  a  stoichiometry,  17  2  the  2  also  addition  data,  as w i l l  stoichiometry  called  these  two  The  seen  be  had  giving Forms  a two  I  to  be  forms  will  doped  and  seen t h a t  subject  to  J  as  2  compound,  close  whereas  towards 13  keeping the  an  as  this are  stoichiometric  possible r  deviations  excess  be  samples,  syntheses of these compounds  F e C l -4H 0  particularly  maximized.  have r e s u l t e d .  product,  section.  2  that  2 2 '  d e t a i l s of the  given  and  ) PO ] , h e r e a f t e r 2  this  ) PO ] ,  17'  of  d i s t i n c t i o n s between  later  Zn [ (C H  17'  state  ensure  be  may  the  2  to a s p e c i f i c  This  seen t h a t  to  would  r a t e , so t h a t some v a r i a b i l i t y of c h a i n lengths  I t was  acid,  to  2  neutralized  the  0  —>  taken to make the  thermal  compounds was  chloride  MeOH/H  ) PO  a  in  solvent.  n e u t r a l i z e d w i t h potassium carbonate, a c c o r d i n g  F e C l -4H 0 + 2K(C H  useful  of  to  from  this  FeCl -4H 0 2  2:1  2  or  potassium  carbonate,  samples  were a l s o  changed  from a l i g h t  suggests forms,  that  seemed  g  2  characterizations  form  II  Upon  compounds.  grinding,  appears  change a l s o  two p o l y m o r p h i c  t o be Form  of the materials  made h a n d l i n g a n d p r e p a r a t i o n  somewhat  t h e samples  This  i n at least  The  I I , whereas  t o be Form I .  state  o f a problem,  i n that  f o r several  of a  quite  f o r the various made  Gouy  due t o t h e i m p o r t a n c e o f  technique.  days  was  and a c t u a l l y  measurements i m p o s s i b l e ,  sample p a c k i n g  temperatures  exists  2  appear  physical  gummy n a t u r e , w h i c h  efficient  i7  t h e ground  t h e u n t r e a t e d samples  balance magnetic  Form  t a n t o a d a r k brown c o l o u r .  Fe [ (C H ) P0 ]  basic  give  pressure sensitive.  and i n f a c t  The  to  d i d not  Drying  remove  at elevated  this  physical  characteristic. Four  different  samples  characterized  i n this  under  reaction  are  similar  work.  light  t o be Form  i7  2  were  2  Samples 1 a n d 2, w h i c h  conditions,  exhibit  I I compounds.  t a n ; 3 a n d 4 were a l i t t l e  INFRARED  Complete  similar  p r e p a r e d and were p r e p a r e d  p r o p e r t i e s and  listings  i>(P0 )  The  2  darker.  c a n be f o u n d i n A p p e n d i x I .  region  between  region  compounds.  In t h e past, t h i s  effects  o f 1 a n d 2 were  o f i n f r a r e d data, along with assignments o f  distinctive  nature  The c o l o u r s  3 and 4 a r e  SPECTRA  t h e bands observed,  the  g  c o n s i d e r e d t o be Form I compounds, w h e r e a s s a m p l e s  considered  B.  o f Fe [ (C H ) P 0 ]  c a . 1150-950  of the infrared  spectra  side  o f metal  14  network ' , 1  groups . 3  i s t h e most  1  has been t h e r e g i o n  o f t h e M-O-P-O-M b o n d i n g  o f t h e hydrocarbon  cm"  2  phosphinate  used  t o assess  as w e l l  as s t e r i c  Results  from  X-ray  crystallographic  s t u d i e s show t h a t t h e n a t u r e o f t h e  ligand  effect  has  an  chromophore.  on  the  geometry  of  phosphinate  the  metal-oxygen  F o r one t h i n g , t h e p r e s e n c e of s m a l l e r groups  t h e c e n t r a l m e t a l makes s i x c o o r d i n a t e s p e c i e s p o s s i b l e .  I t was  4  also  seen  that  larger  four-coordinate tetrahedral studies  asymmetric  species  or  have  alkyl  even  shown  v(P0 ) 2  from  square that  bands  side a  to  geometry.  separation of  appears  seem  tetrahedral  planar  the  groups  to  be  to  a  greater  force  flattened  Also, the  around  infrared  symmetric  i n the  and  case  of  u n s y m m e t r i c a l p h o s p h i n a t e b r i d g i n g groups, making IR s p e c t r o s c o p y a u s e f u l t o o l t o i n v e s t i g a t e the nature of phosphinate b r i d g i n g . A bands  comparison for  informative.  of  compound These  the 1  vibrational with  data,  those along  f r e q u e n c i e s of of  with  similar Lv  (v  2.1.  15  i>(P0 )  complexes -v  asy  compound, a r e p r e s e n t e d i n Table  the  ) sym  for  2  is each  Table 2.1.  F r e q u e n c i e s (cm ) o f v(P0 ) Regions i n V a r i o u s -1  2  Metal(phosphinate)  Compound  V  Polymers  V  asy  source sym  Mn(Me P0 ) -2H 0  1123  1031  92  4  Cu(Et P0 )  2  1110  1049  61  6  CU(BU P0 )  2  1116  1057  59  7  1113  1039  74  7  2  2  2  2  2  2  2  2  Cu(Hex P0 )  2  cu oct Po )  2  2  (  2  2  2  (a  form)  1107  1043  64  (0  form)  1112  1046  66  8  1132  1051  81  9  1130  1018  112  10  1125  1044  81  11  1142 1073  1018  N/A  11  Co(F P0 ) -2CH CN  1280  1155  125  13  Ni(Oct P0 )  1107  988  119  12  1140 1121 1107  1074 1051 1022  1108  1050  CU(* P0 ) 2  2  2  Mn(H«^P0 ) 2  2  Co Oct P0 ) (  2  2  (Form  I)  (Form  II)  2  2  2  2  3  2  Fe(Oct P0 ) 2  (sample 1) (ground)  2  2  2  2  16  N/A 58  8  this work t h i s work  The  infrared  sensitive  spectral  to  the  first  feature  number  of  i>(P0 )  region.  2  atom  Two  2  Ni[(CH 17  8  ]  2  2  is  and  not  be  with  that  ) PO 17  2  The  coordination  Lv  values  of  the  verified  Mn [ (CH ) P 0 ] -2H 0 3  spectroscopic The  Co ( I I )  5  ] 2  proposed  correct.  been  very  metal.  the  the  on  the  2  2  order  to  2  and  2  of  ] \ 2  (Form  2  be  100  cm" .  In  1  Lv  show  to  I ) , which  be  has  data;  octahedral, however,  compound  for  values  of  this  a  Lv  lower  of  81  2  complexes  obtained  pseudooctahedral,  '  is  are  a  the  on  this  light  usually pink.  the  basis  colour,  Crystal  diethyl ,  may  whereas  structures  6  diphenyl ,  of  classification  blue  5  have  the  is  crystallographically  H ) HPO 6  also  octahedral  Mn[(C  Co[(CH  UV/visible  is  proposed  2 8  1  around  influence  values  compounds  1 2  same o r d e r . cm" ,  to  region  2  '  two  ) PO  Lv  show  13  3  addition,  ligands  apparent  seems  i>(P0 )  the  geometry,  CN ,  2  that  the  compounds  pseudooctahedral  2  of  becomes  metal  C o ( F P O ) -2CH  show  geometry  that  the  data  7  di-n-butyl  and  7  d-n-hexylphosphinates four-coordinate planar CuO^  is  about  copper  chromophore,  nearly no  about  planar  of  definitive  complexes  above.  and  a  The  the  diethyl  f a r as  do  17  2  2  were  both  the  be  square  flattened tetrahedral  derivative  being  f o r these  that  pseudooctahedral I,  is  to  species  degree the  the  most show  of p l a n a r i t y  four-coordinate P0  2  complexes  s o - c a l l e d a and  stretching described /3 f o r m s  of  p r o p o s e d t o be four-coordinate; their f f Lv v a l u e s seem t o be c o n s i s t e n t w i t h t h i s a r g u m e n t . With the above c o r r e l a t i o n s i n hand, we see that the IR 8  ]  a  symmetric-asymmetric  indicated in Section  ) PO  show  compounds  derivative  p r e d i c t i n g the  however,  smaller  have  Lv v a l u e s  The  these  diphenyl  others  three. as  showing  the  s e p a r a t i o n than the  As  Cu[(CH  they  have  frequency  the  Cu(II),  copper.  with  trend  concerned;  of  2  17  spectral  data  for  Fe [ (C H  as  those  60  cm  of  other  for  -1  distinction 2.2  It  I and  is  the  in  be  a  be  effects  of the  simple  to  i s seen  shoulders  disappear amount  of  scheme,  or  no  2.1)  I  region  upon g r i n d i n g .  characteristics Lv  a  that  the  the be  made.  Table  region  2  the  sample  c o l l a p s e from 1  Compounds  I samples,  a  of  causes  2  and  compounds 3  and  2.1.  multi-band  behaviour, on  the  either  the  ground  the  in  grinding  the  two  region  (In f a c t ,  unground  samples  2  and  larger  v(P0 )  untreated  more  bands,  2  suggest the  i n the a  v(P0 )  presence  of a 4.).  compound  unground  sample  complicated  interchain association could  of  will and  4  and  4  is  themselves  i n the  spectrum.  of  4;  which small The  bonding  destroyed  conceivably  phosphinate l i g a n d s which c o u l d then  some  compound  ligand  different  18  3  compounds  chemically  IR  ca.  physical  v(P0 )  some i n t e r c h a i n a s s o c i a t i o n w h i c h  This  of  i s shown i n F i g u r e  grinding  to  value  samples.  displayed  implies  perhaps  that  T h i s may  present  on  pattern.  Form  on  here  pressure  2  effect  seen  is  with  This effect  Form I I  between  are  Form 2  (Figure  of  two-band  this  same  Form I I s a m p l e s c a n  2  upon g r i n d i n g .  complex v ( P 0 ) 1  It  and  as  the  species,  i>(P0 ) r e g i o n  referred to  seems t o h a v e a l m o s t  small  1  compounds  contrast  difference  show 2  samples.  r e f e r r e d t o as  In  ] 2  Form I I compounds.  to  hereafter will  the  spectrum  pattern  2  b e t w e e n Form I and  seen  IR  i  four-coordinate  ground  summarizes  Form  ) PO 1-  8  give  manifest  R g  u r e 2., Comparison of P O , « * * * - H » of  1  T a b l e 2.2.  P0  2  S t r e t c h i n g Frequencies  (cm ), Compounds  1-4:  -1  Fe[ ( C H J , P O ] *•  2  8 17' 2  2  J  Untreated Sample  V  V  asy  1  2  Ground V  sym  V  asy  1140  s  1074  s  1121  s sh  1051  s  1107  s  1022  s  1136  m sh  1070m sh  1101  s  1041  S  sym  1108  s  1050  s  1103  S  1043  S  1022m sh 3  1104  S  1041  S  1105  S  1041  S  4  1105  S  1011  S  1101  S  1037  s  1138  sh  1055  sh  1068  Sh  (s=strong  m=medium, sh=shoulder)  /  Comparison disagreement  of  these  results  between the two  i n the i>(P0 ) r e g i o n at 1139, 2  seen  with  studies. 1072  compounds forms.  This are  would not  make  really  I t s h o u l d a l s o be  purely noted  1020  that  Form  I,  8  C.  THERMAL  shows  1 4  t h r e e bands  These bands are  -1  but  along with  other  the  so-called  Form  but  a  of  that Gillman  f o r polymorphism i n h i s work on F e [ ( C H  Gillman  found  cm .  study,  i t appear  of  Gillman  and  i n the Form I compounds of t h i s  bands.  those  mixture  found  no  I two  evidence  ) PO ] . 1/2  2  2  STUDIES  Thermal s t u d i e s were a c h i e v e d through the use of d i f f e r e n t i a l scanning c a l o r i m e t r y (DSC).  As mentioned b e f o r e , the samples were  20  sometimes a n a l y z e d u s i n g DSC solvent  impurities.  however,  in  the  decomposition mentioned  the  sample that  solvent  manifested i t s e l f 100° C.  of  the  previously  OH-containing  at  M e l t i n g p o i n t s may  case  of  as a d i a g n o s t i c  the  slowly  also  compounds occurred  be  found  studied  here,  before  samples  when  technique t o d e t e c t  to  i n the  be  DSC;  thermal  melting.  seemed  left  by  It taking  glovebox.  sample  had  been  c o o l e d and  then  were not  very  on  This  q u i t e c l e a r l y i n the form of an endothermic  Once the  was  peak  reheated,  t h i s event d i d not occur. It  was  found  that  distinguishing  between  representative  heating  the  DSC  Forms curve  results I  and  of  a  II.  Form  Figure I  2.2  compound  from Form I t o Form II n a t u r e . not as e f f e c t i v e forms  of  8  ) PO ] . 17  2  2  a  4) .  temperature  indicate a transition  I t appears, t h e r e f o r e , t h a t DSC i s  as IR i n showing the d i f f e r e n c e between the  Fe[(CH  in  shows  (sample  Upon g r i n d i n g and h e a t i n g the sample through the same ramp as b e f o r e , no f e a t u r e s appear which may  useful  What  the  results  do  tell  us  is  two that  2  the Form I t o Form II t r a n s i t i o n i s not a thermal phenomenon (over the  range  tested),  but  rather  one  entirely  dependent  upon  pressure. The  DSC  results  Gillman  obtained  for  Fe[ (C H 8  s i m i l a r t o those seen i n t h i s for he  h i s endothermic termed  i t , but  study.  The  assignment  peak observed at 104° C may rather  the  loss  of water  ) PO ] 17  2  are 2  G i l l m a n gave  not be m e l t i n g , as  from  h i s sample,  i n d i c a t e d e a r l i e r f o r the samples s t u d i e d i n t h i s work.  21  2  as  Heat Flow (Exothermal)  —>  Heat Flow (Exothermal)  —>  D.  MOSSBAUER SPECTROSCOPY  The the  Mossbauer  effect  provides a  chemical environment  classes  of  compounds.  about A  the  brief  powerful  iron  tool  nucleus  overview  of t h i s  for  examining  i n many  different  t e c h n i q u e may  be  useful. The y  experiment  fluorescence;  sample  thus  receives  excitation.  is an  the  The  based  on  absorption  will  resonance  probability  energy  use  be  observed  without  the Debye-Waller  i f the  experiencing  phonon  |f  =  R  i s the  characterize  recoil lattice  centre-of-mass approaches Also, is  dx  e i s the  vibrations,  -  e  J  Debye  and  values  carried  of  unity  zero out  f o r low  (2.2)  1  x  temperature,  is  coordinate of the nucleus.  % approaches  best  , X  energy,  the  I t can  temperature  f o r high temperatures,  at  77  r e l a t e d to the y t r a n s i t i o n  K  7  factor  e o  Here  1  (2.1)  temperature  4  occurring i s  2w(T)  0/T W(T)  resonance only  of such a t r a n s i t i o n  £=e" where we  recoilless  or  energy  lower.  The  used  to  time-dependent be  shown t h a t  (T«e) so  the  recoil  and  £  Rs2ke.  experiment energy  is  and t h e mass by t h e e x p r e s s i o n  •p  2  R =  (2.3) 2mc  t h u s we and  the  c a n s e e f r o m e q u a t i o n s 2.1, atomic  number  of  the  Mossbauer s p e c t r o s c o p y s p e c i f i c The  source  spectroscopy  is  of 57  Co,  nucleus  and 2.3 must  to a select  y-radiation which  2.2  follows 23  used the  be few for  decay  that  E must be  high.  This  low  makes  elements. iron scheme  Mossbauer shown  in  F i g u r e 2.3. "Mossbauer  Here y  i s the t r a n s i t i o n  Ml  transition."  The  of i n t e r e s t ,  natural  abundance  t h e 14.4 keV of  57  Fe  is  a p p r o x i m a t e l y 2%, t h e r e f o r e c o l l e c t i o n t i m e f o r a t y p i c a l -spectrum i s on t h e o r d e r o f hours o r days.  F i g u r e 2.3. Decay Scheme f o r C o (Ref. 18) 5 7  5 7  Co  270d  / E C  /  / 9 9 . B 4 *  /  13  6.4  14.4  M 1  Energy, keV The forth, If  experiment  consists  the stationary  sample,  t h e s o u r c e and sample  absorption w i l l  o f t h e Co s o u r c e , moving back and 57  and a d e t e c t o r b e h i n d t h e sample.  have t h e same resonance  be seen a t AE=0.  r e l a t e d t o energy by t h e D o p p l e r AE E  Energies  i n this  The v e l o c i t y  energy,  E , an  of the source i s  effect:  + v c  (2.4)  technique are therefore  commonly  expressed i n  terms o f v e l o c i t i e s . The Mossbauer splitting,  two  most  important  parameters  s p e c t r o s c o p y a r e t h e isomer s h i f t , AE .  The isomer s h i f t  24  to  be  extracted  by  6, and t h e q u a d r u p o l e  i s t h e d i f f e r e n c e between t h e  sample and s o u r c e resonance e n e r g i e s d e n s i t i e s at those respective nuclear  and i s r e l a t e d t o e l e c t r o n sites by  1 9  «=|«Ze r <5r/r) [|0 (0) | -| ^ (0) | ] 2  2  ft  S  2  (2.5)  2  a  where Z i s t h e a t o m i c number, e i s t h e charge o f an e l e c t r o n , r i s the  mean n u c l e a r  radius,  6r=r - r (the d i f f e r e n c e between e g  excited  2  and  ground  state  the  s-electron  respectively. is  readily  nuclear  radii),  and \\f> (0) | and a  The d i f f e r e n c e i n 5 between i r o n (II)  seen;  the extra density  d-electron  i nd  6  so t h e isomer s h i f t  of  0.2-0.6  57  mm s~ a r e t y p i c a l  complexes  increase ( I t Isomer  f o r i r o n ( I I I ) compounds,  l  shifts whereas  compounds have isomer s h i f t s i n t h e range 0 . 7 - 1 . 5 mm s . - 1  i n t e r a c t i o n o f a nucleus having  an e l e c t r i c  nuclear  and i r o n ( I I I )  will  i m p o r t a n t here t o note t h a t 5 r / r < 0 f o r F e ) .  with  b  i r o n (II)  is  The  \\p (0) | a r e  d e n s i t i e s a t t h e n u c l e i o f t h e s o u r c e and sample  screens s - e l e c t r o n  i r o n (II)  2  spin  field  gradient  I> /2 into  (efg) w i l l  distinct  1  e  2  q  Q  41(21-1)  f 3I L  - I  2  2  z  split  sublevels.  quadrupole c o u p l i n g Hamiltonian i s given b y H =  a q u a d r u p o l e moment Q a level The  having nuclear  1 9  + f * 1 (I + I ) 1 I 2 > " J 2  2  Here e q i s V , t h e z-component o f t h e e f g t e n s o r ,  (2.6)  and TJ i s t h e  zz  asymmetry parameter, d e f i n e d as  T)  = | (V -V ) | /V 1  The  e f g tensor  xx  yy  i s written  25  zz  (2.7)  efg  V V v  V  xx  V  yx  V  zx  v  xy  V  yy  V  zy  xz  )  (2.8)  yz zz'  where V i s the e l e c t r i c a l p o t e n t i a l and  a v 2  .=  V.  (2.9) siaj  1 3  The  efg  tensor  is  symmetric  traceless,  so  that  d i a g o n a l i z e d by the c o r r e c t c h o i c e of a x i s system. s p l i t t i n g f o r 1=3/2  efg  may  following  arise  four  non-bonding  Q  = VqQ^l  from  one  sources : 20  electrons  about  bonds between the c e n t r a l (iii)  i n the  lattice.  give r i s e  t o an e l e c t r i c  case  of  unless  one  an asymmetric  (2.10)  a  combination  (i)  an  asymmetric  central  can  environment  low-spin octahedral shell,  The quadrupole  1 / 2  or  It  will  2g  be  would ligand  of  any  of  the  distribution  atom;  of  ( i i ) electrons  in  (i.e. delocalization);  (iv) charges on s u r r o u n d i n g ions and  symmetric  t  2  atom and l i g a n d s  nonspherically  filled  + ^ ]  the  charges on the l i g a n d s ;  molecules  may  i s then  AE  The  it  be  seen  about  therefore,  the c e n t r a l  f i e l d gradient. Fe(II)  complexes  expect  no  environment  26  electric exists  iron  Therefore, with  that  a  atom  i n the  a completely  field  gradient,  about the  central  Fe  atom.  only  on  Therefore, the  quadrupole  will of  the  electric  l i g a n d environment splitting  the  be  more complex, b u t  the  case  of  magnitude  high-spin  and  gradient  in this  seen s h o u l d  In  field  be  case,  Fe(II),  AE  of  can  q  factors  of  the  which  iron(II) causes  of  thus,  one  experimentally  Mossbauer  spectral  undertaken  at  study,  the  iron  be  field  insight  into  nature 2 2  Fe [ (C H  Mossbauer ) PO  17  2  ] 2  spectra  the  many  about  postulating  this  only.  more AE  of  techniques, field  The  thesis  A  were  rigorous  and  q  can  an the  splittings.  dependence  electric  are  gradient in  in  temperatures  There  using  give  gradient  more  seen  in  of  2),  (compound  the  taken  ground at  line  shapes  half  maximum f o r b o t h  2.4b.  The  are  resulting  shift  Lorentzian  summarized  i n Table r  lines,  values,  assumed t h a t samples.  K,  unground  are  and  there  the  forms  of  shown  in  too  order  of  T , are  AE  from  low 0.3  is a negligible the  The  fits full  to  Lorentzian  line  included  as  i r o n (II)  be  assigned  complexes.  to This  widths well.  least-squares  to mm  be  s  values  here.  - 1  amount  consistent  of  are  It  at The  with  to S=2  course  i r o n ( I I I ) present  in  (AE*0.4  mm  too  small  Q  tetrahedral s u g g e27 sts  fits  i s of  Q  to  Figures  2  are  Moreover,  from  2.3.  calculated  lineshapes, 5 i s on  iron(II):  77  parameters  1  isomer  and  2  and  -1  on  2 4  2.4a  s )  Analysis  complexes " .  The  the  field  described  the  .  quadupole  perturbation of  atom  cautious  observed  temperature  magnetic the  the  situation  much i n f o r m a t i o n  electric  must  nitrogen  applied  8  the  studies  liquid  examining  Fe(II)  about  i n f l u e n c e the  nucleus;  the  is available.  give  of  21  ligands  may  dependent  simple.  •  geometry  be  analysis  however,  much i n f o r m a t i o n  sign  and  relatively  S=2  will  the  or  octahedral  presence  of  high a  spin  different  Figure 2.4. at  Mossbauer Spectra of (a) Untreated and (b) Ground forms of compound 2  77 K.  Doppler Velocity (mm  s ) 1  Doppler Velocity (mm  s- ) 1  Fe(II)  spin  ligand  field  to t h i s  state,  S=l, caused by a h i g h l y  geometry.  spin  state  Two  tetragonally  electronic configurations  are shown i n F i g u r e  2.5.  precedent; i t has been w e l l documented t h a t  This  seen  . •  .  f o r several  porphyrin  giving  rise  i s not without  square p l a n a r  25 26  is  distorted  iron(II)  27 28  ' , phthalocyanine  '  as w e l l  as  29 30  dumine  '  complexes  t h i s conclusion magnetic  The  tools  used  t o a r r i v e at  of S=l i r o n ( I I ) i n the aforementioned s t u d i e s  moment  Intermediate  of i r o n ( I I ) .  measurements  spin  states  p o r p h y r i n a t o i r o n (III)  and  have  also  complexes ' , 31  32  Mossbauer  spectroscopy.  been  observed  giving  rise  for to  a  an  system. Table  2.3  Mossbauer Parameters  s  Untreated Ground  AE  (mm s ) f o r x  r  Q  i  Compound 2  r  2  0.30  0.42  0.52  0.47  0.31  0.40  0.53  0.47  29  were  few S= /2 3  Figure  2.5.  E l e c t r o n i c C o n f i g u r a t i o n s as a F u n c t i o n for F e ( I I ) Complexes  xy  JL JL JL  d 2 2  xz  x -y  yz  1  x -y  d 2  z  z  t  d  t  xz  d  v  z  li_L  v z  Li  d 2  z  a. T  (S=2) a  Symmetry  xy  xy  d 2 2  d 2  of  b.  (S=l) 2d  C. D  (S=l) 4n  30  Comparison 2  with  6 values  the show  25-30  o f t h e isomer s h i f t s o f t h e two forms o f compound  that  17  2  2  f o r the  t h e S=l s t a t e  F e [ ( C H ) PO ] . 8  observed  of iron  Furthermore,  of references  i s quite  t h e magnetic  possible i n susceptibility  2  r  results  of t h e various  analyzed  s a t i s f a c t o r i l y by assuming  models.  compounds  This  samples  proposed high  of this  complex  J  may o n l y be  an S=l s t a t e , and not by S = 2  degree  o f p l a n a r i t y can perhaps be  accounted f o r a f t e r c o n s i d e r i n g the s t e r i c e f f e c t s the bulky side  groups  will  have  on t h e complex.  e x p l a n a t i o n f o r t h i s r a r e geometry  i s the cooperative  t h e polymer c h a i n , which c o u l d c o n c e i v a b l y i n t o a h i g h l y compressed It  Another  alkyl  possible  strength of  " p u l l " t h e FeO^  moiety  conformation.  i s i n t e r e s t i n g t o note t h a t g r i n d i n g t h e undoped sample o f  di-n-octylphosphinatoiron(II) Mossbauer  spectrum  (5=0.31  has a mm  s" , 1  negligible AE  Q  =0.40  effect  mm  on  s ) .  the  Thus,  -1  d i s t i n c t i o n s between Forms I and I I can not be made by Mossbauer spectroscopy, affect there  the structural  t h e isomer s h i f t  and  differences efg values.  The comment.  too subtle t o  It will  i s i n f a c t evidence o f a s t r u c t u r a l  one, m a n i f e s t e d  being  change,  be shown albeit  markedly i n t h e magnetic s u s c e p t i b i l i t y A E , of this  quadrupole s p l i t t i n g , Quadrupole  q  splittings  sample  that  a small  data.  i s worthy o f  may be e s t i m a t e d  easily  c a l c u l a t i n g the c o n t r i b u t i o n of the metal o r b i t a l s t o V  from  by 20  zz  = e q = - e < 3 cos e - l><r" >(l-R) 2  V  3  (2.11)  zz  where r and e a r e t h e p o l a r c o o r d i n a t e s the  o f t h e o r b i t a l s and R i s  S t e r n h e i m e r f a c t o r , which a c c o u n t s f o r s h i e l d i n g e f f e c t s due  31  to  the p o l a r i z a t i o n of the inner  b r a c k e t s denote t h e e x p e c t a t i o n following  contributions  d 2 2=d = <r" >, 1  electrons.  a r e then  calculated  d 2=- <r" >.  and  3  factor  1  extent  o f t h e 4p  substantially electron  z  i s implicit  (although  orbitals  (d ,d ) xz  q=--<r~ >.  Similarly  3  The  3  7  i n t h e s e r e s u l t s and t h e g r e a t e r  n o t always  configuration  The  f o rthe d-orbitals:  x z y z 7  Sternheimer  The a n g u l a r  value of the given function.  d =d =--<r~ >,  3  x - y x y 7  radial  shell  reduces  their  completely). (d 2 )  4  yz  contribution Thus,  (d J ,  1  we  1  z  xy  (d 2 )  f o r the configuration  f o r the  7  obtain (d ,d )  2  z  xz  3  yz  (d ) , we c a l c u l a t e q=-i^<r" >.  I n t h e s e two c a s e s t h e quadupole  splitting  large  x  3  i s expected  t o be  and n e g a t i v e . T h i s  c a l c u l a t i o n does n o t t a k e i n t o account c o n t r i b u t i o n s cr-donor and/or n - a c c e p t o r p r o p e r t i e s  the  useful  t o compare  complexes,  this  namely  porphyrinatoiron(II) to  have  system  with  substantial  other  known  It is  S=l i r o n ( I I ) and  several  These compounds have been shown  20  positive  a r i s i n g from  of the ligands.  phthalocyanatoiron(II) complexes .  simple  quadrupole  splittings,  with the  p h t h a l o c y a n i n e complex b e i n g t h e l a r g e s t , a t 2.7 mm s" .  We see  1  that  V  has been g r e a t l y  by 0— d o n a t i o n  affected  i n t o t h e empty  zz  metal  d2 2  orbital,  giving  a  positive  contribution.  This  x -y  suggests  that  t h e same  but t o a l e s s e r e x t e n t .  effect  i s happening  i n Fe [ (C H ) P 0 ] , fi  i7  2  2  2  A n o t h e r p o s s i b i l i t y e x i s t s w h i c h w i l l add  a positive contribution to V  i f t h e h y b r i d bonding o r b i t a l s are  zz  considered.  The c o n t r i b u t i o n s t o t h e e l e c t r i c f i e l d g r a d i e n t 20  p  o r b i t a l s a r e as f o l l o w s  2  :  dsp  2  hybrid  4  3  p =p =-<r~ > and p =—<r" >. x  for  3  bonding o r b i t a l s ,  y  5  cr-donation  z  from Thus,  5  i n t o t h e 4p x  and 4p y  o r b i t a l s , w i t h 4p v a c a n t , would a l s o make a p o s i t i v e c o n t r i b u t i o n z  to  the e l e c t r i c  field  gradient.  32  The s i g n  o f AE  i s n o t known  here, but  temperature dependent Mossbauer s t u d i e s would be  in  determination.  this  quadrupole c o u p l i n g by  At  of t h i s  any  rate,  compound has  it  appears  useful  that  the  been made more p o s i t i v e  s u b s t a n t i a l <r-donation from the phosphinate l i g a n d s .  E.  ELECTRONIC  We  SPECTROSCOPY  have now  structure  of  seen, based on Mossbauer data t h a t the e l e c t r o n i c  Fe[ (C H 8  is  exhibited.  triplet  are  must be mean  in  i r o n (II)  that  28  the  S=l  the  best  complex,  with  spin  it  To  will  state  have  triplet  shows  is  required  the  interesting  observe a t r i p l e t  is  that  ground d 2 2  the  x  orbital  is  orbitals, magnetic  sufficiently such  that  i t will  properties  significantly  of  affected  triplet  ground  state.  This  state,  can  far  peak  at  not  S=l by  as  be  i r o n (II)  would be  make the  from  coupling,  the  case  the  -y  lower  populated.  The  will  also  be  arising  from  the  for a quintet  ground  magnetic p r o p e r t i e s  of  straightforward. of  1300  (see  (7700  energy  complexes  a n a l y s i s of the  e l e c t r o n i c spectrum nm  in  appreciably  spin-orbit  i r o n (II) complexes l e s s than The  separated  a  ground  known example  which  properties.  complexes,  compound  complexes  Perhaps  phthalocyanine 33  an  ^  Iron(II)  unknown.  such t h a t  2  will  m a g n e t i c a n d Mossbauer state  2  state.  not  i r o n (II)  2  This  ground  states  ) PO ] 17  cm" ) 1  Fe [ (C H ) P0 ] g  i7  Figure  2  2  2.6).  displays In  a  broad  comparison,  14  r e s u l t s o b t a i n e d by Gillman showed a s i n g l e a b s o r p t i o n at 8400 cm" . T h i s r e s u l t l e d Gillman t o conclude t h a t Fe[ (C H ) PO ] 1  8  had this  an  octahedral  thesis  Mossbauer  coordination  seem t o  and  scheme.  oppose t h i s  electronic  The  assignment,  spectral 33  results  17  2  r e s u l t s presented on and  the the  basis  of  22  in the  temperature  Figure 2.6. Electronic spectrum in the near-infrared region of compound 1.  WAVELENGTH (NM)  dependent Assignment  magnetic of t h i s  possibilities ground  state  Figure  2.5.  susceptibility  studies  (vide  spectrum i s d i f f i c u l t because o f the  available triplet  d  6  f o r the  electronic  system.  Two  35  infra). different  configuration  possibilities  of  a  are shown i n  F.  MAGNETIC  The  SUSCEPTIBILITY  MEASUREMENTS  s t u d y of t h e magnetic p r o p e r t i e s o f i n o r g a n i c  compounds  has been o f much importance over t h e y e a r s and c o n t i n u e s t o be a dynamic  field  of research.  A s i d e from r o u t i n e  magnetic  moment measurements,  to  4 K can i l l u s t r a t e  below  these m a t e r i a l s . paramagnetism property  The  and  variable  temperature  two b a s i c t y p e s o f magnetic b e h a v i o u r are  o f diamagnetism,  A l l materials  which g i v e s  rise  This i s the r e s u l t  e l e c t r o n p a i r s w i t h t h e magnetic f i e l d .  to a  measuring  possess  small negative  diamagnetism  magnetic  of  the  loops  susceptibilities  sample  is  of  T h i s i n t e r a c t i o n can be 3 4 3  ,  which, as a  o f Lenz's law, w i l l be r e p e l l e d from t h e f i e l d . the  the  of the i n t e r a c t i o n  thought o f i n terms of a system o f c u r r e n t consequence  measurements  some v e r y i n t e r e s t i n g p r o p e r t i e s i n  diamagnetism.  molar s u s c e p t i b i l i t y .  room-temperature  of  corrected  When  materials,  for  using  the  Pascal's  34a  constants  .  Each  atom has  i t s own  diamagnetism  and,  based  on  the  a d d i t i v i t y of atomic s u s c e p t i b i l i t i e s , t h e n e t diamagnetism o f  the  molecule i s accounted f o r . Paramagnetism,  of  on t h e o t h e r hand, i s not g e n e r a l l y a p r o p e r t y  a l l materials.  interaction  of  Instead,  an  applied  s p i n - a n g u l a r momenta. to  diamagnetic  Susceptibility magnetic  may  it  is  magnetic  consequence  field  with  of  the  orbital-  and  Paramagnetic s u s c e p t i b i l i t i e s a r e , compared  susceptibilities, be  the  calculated  susceptibility  36  using  large Van  and  positive.  Vleck's  equation of  I [w' ' /  y  kT - 2W< j exp |-W° / kTJ  1  N  =  2)  i  x  Here  i s magnetic  A  (2.12)  |-W° / k T J  Z exp  A  susceptibility  p e r gram  atom,  N  i s the  number o f atoms b e i n g c o n s i d e r e d , W° i s t h e energy o f l e v e l the  absence  the  first  o f magnetic  and  second  field  i s applied  magnetic  susceptibility  polymeric  equation 2.12.  The  terms  order Zeeman e f f e c t  magnetic  while  field.  W  systems  be  are then  (2)  when  the  Exact e x p r e s s i o n s f o r  calculated  require  W  coefficients  on the sample.  may  and  (1)  i in  for  simplifying  finite  systems,  approximations  The e f f e c t i v e magnetic moment i s o f t e n  to  considered  i n magnetic measurements; i t i s r e l a t e d t o the s u s c e p t i b i l i t y by  u  - 2.828 (> T ) eff  Paramagnetic phenomena, may  V  behaviour,  in  A  the  '  absence  be d e s c r i b e d by the C u r i e  X  (2.13)  1 / 2  of  any  cooperative  Law:  = C/T  s  (2.14)  A  where C  i s a constant.  magnetic behaviour may If  we  combine  paramagnetism More schematic  Good d e s c r i p t i o n s  of how  non-Curie  a r i s e are g i v e n i n r e f e r e n c e s 30a and  equations  2.13  and  2.14,  we  see  that  Curie  law 30b. law  g i v e s a temperature independent magnetic moment.  exotic diagrams  Antiferromagnetism  behaviours of  such  (Figure  are  sometimes  systems 2.7a)  37  are  arises  displayed.  shown when  in the  Simple  Figure alignment  2.7. of  adjacent  spin vectors  i n the l a t t i c e  i s antiparallel;  this  will  g i v e r i s e , upon complete o r d e r i n g , t o a magnetic moment o f z e r o . The  w i l l d i s p l a y a maximum i n i t s x  magnetic s u s c e p t i b i l i t y  vs. T  M  curve. to  The t e m p e r a t u r e a t which t h i s maximum o c c u r s  as t h e N e e l  when  adjacent  parallel  point.  Ferromagnetism  centres  have  manner;  magnetic moment.  this  will  The x  their give  i s referred  ( F i g u r e 2.7b) i s o b s e r v e d  spin rise  v s . T behaviour  vectors  aligned  in a  t o an anomalously  large  will  a l s o be d i s t i n c t i v e .  M  As  temperature decreases,  Curie  or Curie-Weiss  temperature, with  law  a t which  decreasing  until  temperature.  will  typically  will  grow much f a s t e r  Ferrimagnetism  (Figure  o f t h e above two b e h a v i o u r s .  of the antiferromagnetic  obey  a t e m p e r a t u r e , termed t h e C u r i e  the s u s c e p t i b i l i t y  somewhat o f a c o m b i n a t i o n result  the s u s c e p t i b i l i t y  coupling  s u b l a t t i c e s o f unequal s p i n magnitudes.  2.7c) i s I t i s the  o f two i n t e r p e n e t r a t i n g Examples o f f e r r i m a g n e t i c  i n t e r a c t i o n s a r e seen i n systems i n v o l v i n g two m e t a l s o f d i f f e r i n g spins,  ordered  identical These  spins  systems  antiferromagnetically but  oriented  a r e t h e so  /K  a.  >ts  also  differently  called  systems, as opposed t o " m a g n e t i c a l l y F i g u r e 2.7.  and  along  "magnetically  sf.  c.  b.  X  X  >L  ferrimagnetism 38  a  11  >K  Systems >N  of  chain ' . 3 5  3 6  concentrated"  dilute."  M a g n e t i c a l l y Concentrated  antiferromagnetism  i n systems  yK  ferromagnetism  TEMPERATURE (K) Figure 2.8. Magnetic susceptibility vs. temperature plot of compound 1. untreated. Solid line is generated by the Fisher S - l model. J—2.54 K, g-3.21, P=0.0.  TEMPERATURE (K) Figure 2.9. Magnetic susceptibility vs. temperature plot of compound 2. untreated. Solid line is generated by the Fisher S=l model. J=-3.00 K. g=3.29, P=0.5.  Systems  like  dimensional  the  ones  compounds  above  and  are  of  clusters,  special where  interest  ordering  in is  low more  pronounced due t o the p r o x i m i t y of the metal c e n t r e s . complete x  The  vs. T data f o r the m a t e r i a l s s t u d i e d here  are  M  reported  in  Appendix  theoretical  curves  polymorphism  us  first  where  described  i n the x  manifested  II.  examine  The  data  applicable, earlier  in  vs. T curves  the  are  untreated  plotted,  i n Figures  along  with  2.8-2.18.  The  Fe [ (C H ) P0 ] g  i7  2  f o r the d i f f e r e n t 1  samples  2  and  is  2  clearly  samples.  and  Let  attempt  to  model them with t h e o r e t i c a l e x p r e s s i o n s . x  The  vs.  T  behaviour  of  unground  samples  of  M  Fe [ (C H ) P0 ] , g  i7  2  2  a n t i f e r r o m a g n e t i c behaviour temperatures systems  by  results  for  later. The  at S=2 the  1  compounds  (see F i g u r e s 2.8  approximately models  proved  fitting  2,  and  6  K.  and  Attempts  fruitless,  parameter  show  F,  2.9), to  giving  which  will  typical with  model  Neel these  unsatisfactory be  explained  On the other hand, S=l models y i e l d e d b e t t e r r e s u l t s . model f o r an  S=l  m a g n e t i c a l l y coupled  Heisenberg  linear  37  c h a i n system, from work by F i s h e r , i s based  on the  spin-exchange  Hamiltonian H = -2J X S -S L. 1 j and the s u s c e p t i b i l i t y has the f o l l o w i n g form:  Ng u S(S+1) ' 2  x =  (2.15)  2  B  1 + u  (2.16)  1 - u  3kT  where u=cosh[2JS(S+l)/kT] - kT/2JS(S+l).  40  Here J i s the  exchange  integral  and  will  be  positive  f o r ferromagnetic A  negative  f o r antiferromagnetic  coupling.  coupling  and  A  S, and S_. are the s p i n  v e c t o r s o f atoms i and j , N i s Avogadro's number, g i s the Lande splitting  factor, u  i s the Bohr magneton, S i s the i n t e g r a l  value and k i s Boltzmann's A numerical Weng  constant.  approximation o f these  i n h i s extension  38  spin  o f the work  r e s u l t s was worked out by  by  Fisher  and Bonner and  3 9  40  Fisher  , y i e l d i n g t h e f o l l o w i n g r e s u l t s f o r an S=l system: 2  Ng u X =  2  f  kT  0.6667 + 2.5823 x' 1 + 3.6035 x + 39.558 x  (2.17) -  where x = |J|/kT. The  expression  for  a  two-dimensional .  .  a n t i f erromagnet spin-exchange  comes  from  work  A =  y  J  1  ,  based  on  the  A  s -s  L  i  (2.18) j  i s written »j N  2  G  where e = k T / J S ( S + l ) . n=6  provided  coefficients  "  2 U  B  xJ~  to  Lines  layer  Hamiltonian H  and  by  4  quadratic  3e  =  A  + y  C —  —  e""  (2.19)  1  I t was found t h a t t a k i n g the c o e f f i c i e n t s  suitable  f o r S=l a r e :  convergence C = 4, C = 1  2  of  the  1.834, C =  solution. 0.445, C =  3  The 0.224,  4  C = 0.132 and C = 0.019. 5  6  A  least-squares  fitting  above models and m i n i m i z i n g  procedure was c a r r i e d  out u s i n g the  the f i t t i n g parameter F, d e f i n e d by  41  I  F = n  where  n  i s the  number  i calc  1/2  i ^"obs  (2.20)  obs  of  data  y  points,  i s the calc  susceptibility  calculated  from  the  model  magnetic  x  and  is  the  obs  experimentally  observed  augmented t o i n c l u d e  susceptibility.  a paramagnetic  A l l models  component,  used  assumed t o  were follow  C u r i e law, which goes as  >  = NgVs(S+l)  (2.21)  3kT  This  paramagnetic  polymeric observed  component  component using  obs  Comparison  coupled  to  the w e i g h t i n g parameter  the  regular  P to give  the  Fisher  parameters  = P*+  (l-P)z  P  .  (2.22)  poly  of the t h r e e models f o r the case o f the u n t r e a t e d  form of compound 2,  are  then  susceptibility:  X.  the  was  as seen i n F i g u r e s 2.9,  2.10  S=l model t o be the most s u i t a b l e  and 2.11,  in this  case.  shows The  from each of these models f o r the case of compound 2  g i v e n i n Table 2.4.  42  Figure 2.10. Magnetic susceptibility vs. temperature plot of compound 2. untreated. Solid line is generated by the Weng S=l model. J=-2.65 K, g=3.26. P=2.2.  Figure 2.11. Magnetic susceptibility v s . temperature plot of compound 2, untreated. Solid line is generated by the Lines S=l model. 1—1.89 K . g=3.31. P=9.5.  <  O  oH  0.0  1  1  r  40.0  TEMPERATURE (K)  80.0 0.0  40.0 TEMPERATURE (K)  Table 2.4.  Comparison  of the Fisher,  Lines,  and Weng S=l Models  f o r Compound 2  The  Model  J (K)  g  P  F  Fisher  -3.00  3.29  0.4  0.003  Weng  -2.65  3.26  2.2  0.015  Lines  -1.89  3.31  9.4  0.017  Lines  and Weng  models  do not reproduce  the s u s c e p t i b i l i t y  maximum at t h e Neel p o i n t as w e l l as t h e F i s h e r model.  I t i s seen  a l s o t h a t t h e f i t t i n g parameter F i s lowest f o r t h e F i s h e r indicative  of a  better  parameters  obtained  fit.  Perhaps  for Fe[(CH  factor the  g, which  case  complexes the  of filled  long  crystal  orbital 3  e  ago by by  field  angular  level,  and s p i n - o r b i t  g  o f 2.2.  momentum  of  values This  This  from  i n Figure  2.5c.  I t was  an  coupling.  42  that orbital  g  values  impossible suggest  that  with  o f a room  our equipment,  t h e moment w i l l  contribution  contribution  but t h e low  44  by  which i s the  Due t o t h e  c o u l d not be  moment measurements.  temperature  not exceed  a  can be  Another o b s e r v a t i o n  enough f o r Gouy tube magnetic  made t h e obtainment  3 in  f o r Fe(II)  o f t h e magnetic moment at h i g h temperatures.  finely  than  g v a l u e may be  troublesome p h y s i c a l nature o f t h e compound, samples ground  3  arises  may i n d i c a t e t h e presence o f a l a r g e o r b i t a l magnitude  splitting  which  and Bowers  the introduction  o f the  c  normal  as i s seen  Bleaney  i s t h e Lande  values of greater  samples;  a r e i n the neighbourhood  partially  increased  I  remarkable  2 2 2  has extremely l a r g e  o f t h e Form  result  shown  ) PO ] 17  8  c  most  model,  magnetic temperature  moment data  a v a l u e o f 4.4 B.M. f o r  Fe[ (C H  ) PO ] .  8  2  17  value  of  This  value  i s much  h i g h e r than  the  spin-only  2 2  2.83  B.M.  f o r S=l  s p i n - o n l y v a l u e of 4.90  B.M.  the magnetic moment r e f l e c t s  (and  substantially  f o r S=2  lower  complexes).  than  the  I t appears t h a t  a very l a r g e o r b i t a l  contribution in  t h i s case. Another  noteworthy  feature  of  the  magnetic  susceptibility  results  f o r these compounds i s the d i f f e r e n c e between the Forms I  and  of  II  Fe[(CH 8  exchange  ) PO ] . 17  integral  2  2  Table  2.4  shows  the  values  J i n Kelvin,  the Lande  splitting  F, o b t a i n e d by f i t s t o the F i s h e r l i n e a r c h a i n S=l 2.5.  1,  3,  and  model.  (K)  F  P  g  Model  1  -2.54  3.21  0.0  0.015  ground  -2 . 92  2.79  4.7  0.032  2  -3.00  3.29  0.4  0.003  3  -2.86  2.89  2.4  0.017  ground  -3.40  3.00  1.9  0.021  4  -2.82  2. 92  1.1  0.030  The Figure  J  g  parameter  Magnetic Parameters f o r Compounds 1-4, F i s h e r  Compound  the  factor  p e r c e n t paramagnetic component P, along w i t h the f i t t i n g  Table  of  2  difference  2.12.  susceptibility grinding magnetic  Form  between  the  I compounds  two (1  forms  and  2)  than the Form II analogues.  compound  1  susceptibility  (see  Figures  2.15  is  have  clearly a higher  It i s also and  seen  2.16)  in  overall  seen  that  causes  its  vs. temperature behaviour t o become much  140-1  O  S  Figure 2.12. Magneric Susceptibility vs. Temperature of compounds 1-4, untreated. 120-  U o 1—1  100  d .a  80  U  H O  Legend  60 H A  P  A  CO  U  40  H  +  O  z o  <  20 10  20  30  40  50  TEMPERATURE (K)  60  70  I  80  O  SAMPLE 1  •  SAMPLE 2  A  SAMPLE 3  +  SAMPLE 4  c s  Figure 2.13 Comparison of magnetic susceptibility vs. temperature of untreated and ground sample 1. 140-,  u  120-  *  o  \  %  100-  CO  80  8  60  CO CO  40  U  Legend e SiM^U 1  20  < 2  _,  ,  10  20  ,  30  ,  40  T E M P E R A T U R E  1  SO  ,—  60  (K)  o  0.0  40.0 TEMPERATURE  80.0 (K)  47  —r70  —i  80  the  same a s t h e Form I I compounds.  Form be  I  compounds  the  result  have  of  higher  a  g  I t i s seen  values  diminishment  of  contributions t o the g value.  This  Figures  see t h a t  2.5b  and  iron-oxygen  2.5c.  We  chromophore  tetrahedral  geometry,  eliminating the  the o r b i t a l  degenerate  quite high, of  these  thus  results will  than  Grinding effect fact  to  that  their  depicted  go  From  sample  II  3,  a Form  the. g  as w i l l  to  of  this  reduction  paramagnetic consequence breaking  component of  i t  "paramagnetic  tail"  manifestiation antiferromagnetic  has  of  the  finite at  appear  This  decreases should  Therefore, have  extended  polymer The  temperatures  i f no  slight  the a  chain  appearance  in  rise  In a d d i t i o n  seems  paramagnetic  i nthe  I t i s seen, i n  i s the  component  lower  I compounds  soon.  this  48  momentum  little  this  increased;  I  accordingly.  have  although  Form  i s seen  contributions,  The  a mixture  that  should  2.17 a n d 2 . 1 8 ) .  paramagnetic compound.  thus  are s t i l l  angular  I samples  value  sections.  low  more  cross,  I I compounds.  be d e m o n s t r a t e d  orbital  grinding  into  Form  slightly,  may be i n s i g n i f i c a n t ,  a  i s really  orbital  I I compound,  rises  of the  towards  the g values  counterparts.  (see F i g u r e s  the g value  by comparing  2.5; upon g r i n d i n g , t h e Form  and  momentum  t h e geometry  I t would  g r o u n d Form  i n Table  angular  may  c o n t r i b u t i o n s by l e a v i n g  Since  higher than  untreated  on t h e g v a l u e  that  have  t o the g values  w o u l d be e x p e c t e d values  momentum  scenarios. to  This  x -y  half-filled.  seem  that the  II.  and d 2 2 l e v e l s  yz  angular  two d i f f e r e n t  contributions  g  as  i t would appear t h a t t h e case here  compounds  it  level  orbital  distorted  (d , d ) xz  Form  c a n be e n v i s i o n e d  becomes  the  than  i n general  most a  observed logical and of  thus the  visible polymeric  component  is  TEMPERATURE  flO  TEMPERATURE (K)  Figure 2.17.  Comparison of the magnetic susceptibility vs. temperature behaviours of  untreated and ground compound 3.  j O  s  120  H  CI  u  6 C  d  CD  ioo H  •o  80  U  g  60  U  40  i  C < ^  Legend • SAM»L( J . G»0U*D  20  -1  10  —i—  —I—  20  30  40  —I—  50  —i—  60  —l—  70  i  60  TEMPERATURE (K)  Figure 2.18. Magnetic susceptibility vs.temperatureof compound 3, ground, Solid line is generated from the Fisher S - l model, J—3.40. g-3.00. P=1.98.  0.0  80.0  40.0 TEMPERATURE  (K)  50  a c t u a l l y seen t o decrease m a r g i n a l l y f o r 3 upon g r i n d i n g . not e x p e c t e d , a  larger  This i s  but t h e v a l u e o f F i n d i c a t e s t h a t t h i s f i t may  amount of u n c e r t a i n t y a s s o c i a t e d w i t h  i t than  have  for  the  u n t r e a t e d sample. Note t h a t t h e x  vs. T c u r v e s f o r unground samples of 1 and 2 M  are almost  identical  discussion  of  theoretical  the  ( F i g u r e s 2.8 precision  fits.  of  Figures  t h e o r e t i c a l f i t s t o the x  and  2.9).  the  output  2.19  and  This necessitates a parameters  2.20  show  of  the  Fisher  S=l  v s . T d a t a of t h e unground sample of  2.  M  In F i g u r e  2.19,  3.36,  3.29  2.20,  g i s f i x e d at 3.29  and  -2.85,  error  bars  and  J i s fixed 3.22,  at  and 5%  constituting  +2%  are  and  representing a  representing a  susceptibility  -3.00  drawn i n  2%  g  i s given  variation.  J i s given the values variation in  the  (see Chapter  in this value  In  Figure  -3.15,  the see  v a r i a t i o n s i n g and J are w i t h i n e x p e r i m e n t a l e r r o r . say t h a t J i s a c c u r a t e t o +5%  values  If  magnetic that  these  Thus, we  and g i s a c c u r a t e t o +2% as  51  -3.00  parameter.  of  V) , we  the  can  quoted.  MAGNETIC SUSCEPTIBILITY ( l O C M M O L ) 3  CD  0-0  3  1  120.0  60.0  a  cr *-~>  5 :-»» 3  — TJ o <»" c  3 jo n —  II  1-2 Ni  be  2 <w  ^  —i  3  O  I c/>  3  — c  o r> T1TJ  to  ^ =f II  2;  cn > H  C  o o  m "-jr*  <  o IS  S- n 3  MAGNETIC SUSCEPTIBILITY ( l O C M M O L ) 3  II  II  a  3  a  c  2  a o  o  s i c o §  cn  3  c 3 -  O  c  cr  CX  m  3  aw  >  2.  H  II  C  cn  0.0  60.0  3  120.0  1  CHAPTER  1.  Du, J . - L . ; 67,  2.  Oliver,  Haynes,  J.S.;Oliver,  63,  3.  Gillman,  4.  Cicha,  Thompson,  K.W.;  R.C. Can. J. Chem. 1989,  W.V.;  Haynes,  B i n o , A.; S i s s m a n ,  6.  Oliver,  J. Chem.1982,  Chem. 1976, 15, 840 .  60,  R e t t i g , S.J.;  1987, 128,  Chim. Acta  1055. L21.  R.C; Trotter,  J . Can.  2017. K.W.;  Rettig,  J . Can. J. Chem. 1984, 62, K.W.,  K.W.;  J . Can. J. Chem. 1985, 63,  S . J . ; Thompson,  J.S.; O l i v e r ,  Oliver,  J . L . Inorg.  L . Inorg.  K.W.; R e t t i g ,  Trotter,  R.C. Can. J. Chem.  J.S.; O l i v e r ,  R.C; Trotter,  5.  Haynes,  Thompson,  1111.  H.D.; E i c h e l b e r g e r ,  Thompson,  8.  K.W.;  REFERENCES  1239.  1985,  7.  I I  Ph.D. T h e s i s ,  S . J . ; Thompson,  R.C;  891.  University  of British  Columbia,  1984 . 9.  10.  Du, J . - L . ;  Oliver,  1988,  19.  Du,  141, J.-L.,  K.W.;  M.Sc. T h e s i s ,  Thompson,  R.C  University  Inorg.  Chim.  Acta  of British  Columbia,  of British  Columbia,  of British  Columbia,  R . C ; Logan,  N.; Nunn,  1987. 11.  Banks,  P.R., B . S c . T h e s i s ,  University  1986. 12.  Peers,  J.R.D., B.Sc. T h e s i s ,  University  1987. 13.  Begley,  M.J.; Dove,  M.F.A.; H i b b e r t ,  M.; Sowerby, D.B. J. Chem. Soc. Dalton 14.  Gillman,  H.D. Inorg.  Chem. 1972, 22,  53  Trans. 3124.  1985, 2433.  15.  16.  Mackey,  D . J . ; McMeeking,  R.F. H i t c h m a n ,  M.A. J. Chem. Soc.  1979, 300.  Dalton  Trans.  Burns,  R.G.; C l a r k ,  M.G.; S t o n e ,  Chem. 1966, 5,  A . J . Inorg.  1268. 17.  Gol'danskii, in  18.  Chemistry,  Muir, Data  19.  V . I . The Mossbauer C o n s u l t a n t s Bureau,  A.H., j r . ; Ando, Index  Haynes,  Effect  and Its  New Y o r k , 1964.  K . J . ; Coogan,  1958-1965, I n t e r s c i e n c e ,  J . S . , Ph.D. T h e s i s ,  Applications  H.M. Mossjbauer  Effect  New. Y o r k , 1966.  University  of British  Columbia,  1985. 20.  Sams, J.R. MTP Int. Rev. 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Proc. 451.  55  124.  1970, 31,  640.  101.  Roy. Soc. London 1952, A214,  I I I .  RESULTS  AND  DISCUSSION  I I :  ZINC  DOPED  POLY-u-BIS(DI-N-OCTYLPHOSPHINATO)IRON(II)  We  now t u r n t o a d i s c u s s i o n o f t h e p r e p a r a t i o n s ,  magnetic doped  and i n f r a r e d  analogues  and Mossbauer  of the type  ^  c  J  the  values  but  not analyzed  Fe  0.05, 0.1 and 0.2  x  8  17 2  2  i n detail) .  It will  but a l s o d i s p l a y evidence  x  takes  2'  (a sample was p r e p a r e d  w i t h x=0.9,  be seen t h a t n o t o n l y do  t h e s e samples f o l l o w t h e same p o l y m o r p h i c analogues,  properties of the  Zn [ (C H ) PO ] , where  l-x  C  spectral  thermal,  behaviour  as t h e undoped  o f h a v i n g two d i f f e r e n t  spin  s t a t e s p r e s e n t a t t h e same t i m e . A .  SYNTHESES  As  discussed  stoichiometries  of  i n Section  I I , the reaction  the preparations  of these  c o n d i t i o n s and species  s i g n i f i c a n t e f f e c t on t h e p r o p e r t i e s o f t h e sample.  have  a  Thus, f o r t h e  same r e a s o n s , Form I and Form I I doped samples have been o b t a i n e d . The were  classifications prepared  a r e as f o l l o w s :  according  to  samples w i t h x=0.2 and 0.05  procedures  which  yield  Form  I  m a t e r i a l s ; t h e sample w i t h x=0.1 was p r e p a r e d a c c o r d i n g t o Form I I synthetic techniques. and  yield  analysis  o f t h e presence  o f t h e x=0.2 sample of the thermal  ground form o f t h i s was  case t h e i s o l a t i o n  o f pure Form I  I I m a t e r i a l s was n o t as good as w i t h t h e undoped samples, b u t  nonetheless evidence The  In t h i s  enough  sample  o f t h e two forms i s observed.  was t o o low t o do  p r o p e r t i e s o f t h e sample,  an  in-depth  and o n l y t h e  compound was a n a l y z e d by IR.  However, t h e r e  f o r a n a l y s i s o f t h e magnetic  and Mossbauer  56  spectral  B.  p r o p e r t i e s of the  INFRARED  SPECTRA  Infrared in  Table  Appendix  spectral  3.1. I.  compound.  data  Complete  I f we  f o r the assignment  compare t h e s e  f o r the  data,  i>(P0 )  region  effect  d i s p l a y e d upon t h e e x e r t i o n  2  complex m u l t i b a n d  Table.  3.1.  zinc-doped  polymorphic  of  bands  we  see  Forms  I  Regions  Stretching  r  the  and  II,  c  Zn  1-X  [ (C H  X  5  V  X  the  same  sample:  the  band r e g i o n .  -1  of  ) PO 1 J  V  asy  1110  s  1137 m sh  0.1  7  0.05  (sh=shoulder; These  results  1098  1040  s  sym  1045  s  1060  sh  1110  s  1046  s  1135 m sh  1070 m s h  1138  sh  1071  sh  1103  s  1021  s  1102  s  1019  sh  1119  sh  1050  s  1136  sh  1042  s  1138  s  1072  S  1070  sh  s=strong; show  s  2  8 17' 2 2 2  V  sym  0.2  6  i>(P0 )  Ground V  asy  in  distinctive  (cm )  Untreated Sample  shown  found  with  the  t o a two  are  be  same  Frequencies  o f Doped Samples Fe  3  can  o f p r e s s u r e on  i>(PO ) r e g i o n s i m p l i f i e s  Infrared  samples  the  m=medium) same  type  57  of  behaviour  as  the  undoped  samples, w i t h g r i n d i n g h a v i n g t h e e x p e c t e d e f f e c t .  We a l s o see,  as i n compound 4, t h a t 6 l i k e l y c o n t a i n s some Form I c o n t a m i n a t i o n which i s removed upon g r i n d i n g .  I t seems t h a t g r i n d i n g 7 gave an  incomplete  II i n this  c o n v e r s i o n t o Form  case,  with  just  a  r e d u c t i o n i n t h e i n t e n s i t y o f t h e s i d e bands as a r e s u l t .  C.  THERMAL  STUDIES  DSC s t u d i e s f o r t h e s e compounds  showed t h e appearance  o f an  endothermic event a t 65° C (see F i g u r e 3.1), w h i c h seems t o be a r e s u l t of z i n c doping.  As w i t h t h e pure samples, no e v i d e n c e o f  m e l t i n g b e f o r e t h e r m a l d e c o m p o s i t i o n i s seen. sample  with  disappears displays  x=0.1,  after  a small,  endothermic  event  show  an endothermic  one r u n .  The second  b r o a d endothermic i s seen  difference  a t 100°C,  which  r u n on t h e same sample  event  a t 65° C. sample,  T h i s same and becomes  There appears t o be no s i g n i f i c a n t  i n t h e t h e r m a l p r o p e r t i e s o f 6 and 7, p r o p o s e d t o be  Forms I and I I r e s p e c t i v e l y , pronounced  event  i n 7, t h e x=0.05  l a r g e r upon s u c c e s s i v e r u n s .  The d a t a f o r 6, t h e  i n t h e case  except t h a t t h e 65° C event i s more  o f 7.  This could  be a  distinguishing  f e a t u r e o f t h e Form I doped samples and may t h e n r e f l e c t some Form I  impurity  results  i n 6.  As b e f o r e w i t h  t h e undoped samples,  seem t o i n d i c a t e t h a t t h e Form I  » Form I I t r a n s i t i o n  i s one t h a t i s i n d u c e d by p r e s s u r e o n l y , and n o t h e a t .  58  t h e DSC  Heat Flow (Exothermal)  —>  Heat Flow (Exothermal)  —>  D.  MOSSBAUER  SPECTROSCOPY  The Mossbauer ascribed  spectra  t o S=l F e ( I I )  as  o f the doped seen  contain  a doublet  doublet  has parameters t y p i c a l  large  quadrupole  1.1 mm  s" . 1  parameters  samples  i n the pure  i n the h i g h e r v e l o c i t y  splitting  o f S=2  samples,  region.  i r o n (II)  and an isomer  show the doublet  shift  but  This  second  complexes,  with a  i n the region of  The a c t u a l s p e c t r a are shown i n F i g u r e s 3.2-3.4. f o r samples  5-7  are  shown  also  i n Table  3.2.  The  Another  parameter, t h e r e l a t i v e area of the S=2 d o u b l e t t o t h e S=l doublet y, i s i n c l u d e d here.  Table 3.2.  Mossbauer  Sample  6  5  6  7  It fit  S p e c t r a l Parameters f o r Zinc-doped Compounds  (mm s  AEQ  S  (mm s "*")  0.28  0.31  1.12  3.17  0.31  0.45  1.10  3.18  0.36  0.45  y 0.14  0.16  N/A  s h o u l d be noted here t h a t the spectrum f o r 7 was d i f f i c u l t t o t o L o r e n t z i a n s f o r two d o u b l e t s , owing t o t h e s m a l l  of t h e S=2 d o u b l e t .  magnitude  However, an examination o f t h e spectrum shows  c l e a r evidence o f t h i s d o u b l e t . The compounds  presence raises  o f the two  spin  some i n t e r e s t i n g  these s p e c t r a and from arguments  states points.  o f i r o n (II)  i n these  I t i s apparent  from  a l r e a d y made about t h e i n f l u e n c e  60  Figure 3.2. Mossbauer spectrum of compound 5 (x=0.2) at 77 K.  Figure 3.3. Mossbauer spectrum of compound 6 (x=0.1) at 77 K .  •$  T  1  — i  - 3 - 2 - 1  1  0  r  1  2  - 3 - 2 - 1  Doppler Velocity (mm s- ) 1  0  1  2  Doppler Velocity (mm s* ) 1  Figure 3.4. Mossbauer spectrum of compound 7 (x=0.05) at  Doppler Velocity (mm s- ) 1  62  of  geometry  of  doping  on t h e s p i n zinc  atoms  state  into  the polymeric  change i n t h e geometry about that  since  this  i s indeed  fact  puckered  the  iron  zinc  adjacent  centres  Mossbauer  chain.  rather  5)  The  be t h a t  the  of the zinc  about  are  zinc  greatly  because  each  into  zinc  atom  by  iron  x=0.2  an  o f t h e x=0.1  would  a  more  consequences  seen  i n the  s h o u l d be i n the  t h e x=0.2  sample  level  level,  but  (compound  6) .  becomes h i g h e r ,  adjacent  t o each  affected  seem s m a l l e r t h a n  other  by  the  expected.  a l l o w u s t o make  dimensionality. as  If  proposed,  a  i s unfeasible.  I f we c o n s i d e r  we  the effect  can imagine  A two-dimensional than  a  "influence"  63  that  centres  sample  four-coordinate  doping  a way  doping  centres  structural  systems,  have i n  adopted  doublet  f o r t h e compounds a l s o  systems.  affected  have  have  p o l y m e r i c system  such  atoms  i n such  seem t h a t  iron  a  environment  of the doublets  centres being  indeed  and one-dimensional  zinc  i t would  centres w i l l  their  velocity areas  of  causes  t o a g r e a t e r number o f S=2  as t h e d o p i n g  number  Mossbauer r e s u l t s  compounds  doping more  that  o f two z i n c  three-dimensional two-  atoms  of tetrahedral  really  like  also  thus  arguments these  not  more  likelihood  increases,  The r e l a t i v e  does  ligand  F i g u r e 2.5 shows t h e  the high  i s t h e case,  i t may  proximity  thus  t o t h e amount  a level  However, the  and  If this  (compound  to the zinc  T h i s would g i v e r i s e  spectra.  proportional  these  the effect  I t c a n be s u r m i s e d  M-0-P-O-M b a c k b o n e  environment.  such a change.  iron  and t h a t  that  backbone  the iron nucleus.  here  the inorganic  ligand  iron  found i n a t e t r a h e d r a l  t h e case  atoms  tetrahedral of  i s often  o f F e ( I I ) complexes  system  w o u l d be  one-dimensional a s many  as  of  system,  four  iron  atoms  around  influenced  i t ,  per  whereas zinc  atom  This  i n turn  seen  i n the Mossbauer  Instead,  would  we  spectral  As  i n the  t h e doped  doublet  is  splitting than  case  i 7  warrant  complex.  2  that  seen  If  again  d 2 2 level  will  reduce  iron for  to  of  system. to  y  seen  the  use  be  x=0.1).  be  modelling  the  of  a  i n the of  a  magnetic  at  splittings  The s p l i t t i n g  o f t h e S=l  undoped  of a normal  as  samples.  i s much l a r g e r  Figure  i n energy  quadrupole  i n the  however,  i n the case  look  ,  2  comment.  be e x p e c t e d we  in  would be  compounds.  Fe [ (C H ) P0 ] g  S=2  unity  supports  model  f o r these  approximately  of  chain  low values  also  o f t h e S=2 d o u b l e t ,  would  the  atoms  polymeric  amount  polymeric  chain  of  compounds  higher  the  This  results  two i r o n  (y s h o u l d a p p r o a c h  due t o  linear  just  one-dimensional  much  propose  parameters.  susceptibility  of  a  a  spectra  nature,  one-dimensional  in  cause  can  one-dimensional  a maximum o f  2.6  The  i n magnitude  four-coordinate  and consider  the metal-oxygen  that  S=2 the  chromophore  x -y  becomes  more  thermally  tetrahedral,  accessible.  this We  upper  will  state  then  have  will a  then  (d 2 )  2  become (d xz  z  (d  )  (d 2 2)  1  xy  Equation  configuration,  1  x -y  2.11).  tetrahedral  If  the  conformation,  giving  geometry  the  d 2 2 x -  the value  values the  of  of q will  the  S=l  quadrupole  which  accounts  a n d S=2  splittings  f o r the large  doublets  of  the  proposed  to  be  doped  b e ~~<r  species of  the  >•  quadrupole  64  levels  yz  towards  will  The d i f f e r e n c e  two s p i n  although  7  2  (see  3  further  corresponds  compounds.  positive,  moves  q=-^<r~ >  )  a  cross,  -3  4  s t i l l  and  and d xy  y  •  but  S=2  , d  to  a  states  splitting  difference of  before,  2-3  seen  The q u a d r u p o l e as  i n the q  this  in  mm s " , 1  i n the  S=2  splitting  is  can  only  be  v e r i f i e d through temperature dependent  E .  MAGNETIC  SUSCEPTIBILITY  Again, the  two  as  i s the  different  f o r pure  of  will  discussing  be  argued  be  analyzed using  the  two d i f f e r e n t two .  an  of  compounds  Fe [ (C H ) P0 ] , g  showed  manner  However, the x  the models d e s c r i b e d  to  that  spins,  such  as  mixed  2  vs. T data  previously,  metal  systems,  in  could  owing  to  Systems  have  been  1 2  i n cases of c l a s s i c a l l y a l t e r n a t i n g random  existing systems  2  used  s p i n s t a t e s p r e s e n t i n these compounds.  different  2  differing  s t u d i e d ' , but the models used i n these cases are only  a  i7  The d i f f e r e n c e between the two  analogous  the undoped samples.  not  of  in  samples  these  magnetic s u s c e p t i b i l i t y behaviour. forms  studies.  MEASUREMENTS  case  forms  Mossbauer  system models  will  of  two  different  f o r mixed  t h e r e f o r e be  spins.  metal  In t h i s case, we  spins,  systems  discussed  only  applicable  thus  rendering  inappropriate. qualitatively,  have the These  but some  noteworthy c o n c l u s i o n s a r i s e from these d i s c u s s i o n s . We  first  discuss  compound 5,  where x=0.2.  This  proposed t o be  a Form I m a t e r i a l ,  but the o v e r a l l  is  f o r the u n t r e a t e d  forms  h i g h e r than  Figures  2.9  inclusion  of  susceptibility effect  and  2.10).  S=2  components  to  increase.  This  is  i n the  certainly  sample,  When the  susceptibility  of samples  most  causing  sample  i s seen, as d i s p l a y e d i n F i g u r e 3.5.  compound i s  1  and  2 (cf.  due  to  the  overall  i s ground,  the  little  There appears t o be  some s l i g h t l o w e r i n g of the o v e r a l l magnetic s u s c e p t i b i l i t y of the sample, which i s p r o b a b l y due t o the d i s t o r t i o n symmetry, as seen i n the pure samples.  65  from almost p l a n a r  The paramagnetic component  3 O  COMPARISON OF GROUND/UNGROUND 5 x=0.2  u  •  o  ri CO  w u m  D t/3  K»0 e •  e  SO •  u  E Z  o<  10  —I—  20  i 30  i  I  I  *0  SO  40  o  I  70  »0  T E M P E R A T U R E (K)  Figure 3.5. Magnetic susceptibility vs. temperature plots of untreated and ground samples of compound 5 (x=0.2).  £  ©  COMPARISON OF GROUND/UNGROUND 6  x=0.1  200  ri *° CQ  e  KM  Xfi D to U  9 <  2  to t•  «1 0  1 tt  1  SO  r M  . 40  . SO  . SO  . ?0  TEMPERATURE (K)  Figure 3.6. Magnetic susceptibility vs temperature plots of untreated and ground samples of compound 6 (x=0.1). 66  of  the  the  sample  also  seems q u i t e  magnetic behaviour  component cause  i s expected  more  appear,  we  turn  sample,  properties  the  as  difficult here,  more  driving  Next this  and  same s o r t o f b e h a v i o u r untreated  feature, It  is  however,  expected  appreciable expect  The  form  only  paramagnetic  of  on  of  alterations in  high  x=0.1. this  of  f o r the  3.6), 4  atoms  IR  II  for  display  the  compound  and  especially  form  the  II  geometry  effect  to  Form  compared  An  unusual  2.12).  x  the  of  here  compound the  to  data  as  a  grinding.  will  species.  be  the  show  when  compound i s i t s b e h a v i o u r upon a  to  results  unground  (Figure  will  up.  section, Form  x=0.2  iron  The  of mostly  T data  paramagnetic  level  contiguous  in  compound  visible  component  This  doping  with  (Figure  grinding  effect  the  vs.  of t h i s  that  6,  a mixture  the  the  the  earlier  Form  to  I compound.  spot.  subtle  magnetic s u s c e p t i b i l i t y  discussed  som  making  chains  compound  a t t r i b u t e d to  to  since  finite  overall  to  high,  cause  no  Thus,  we  introduction  result  of  the  of  breaking  M  of 3.6  quasi-infinite shows t h a t  sample  is  inclusion the  chains  the  much  into smaller,  increase  higher  i n the  than  finite  overall  expected.  components.  Figure  suceptibility This  o f a l a r g e amount o f p a r a m a g n e t i c  may  of  this  be  the  well  component, b u t  a p p l i c a t i o n o f a s u i t a b l e q u a n t i t a t i v e model, t h i s  without  can  only  be  conjectured. Finally, compound,  we  as  look  seen  in  at  the  Figure  unground 3.7,  form  shows  of  7  (x=0.05).  very  smooth  x  This vs.  T  M  behaviour,  with  susceptibility paramagnetic  at  a  well-defined around  component  as  8  K  maximum  and  evidenced  67  in  in  only  a  the  low  the  small  magnetic amount  temperature  of  tail.  Figure 3.7. (x=0.05),  Magnetic susceptibility vs. temperature untreated.  200  O u «? o  d  CD  150  A  100  S 50 U  H  E O <  10  -1—  20  -1—  —I—  40  30  TEMPERATURE (K)  68  —I—  50  T h i s compound i s proposed t o be Form I , b u t has a h i g h e r  overall  magnetic s u s c e p t i b i l i t y t h a n t h e pure Form I compounds, 1 and 2. T h i s i s most l i k e l y due t o t h e i n c l u s i o n  o f S=2 c h a r a c t e r i n t h i s  case,  susceptibility  which  probably  have  integral. higher  will  increase  some  the overall  influence  on t h e magnitude  Presumably, s i n c e t h e maximum i n ^  temperature  here,  the  stronger.  69  and  will  o f t h e exchange vs. T occurs  antiferromagnetic  exchange  at a is  CHAPTER  1.  Drillon,  M.; Coronado,  Phys. 1983, 79, 2.  Coronado, Beltran,  I I I  REFERENCES  E.; B e l t r a n ,  D.; Georges,  R. Chemp.  449.  E.; D r i l l o n ,  M.;  Nugteren  P.R.;  de Jongh, L . J . ;  D.; Georges, R. J. Am. Chem. Soc. 1989, 111, 3874.  70  IV.  The  CONCLUSIONS  compounds  interesting  and  AND  SUGGESTIONS  prepared  unusual  in  this  results.  FOR  FURTHER  study  yielded  Firstly,  it  p o l y - / x - b i s (di-n-octylphosphinato) i r o n (II) p o l y m o r p h i c forms. planar high  i r o n (II)  WORK  some  appears  occurs  complex. the  The  geometry o f t h i s  uppermost  energy  complex and d 2 2,  level,  ground  spectrum  characteristic quadrupole due  to  are  of  i s most the  strongly  compound,  iron  dictates  giving  different  possible  Analysis  w i t h the  S=l  assignment;  magnetic  the  high  moments o f t h e samples are t o o low t o be  a l o w - s p i n S=0  complex.  Heisenberg  a p p r o x i m a t e l y J=-3  compounds, t h r o u g h  exchange  coupled,  with  model,  excess  of  the  properties temperature  an  t h e use  shows  exchange  isolated  FeCl  them  from  reactions  having  i s conducive  71  to  the  of  a  to  be  integral  of  K and an e x t r e m e l y h i g h Lande s p l i t t i n g  d i f f e r e n t from t h o s e p r o d u c i n g Form I m a t e r i a l s . an  to  susceptibility  g b e i n g on t h e o r d e r o f 3 f o r t h e Form I complexes. are  the  characteristic  A n a l y s i s o f t h e magnetic  d a t a of t h e s e  antiferromagnetically  complexes  of  i r o n ( I I ) complex, and t o o h i g h t o be d i s p l a y e d by  temperature,  one-dimensional  shifts  straightforward,  contributions  The  i n the  isomer  of t h e s e compounds i s not  of  iron(II).  i n evidence  ( I I ) compounds.  f i e l d g r a d i e n t of t h e complex.  of a r e g u l a r S=2  vs.  S=l  wealth  consistent  magnetic  of  splittings  the  electric  state  the  *-y  t h a t t h i s compound w i l l have t h e r a r e S=l s p i n s t a t e o f  Mossbauer  two  I t i s proposed t h a t Form I i s a q u a s i - s q u a r e  s e p a r a t i o n of  triplet  that  in  x  This  very  factor,  The Form I I  a stoichiometry I t appears  formation  of  Form  that II  materials.  In a d d i t i o n t o t h i s ,  be more s t a b l e apparent  I  samples.  t o pressure  t h e Form I I m a t e r i a l s  than  >II t r a n s i t i o n  t h e Form  occurring  I compounds,  upon  The Form I I compounds, w h i l e  appear t o  grinding  with  an  t h e Form  I  h a v i n g exchange i n t e g r a l s  similar  i n magnitude t o t h e Form I compounds, have s u b s t a n t i a l l y  smaller  g  values,  indicating possibly  smaller  orbital  angular  momentum c o n t r i b u t i o n s i n t h e case o f t h e Form I I compounds.  The  d i f f e r e n c e i n s t r u c t u r e and o r b i t a l a n g u l a r momentum c o n t r i b u t i o n s is  not m a n i f e s t e d  that  Form  i n t h e Mossbauer s p e c t r a l r e s u l t s , i n d i c a t i n g  I I compounds  are a l s o  ground  state  triplets.  The  magnetic s u s c e p t i b l i t y vs. t e m p e r a t u r e r e s u l t s show t h a t w h i l e t h e exchange compounds, the  case  reduction  i n t e g r a l i s roughly  t h e same  t h e Lande s p l i t t i n g of  Form  i n Form  I  and Form I I  f a c t o r i s s u b s t a n t i a l l y lower i n  I I compounds.  This  i s indicative  of the  o f o r b i t a l a n g u l a r momentum c o n t r i b u t i o n s , a l t h o u g h t h e  mechanism f o r t h i s e f f e c t i s not c l e a r . Doping s t u d i e s i n which s m a l l amounts o f z i n c ( I I ) were added to  p o l y - j i - b i s ( d i - n - o c t y l p h o s p h i n a t o ) i r o n (II)  c h a r a c t e r i s t i c features isolation  o f pure  difficult. presence  Form  Mossbauer of  two  also  showed  o f Form I and Form I I compounds, I I samples studies  different  from  on t h e s e  spin  states  the reactions compounds of  the  although was  more  i n d i c a t e d the  iron (II),  with  a  h i g h - v e l o c i t y d o u b l e t a p p e a r i n g , i n d i c a t i n g t h e o c c u r r e n c e o f S=2 i r o n ( I I ) a l o n g w i t h t h e S=l s p e c i e s . z i n c atoms a r e i n c o r p o r a t e d  T h i s s u g g e s t s t h a t when t h e  i n t o t h e r e g u l a r Fe-O-P-O-Fe backbone,  t h e i r o n atoms a d j a c e n t t o t h e z i n c atoms a r e i n f l u e n c e d towards a more t e t r a h e d r a l environment, perhaps due i n p a r t t o t h e f a c t t h a t  72  four-coordinate  zinc  i s normally  tetrahedral.  p r o p e r t i e s d i s p l a y e d a complicated mixture  The  magnetic  of the t r a i t s  seen i n  t h e undoped compounds, a l o n g w i t h t h e appearance o f o t h e r  effects  due t o some o f t h e i r o n atoms h a v i n g a p e n t e t ground s t a t e . The  randomly  diluted  magnetic  systems  described  in  this  t h e s i s c o u l d n o t be m o d e l l e d u s i n g t h e c o n v e n t i o n a l e q u a t i o n s . would appear here t h a t a s i t e  dilution  approach i s n e c e s s a r y i n  a n a l y z i n g t h e magnetic p r o p e r t i e s o f such systems. formidable  computational  challenge,  It  but  would  T h i s may be a be  useful  in  u n d e r s t a n d i n g t h e magnetic p r o p e r t i e s o f t h i s t y p e o f compound. Synthetically, line.  many  other  possibilities  exist  along  this  Other o r g a n i c s i d e groups may be used on t h e p h o s p h i n a t e  ligand.  S t u d i e s i n v o l v i n g v a r y i n g t h e s e groups and examining t h e  e f f e c t s on t h e magnetic 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  species  c o u l d be e n l i g h t e n i n g . In  addition,  determine nature  f u r t h e r Mossbauer  the sign of A E , q  o f t h e <r- and  studies  are necessary  to  i n o r d e r t o g e t a good e s t i m a t e o f t h e  re-bonding  o f t h e compounds s t u d i e d .  This  would r e q u i r e temperature  dependent s t u d i e s down t o l i q u i d  helium  temperatures.  s t u d i e s i n t h e low t e m p e r a t u r e  region  would  also  Mossbauer provide  direct  evidence  of  the  onset  of  a n t i f e r r o m a g n e t i c o r d e r i n g i n t h e s e compounds, by showing magnetic h y p e r f i n e c o u p l i n g beginning at the Neel  73  temperature.  V.  A .  MATERIALS  All  AND  PREPARATIVE  materials  without  further  EXPERIMENTAL  TECHNIQUES  used were o f r e a g e n t grade q u a l i t y  purification.  For  and  syntheses d i r e c t e d  used  towards  F e ( I I ) complexes, s t a n d a r d vacuum l i n e and drybox t e c h n i q u e s were employed. three  or  Solvents more  thereafter.  used i n t h e s e p r e p a r a t i o n s  freeze-pump-thaw  Air-sensitive  cycles  and  compounds were  were degassed used  stored  by  immediately  in a  nitrogen  atmosphere drybox and p r e p a r e d f o r c h a r a c t e r i z a t i o n t h e r e .  B.  ELEMENTAL  ANALYSES  A n a l y s i s f o r carbon and hydrogen was p e r f o r m e d by Mr. Borda,  Microanalysis  Lab,  C h e m i s t r y Department,  Peter  University  of  B r i t i s h Columbia.  C.  INFRARED  SPECTROSCOPY  I n f r a r e d s p e c t r a were o b t a i n e d u s i n g a P e r k i n - E l m e r Model 598 spectrophotometer.  The  between two KRS-5 p l a t e s  D.  ELECTRONIC  E.  i n Nujol  and  smeared  (Harshaw C h e m i c a l C o . ) .  SPECTROSCOPY  Electronic Nujol.  samples were m u l l e d  spectroscopy  was  p e r f o r m e d on  samples m u l l e d i n  A Cary 14 S p e c t r o m e t e r was used.  MAGNETIC  SUSCEPTIBILITY  MEASUREMENTS  M a g n e t i c s u s c e p t i b i l i t y d a t a were o b t a i n e d u s i n g a P r i n c e t o n  74  A p p l i e d Research Model over  t h e temperature  through  range  2-80 K.  t h e use o f l i q u i d  achieved using temperature Model  155 V i b r a t i n g Sample Magnetometer o p e r a t i n g  152  helium.  Temperature  a J a n i s Research Company Model  was  controlled  Cryogenic  temperature  The sample  sensor.  Temperature  susceptibility  a  Controller  estimated studied.  ,  versus  be  Electromagnet  capsules,  diode versus  behaviour  tetrachlorocuprate(II)  calibrations,  accurate  to  the  ±1% over  of  and checked  with  From t h e s c a t t e r  seen  1  temperature  data  t h e temperature  are range  The p o t e n t i a l across the thermocouple was measured on a  was a t t a i n e d  weighed  GaAs  h o l d e r immediately  temperature  F l u k e 8200 A D i g i t a l V o l t m e t e r . G  The  The thermocouple was c a l i b r a t e d u s i n g t h e known  separate to  a  was  Research  was a chromel  mercury (II) t e t r a t h i o c y a n a t o c o b a l t a t e (II) . several  Applied  l o c a t e d i n t h e sample  tetramethylenediammonium  in  equilibrium  with  used  cooled  153 C r y o s t a t .  Princeton  The thermocouple  Au-0.02% Fe thermocouple above t h e sample.  using  area was  An a p p l i e d magnetic f i e l d o f 7501  through the use o f a Walker-Magnion with  a  Model  samples  of  were  attached  HS  1050 Power  approximately t o a Kel-F  Supply.  lOOmg, holder  Model  L75BF  Accurately  contained  in  w i t h an epoxy  Kel-F resin.  C o r r e c t i o n s were made f o r t h e diamagnetic background o f t h e sample holder.  The  accuracy  o f magnetic  susceptibility  measurements  u s i n g t h i s t e c h n i q u e i s e s t i m a t e d t o be ±2%. Corrections  t o measured magnetic  using Pascal's constants susceptibilities 0,  -4.61; Zn , 2+  (xlO  -6  and c a l c u l a t e d  2  cm  3  -10; F e , 2+  susceptibilities  mol" ): 1  -13.  Diamagnetic  H, -2.93; C, -6.00; P, -26.3;  Thus,  75  as f o l l o w s .  were made  f o r a l l compounds  studied,  the diamagnetic  F.  MOSSBAUER  The  c o r r e c t i o n i s equal t o -475x10  anchored i n a Rh  spectrometer  matrix,  Model  achieved  using  analyzed  using  306  a a  and  drive  Xe-C0  2  Tracor  was  held together  calibrated  relative at  77  t o the  estimated  and  s  57  Co  source,  Detection  counter.The  TN-1706  epoxy.  foil  The  and  the  signal  Analyzer.  To  iron  to Lorentzian  foil  line and  f o r the s m a l l e r S=2  shifts  holder  are  spectrum.  shapes by  a  The  was avoid  Doppler v e l o c i t y  isomer  was  scale quoted  spectra  least-squares  quadrupole s p l i t t i n g s  mm  s"  1  f o r the S=l  are  lines  and  method  of  lines.  SYNTHESES  S y n t h e s i s of D i - n - o c t y l p h o s p h i n i c A c i d ,  This Peppard  synthesis  et  1-pctene,  al. .  In  2  90  ml  was  50%  carried a  out  aqueous  H P0 H 2  2  1.0  M HC1  and  800  C  H 8  flask,  (0.96  mol  1 7  The  315  P 0  2  H 2  -  the ml  (2.01  H PO.H) , 2  s o l u t i o n was  ml benzene were added.  76  )  to  350 ml e t h a n o l and  combined and r e f l u x e d f o r 24 h r . ml  (  according  round-bottom  (59.94 mmol) benzoyl peroxide,  500  a  samples were encased i n a Mylar  with  iron  of  motor.  proportional  E r r o r s i n isomer s h i f t s  - 1  1  t o a T e c h n i c a l Measurement  linear  t o be no g r e a t e r than +0.01  +_0.03 mm  Gl.  attached  c e n t r o i d of the  K were f i t t e d  procedure.  6.  using  consisted  Northern  problems of o x i d a t i o n , the which was  mol .  3  SPECTROSCOPY  Mossbauer  Corporation  cm  6  mol)  14.5191  g  65 ml water were then c o o l e d  and  The  was  mixture  agitated  and the aqueous l a y e r d i s c a r d e d .  scrubbed  with  two  fraction  with  undissolved  200  d i s s o l v e d upon a d d i t i o n ether. The  The mixture  organic  from  layer  ml  portions  The o r g a n i c  of  product  1.0  M  HC1,  present.  yielding  The  product  a  was  o f 400 ml 1.0 M HC1 and 600 ml petroleum  was shaken and the aqueous  was  acetone t o y i e l d  l a y e r was  evaporated the f i n a l  t o dryness  product.  J  layer  and  discarded.  recrystallized  Analysis  f o r C H PO : 16  c  35  2  c a l c . C 66.17, H 12.15; found C 66.49, H 12.30.  G2.  Synthesis  of  Bis(di-n-octylphosphinato)iron(II),  Fe[(C H ) PO ] . 17  8  As in  2  2  2  displayed  determining  i n Section  which  II, reaction  of the polymorphic  3  is  obtained.  the  j  IT  It  appears  stoichiometric  ratio  2:1 and when no p r e s s u r e  other  hand,  excess  Form  of F e C l  or  (C H ) PO  2  the  sample.  8  The  17  2  A  17  2  2  methanolic  2  17  7  2  2  17  2 2 2  form  when  t o FeCl  i s quite 2  upon t h e sample. t o form  when  pressure  each  On the  there  0.2988 g  3  i s an  i s applied c  r  of  close  ^  individual  to  c  sample  of  to i l l u s t r a t e t h i s point. ^  r  solution  of  with  0.9792  g  (3.372  an aqueous s o l u t i o n  To t h i s s t i r r e d  3  s o l u t i o n an aqueous s o l u t i o n  (1.503 mmol) FeCl »4H 0 was added dropwise, 2  mmol)  o f 0.2512 g  ^ 2  2  a white p r e c i p i t a t e formed immediately. overnight,  compounds  2  appear  2  (1.818 mmol) K C0 . of  17  and when  synthesis  (C H ) PO H was n e u t r a l i z e d 8  I  2  F e [ ( C H ) PO ] w i l l be d e s c r i b e d 17 2 2 2 ) PO ] , sample 1 . G2.1 8 Fe[(C H 8  Form  i s exerted  I I compounds  o f Fe [ (C H ) PO ] 8  (C H ) PO 8  to  forms  are c r u c i a l  IT  that  of  conditions  whereupon  The s o l u t i o n was  stirred  f i l t e r e d and washed with water, then d r i e d at 60° C f o r 77  about  4 hr.  Analysis  The product,  a f t e r drying,  f o r FeC H P O : 32  J  68  2  had a l i g h t  tan colour.  c a l c . C 60.56, H 10.80; found C 60.44,  4  H 10.88.  G2.2  Fe[ ( C H ) P 0 ] , 8  i7  2  2  sample 2  2  A methanolic  solution  o f 0.9914  g  (3.414 mmol)  ( C H ) POH 8  was n e u t r a l i z e d K C0 2  with an aqueous s o l u t i o n  To t h i s s t i r r i n g  3  solution  formed  an aqueous s o l u t i o n  The product  was  filtered  then d r i e d under vacuum at room temperature C  for a  total  of  10.5 h r .  l i g h t tan a f t e r drying. the p o s s i b l e in  ethanol  FeC  68  2  with  precipitate  o f f immediately,  f o r 2 h r , then an 50°  1,  t h e product  I n i t i a l microanalytical  results  was  a  indicated  excess o f unreacted a c i d , so t h e compound was s t i r r e d for 4  H PO : 32  As  2  o f 0.2851 g  A white  2  immediately.  2  o f 0.1885 g (1.364 mmol)  (1.434 mmol) FeCl -4H 0 was added dropwise. 2  17  days  calc  C  t o remove 60.56,  this  H  excess.  10.80;  Analysis  found  C  for  60.90,  H  4  10.82 . A n a l y s i s  f o r FeC H P 0 : 32  J  68  2  calc  C 60.56,  H 10.80;  found C  4  60.33, H 11.00.  F e [ ( C H ) PO ] , sample 3.  G2.3  8  A  17  2  2  2  methanolic  solution  of  3.271  mmol  (C H ) PO H 17  8  partially K CO . 2  was  neutralized  To t h i s ,  with  an  aqueous  an aqueous s o l u t i o n  solution  of  2  1.153  mmol  o f 1.576 mmol o f F e C l -4HO  3  2  added dropwise,  product water  was  2  giving  was s t i r r e d  and d r i e d  The d r i e d  product  a white p r e c i p i t a t e  f o r 36 h r s , then  under vacuum  washed  for a total  was a darker t a n than  78  immediately. with  2  The  methanol then  o f 10 h r a t 75° C.  1 or 2.  Analysis f o r  FeC  32  H P 0 : 68  G2.4  c a l c . C 60.56, H 10.80; found C 60.33, H 11.00.  2 4  Fe[(CH  ) PO] , sample 4  8  A  17  2  2  2'  J  methanolic  ^  solution  of  3.425  mmol  ( C H ) PO H 8  2  17  2  n e u t r a l i z e d w i t h an aqueous s o l u t i o n o f 2.312 mmol K C0 . 2  an  aqueous  solution  2  g i v i n g a white p r e c i p i t a t e immediately. off  immediately  methanol, sample hr.  then  was  after left  then  addition  was  o v e r n i g h t under  dried  a t room  To t h i s ,  3  o f 1.138 mmol FeCl -4H 0 was added  was  dropwise,  2  The product was f i l t e r e d complete  a stream  temperature  and  washed  with  of nitrogen.  The  under  vacuum  for 6  The product was approximately t h e same shade o f t a n ( f a i r l y as 3.  dark)  Analysis  f o r FeC H P 0 : 32  J  found C 60.29, H 11.00. G3.  Synthesis  of  68  2  c a l c . C 60.56,  4  H 10.80;  '  bis(di-n-octylphosphinato)zinc(II),  Zn [ (C H ) PO ] . 8  17  2  The above A  2  procedure  (C H K C0 2  used  here  methanolic  solution  ) PO H was p a r t i a l l y  1  7  3  dissolved  2  2  mmol) Z n C l and  was  analogous  r  2  of  described  g  was  mmol)  3  An aqueous s o l u t i o n o f 0.2316 g (1.699  stirred  forming a white s o l i d f o r 4 hr.  filtered  o f f and washed with methanol,  again.  The product  Analysis  f o r ZnC H P O : 68  (1.726  n e u t r a l i z e d w i t h 0.0915 g (0. 662 mmol)  was added dropwise,  32  0.5013  J  i n water.  t h e mixture  J  to that  f o r the preparation of b i s ( d i - n - o c t y l p h o s p h i n a t o ) i r o n ( I I ) .  stirred 8  2  was d r i e d  under  immediately,  The white  then water, vacuum  solid  then  a t 60°C  was  methanol  f o r 8 hr.  c a l c . C 59.66, H 10.64; found C 59.57,  2 4  79  H 10.73.  G4.  P r e p a r a t i o n o f Mixed-Metal  Compounds, Fe Zn  ^  G4.a.  ^  Fe  x  [(C H ) PO ]  1-x  0.2  8  A stirred  17  2  2  solution  2  neutralized  o f 0.7182 g  (2.473 mmol)  2  with  was  dissolved  neutralized  immediately left  acid  0.1989 g  (1.439 mmol) K C0 2  2  2  i n water.  3  and 0.1715 g (0.8626 mmol)  2  i n water  and  solution.  A  a f t e r the i n i t i a l  stirring  added  dropwise  t o the  light  white  precipitate  The product  was f i l t e r e d  under vacuum f o r 1 h r .  The product was  80°C f o r 4 hr the product became a darker brown c o l o u r .  Analysis  Zn  0.8  C H P 0 :  0.2  32  68  2  calc.  C  Upon d r y i n g  and  vacuum at  Fe  stage.  off  under  for  t a n c o l o u r at t h i s  formed  few drops were added and t h e mixture  overnight.  d r i e d at room temperature a  17  2  stirred  was  2  (C H ) PO H was 8  A mixture o f 0.030 g (0.22 mmol) Z n C l F e C l -4H 0  2  ^  ^  partially  11 2  8  [(C H ) PO ] , sample 5  Zn  0.8  '  60.38,  H  10.77;  found  C  60.22,  4  '  H 11.00. G4.b.  Fe  Zn  0.9  A  [ (C H ) PO ] , sample 6  0.1  stirred  8  17  2  2  solution  2  c  o f 1.0542 g  (3.630 mmol)  (C H ) PO H was 17  8  partially  neutralized  with  0.2322 g  (1.680 mmol) K C0 2  i n water.  A combination o f 0.0284 g (0.208 mmol) Z n C l  g  mmol)  (1.489  dropwise formed  F e C l -4H 0 2  3  t o the s t i r r e d  was  dissolved  i n water  2  2  2  dissolved  3  and 0.2961 and  added  A white  solid  2  neutralized acid solution.  immediately and was f i l t e r e d o f f immediately  80  after  addition  and  then  washed  temperature product an  with  under  methanol.  vacuum  for 7  t o be h i g h i n carbon  excess  of unreacted  The  product  hr.  i7  dried  and hydrogen content, 2  at room  M i c r o a n a l y s i s showed  (C H ) P0 H was g  was  present.  2  implying that  The product  s t i r r e d i n methanol f o r one week t o remove t h i s u n r e a c t e d reagent, Fe  Zn 0.9  then  filtered  C H PO 32  0.1  68  2  :  o f f and  calc.  C  dried  60.47,  H  at  85°C.  10.78;  the  was  starting  Analysis for  found  C  60.68,  H  4  10.86. G4.c. Fe  A  0.95  Zn  ) PO ] , sample 7  [ (C H  17  8  0.05  stirred  2  2  solution  2  c  of  1.0  g  (3.5  ^  mmol)  (C H 8  ) PO H  in  2  17'2  methanol was p a r t i a l l y n e u t r a l i z e d with 0.20 g (1.5 mmol) K C0 i n 2  water. (1.5  An aqueous s o l u t i o n of 0.011 g (8.1 pimol) Z n C l  mmol) FeCl -4H 0 was 2  added dropwise  2  s o l u t i o n and s t i r r e d about and  washed with methanol.  the compound need  20 min. After  drying.  The  and 0.30 g  2  t o the n e u t r a l i z e d  acid  A white s o l i d was f i l t e r e d o f f d r y i n g f o r about  analyzed low i n carbon  f o r more  3  and hydrogen,  compound  was  dried  7 hr at 60° C i n d i c a t i n g the  at 12 0° C  under  vacuum f o r 3 hr, whereupon the compound t u r n e d t o an i n t e n s e brown colour.  The s o l i d  normally Fe  gummy  Zn 0.95  32  68  2  seemed b r i t t l e  texture  C H PO 0.05  also  :  of  calc.  C  these 60.51,  4  '  10.90. G4.d. Fe  0.1  Zn  0.9  [ (C H ) PO ] 8  17  2  2  2  81  upon g r i n d i n g , compounds.  H  10.79;  found  u n l i k e the Anal. C  for  60.80, '  H  A  stirred  partially  neutralized  i n water. of  g  FeCl -4H 0.  Zn 0.1  then 32  68  ZnCl  solid,  (3.583 mmol)  (C H ) PO H was 8  (1.651 mmol) K C0 2  17  2  3  dissolved  2  and  2  which  0.0339 formed  g  (0.171  mmol)  immediately  after  few drops, was f i l t e r e d o f f and washed with  dried  C H PO :  0.9  0.2282 g  mmol)  white  of the f i r s t  methanol, Fe  with  (1.440 The  2  addition  of 1.0406 g  To t h i s s t i r r i n g s o l u t i o n was added an aqueous s o l u t i o n  0.1961 2  solution  at  calc.  100°C C  under  59.75,  H  vacuum. 10.65,  Analysis  Zn  9.15;  for  found  C  2 4  60.16, H 10.85, Zn 8.88.  H.  ATTEMPTED  HI.  SYNTHESES  Fe[(C H ) PO ] 13  6  A synthesis route  2  2 2  o f d i - n - h e x y l p h o s p h i n a t o i r o n ( I I ) was attempted u s i n g a  analogous  derivative.  t o that  f o r the preparation  Di-n-hexylphosphinic  acid,  (C H ) PO H 6  4.287 mmol),  was d i s s o l v e d  i n ethanol  w i t h 0.2854 g (2.065 mmol) K C0 2  (2.009 solid  mmol)  FeCl -4H 0 2  precipitated  2  was  3  out o f s o l u t i o n .  13  2  9.60.  Further  drying  dropwise,  whereupon  Fe  0.9  Cd  0.1  17  2  white  The product was washed with  at 75° C f o r 15 h r f a i l e d  [ (C H ) PO ] 8  a  A n a l y s i s was,  c a l c C 55.17, H 10.03; found C 54.13, H  microanalysis. H2.  neutralized  A s o l u t i o n o f 0.3994 g  e t h a n o l and d r i e d under vacuum a t 60° C f o r 8.5 h r . however, u n s a t i s f a c t o r y :  (1.0045 g,  2  and p a r t i a l l y  i n water.  added  of the d i - n - o c t y l  2 2  82  t o improve the  I t was thought t h a t perhaps cadmium would make a good dopant f o r these types o f compounds. of  a  cadmium(II)  Di-n-octylphosphinic  To t h i s end an attempt at t h e s y n t h e s i s doped  acid  system  was  (1.00 g, 3.45 mmol)  methanol and n e u t r a l i z e d with 0.254 g  was d i s s o l v e d i n  (1.84 mmol) K CO  ^  To t h i s  stirring  solution,  an aqueous  mmol) F e C l -4H 0 and 0.0418 g 2  2  undertaken.  2  solution  i n water. 3  o f 0.298 g (1.50  (0.180 mmol) CdCl -2.5HO were added  ^  2  2  dropwise, b r i n g i n g t h e immediate formation o f a white p r e c i p i t a t e . T h i s s o l u t i o n was s t i r r e d o v e r n i g h t , then f i l t e r e d and washed with methanol  and water.  The product was d r i e d  under vacuum f o r 6 h r . A n a l y s i s : 60.76, H 10.71.  83  at room temperature  c a l c C 60.02, H 10.70; found C  CHAPTER  Brown,  D.B.; Crawford,  V  REFERENCES  V.H.; H a l l ,  J.W.;  Hatfield,  W.E. J .  Phys. Chem. 1977,82, 1303. Konig,  E. Landolt-Bbrnstein  Relationships  in Science  Numerical and Technology.  Data  and  Neue  Functional  S e r i e 11/2.  Hellwege, K.H.; Hellwege, A.M. eds.. S p r i n g e r - V e r l a g , B e r l i n , 1966. Peppard, 1965,  D.F.; Mason, G.W.;  Lewey,  27, 2065.  84  S. J. Inorg.  Nucl. Chem.  

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