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UBC Theses and Dissertations

Studies on some Ligand-Bridged Rhenium and Manganese Carbonyl complexes. Hou, Frank Liang 1974

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S T U D I E S ON SOME L I G A N D - B R I D G E D AND M A N G A N E S E  CARBONYL  RHENIUM  COMPLEXES  by  FRANK LIANG B.Sc.  HOU  University of B r i t i s h Columbia,  A Thesis Submitted  In P a r t i a l  Of T h e R e q u i r e m e n t s  1969  Fulfilment  For The Degree  Of  Doctor of Philosophy  in the Department  of  Chemi s t r y  We a c c e p t t h i s t h e s i s a s c o n f o r m i n g required  THE  standa^  A  to the  ti  U N I V E R S I T Y OF B R I T I S H June,  1974  COLUMBIA  In p r e s e n t i n g an a d v a n c e d  this  thesis  degree at  for  scholarly  by h i s of  this  written  it  freely  available  p u r p o s e s may be g r a n t e d  for  It  of  for  financial gain  c  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, Canada  Columbia  the  requirements  Columbia, reference  copying of  I agree and this  shall  that  not  for  that  study. thesis  by t h e Head o f my D e p a r t m e n t  is understood  permission.  Department  British  that permission for extensive  representatives. thesis  fulfilment of  the U n i v e r s i t y of  t h e L i b r a r y s h a l l make I f u r t h e r agree  in p a r t i a l  or  copying or p u b l i c a t i o n  be a l l o w e d w i t h o u t my  - i  Abstract —-'"  A number o f rhenium  p l e x e s have been f fars, 4  f r o m t h e r e a c t i o n s of  prepared  f g f a r s and . f ^ f o s w i t h R e ( C 0 ) ' , 2  ReMn(C0) .  t y p e has  the general formula  t h e l i g a n d L - L b r i d g e s t h e two The of  second  type of complexes,  the f i r s t  t y p e and  2  metal  3  2  carbonyl  which  moieties.  i-f^farsM^(CO)g, are  3  2  2  result of a ligand rearrangement new  in  8  The  isomers  have the s t r u c t u r e 4  The  and  1 Q  types.  (L-L)M (C0)  (C0) M-(CH ) As-M(C0) -(CH ) AsC=CCF CF 4  2  i n t o two  com-  the l i g a n d s  Mn (C0)  1 0  T h e y c a n be c l a s s i f i e d  1 0  first  and manganese c a r b o n y l  complexes  2  which  i s the  reaction.  (L-L)M (C0)g  are the  2  first  examples of 1igand' bridged d e r i v a t i v e s c o n t a i n i n g metal carbonyl metal  fragments  bonds.  otherwise  h e l d t o g e t h e r o n l y by  They r e a d i l y r e a c t with i o d i n e with (L-L)[M(C0) I1 .  of  t h e M-M b o n d t o y i e l d  of  t h e s e f a s t c l e a v a g e r e a c t i o n s were s t u d i e d by  stopped-flow  4  technique.  The  f farsRe (C0) , f farsRe (C0) 4  a r e 6.9  2  ± 0.3,  8  g  9.3  2  ± 0.9,  2  e n t h a l p i e s of g  14.2  and + 0.9  The  metalcleavage  kinetics the  activation  for  f fars(CO) ReMn(CO) 4  4  kcal  mole"  r e s p e c t i v e l y while the approximate entropy values are  1  -13.8±1.0,  4  11  -  -11.1  ± 3.0 a n d 1.4 ± 3.2 e . u . r e s p e c t i v e l y .  results give  of f farsM (CO)  heating  i n the thermal  4  2  2  46.8  than  4  complexes to  The k i n e t i c s o f  were s t u d i e d  these  b y ^H n . m . r . 4  and f f a r s ( C 0 ) R e M n ( C 0 )  8  (M = R e , Mn)  g  4  2  g  a r e 36.8 ± 2.0,  4  ± 0.5 a n d 3 9 . 2 ± 5.2 r e s p e c t i v e l y w h i l e  values  g  of activation for f farsMn (CO) ,  The e n t h a l p i e s  f farsRe (C0) 4  g  rearrangement reactions  spectroscopy.  2  rearrangement o f these  t h e i r isomers i-(L-L)M (CO) .  thermal  time o f less  (CO)  2  a t 25°C.  Prolonged  the  entropy  a r e 1 5 . 0 i 4 . 7 , 2 3 . 2 x 1.1 a n d 2 0 . 9 ± 2.8 e . u .  respectively.  The mechanisms o f these  iodine cleavage  reactions  mediates a r e suggested related chemical The are unstable and  4  i o d i n e because i t has a h a l f - l i f e  2 milliseconds  No a c t i v a t i o n  f o r the reaction of f farsMn  p a r a m e t e r s were o b t a i n a b l e with  -  reactions  are discussed  and possible  and s p e c t r o s c o p i c  studies.  4  a n d , on h e a t i n g , 4  related to f farsM(CO) C1 3  4  give metal  complexes f farsM(C0)gl.  4  inter-  i n the l i g h t o f the k i n e t i c and  iodine complexes f f a r s [ M ( C O ) 1 ]  the chelate  and the  2  (M = R e , Mn)  carbonyl  iodides  The l a t t e r a r e  (M = R e , Mn) w h i c h w e r e  as b y - p r o d u c t s i n t h e r e a c t i o n o f t h e l i g a n d s  with  obtained the  parent  carbonyls. As a n a p p e n d i x t o t h i s t h e s i s , r e a c t i o n s fluorinated acetylenes  with  o f some  tetrakis(triphenylphosphine)-  platinum(O) and the r e a c t i o n o f bi s (tri.f 1 uoromethy 1 )di azomethane with  bis(trimethyl silyl)acetylene are  described.  /  - i n  -  Acknowledgements I would l i k e t o express to P r o f e s s o r and  my s i n c e r e s t  W. R. C u l l e n f o r h i s i n v a l u a b l e  i n s p i r i n g guidance  o f this research  appreciation  assistance  w o r k t o i t s com-  pletion. I would also l i k e t o thank Professor for h i s h e l p f u l d i s c u s s i o n s and a s s i s t a n c e work w h i l e  B. R. J a m e s  in the kinetic  D r . C u l l e n was on l e a v e o f a b s e n c e  (1972-73).  My t h a n k s a r e e x t e n d e d t o Dr.  F.W.B. E i n s t e i n f o r X - r a y  Professors  c r y s t a l1ographic  G.B. P o r t e r a n d R . E . P i n c o c k  determinations,  f o rthe use o f  t h e i r laboratory equipment , the  graduate  students  and postdoctoral  fellows  i n Rooms  459 a n d 4 7 1 , e s p e c i a l l y D r . ' J . P . Crow, f o r - t h e i r many s t i m u l a t i n g  discussions,  Mr. M i k e L e G e y t f o r d r a w i n g some d i a g r a m s , M i s s  Louise  Hon  f o r t y p i n g t h e t h e s i s a n d Mr. Lynn M i h i c h u k f o r proof  reading i t .  I am a l s o i n d e b t e d Council  t o the National  o f Canada f o r t h e a w a r d o f a s c h o l a r s h i p F i n a l l y , b u t n o t l e a s t , I am d e e p l y  the encouragement and support out t h e years this  Research  thesis  o f study  from  that  grateful f o r  I have r e c e i v e d  my p a r e n t s ,  (1969-71).  through-  t o whom I d e d i c a t e  -  i v  -  TableofContents Page Abstract  i  Acknowledgements  i i  ListofFigures  xi  L i s t of Tables  xiv  L i s t of  Abbreviations  xvi  Chapter  I  1  Chapter  II  General  Introduction  P r e p a r a t i o n of  The  Rhenium and  Ligand  Bridged  Manganese Carbonyl  Complexes  14  11.1.  Introduct ion  14  11.2.  Experimental  IS  II.2.(A)  Techniques  19  II.2.(B)  Materials  20  II.2.(C)  The  (a) The  Thermal  (b) The  Photochemical  II.2.(D) :  R e a c t i o n of  The  f f a r s with R e ( C 0 ) 4  2  Reaction  R e a c t i o n of  (a) The  Photochemical  (b) The  Thermal  Reaction  22  f f a r s with M n ( C 0 ) 4  2  1 0  Reaction  f fos  25  Reaction  I I . 2 . ( F ) The  R e a c t i o n of  f f o s with Mn (C0)  II.2.(G)  R e a c t i o n of  f fars with Re (C0)  4  4  f i  23 23  Reaction of  21 21  I I . 2 . ( E ) The  The  l Q  with  Re (C0) 2  2  ?  26  l f J  l f J  i n  26 27  -  V  -  P a  11.2. (H) The  Reaction of f^fars  (C0) ReMn(C0)  with  4  4  28  (a) The  Thermal  Reaction  28  (b) The  Photochemical  11.3.  R e s u l t s and  I I . 3 . ( A ) The  Reaction  30 with  4  2  I I . 3 . ( B ) The  and M n ( C 0 )  1 0  2  with  4  2  I I . 3 . ( C ) The  and M n ( C 0 )  1 Q  2  Reaction of fgfars  Re (C0) 2  I I . 3 . ( D ) 'The  with 38  4  (C0) ReMn(C0) 5  Cleavage  37  1 Q  1 Q  Reaction of f f a r s  I I I . The T h e r m a l  30  ] Q  Reactions of f f o s  Re (C0)  29  Discussion  Reactions of f f a r s  Re (C0)  Chapter  ge.„  with 38  5  Rearrangement  and the  R e a c t i o n s o f t h e New  Halogen  Complexes  43  I I I . 1.  Introduction  43  III.2.  Experimental  48  III.2.(A) Materials  48  I I I . 2 . ( B ) The  Thermal  Rearrangement  f farsMn (C0) 4  1 1 1 . 2 . ( C ) The  2  Thermal  4  I I I . 2 . ( D ) The  2  Thermal  49  Rearrangement 4  of  8  f fars(C0) ReMn(C0) 4  48  8  Rearrangement  f farsRe (C0)  of  4  of 49  - vip  III.2..(E) The Iodine Cleavage f farsMn (C0) 4  2  111.2.(F) The Iodine 4  2  111.2.(G) The Iodine  Cleavage  i-f farsRe (C0)  8  2  f farsRe (C0) 4  2  The Iodine 6  Chapter  52  2  Reaction 53  8  Cleavage  f farsRe (C0)  o f Reactions o f  and  The Bromine Cleavage  111.2. (1)  111.3.  51  8  of  Reaction o f  8  2  4  III.2.(H)  50  i-f farsMn (C0) 4  Reaction o f 54  8  Results and Discussion  54  I I I . 3 . ( A ) The Thermal  Rearrangement Reactions  54  I I I . 3.(B)  Cleavage  56  IV  The Halogen  The S p e c t r o s c o p i c  e  Reaction o f  8  Cleavage  f farsRe (C0)  a 9  Reactions  Properties of the  Mew C o m p l e x e s  61  I V . 1.  Introduction  61  IV.2.  Experimental  64  I V . 2 . ( A ) Raman S p e c t r a  65  IV.2.(B) U l t r a v i o l e t  66  Spectra  IV.2.CC) Mass S p e c t r a IV.3.  ,  68  Results and Discussion  72  I V . 3 . ( A ) Raman S p e c t r a  72  IV.3.(B) U l t r a v i o l e t  73  I V . 3 . ( C ) Mass S p e c t r a  Spectra  75  - vii -  Chapter  V  K i n e t i c s of Iodine Cleavage Metal  V.1.  Introduction  Mn (C0) 2  1 0  of the R e a c t i o n  with  V.l.(B) K i n e t i c Study Re (C0) 2  3  The  I  with  1 Q  I  of  2  of the Reactions  with  1 2  of  2  of the R e a c t i o n  K i n e t i c Study 0s (C0)  V. 1 . ( D )  Metal-  Bonds  V . l . ( A ) K i n e t i c Study  V. 1 . ( C )  of  of  Halogens  Mechanism of Halogenation  of  Tetracarbonylbis-ir-cyclopentadienyld i - i r o n and V.2.  its Derivatives  Experimental  V.2.(A) S t a r t i n g M a t e r i a l s V.2.(B) Low-Temperature Nuclear Magnetic  K i n e t i c Study  by  Resonance  Spectroscopy V.2.(C) D e s c r i p t i o n of the  Stopped-Flow  Apparatus V.2.(D) Experimental  Procedure  V.2.(E) K i n e t i c s of the f farsRe (C0) 4  2  8  Iodine Cleavage  of  - viii Page V.2.(F) K i n e t i c s o f the f farsRe (C0) 6  2  Iodine Cleavage o f 108  8  V.2.(G) K i n e t i c s o f the  Iodine Cleavage o f  f fars(C0) ReMn(C0) 4  4  V.2.(H) K i n e t i c s o f the f farsMn (C0) 4  2  Iodine Cleavage o f 119  8  V. 2 . ( I ) K i n e t i c s o f t h e f farsRe (C0) 6  2  113  4  Iodine Cleavage o f i n the Presence o f  8  Free Radical Scavengers V.2.(J)  TheIodine Cleavage in the Presence  121  of f farsRe (C0) 4  2  g  c f Sodium T e t r a -  phenylborate  122  V.2.(K) P h o t o l y s i s o ff f a r s R e ( C O ) i n 4  2  g  Tetrahydrofuran V.3.  R e s u l t s and  122  Discussion  123  V.3.(A) K i n e t i c Results  123  V.3.(B) P o s s i b l e Reaction V.3.(C) Comparisons V.3.(C)(a)  o f Kinetic Results  Comparison 4  2  f farsRe (C0) 4  2  Comparison  o f Results  f farsRe (C0)  8  2  2  141  8  8  g  139  and  8  f farsRe (C0) 4  126  o fResults for  f farsMn (C0)  V.3.(C)(b)  Mechanisms  for  and 142  - ix Page  V. 3 . ( C ) ( c ) C o m p a r i s o n o f R e s u l t s f o r f farsRe (CO) 4  2  and  g  f fars(C0) ReMn(C0) 4  4  146  4  V . 3 . ( C ) ( d ) Summary C h a p t e r VI  147  K i n e t i c s o f The Thermal of  (L-L)M (C0) 2  Rearrangement 151  8  V I . 1.  Introduction  151  VI.2.  Experimental  152  VI.2.(A) Starting Materials  152  VI.2.(B) Unsatisfactory Kinetic Study  152  VI.2. (C) E x p e r i m e n t a l P r o c e d u r e  153  V I . 2 . (D) K i n e t i c s o f t h e Thermal of f f a r s M n ( C 0 ) 4  2  Rearrangement. 154  8  VI.2.(E) K i n e t i c s o f the Thermal of f farsRe (C0) 4  (a) CDC1  3  2  161  8  as s o l v e n t  (b) Benzene V1.2.(F)  Rearrangement  161  as s o l v e n t  162  K i n e t i c s o f the Thermal of f f a r s ( C 0 ) R e M n ( C 0 ) 4  4  Rearrangement 167  4  VI.2.(G) K i n e t i c s o f the Thermal  Rearrangement  of f f a r s M n ( C 0 ) g in the Presence of 4  2  a Free Radical VI.3.  Scavenger  R e s u l t s and D i s c u s s i o n  VI.3.(A) Kinetic  Results  171 171 171  . (a) The Thermal  Rearrangement o f  f farsMn (C0) 4  2  (b) The Thermal  Rearrangement o f  f farsRe (C0) 4  2  (c) The Thermal  8  8  Rearrangement o f  f fars(C0) ReMn(C0) 4  4  4  VI.3.(B) Possible Rearrangement  Mechanisms  and Comparisons o f K i n e t i c R e s u l t s V I . 3 . ( C ) Summary Appendix I  R e a c t i o n s o f Some F l u o r i n a t e d A c e t y l e n e s wi t i l T e t r a k i s ( t r i p h e n y l p h o s p h i n e ) platinum(O)  Appendix II  The R e a c t i o n o f B i s ( t r i f 1 u o r o m e t h y l ) diazomethane with Bis(trimethyl s i l y l ) acetylene  - xi -  L i s t of Fi gures Fi gure 11-1 111-2 11-3  Page The S t r u c t u r e o f f f a r s M n ( C 0 ) 4  2  The S t r u c t u r e o f i - f f a r s M n ( C 0 ) 4  The Proposed  2  3  4  2  2  40  3  III-l  The S t r u c t u r e o f f f a r s F e ( C 0 )  111-2  The S t r u c t u r e o f  4  3  4  2  The S t r u c t u r e o f M ( C 0 )  IV-2  The U l t r a v i o l e t  2  4  61  l 0  i n CH C1  4  2  2  67-  96  vs. t f o r the Reaction  t  2  Graph.of  Stopped-Flow  System  of f f a r s R e ( C 0 ) 4  with  8  I  .  2  1og[f farsRe (C0)g] 4  2  '.  4  Graph o f l o g k f farsRe (C0) 4  V-5  2  Q b s  2  vs. j  with  8  I  with  I  105  2  of 107  2  Graph o f l o g [ f g f a r s R e ( C 0 ) ] v s . t f o r the 2  6  2  Graph of 1 o g [ 1 ] 2  •f farsRe (C0) 2  6  V-7  8  f o r the Reaction  8  Reaction of f f a r s R e ( C 0 ) V-6  1 0 3  vs. t f o r  t  the R e a c t i o n o f f f a r s R e ( C 0 ) V-4  and  2  Functional Block Diagram of  Graph o f l o g [ I ]  46  g  4  Spectrophotometer  V-3  4  Spectra of f f a r s  f fars(C0) ReMn(-C'0)  V-2  44  g  (f fars) Co (C0) (2H?)  IV-T  4  35  8  Structure for  (CO) Re(f fars)(AsMe ) Mn(C0)  V-l  32  8  6  2  8  Q b s  with  I  I  I  of 112  g  vs. j  with  110  2  vs. t f o r the Reaction  with  8  Graph o f l o g k f farsRe (C0)  t  8  t  g  f o r the Reaction  of 114  - xii -  Fi gure  V-8  Page  Graph  of 1og[f fars(CO) ReMn(CO) ] 4  4  for the Reaction of  Graph  of log[I ] 2  t  4  4  Graph  of log k j Q  4  ) S  4  The  with  vs. j  4  4  1"  ...  2  Graph  with  I  1 2 0 2  Thermal  of f farsMn (C0)g 4  of log[f farsMn (C0)g] 2  Conversion of f farsMn (CO)g 4  i-f farsMn (C0) 4  Graph  2  158  o f l o g k v s . j f o r the Thermal  i-f farsMn (C0) 4  2  160  8  of 1og[f farsRe (CO)g] 4  2  4  i-f farsRe (C0) 4  Graph  2  VI-6  The  2  t  vs. t f o r the into 164  g  of l o g k vs. j f o r the Conversion of  f farsRe (C0) 4  into  2  Conversion of f farsRe (CO)g  VI-5  vs. t f o r the  g  4  Graph  t  into  2  Conversion of f farsMn (C0)g  VI-4  155  2  4  118  f o r the Reaction of  n.m.r. S p e c t r a o f t h e  Rearrangement  V I -3  4  vs. t f o r the Reaction of  f fars(C0) ReMn(C0)  VI-2  4  1 1 6  4  VI-1  f fars(C0) ReMn(C0)  1  f fars(C0) ReMn(C0) V-10  vs. t  t  z  with V-9  4  2  8  into  i-f farsRe (CO)g 4  2  166  n.m.r. S p e c t r a o f t h e T h e r m a l  Rearrangement  of f fars(C0) ReMn(C0) 4  4  4  168  - xiii -  Fi gure VI-7  Page Graph of l o g [ f f a r s ( C 0 ) R e M n ( C 0 ) ] 4  4  f o r the Conversion  of  4  VI-8  4  4  Graph of l o g k vs. j • f fars(C0) ReMn(C0) 4  4  4  4  4  4  170  4  f o r the Conversion  of  into  4  i-f fars'(C0) ReMn(C0)  vs. t  f fars(C0) ReMn(C0)  into i-f fars(C0) ReMn(C0) 4  t  4  172  - xiv -  List of Tables  Table  Page  IV-1  T h e Raman M e t a l - M e t a l  Stretching Frequencies  IV-2  The U l t r a v i o l e t M e t a l - M e t a l  (o+o*)  Transitions  66  IV-3  The Mass Spectrum  of f^fosRe (C0)  IV-4  The Mass Spectrum  of f farsRe (C0)  IV-5  The Mass S p s c t r u m  of f fars(C0) ReMn(CO)  IV-6  Relative  2  4  Reaction o f Excess  V-2  Reaction of f f a r s R e ( C 0 )  V-3  Reaction of f f a r s R e ( C 0 ) 2  2  101  8  with Excess  I  2  104  8  with  V-5  Reaction o f Excess  V-6  Reaction of" f f a r s R e ( C 0 )  4  4  2  8  2  fgfarsRe (C0) 2  2  8  g  I  2  109  with I  2  111  with I 2  Dependence o f k 4  113  4  with  4  2  ^  Reaction of Excess I  I .Temperature  with Excess  Reaction of f fars(CO) ReMn(CO)  with  8  106  Reaction of f farsRe (CO )  J  68  o  Q b s  V-4  Excess  Multiplet  I  2  2  71  4  with  4  4  Dependence o f k  V-9  4  f farsRe (C0)  4  70  Q  of f„fosReo(C0)  V-l  V-8  2  4  i n t h e Mass Spectrum  V-7  69  8  Intensities of the Parent  Temperature  f fars(C0) ReMn(C0) 4  4  5  4  117  2  Reaction of f fars(C0) ReMn(C0) 4  Temperature  65  4  Dependence o f k  o b s  4  with I . 2  119  -  -  XV  Table V-10  Results of Kinetic of Iodine with  V-'ll VI-1  Intra-ligand The T h e r m a l into  VI-2  Study of the  (L-L).M (C0) 2  P--P  i-f farsMn (C0) 4  2  The T h e r m a l  at  g  into 1-f farsMn (C0)g VI - 3  of  Conversion 2  2  1 0  Distance f farsMn (C0) 4  2  g  f farsMn (C0) 4  2  g  139°C  of  into i-f farsMn (CO) . 4  M (C0)  139°C  at  2  The Thermal  of  Conversion  4  and  g  or As--As  Conversion  Reactions  f farsMn (C0) 4  2  g  Temperature  g  Dependence of k VI-4  The T h e r m a l into  VI-5  Conversion  i-f farsRe (C0) 4  2  The T h e r m a l  of f f a r s R e ( C 0 ) 4  at  g  Conversion  4  2  g  193°C  of  into i-f farsRe (C0) .  2  f farsRe (CO) 4  2  g  Temperature  g  Dependence of k VI-6  The T h e r m a l  Rearrangement  f fars(C0) 'ReMn(C0) 4  VI-7  4  The T h e r m a l  4  156°C  Rearrangement  f fars(C0) ReMn(C0) . 4  at  4  4  of  of  Temperature  Dependence of k VI-8  Results of K i n e t i c Studies of the Rearrangement  of  f-farsM-^CO)^  Thermal  - xvi  L i s t of  The  Abbreviations  following abbreviations will  be u s e d  in  this  thesis: Me:  methyl  group  Ph:  phenyl  group  f^fars:  1,2-bis(dimethylarsino)tetrafluorocyclobutene  f^fos:  1 ,2-bis(diphenylphosphino)tetrafluorocyclobutene  \  f g f a r s : 1 ,2-bi s(dimethylars i no)hexafluorocyclopentene fgfos:  l,2-bis(diphenylphosphino)hexafluorocyclopentene  fgfars:  1 ,2-bis(dimethylarsino)octafluorocyclonexene  f g f os :  1 , 2 - b i s ( d i p h e n y l p h o s p h i no )o c t a f 1 u o r o c y c l o h a x e n e  diars:  1,2-bis(dimethylarsino)benzene  diphos:  1  ,2-bis(diphenylphosphino)ethane  py:  p y r i d i ne  L:  monodentate  L-L:  bidentate  ligand ligand  n.m.r.: n u c l e a r m a g n e t i c  resonance  p . p . m. : p a r t s p e r m i 11 i o n ca.:  about,  Et:  ethyl  approximately group  - xvii -  T o My  Parents  - 1 -  Chapter I General  Introduction  T h i s t h e s i s d e s c r i b e s s t u d i e s o n some a r s i n e and phosphine carbonyl  1igand-bridged  II o f this  live  s Is d e s c r i b e s  p r e p a r a t i o n o f t h e s e new c o m p l e x e s photochemical  rearrangement  o f t h e new c o m p l e x e s  Chapter  and the halogen while chapter  spectroscopic properties. cleavage and t h e thermal new c o m p l e x e s  from  rhenium  Live  the thermal a n d  reactions o f the ligands with  dimanganese decacarbonyIs.  thermal  manganese and  complexes. Chapter  and  ditertiary  dirhenium  III describes the  cleavage reactions  IV d i s c u s s e s  their  K i n e t i c studies o f the iodine rearrangement  reactions o fthe  a r e p r e s e n t e d i nc h a p t e r V and VI r e s p e c t i v e l y .  As a n a p p e n d i x  to this thesis, reactionsof  some " f l u o r i n a t e d a c e t y l e n e s w i t h t e t r a k i s ( t r i p h e n y l phosphine)platinum(O) diazomethane described.  andthe r e a c t i o n of b i s ( t r i f l u o r o m e t h y l )  with b i s ( t r i m e t h y l s i l y l )acetylene are These  i n v e s t i g a t i o n s were c a r r i e d o u t b e f o r e  - 2 -  the work on 1 i g a n d - b r i d g e d  metal  carbonyl  complexes  was  started. In t h e p a s t t w o d e c a d e s t h e r e h a s b e e n able i n t e r e s t i n the chemistry carbonyls  and t h e i r  Although  of transition  consider-  metal  ligand s u b s t i t u t i o n products  the s u b s t i t u t i o n r e a c t i o n s have been  (1-4).  extensively  s t u d i e d , i n t e r e s t has been m a i n l y  d i r e c t e d toward  involving mononuclear carbonyls.  Reactions  ' d i n u c l e a r .carbonyl phosphines  compounds with  those  of neutral  ligands in general  and a r s i n e s i n p a r t i c u l a r have r e c e i v e d  less attention.  Since  this thesis i s concerned  and much  with  ligand  d e r i v a t i v e s o f dimar, g a n e s e a n d d i r h e n i u m d e c a c a r b o n y l s , a b r i e f review  o f t h e r e a c t i o n s o f v a r i o u s mono- and  bidentate  ligands with  presented  next.  f^^O)-^  and R e ^ f C O ) ^ i s  In g e n e r a l , t h e p r o d u c t s  of the reactions  b e t w e e n M C CO) -j Q (M = R e , Mn) a n d v a r i o u s m o n o - a n d 2  bidentate  l i g a n d s c a n be c l a s s i f i e d  (i) neutral (ii) neutral (iii)  as f o l l o w s :  dinuclear mononuclear  ionic  (iv) bridged (i) Neutral  dinuclear Dinuclear  compounds, Compounds  Reactions'between.monodentate l i g a n d s and  M (C0) 9  l f  - 3(M = R e , M n ) r e s u l t i n t h e r e p l a c e m e n t carbonyl  groups  with the f o r m a t i o n o f d i n u c l e a r compounds  of the type M (CO) L 2  (5-8) , [ M ( C 0 ) L ]  g  4  (7-9), and [ M ( C 0 ) l _ ] 3  2  2  (15) i n which  bond o fthe p a r e n t c a r b o n y l each (a)  o f one t o f o u r  (6-15), M ( C 0 ) L  2  2  the  Examples o f  next,  M (C0) L 2  g  The  r e a c t i o n between PMePh  monosubstituted the phosphine  2  and Re (C0)-|Q y i e l d s a 2  product, R e ( C O ) g ( P M e P h ) , A, i n which 2  2  l i g a n d i s t r a n s t o t h e Re-Re bond ( 8 ) . O  O  o Ph MeP 0  Re  Re—-CO  o  o  A  In t h i s c a s e , t h e s u b s t i t u t i o n o f R e ( C 0 ) 2  parallels  that o fPPh  Mn (C0) PPh 2  g  3  3  has a l s o been  1 Q  t oproduce  substitution  by PMePh  2  reported (5, 6). 2  Re (C0)  1 0  ( 1 6 ) . The a x i a l l y s u b s t i t u t e d  However, i n c o n t r a s t , PMe Ph 2  3  metal-metal  i s preserved.  type o fthese compounds a r e given  ?  reacts with  R e ( C O ) ( P M e P h ) , B, i n which 2  g  2  i s c i s t o t h e Re-Re bond ( 9 ) .  the  - 4 -  o o  O O  OC—Re  0  Re— 0  CO  B  o  PMe Ph 2  The  only other  reported  of t h e dimeric  case  carbonyls,  o fequatorial  M (C0)-]Q, 2  is  substitution  eq-Mn (C0) L 2  G  (L = pyridine o rn i t r i l e ) ( 5 ) . (b)  [ M ( C 0 )  4  L ]  2  Disubstituted  products  [Re(CO  )  4  L ]  2  (L  = PMePh , 2  P M e 2 P i 1» A s M e ? h ) ( 3 , 9 ) , p r o d u c e d f r o m t h e r e a c t i o n o f 2  the  respective  phosphine o rarsine  ligand with  have t h e s t r u c t u r e  C i n which t h e ligands  substituted.  i si n contrast with  This  O  OC—Re o O o C  O  Re—CO o o  Re (C0)-| , 9  Q  are equatorially  the axially  - 5 substituted  Ph P(CO) Re-Re(CO) PPh 3  4  4  (13,15).  3  manganese a n a l o g u e s , P h P ( C 0 ) M n - M n ( C 0 ) P P h 3  F P(C0) Mn-Mn ( C 0 ) P F 3  (20)  4  4  4  4  3  4  (20),  4  3  (19)  3  the structures  (10,17,18),  (7,19) and E t P ( C 0 ) M n - ' M h ( C 0 ) P E t  3  are also a x i a l l y substituted.  F P(C0) Mn-Mn(C0) PF  3  The  and  4  4  3  In t h e c a s e o f  EtgP(C0) Mn-Mn(CO) PEt 4  4  3  h a v e b e e n c o n f i r m e d by X - r a y  crys tal1ography. It i s i n t e r e s t i n g to note that the c r y s t a l structures  ( 2 1 ) o f M n ( C O ) ( P M e P h ) > D, a n d 2  g  ( A s M e P h ) , E, h a v e . s h o w n 2  attached  (c)  are attached a x i a l l y the arsine  Mn (C0) 2  8  ligands  are  equatorially.  M (C0) L 2  2  that while the phosphine  2  ligands  2  ?  3  R e c e n t l y two i s o m e r i c complexes, Re (CO) (PMePh ?  7  9  trisubstituted dirhenium  )~ , have been i s o l a t e d from the  - 6r e a c t i o n s o fPMePh distinct  melting  2  2  (8).  1 Q  isomers  from the products o f t h e i r  have  reactions  HC1.  o OC—Re  -Re—CO  Si SI o  L  o  Compound F i s a n a l o g o u s reported  earlier  [M(C0) L ] 3  2  o  Re  Re  s  o  toRe(CO) (EMe Ph) 7  o  2  2  drastic conditions  (15) produces  1 0  with PPh  3  under  [Re(C0) (PPh ) ] 3  3  2  2  more which  to be p a r a m a g n e t i c and monomeric i n s o l u t i o n ,  but d i a m a g n e t i c and d i m e r i c  i n the s o l i d  state.  compound has a l s o been p r e p a r e d b y h e a t i n g under vacuum Bidentate chelated  (E = As o r P)  3  (9).  2  to 200°C  CO  2  The r e a c t i o n o f R e ( C 0 )  appears  o  Si  L=PMePh  (d)  The  p o i n t s and the p r o p o s e d s t r u c t u r e s , F  a n d G, w e r e d e d u c e d with  with R e ( C 0 )  This  ReH(CO) (PPh ) 3  (22).  ligands are reported  products i n which  to y i e l d  the l i g a n d replaces  some  two t o  3  2  - 7 four carbonyl groups between  [Mn(CO)^SePh]  produces  on a s i n g l e m e t a l  The  reaction  with the c h e l a t i n g l i g a n d  2  the asymmetric  (23), in which  atom.  p r o d u c t , (CO)  diphos  ^Mn(SePh) Mn(CO) diphos 2  2  the d i m e r i c s e l e n i u m - b r i d g e d s t r u c t u r e  is r e t a i n e d .  In t h e c a s e o f t h e r h e n i u m  analogue,  however,  the diphosphine causes f i s s i o n of the selenium b r i d g e to produce  diphos Re(C0) SePh  (23).  3  (M = Re o r Mn)  Treatment  w i t h d i p h o s has been  o f M ( C O ) -j 2  r e p o r t e d to y i e l d  symmetrically  s u b s t i t u t e d p r o d u c t [M(C0) ^ d ip h o s ]  The a n a l o g o u s  d i a r s .compound, [ M n ( C O ) d i a r s ]  been  3  r e p o r t e d from the r e a c t i o n of Mn (C0)^g  cleavage of the metal-metal  c o m p o u n d on s u b s t i t u t i o n ligand.  The  paramagnetic  Re(C0) (PPh ) 3  3  3  2  2  3  Mn(C0) diars 3  somewhat i n  2  The  of  parent  by  the  (6,14,26),  3  ( E = A s o r P) ( 9 ) , ( 1 5 ) , Re(CO ) ( d i p h o s )  (24,27), Mn(CO)(diphos)  2  (24,27),  from the r e a c t i o n s of  with the a p p r o p r i a t e l i g a n d , f a l l  2  category.  2  3  (25), isolated  and Mn (C0)-jQ  i n the  4  (8), Re(CO) diphos  (15), Mn(C0) diphos  bond  compounds M n ( C 0 ) P P h 3  Re(C0) (PMePh )  as a r e s u l t  of the carbonyl groups  (15), Re(C0) (EMe Ph)  2  (25)  Compounds  This type o f product i s formed symmetric  also  with diars  2  ( i i ) Neutral Mononuclear  a  (15,24).  2  has  2  Q  and  Re (C0)-jQ  into  2  this  t r u e n a t u r e o f some o f t h e s e compounds i s  doubt.  2  - 8(iii)  Ionic  Compounds  Dimanganese decacarbonyl disproportionate the  on r e a c t i o n with  been shown t o  pyridine  (28)  to afford  i o n i c d e r i v a t i v e , [Mn(py)g][Mn(CO ) ^ ] , c o n s i s t i n g o f 2  a substituted (iv) Bridged  c a t i o n and Dinuclear  The 3  3  2  compounds o f the ligands  an u n s u b s t i t u t e d  bridge  2  o rMe As-AsMe 2  4  two  2  2  4  /M<  /  r e a c t i o n o f the  Abel  and  silylphosphine  (M = Re,  Me SiPPh 3  Under more r i g o r o u s  the  (29-31).  R=Me,Ph  and  these  2  with  bridged  - a r s i n e s , RgECl  (29).  prepared  Mn) by the r e a c t i o n pentacarbony1  conditions,  dinuclear  sodium s a l t s o f these  co-worker have a l s o 4  in which  2  chlorophosphines  2  4  dinuclear  E=As,P C 0 )  with  2  produce  M= Re.Mn  a l t e r n a t i v e method o fpreparing  (C0) M(PPh ) M(C0)  Mn) w i t h  moieties  2  R  carbonyls  2  metal carbonyl  •A  compounds i s by the  (M = Re,  1 0  (CO) M(ER ) M (CO)  R  (com;  o fM ( C 0 )  2  type  the  anion.  Compounds  reactions  A s P h , PPh , Ph P-PPh-  An  has  o f the  halides  a trimeric species,  (32). H, i s  - 9 is  produced  H  The p h o s p h i n e f r a g m e n t  pp\\  2  and P ( C F ) 3  r e p o r t e d t o b r i d g e two m a n g a n e s e c a r b o n y l parallel  with a hydrogen  (C0) Mn(PPh )(H)Mn(G0) 4  (33).  2  4  (29,30) and  (CO) Mn[P(CF ) ](I)Mn(CO) 4  2  I, has been  3  4  confirmed (34).  d i f f r a c t i o n results alone cannot d i s t i n g u i s h  the  symmetric  p l a c e m e n t o f the h y d r o g e n atom i n a single-minimum  placement of the hydrogen a symmetric  double-minimum  atom  potential  between  potential  2  the proposed  the  two m e t a l a t o m s  been  or a halogen bridge, i . e .  4  structure,  have  groups i n  In t h e c a s e o f ( C O ) M n ( P P h ) ( H ) M n ( C O )  bridging  2  However, between  between well  and' t h e  two m e t a l a t o m s well.  the  in  4  - 10 -  Another example is P h S i H R e ( C 0 ) 2  2  irradiation  benzene  2  8  of bridging  ( 3 5 ) , J , p r o d u c e d by t h e  of a solution of Re (C0)^  (35).  2  T h e tv/o h y d r o g e n  occupy the vacant octahedral rhenium atom, ReReSi  plane.  hydrogen  bridging  Q  atoms  ultraviolet  and P h S i H  in  are assumed  to  2  coordination  the Re-Si bonds  groups  2  s i t e of each  and l y i n g  in the  -  11  -  References  1.  E . W. A b e l a n d F. G. A . S t o n e , Q u a r t . ( 1 9 6 9 ) a n d 2_4 , 4 9 8 (1 9 7 0 ) .  R e v . 2_3_, 3 2 5  2.  F. C a l d e r a z z o , R. E r c o l i , a n d G. N a t t a i n O r g a n i c S y n t h e s e s v i a M e t a l C a r b o n y l s " , V o l . 1, I . W e n d e r a n d P. P i n o , E d . , I n t e r s c i e n c e P u b l i s h e r s , New Y o r k , N. Y. , 1 9 6 8 , p p . 1 - 2 7 2 .  3.  G. R. D o b s o n , I . W. S t o l z , a n d R. K. S h e l i n e ,  Advan.  I n o r g . C h e m . R a d i o c h e m . , 8, 1 (1 9 6 6 ) . 4.  T. A. M a n u e l ,  5.  M. L . Z i e g l e r , H. H a a s , a n d R. K. S h e l i n e , C h e m . B e r . , 98, 2454  Advan.  Organometal.  C h e m . , 3, 181  (1965).  (1965).  6.  H. W a w e r s i k a n d F . B a s o l o , C h e m . Commun., 3 6 6  7.  R. J . C l a r k , J . P. H a r g a d e n . H. H a a s , a n d R. K. S h e l i n e . I n o r g . C h e m . , 7 , 6 7 3 (1 3 6 8 ) . R. J . M o e l w y n - H u g h e s , A. W. B. G a r n e r , a n d N. G o r d o n , J . O r g a n o m e t a l . C h e m . , 2_6 , 3 7 3 (1 971 ) . E . S i n g l e t o n , J . T. M o e l w y n - H u g h e s , a n d A . W. B. G a r n e r , i b i d . , 2 1 , 4 4 9 (1 9 7 0 ) . A. G. O s b o r n e a n d M. H. B. S t i d d a r d , J . C h e m . S o c ,  8. 9. 10.  (1966).  J  634  (1964).  11.  W. H i e b e r a n d W. F r e y e r , C h e m . B e r . , 9_3 , 4 6 2 (1 9 6 0 ) .  12.  J . L e w i s , R. S. N y h o l m , A. G. O s b o r n e , S. S. S a n d h u , a n d M. H. B. S t i d d a r d , C h e m . I n d . ( L o n d o n ) , 1398 ( 1 9 6 3 ) . P. W. J o l l y a n d F . G. A. S t o n e , J . C h e m . S o c , 5 2 5 9 (1965).  13'. 14.  W. H i e b e r a n d W. F r e y e r , C h e m . B e r . , 92.,' 1 765  (1 9 5 9 ) .  15.  M. F r e n i , D. G i u s t o , 'and- P. R o m i t i , J . I n o r g . C h e m . 29., 761 ( 1 9 6 7 ) .  Nucl.  16.  L . I . B. H a i n e s a n d A. J . P o e , J . C h e m . S o c , ( A ) , 2826 ( 1 9 6 9 ) .  12  17.  L . I.  18.  J . L e w i s , A. R. M a n n i n g 845 ( 1 9 6 6 ) .  19.  A. S. K a s e n a l l y , R. S. N y h o l m , D. J . P a r k e r , M. H. B. S t i d d a r d , 0. J . R. H o d d e r a n d H. M. P o w e l l , Chem. I n d . , 2 0 9 7 ( 1 9 6 5 ) .  20.  M. J . B e n n e t t a n d R. M a s o n , J . C h e m . S o c , ( A ) , 75 (1968).  21.  M. L a i n g , T. A s h w o r t h , P. S o m m e r v i l l e , E . S i n g l e t o n , a n d R. R e i m a n n , C h e m . Commun., 1 2 5 1 ( 1 9 7 2 ) .  22.  M. F r e n i , D. G i u s t o a n d V. V a l e n t i , J . I n o r g . C h e m . , 2_7 , 7 5 5 ( 1 9 5 5 ) .  •23.  E . -W. A b e l , A . M. A t k i n s , B. C. C r o s s e a n d G. V. J . C h e m . S o c . , ( A ) , 6 8 7 (1 9 6 8 ) .  24.  R. H. R e i m a n n a n d E . S i n a l e t o n , J . O r a a n o m e t a l . 33, 113 ( 1 9 7 2 ) .  25.  R. S. N y h o l m a n d D. V. R a m a n a R a o , P r o c . C h e m . S o c . , 1 30 (1 9 5 9 ) .  26.  G. W. P a r s h a l l , J . A m e r . C h e m . S o c , 8 6 , 361 (1 9 6 4 ) .  27.  A. S a c c o , G a z z .  28.  W. H i e b e r a n d W. S c h r o p p , (1960).  29..  R. G. H a y t e r , J . A m e r . C h e m . S o c , 86_, 8 2 3 (1 9 6 4 ) .  30.  M. L . H. G r e e n a n d J . T. M o e l w y n - H u g h e s , Z. N a t u r f o r s c h . , 17b, 783 ( 1 9 6 2 ) .  31.  A . B. L a m b e r t ,  32.  E . W. A b e l a n d I . H. S a b h e r w a l ,  B. H a i n e s , D. H o p g o o d a n d A. J . P o e , i b i d . , 421 ( 1 9 6 6 ) . a n d J . R. M i l l e r ,  ibid.,  Nucl. Hutson, Chem.,  C h i m . I t a l . , 9_3, 6 9 8 (1 9 6 3 ) . Z. N a t u r f o r s c h . , 1 5 b , 271  Chem. a n d I n d . , 830  (1961).  J . Organometal.  Chem.,  1 0., 491 (1 9 6 7 ) . 33.  J . Grobe,  Z. a n o r g . C h e m . , 6_3 , 331 (1 9 6 4 ) .  34.  R. J . D o e d e n s , W. T. R o b i n s o n a n d J . A . I b e r s , J . A m e r . Chem. S o c , 8 9 , 4 3 2 3 (1 9 6 7 ) .  - 13 -  35  M. E l d e r ,  Inorg.  C h e m . , 9, 7 6 2  (1970).  36.  J . K. H o y a n o , M. E l d e r a n d W. A. G. G r a h a m , J . A m e r C h e m . S o c . , 91 , 4 5 6 8 ( 1 9 6 9 ) .  - 14 -  Chapter II The  Preparation of Ligand-Bridged and  Manganese Carbonyl  Rhenium  Complexes  I I . 1. I n t r o d u c t i o n As d i s c u s s e d i n t h e p r e v i o u s  chapter,  the  c o m p l e x i n g a b i l i t i e s o f d i a r s , A , a n d d i p h o s , B, h a v e b e e n much i n v e s t i g a t e d .  However, analogues c o n t a i n i n g  A  B  I C  unsaturated  - 15 b r i d g i n g groups such use  the double  unstudied  ditertiary  Oc  bond i n complex f o r m a t i o n ,  until  in t h i s area  a s C, w h i c h c o u l d c o n c e i v a b l y  recently.  (1-6).  The  a r s i n e s and  Several novel  were unknown  g r o u p s a r e now  phosphines,  D, a l s o h a v e  working  an  L = ( C H ) A s , n = 2, f f a r s 3  / L  fgfars  L = ( C H ) A s , n = 4,  fgfars  L = ( C H ) P , n = 2,  f fos  L = ( C H ) P , n = 3,  fgfos  L = ( C H ) P , n = 4,  fgfos  3  11  6  g  unsaturated  2  2  5  2  5  2  5  2  , A number of these  b r i d g i n g group.  been s y n t h e s i z e d  4  2  L = ( C H ) A s , n = 3,  6  ( 7 - 1 2 ) and  they  bridging  4  ligands  groups the ir-acceptor p r o p e r t y  ( i . e . , the d i r e c t donor-to-donor  and  electronegative the " b i t e "  d i s t a n c e ) of the  ligand  varied. In t h e c o u r s e  of a systematic  reactions of the f l u o r o c a r b o n carbonyls, products  bridged  study  of  ligands with  the metal  C u l l e n e t . a l . have r e p o r t e d a v a r i e t y of  i n which the l i g a n d i s monoligate,  biligate,  triligate,  or even rearranged.  For example, f f a r s i s  monoligate  i n f f a r s F e ( C 0 ) , E,  (13), is b i l i g a t e  4  f farsMo(C0) , 4  have  a r e i n t e r e s t i n g and  v e r s a t i l e b e c a u s e by v a r y i n g t h e n u m b e r o f  be  and  f 1 u o r o a l i c y c l i c bridged  3  can  also  4  F,  4  4  (14), f f a r s F e ( C O ) g , 4  2  G,  (13),  in  -  16  I  -  - 18 -  L  - 19 f farsCo (C0). , 4  2  H,  6  f farsRu (C0) 4  3  (17,19),  1 0  ,  (15), f f a r s F e ( C 0 ) 4  J, (17,18),  is triligate  rearranged  4  2  bridged  3  g  were known. ligands with were  (22)  2  Q  (see  (see  ( 2 0 ) , and  is  111 -1 )  and  Figure  Figure  K,  8  111 - 2 ) .  Therefore  s t u d i e s of the  d i m a n g a n e s e and  dirhenium  reactions deca-  undertaken.  Techniques  constructed  sealed  solvent.  Carius  tubes  used  of t h i c k - w a l l e d  a b o u t 80 m l .  Pyrex glass with  All nitrogen  tubes  the  w e r e s h a k e n and  c h r o m a t o g r a p h y was  atmosphere using  petroleum  a volume  U l t r a v i o l e t i r r a d i a t i o n s were c a r r i e d  C a r i u s tubes c o n t a i n i n g The  i n t h i s work were  W a t t H a n o v i a l a m p a t da_. 20 cm  boiling  L,  6  (21)  3  E x p e r i men t a l  The  The  2  rhenium  I I . 2.(A)  100  4  l i g a n d d e r i v a t i v e s o f m a n g a n e s e and  carbonyls  on  (f fars) Ru (C0) ,  f1uorocarbon-  of these  2.  4  (16),  A t t h e s t a r t o f t h i s w o r k , no  carbonyls  11.  4  and  I,  1 Qi  in f f a r s F e ( C O ) ,  in f f a r s F e ( C 0 )  (f fars) Co (C0) (2H?) 4  3  nitrogen  reactants  out the  i r r a d i a t e d with  a  distance. c a r r i e d out  under a  saturated  solvents.  e t h e r mentioned below i s the  fraction.  and  of  30°C-60°C  - 20 -  I n f r a r e d s p e c t r a were r e c o r d e d on a P e r k i n E l m e r 457 s p e c t r o p h o t o m e t e r rene and cyclohexane.  and c a l i b r a t e d  using polysty-  U n l e s s o t h e r w i s e s t a t e d , a l l n.m.r.  " s p e c t r a were r u n on V a r i a n T-60 and HA-100 with chemical internal 19  shifts  g i v e n i n p.p.m. d o w n f i e l d  TMS f o r H a n d u p f i e l d  samples.  from CFC1 ^ f o r  M a s s s p e c t r a w e r e m e a s u r e d w i t h a n A E I MS-9  mass s p e c t r o m e t e r w i t h d i r e c t  of this  from i n t e r n a l  1  F spectra.  spectrometers  introduction of solid  M i c r o a n a l y s e s were performed  b y M r . P. B o r d a  Department. -  I I . 2 . ( B ) Me t e r i ? 1 s Rhenium and manganese c a r b o n y l s were from Strem  Chemicals  respectively.  Inc. and P r e s s u r e Chemical  ( C O ) ^ R e M n ( C O ) ^ was p r o d u c e d  r e a c t i o n between NaMn(C0)g and Re(C0)gBr. carbon-bridged ligands f fars n  details  Co.  from the The f l u o r o -  ( n = 4, 6, 8 ) a n d f ^ f o s  were p r e p a r e d using_ publ i shed p r o c e d u r e s experimental  purchased  ( 9-1 4 )..  The  given below have been s e l e c t e d from  a number o f r e l a t e d e x p e r i m e n t s t h a t have been found to r e s u l t the d e s i r e d compounds.  and d e s c r i b e the c o n d i t i o n s i n the highest yields of  Experiments  producing  intractable  or u n i d e n t i f i a b l e products are not d e s c r i b e d i n d e t a i l .  - 21 I I . 2.(C)  The  ( a ) The  Reaction of f f a r s with 4  Thermal  (5.0  decacarbony1  ( 5 . 0 g , 7.7  A f t e r removal  chromatographed  column.  1 0  Unreacted  Re (C0) 2  A second  (2.9  petroleum  ether.  petroleum  e t h e r - d i e t h y l e t h e r and  acetone-hexane, g, 59% b a s e d  H, 1.2.9; F, 8 . 1 7 . 1 1 9 H and a t 1.98 carbonyl  mmol)  on a  g ) was  eluted  y e l l o w b a n d was gave,  2  Found  C, 2 0 . 6 6 ; H,  106.9  s t r e t c h i n g bands  Florisil with  A n a l . C a l c d . C, 1.22;  F, 8 . 0 0 .  The  The 2076(8),  2 0 2 4 ( 9 ) , 1 9 8 5 ( 1 0 ) , 1 957 ( 9 ) , 1 9 5 3 ( s h ) , 1 937 ( s h ) , 1 9 3 2 ( 1 0) The  d e t a i l e d mass s p e c t r u m  20.65;  showedsinglets  s o l u t i o n ) were at  2  9:1  2  p.p.m. r e s p e c t i v e l y . (CgH^  reduced  eluted with  F n . m . r . s p e c t r a (CDC1 ^ s o l u t i o n ) p.p.m. and  m-xylene  f^farsRe (CO)g  used);  1 0  and  after crystallization  yellow c r y s t a l s of on R e ( C 0 )  of  of s o l v e n t under  p r e s s u r e , t h e r e s i d u e was  (1.77  1 Q  g , 15 m m o l ) w e r e r e f l u x e d i n 50 ml  (139°) f o r 5 hr.  from  2  Reaction  Dirhenium f^fars  Re (C0)  is discussed in Chapter  cm" . 1  IV  of  this thesis. A third T h i s p r o d u c t was temperature and  r e d b a n d was  concentrated  to y i e l d  f farsRe(C0)2Cl . 4  f « f a r s R e ( C O ) , C 1 was  0.15  eluted with and  diethyl ether.  crystallized  g of a mixture  at dry-ice  o f f f a r s R e ( C O )g 4  2  S i n c e o n l y a small amount o b t a i n e d even  when u s i n g  of  large  - 22 -  q u a n t i t i e s o f Re^CCOJiQ to i s o l a t e (CDCI3  a n d f g f a r s , no f u r t h e r n.m.r.  spectrum  s o l u t i o n ) o f t h e m i x t u r e c o n s i s t e d o f two  singlets  a t 1.98  t h i s p r o d u c t was  a n d 2.02  p . p .m.  made.  The  1  H  attempt  and the i n f r a r e d  spectrum  s o l u t i o n ) i n the c a r b o n y l r e g i o n showed the absorptions:  (CgH-^  following  2 0 7 6 ( 4 ) , 2 0 4 8 ( 8 ) , 2 0 2 4 ( 6 ) , 1 985(1 0 ) , 1 967 (9 ) ,  1957(3),1953(sh),1937(sh),1932(10),1916(10)  cm" .  qualitative  chlorine  was  test to c o n f i r m the presence of  d o n e by d i s s o l v i n g  d i l u t e HNOg t o w h i c h added.  White  a few c r y s t a l s o f A g N 0  detected.  carbonyl  4  3  same  a n d no w h i t e  :  and  another  f o l l o w e d by l o s s o f t h r e e  groups.  (b) The  Photochemical  Reaction  D i r h e n i u m d e c a c a r b o n y l (2.61 fgfars  then  for f^farsRe2(CO)  f o l l o w e d by l o s s o f e i g h t c a r b o n y l g r o u p s f f a r s R e ( C O ) C1  were  The mass s p e c t r u m o f t h e  m i x t u r e showed a p a r e n t m u l t i p l e t a t 930  a t 639  3  The  r e p e a t e d w i t h o u t the sample  p r e c i p i t a t e was  A  a small amount o f the m i x t u r e i n  p r e c i p i t a t e s were o b s e r v e d .  e x p e r i m e n t was  peak  1  ( 2 . 5 0 g , 7.5  i n a C a r i u s t u b e and f o r 24 h r .  g , 4.0  mmol ) a n d  m m o l ) i n 40 ml o f a c e t o n e w e r e s e a l e d irradiated with u l t r a v i o l e t  light  A f t e r o p e n i n g the tube and c o n c e n t r a t i n g  t h e s o l u t i o n . , t h e :oi l y - r e s i d u e was  chromatographed  on a  - 23 Florisil  column.  ether-diethyl  P e t r o l e u m e t h e r a n d 9:1  petroleum  e t h e r e l u t e d 1.50 g o f u n r e a c t e d  and 0.20 g o f a m i x e d t i o n o f t h i s mixed  Re (C0) 2  product, respectively.  product from d i e t h y l  Crystalliza-  ether at dry-ice  t e m p e r a t u r e gave w h i t e c r y s t a l s o f i - f ^ f a r s R e ( C 0 ) 2  (0.17 g, 11%, based o n ' R e ( C 0 ) 2  H, 1 . 2 9 ; F , 8 . 1 7 . 1  K n.m.r. s p e c t r u m  Found  C, 2 0 . 6 6 ; H, 1 . 3 7 ; F , 8 . 0 0 . . T h e  ( C D C l ^ s o l u t i o n ) showed two s i n g l e t s  s o l u t i o n ) showed complex p.p.m.  g  u s e d ) ; A n a l . C a l c d . C, 2 0 . 6 5 ;  1 Q  a t 2.13 a n d 2.27 p.p.m. a n d t h e  134.5  1 0  1  9  F n.m.r. s p e c t r u m  s o l u t i o n ) were a t  2  21 0 2 ( 1 ) , 2 0 8 6 ( 6 ) , 2 0 0 3 ( 1 0 ) , 1 9 7 4 ( 9 ) ,1 9 6 3 ( 7 )  cm" .  The mass  1  to that observed f o r f^farsRe (CO ) . 2  F u r t h e r d i s c u s s i o n on t h e mass s p e c t r u m  i s found i n  C h a p t e r IV-.  I I . 2.(D) The R e a c t i o n o f f f a r s w i t h 4  (a) The P h o t o c h e m i c a l Dimanganese and f ^ f a r s  Mn (C0) 2  1 Q  Reaction  d e c a c a r b o n y l ( 1 . 1 g , 2.8 mmol)  ( 1 . 2 g , 3.6 m m o l ) w e r e s e a l e d i n a C a r i u s  t u b e i n 2 0 ml o f a c e t o n e a n d i r r a d i a t e d w i t h l i g h t f o r 18 h r . s o l v e n t was r e m o v e d  3  p a t t e r n s c e n t e r e d a t 130.5 and  T h e c a r b o n y l bands'.(CgH-j  s p e c t r u m was i d e n t i c a l  (CDC 1  T h e t u b e was o p e n e d and the s o l i d  ultraviolet  and the acetone  contents o f the tube  g  - 24 -  were chromatographed eluted  on F l o r i s i l .  The f i r s t  band  which  i n p e t r o l e u m e t h e r c o n t a i n e d u n r e a c t e d Mn (C0).|Q 2  ( 0 . 3 g ) . A s e c o n d o r a n g e b a n d was e l u t e d w i t h 9 5 : 5 petroleum ether-diethyl  e t h e r and gave, a f t e r  crystalliza-  t i o n f r o m 1:1 h e x a n e - a c e t o n e , o r a n g e c r y s t a l s o f f farsMn (CO) 4  2  Anal. Calcd.  ( 0 . 6 g, 4 4 % , b a s e d on M n ( C O )  g  2  C , 2 8 . 8 ; H, 1 . 8 ; F , 1 1 . 4 .  H, 1 . 8 ; F , 1 1 . 1 .  The H and  s o l u t i o n ) showed  singlets  respectively.  ]  1  9  1 Q  Found  F n.m.r. s p e c t r a  a t 1 .88 ( e x t e r n a l  used); C, 2 8 . 9 ; (CDC1  3  TMS) a n d 1 0 7 . 0 p.p.m.  T h e i n f r a r e d c a r b o n y l s p e c t r u m . (CgH-j _ 2  s o l u t i o n ) showed  a b s o r p t i o n s a t 2 0 6 2 { 5 ) , 1 9 9 4 ( 1 0 ) , 1 9 8 8 (1 0 ) ,  i 9 4 4 (7 ) , l 9 3 0 (9 ) cm "'. -  The mass s p e c t r u m showed t h e  p a r e n t peak a t 668 f o l l o w e d by l o s s o f e i g h t c a r b o n y l groups.  The X-ray c r y s t a l  was  by E i n s t e i n and c o - w o r k e r s ( 2 3 ) .  done  A third diethyl  s t r u c t u r e o f f^farsMn,,(CO)g  b a n d e l u t e d w i t h 1:1 p e t r o l e u m e t h e r -  e t h e r gave, a f t e r c r y s t a l l i z a t i o n  from cyclohexane,  yellow crystals of f^farsMn(CO)^C1  (0.05 g, 5 % ) ; A n a l .  Calcd.  Found  C , 2 5 . 9 ; H, 2 . 3 ; C l , 7 . 0 .  H, 2 . 2 ; C l , 7 . 0 .  C, 2 5 . 8 ;  .''H n . m . r . s p e c t r u m ( C H C 1 solution): 19 two s i n g l e t s a t 1.70 a n d 1.80 p.p.m. F n.m.r. s p e c t r u m ( C H C 1 s o l u t i o n ) : s i n g l e t a t 110.3. p.p.m. Infrared 3  3  carbonyl -1  cm  bands  (CgH  ] 2  solution):  2 0 4 0 ( 8 ) , 1 9 7 2 ( 8 ) , 1 9 2 2 (1 0 )  (b) The Thermal  Reaction  Dimanganese decacarbonyl and  ( 1 . 0 g , 2.6 mmol)  f g f a r s ( 1 . 0 g , 3.0 m m o l ) w e r e r e f l u x e d i n m - x y l e n e  for 5 hr. removal  After filtration  o f the p r e c i p i t a t e and  o f t h e xylene a t low p r e s s u r e , repeated  lization  o f the combined s o l i d s from  crystal-  dichioromethane-  hexane y i e l d e d l i g h t y e l l o w c r y s t a l s o f i - f ^ f a r s M n ( C O ) g 2  (0.4  g, 2 9 % ) ; Anal . C a l c d .  Found  C, 2 8 . 8 ; H, 1 . 8 ; F , 1 1 . 4 .  C, 2 8 . 8 ; H, 1 . 9 ; F , 1 1 . 2 .  n.m.r.  spectrum  (CDC 1^ s o l u t i o n ) : t w o s i n g l e t s a t 1 . 8 6 a n d 1 . 9 2 p . p . m . 19 F n.m.r. s p e c t r u m centered (C H 6  1 2  (CDC1, s o l u t i o n ) : complex  a t 1 0 3 . 0 a n d 1 0 6 . 8 p.p.m.  solution):  1964(7) cm" . 1  observed  patterns  Infrared carbonyl  bands  2080(1 ) , 2 0 6 0 ( 7 ) ; 2006 (8) , 1 996 (10 ) , 1 9 7 4 ( 9 ) ,  The mass s p e c t r u m  f o r f^farsMn (CO)g. 2  was i d e n t i c a l  An X - r a y  to that  crysta11ographic  s t u d y o f i - f f a r s M n ( C 0 ) g was d o n e ( 2 5 ) . 4  2  I t was n o t e d {h h r . f r o m  that during the thermal  s t a r t ) 50% o f the mixture  f^farsMn (CO)g 2  2  major component  consisted of  as shown by t h e i n f r a r e d c a r b o n y l  However, a f t e r 5 h r . i - f ^ f a r s M n ( C O ) g (80%).  reaction  spectrum.  was p r e s e n t as t h e  - 26 II.  2 . ( E ) T h e R e a c t i o n o f f fos w i t h  Re (C0)  fl  Dirhenium (0.50  decacarbonyl  g , 1 mmol) were r e f l u x e d  Chromatography  on a F l o r i s i l  ether-dichloromethane diethyl 4  2  8  i n 10 ml o f m - x y l e n e f o r 3 h r .  followed by r e c r y s t a l 1 i z a t i o n  F, 7 . 0 .  Found  spectrum 19  (CDC1^ s o l u t i o n ) : /  p.p.m.  ( 0 . 6 5 g , 1 mmol) a n d f ^ f o s  yielded  C , 3 9 . 1 ; H, 2 . 0 ; F , 6 . 7 .  Infrared  (CDC!  broad  3  C , 39.1 ; H, 1 . 8 ; 1  H n.m.r.  p e a k a t 7.63 p.p.m. %  solution):  c a r b o n y l bands  (CgH^  s i n g l e t a t 107.8 solution):  2  2 0 2 6 ( 6 ) , 1 9 9 0 ( 9 ) , 1 9 6 5 ( 6 ) , 1 957 ( 3 ) , 1 942 ( s h ) , 1 9 3 5 ( 1 0 ) The  mass s p e c t r u m  chemical  reaction  d i d not produce  II.  2 . ( F ) T h e R e a c t i o n o f f fos w i t h 4  diethyl  Mn (C0) 2  1 Q  ( 1 . 0 g , 2.6 mmol) and  ( 1 . 3 g , 2.6 mmol) were r e f l u x e d  i n toluene f o r  Evaporation o fthe s o l v e n t and chromatography  a Florisil  column  photo-  product.  Dimanganese decacarbonyl  2 hr.  1  o ff ^ f o s w i t h Re (C0)-jQ  identifiable  4  cm" .  IV.  2  The  2079(6),  i s discussed i n Chapter  any  f fos  from  red crystals o f  (0.22 g , 2 0 % ) ; Anal. Calcd.  F n.m.r. s p e c t r u m  1 Q  c o l u m n a n d e l u t i o n w i t h 1:1 d i e t h y l  ether-dichloromethane  f fosRe (C0)  2  ( e l u t i o n w i t h 20:1 p e t r o l e u m  ether followed by c r y s t a l l i z a t i o n  hexane) gave y e l l o w c r y s t a l s  from  o ff fosMn (C0) &  7  R  on  etheracetone(0.3 g, 1 4 % ) ;  - 27 -  Anal. Calcd. H, 2 . 6 ;  C, 5 2 . 2 ;  F , 9.0.  H, 2 . 4 ;  F. 9.2.  n.m.r. s p e c t r u m 19  b r o a d p e a k a t 7.60  p.p.m.  Found  (CDCl^  C,  solution):  F n.m.r. s p e c t r u m  (CDC1  s o l u t i o n ) : c o m p l e x p a t t e r n s c e n t e r e d a t 106.5 p.p.m.  I n f r a r e d c a r b o n y l bands ( g H c  1 2  51.9;  and  3  110.1  solution):  2074(4)  2 0 3 4 ( 8 ) \ 2 0 0 0 ( 7 ) , 1 9 8 2 (1 0 ) , 1 9 7 6 ( 8 ) , 1 9 6 0 ( 6 ) , 1 934 ( 6 )  cm" . 1  The mass s p e c t r u m showed t h e p a r e n t peak a t 828 f o l l o w e d by l o s s o f e i g h t c a r b o n y l g r o u p s .  The  photochemical  r e a c t i o n o f f ^ f o s w i t h M n (CO)-| Q . p r o d u c e d  no  2  identifiable  product. II.  2.(G)  The R e a c t i o n o f f g f a r s w i t h  fgfars ( 1 . 3 0 g, 2.00  ( 1 . 5 0 g , 3.91  T h e s o l u t i o n was  c h r o m a t o g r a p h e d on a F l o r i s i l  2  mmoles) and  mmoles) were r e f l u x e d  (139°) f o r 6 hr.  Re (C0)  2  diethyl  2  1 Q  of m-xylene  c o n c e n t r a t e d and  column.  T h e s e c o n d f r a c t i o n was  petroleum ether-diethyl  Re (C0)  i n 30 ml  The  e l u t e d w i t h p e t r o l e u m e t h e r , c o n t a i n e d 0.63 Re (C0)-jQ.  10  first  g of unreacted  eluted with  e t h e r and c r y s t a l l i z e d  ether at dry-ice temperature  fraction,  9:1 from  to g i v e y e l l o w  c r y s t a l s o f • f f a r s R e ( C 0 ) (0.40 g, 4 0 % ) ; A n a l . C a l c d . g  C, 2 0 . 8 ;  H, 1 . 2 ;  2  F. 1 1 . 6 .  H n.m.r. s p e c t r u m  8  Found  C, 2 0 . 9 ;  H, 1 . 2 ;  (CC 1 ^ s o l u t i o n ) : s i n g l e t a t 2.10  F,  11.4.  p.p.m.  - 28 l 3  F n.m.r. s p e c t r u m  (acetone solution):  triplet  a t 101.7  p.p.m. ( a r e a 2 ) a n d q u i n t e t a t 1 2 7 . 0 p . p . m . ( a r e a 1 ) . I n f r a r e d c a r b o n y l bands  (C .H g  1 2  .solution:  2 0 8 4 ( 7 ) ,2031 ( 8 ) ,  1 986(1 0 ) , 1 9 6 4 ( 8 ) , 1 954 ( 7 ) , 1 9 4 0 ( s h ) , 1 934(1 0) c m " ) . 1  r e a c t i o n b e t w e e n f g f a r s a n d • R e ( C O )-j Q d i d  photochemical not produce  The  2  any i d e n t i f i a b l e  product.  The r e a c t i o n o f f g f a r s w i t h R e ^ C O ) - ^ has a l s o been  attempted  b u t no i d e n t i f i a b l e  p r o d u c t was  II. 2.(H) The R e a c t i o n o f f f a r s w i t h  (C0) ReMn(C0)  4  (a) The Thermal  f fars  produced.  4  4  Reaction  ( 1 . 8 g , 5.4 m m o l ) a n d ( C O ) R e M n ( C O )  4  5  g  ( 1 . 7 g , 3 . 3 m m o l ) w e r e r e f l u x e d i n 30 ml o f m - x ' y l e n e f o r 6 hr.  A f t e r removal  chromatographed carbonyl  o f t h e s o l v e n t , t h e r e s i d u e was  on a F l o r i s i l  column.  Unreacted  was e l u t e d w i t h p e t r o l e u m e t h e r .  metal  The second  y e l l o w band,  e l u t e d w i t h 95:5 p e t r o l e u m e t h e r - d i e t h y l  ether, gave,  after crystallization  from n-hexane a t  -78°C, y e l l o w c r y s t a l s o f f f a r s ( C 0 ) R e M n ( C 0 ) f l  3%); Anal. Calcd. H, 1 . 8 .  1  4  C, 2 4 . 1 ; H, 1 . 5 .  H n.m.r. s p e c t r u m  Found  (C D g  f i  solution):  1  ( 0 . 2 5 g,  C, 2 4 . 4 ;  (CgDg s o l u t i o n ) : two  a t 0.72 a n d 0.80 p.p.m. ( e x t e r n a l T M S ) . n.m.r. s p e c t r u m  4  9  singlets  F  s i n g l e t a t 1 0 6 . 2 p.p.m.  - 29 -  I n f r a r e d c a r b o n y l bands  (C H g  solution):  1 2  2086(6),  1 9 9 7 ( 8 ) , 1 9 7 6 ( 1 0 ) , 1 9 5 0 ( 5 ),1 9 3 3 ( 9 ) , 1 9 2 4 ( 8 ) , 1 91 4 ( 6 )  2008(9),  cm" . 1  The mass s p e c t r u m i s d i s c u s s e d i n C h a p t e r IV. (b)  The P h o t o c h e m i c a l (C0) ReMn(C0) 5  Reaction  ( 1 . 8 g , 3.5 mmol) a n d f f a r s  5  4  ( 2 . 2 g , 6.6 m m o l ) i n 3 0 ml o f a c e t o n e w e r e s e a l e d i n a Carius tube and i r r a d i a t e d with u l t r a v i o l e t l i g h t . contents o f the tube g r a d u a l l y changed red  a n d t h e t u b e was o p e n e d  concentrating chromatcgraphed band  i t sc o l o r to orange  a f t e r seven days.  the solution, the oily cn a F l o r i s i l  After  r e s i d u e was  column.  The f i r s t  carefully yellow  eluted with petroleum ether contained a mixture of  0.3 g o f u n r e a c t e d ( C O ) R e M n ( C O ) g  by t h e i r i n f r a r e d s p e c t r a .  crystallization  from ethyl  and M n ( C 0 ) ,  5  2  ether gave,  ether —  n-hexane  after a t -78°C,  y e l l o w c r y s t a l s o f (_C0) R e ( f f a r s ) ( A s M e ) M n ( C 0 ) g  4  6%, b a s e d o n ( C O ) R e M n ( C O ) R e M n ( C O ) g  C, 2 2 . 7 ; H, 2 . 5 . spectrum  (CDC 1  3  g  Found  2  5  2  3  (0.4 g,  used); Anal. Calcd.  C, 2 2 . 9 ; H, 2 . 3 .  solution):  identified  1 Q  The second y e l l o w band e l u t e d  w i t h 9:1 p e t r o l e u m e t h e r - d i e t h y l  1.98 19  The  ]  H n.m.r.  s i n g l e t s a t 1.60 ( a r e a 1 ) ,  ( a r e a 2) a n d 2.10 ( a r e a 1) p.p.m. ( e x t e r n a l T M S ) .  F n.m.r. s p e c t r u m p.p.m. ( e x t e r n a l  (CDC1  CFC1 ). 3  3  solution):  s i n g l e t a t 109.0  I n f r a r e d c a r b o n y l bands ( C C 1  A  - 30 -  solution):  2 0 5 5 ( 5 ) , 2 0 3 2 ( 5 ) , 1 9 9 7 ( 1 0 ) , 1 9 7 6 ( 1 0 ) , 1 946 ( 8 ) ,  1 9 2 8 ( 9 ) cm" .  The  1  a t 950  mass s p e c t r u m  [ c a l c d . 953 f o r  showed a p a r e n t  (CO) Re(f fars)(AsMe ) Mn(CO) ] 3  4  f o l l o w e d by l o s s o f s i x c a r b o n y l  I I . 3. R e s u l t s a n d  I I . 3.(A)  The  2  3  groups.  Discussion  4  2  The  2  Reactions of f f a r s with R e ( C 0 )  Mn (C0)  peak  2  and  1 Q  1 Q  r e a c t i o n s of the  f1uorocarbon^bridgea  ligand, f f a r s , with dirhenium  and d i m a n g a n e s e  bonyls were i n v e s t i g a t e d under  a v a r i e t y of conditions  4  because  we w i s h e d  p r o d u c t s and and  ruthenium  would  to maximize the y i e l d s of d e s i r e d  because  previous experience with iron  (17) c a r b o n y l s i n d i c a t e d t h a t the  be d e p e n d e n t  found  t o be t r u e s i n c e t h e  r e a c t i o n between f f a r s and  Re (C0)  4  while the u l t r a v i o l e t i-f farsRe (CO)g.  isomer,  4  2  was  i r r a d i a t i o n o f f f a r s and 4  i - f f a r s M n ( C 0 ) g , was  reaction.  1 Q  4  2  yielded  This thermal  f farsRe (CO) 4  2  i r r a d i a t i o n afforded i t s isomer,  f farsMn (CO)g  2  ultraviolet  2  (16)  products  upon the r e a c t i o n c o n d i t i o n s .  e x p e c t a t i o n has been  4  decacar-  prepared  produced  from  the  Mn (C0)^Q while i t s 2  from  the  thermal  - 31 -  The  effect of altering  the ratio of the  r e a c t a n t s was i n v e s t i g a t e d t o s e e i f o t h e r p r o d u c t s (f fars) Re (C0) 4  2  2  6  c o u l d be p r e p a r e d .  ratios of f f a r s to Re (C0) 4  2  No o t h e r p r o d u c t s u c h  2  (f^fars ) Re (C0)g 2  was  2  The  different  ( 1 : 1 , 2:1 a n d 3 : 1 ) , o n l y  1 Q  f f a r s R e ( C 0 ) g was p r o d u c e d . 4  With  like  as  obtained.  s t r u c t u r e s o f f f a r s M n ( C O )g and f ^ f a r s R e ( C O ) g 1 19 4  were deduced  2  2  f r o m a n a l y t i c a l , mass s p e c t r a l ,  n.m.r. d a t a .  The a n a l y t i c a l  F  d a t a f o r t h e s e two compounds  i n d i c a t e t h a t they have the g e n e r a l  formula f^farsM (CO ) 2  (M = Mn, R e ) .  The mass s p e c t r a c o n f i r m s t h i s  and  w i t h m/e  show peaks  H and  g  formulation  ratio a t t r i b u t a b l e to [molecular  i o n - n ( C 0 ) ] ( n = 0, 3, 4, 5, 6, 7, 8 ) ( s e e C h a p t e r IV f o r more d e t a i l e d d i s c u s s i o n on mass s p e c t r a ) . S i n c e t h e 1 1 9 +  H and  F n.m.r. s p e c t r a show o n l y a s i n g l e t ,  that f^fars molecule  T h i s has been  f farsMn (CO)g 4  which  suggests  i s bonded s y m m e t r i c a l l y to the r e s t o f the  and a c t s as a b r i d g i n g l i g a n d i n t h e s e  complexes.  this  2  confirmed  by a c r y s t a l  two  i n the case of  structure determination  (23)  i n d i c a t e s a s t r u c t u r e a s s h o w n i n F i g u r e 11 — 1 . These  t w o new c o m p l e x e s  of 1igand-bridged fragments  are the f i r s t  d e r i v a t i v e s c o n t a i n i n g metal  otherwise  examples carbonyl  h e l d t o g e t h e r o n l y by m e t a l - m e t a l  Previous examples o f 1igand-bridged  bonds.  products also contain bridging  - 32 -  - 33 -  carbonyl  g r o u p s as  i n f^farsCo,, (C0)g  SR g r o u p s a s i n f f a r s [ F e ( C 0 ) S R ] 4  s y s t e m s as  4  (24), or  cluster  f farsRu (C0)^g  3  (f fars)  R u  4  shown i n F i g u r e  2  3  11 — 1 h a s  (C0)  4  ligand.  The  staggered  The  carbonyl  structure groups  which  ring involving  the  n.m.r. r e s u l t s , s i n g l e t A s - C H  F resonances, suggest  that the  s o l u t i o n o r , more l i k e l y , t h a t conformational  3  (17,19).  g  in a.nonplanar "cyclohexene"  bridging 19 and  2  bridging  in f farsFe (C0).j g (16),  ( 1 7 , 1 8 ) , and  results  2  (15),  equilibrium  the  3  ring is planar  in  ring is involved  s o t h a t an a v e r a g e d  in a  spectrum  i s o b t a i ned. As m e n t i o n e d e a r l i e r , i-f farsM (CO)g 4  2  reactions and  (M = Re,  Mn)  of f ^ f a r s with  mass s p e c t r a l d a t a  two  other  products.,  were obtained (M = Re,  M (C0).JQ 2  indicate that  from  the  Mn).  Analytical  i-f farsM (C0)g 4  2  are isomers of f f a r s M ( C 0 ) g . H o w e v e r , t h e two s i n g l e t s i n t h e ^H n . m . r . s p e c t r a a n d t h e v e r y c o m p l e x p a t t e r n s i n 19 4  the  2  F n.m.r. s p e c t r a  i-f farsM (C0)g, 4  Initially,  they  the  is chelated  by t h e  formula  explain  the m e t a l - m e t a l  f^farsM^(CO)g.  were thought to have a s t r u c t u r e t o one  m e t a l atom and  f fars(CO) M-M(CO) . 4  3  accounted f o r most of the d i d not  molecules,  have lower symmetry than  2  ligand  i n d i c a t e that the  the  Although  5  spectroscopic  4  2  g  represented this  properties,  lack of r e a c t i o n with  bond in f f a r s M ( C O )  where  iodine,  is readily  it since  cleaved  - 34 -  by i o d i n e ( s e e C h a p t e r study  (25)  has  found  III).  has  been broken  one  of the a r s e n i c - c a r b o n  also expected  X-ray  one  Mn(C0)  formation  i-f^farsMn^(C0)g  Here the metal-metal moiety  4  bonds.  has  bond  inserted into  i-f farsRe (C0)g is 4  t o h a v e an a n a l o g o u s  The  crysta11ographic  the s t r u c t u r e of  i s a s s h o w n i n F i g u r e 11 - 2 . and  An  2  structure.  o f i - f ^ f a r s M ^ ( C 0 ) g (M = Re,  Mn)  is i n t e r e s t i n g in t h a t i t i n v o l v e s the breaking of a normally M-C  s t r o n g As-C  bond and  and M-As a b o n d s .  The  involved  in the formation  unique.  Other  described  (M = Re,  rearrangement 4  3  g  (16,21) and  2  4  are  g  1.Introduction.  Two  of formula  Mn)  i s not  f farsCo (C0) (2H?)  i n s e c t i o n 111. by-products  g  rearrangement 4  were a l s o o b t a i n e d  of  of f g f a r s  of i - f f a r s M ( C 0 )  examples of. such  in f f a r s F e ( C 0 ) 4  r e s u l t s i n the f o r m a t i o n  found (22)  as  f farsM(CO)^Cl 4  i n low y i e l d s from  the  r e a c t i o n s o f f f a r s w i t h M ( C 0 ) ^ Q when l a r g e q u a n t i t i e s 4  2  of r e a c t a n t s were used.  S i n c e they were not i s o l a t e d i n  s m a l l - s c a l e r e a c t i o n s , the source probably  a small amount of  t e t r a f 1 u o r o c y c l o b u t e n e which an i m p u r i t y . unexpected  The  presence  of the c h l o r i n e  1-chioro-2-dimethylarsinowas  present  of this  in f fars  4  (8).  4  as  i m p u r i t y i s not  since the p r e p a r a t i o n of f f a r s  as an i n t e r m e d i a t e p r o d u c t  was  involves i t  - 35  -  CH  O  C t e s  ^ M r T ™ c - 0 "CH  3  a  c  c o  F i g u r e 11-2 .  The S t r u c t u r e o f i - f f a r s M n ( C O ) . This compound i s a n i s o m e r o f t h a t shown i n Figure I I-l. 4  2  Q  - 36 -  The  structure of f^farsMn(CO) C1  was  3  from i t s s p e c t r o s c o p i c p r o p e r t i e s .  deduced  The t h r e e  almost  e q u a l l y i n t e n s e c a r b o n y l s t r e t c h i n g bands which characteristic  o f compounds o f the type  (26) i n d i c a t e t h a t a l l c a r b o n y l groups other in f^farsMn(CO)^Cl . two s i n g l e t s a s e x p e c t e d  The  cis-Mn(COJ^L^X a r e c i s t o each  n.m.r. s p e c t r u m  shows  for this structure.  An a n a l y t i c a l l y p u r e s a m p l e  of  f farsRe(CO) C1 4  c o u l d n o t be o b t a i n e d a n d t h i s c o m p o u n d w a s spectroscopically.  are  The i n f r a r e d  spectrum  3  identified  shows  three  a l m o s t e q u a l l y i n t e n s e c a r b o n y l b a n d s i n t h e same r e g i o n a s f ^ f a r s M n ( C O ) .jCV.  Furthermore,  a mixture of f farsRe(CO) C1 4  parent peaks  3  t h e mass s p e c t r u m  and f f a r s R e ( C 0 ) g shows 4  2  f o r both f f a r s R e ( C 0 ) g and 4  of  2  f farsRe(CO) C1 4  f o l l o w e d by l o s s o f e i g h t a n d t h r e e c a r b o n y l  3  groups  respecti vely. The f o r m a t i o n o f t h e s e two b y - p r o d u c t s rare examples o f complexes  i n which  the ligand  provide fgfars  a c t s as a c h e l a t i n g 1 i g a n d w i t h o u t a l s o u t i l i z i n g t h e double bond o f t h e b r i d g i n g f l u o r o c a r b o n group f farsM (C0) 4  2  in which and  6  [M = Ru ( 1 7 ) , F e ( 2 7 ) ] .  examples  fgfars i s chelated include f^farsCr(CO)  f farsMo(C0) 4  Other  as i n  4  (14).  4  (25)  - 37 -  I I . 3.(B)  The  Reactions of f^fos with Re (C0)^Q  Mn (C0) 2  1 0  The r e a c t i o n s o f f f o s w i t h R e ( C 0 ) ^ 4  Mn (C0) 2  produce  1 Q  respectively. and  2  f fosRe (C0) 4  2  These  g  and  4  2  g  by e l e m e n t a l a n a l y s i s  showed the p a r e n t  peaks  f o l l o w e d by l o s s o f e i g h t c a r b o n y l g r o u p s . of the rhenium  and  Q  f fosMn (CO)  were i d e n t i f i e d  by m a s s s p e c t r a w h i c h  In t h e  case  compound, the d e t a i l e d mass s p e c t r u m  the c a l c u l a t e d i n t e n s i t i e s ( d u e t o t h e two Chapter  and  2  with  f o r the parent m u l t i p l e t  isotopes of rhenium) i s discussed in  IV.  1g S i n c e the F n.m.r. s p e c t r u m o f f f o s R e ( C O ) c o n s i s t s o f a s i n g l e t a t 107.8 p.p.m., a b r i d g e d s t r u c t u r e 4  s i m i l a r to that in Figure I I - l i s proposed 19 F n.m.r. s p e c t r u m two  of f fosMn (C0) ,  a b s o r p t i o n s a t 106.5  t h a t f f o s does 4  4  2  and  110.1  2  for i t .  however,  g  p.p.m.,  g  The  shows  indicating  n o t a c t as a b r i d g i n g l i g a n d i n t h i s  case.  I t i s -not c e r t a i n w h e t h e r i t a c t s a s a c h e l a t i n g l i g a n d w i t h t h e two one  phosphorus  atoms o c c u p y i n g one  e q u a t o r i a l p o s i t i o n of the Mn(C0)  rearranges  i t s e l f a s i n F i g u r e 11-2  of a phosphorus-carbon  bond.  3  axial  moiety  with the  and  or i t breaking  - 38 -  I I . 3.(C)  the  The  Reaction of f g f a r s with  The  reaction  2  The  The  deduced from i t s H  groups are in Figure  bridges  s i m i l a r i t y of the f farsRe (CO) 4  n.m.r. and  1  s i m i l a r to that ligand  structure  2  the  infrared further  g  equivalent. 11-1 two  Thus, a  of  infrared  f o r m e r shows a s i n g l e t , i n d i c a t i n g  arsenic-methyl  fgfars  yields  2  2  spectra.  10  of f g f a r s with Re (C0)^Q  expected product, fgfarsRe (C0)g.  t h i s p r o d u c t was  and  Re (C0)  that  structure  is proposed in which Re(C0)  carbonyl  moieties.  4  spectra  substantiates  the  The  of  the  the  fgfarsRe (C0)g 2  proposed  structure. 19  triplet The  free  The F n.m.r. s p e c t r u m , as e x p e c t e d , shows a a t 101.7 p.p.m. and a q u i n t e t a t 127.0 p.p.m. 1 9 ligand  fgfars  spectrum consisting and  130.3  I I . 3.(D)  p.p.m.  shows a s i m i l a r  o f a t r i p l e t and  F n.m.r.  a quintet  at  respectively.  The  Reaction of f f a r s with  The  thermal  4  reaction  (C0)gReMn(C0) ' 5  between f f a r s  and  4  (CO)gReMn(C0)g y i e l d s , a f t e r column chromatography crystallization, analysis  indicates  103.8  some y e l l o w c r y s t a l s w h o s e the  elemental  formula f farsReMn(C0) . 4  and  g  The  - 39 -  mass s p e c t r u m ,  showing the parent  eight carbonyl  groups,  S i n c e t h e H n.m.r.  also substantiates this  t h e As-CH-j r e g i o n a n d t h e singlet, the product  F n.m.r.  i s expected  spectrum  carbonyl  The two As-CHg r e s o n a n c e s  the ligand  moieties  two d i f f e r e n t m e t a l chemical  snift  atoms.  i s very small  a chemical  Under u l t r a v i o l e t with  (C0) ReMn(C0) 5  5  (0.08 p.p.m.).  4  t h e two m e t a l  shows a p a r e n t of s i x carbonyl  irradiation,  2  i s not great  f fars 4  This formula  3  reacts  i s suggested  a n a l y s i s and t h e mass s p e c t r u m  which  peak a t 950 ( c a l c d . 953) f o l l o w e d by l o s s groups.  T h e ^H n . m . r .  of three s i n g l e t s i n the As-CH 19 of 1:2:1, w h i l e t h e To a c c o u n t  atoms  to y i e l d yellow c r y s t a l s of formula 2  by t h e e l e m e n t a l  The f o u r  shift difference.  (C0) Re(f fars)(AsMe ) Kn(C0) . 3  to  However, the d i f f e r e n c e i n  apparently the d i f f e r e n c e i n environment  enough to cause  by  in the ligand  they are attached  f l u o r i n e atoms a r e f a r t h e r away from and  symmetric-  are easily explained  t h e f a c t t h a t t h e two d i m e t h y l a r s i n o g r o u p s a r e no l o n g e r e q u i v a l e n t b e c a u s e  shows a  t o have a s t r u c t u r e  t o t h a t i n F i g u r e 11 — 1 i n w h i c h  f ^ f a r s b r i d g e s t h e two m e t a l ally.  formulation.  s p e c t r u m c o n s i s t s o f two s i n g l e t s i n 19  1  analogous  peaks and the l o s s o f  f o r these  F n.m.r. n.m.r.  3  spectrum  consists  region with area i n t e g r a l s spectrum  shows a  singlet.  d a t a , t h e s t r u c t u r e shown i n  40 Figure  11- 3 i s p r o p o s e d .  This molecule  contains  three  co co  CO Re  Me  Meo  -<JX-  ^2 As  x  2  Meb  Mec^  As* '  \  A  /  \  Meo Meb  '  !/**»•  Mn  CO  CO CO  Figure  11 - 3 .  The P r o p o s e d S t r u c t u r e f o r (C0) Re(f fars)(AsMe ) Mn(C0) . 3  i n e q u i v a i e n t methvi  4  2  qro-UDS,  -Me,.  ratio.  AsMe? , are two  Although  difference. single  1  H  great  groups.  enough here  Therefore  is c o r r e c t , then  fluorocarbon  t h e two  the  dimethylarsino  the  groups,  are attached  shift  g r o u p s a p p e a r as  If the proposed  formation  to  environ-  to cause a chemical  f o u r Me  the  C  atoms, the d i f f e r e n c e in  n.m.r. r e s o n a n c e .  interesting  and i r e . , i n u  inequivaient because they  d i f f e r e n t metal  ment i s not  3  He.  a  expected  2  of this product  in that i t i n v o l v e s not only the l i g a n d f g f a r s b u t a l s o two  one  structure is bridging  bridging  AsMe  2  -41  -  References  1  1.  A. M. A g u i a r , J . T. M a g u e , H. J . A g u i a r , T . G. > A r c h i b a l d a n d G. P r e j e a n , J . O r g . C h e m . , 33_, 1 681 (1 9 6 8 ) .  2.  M. A . B e n n e t t  5  a n d J . D. W i l d , J . C h e m . S o c , ( A ) , 5 4 5  (1971). 3.  G. J . E r s k i n e , C a n . J . C h e m . , 47_, 2 6 9 9 (1 9 6 9 ) .  4.  R. D. F e l t h a m , H. G. M e t z g e r a n d W. S i l v e r t h o r n , I n o r g . C h e m . , 7_, 2 0 0 3 (1 9 6 8 ) . R. B. K i n g , R. N. K a p o o r a n d K. H. P a n n e l l , J . O r g a n o m e t a l . C h e m . , 2_0, 1 8 7 (1 9 6 9 ) . J . T . M a g u e a n d - J . P. M i t c h e n e r , I n o r g . C h e m . , 8_, 119 ( 1 9 6 9 ) .  5. 6. 7.  W. R. C u l l e n , D. S. D a w s o n , P. S. D h a l i w a l J  U  li  j  . O i l C i h .  o - l i u .  ^ i _O  I iO  i> 11 y  ,  ^  o  u-  ^  ] j  a n d G. E .  U f L  J  .  8.  W. R. C u l l e n , P. S. D h a l i w a l , a n d G. E . S t y a n , J . O r g a n o m e t a l . C h e m . , 6_, 3 6 4 (1 9 6 6 ) .  9.  W. R. C u l l e n , D. S. D a w s o n a n d P. S. D h a l i w a l , C a n . J . C h e m . , 4 5 , 6 8 3 (1 9 6 7 ) .  10.  W. R. C u l l e n , D. A. H a r b o u r n e , B. V. L i e n g m e a n d J . R. S a m s , I n o r g . C h e m . , 8, 9 5 ( 1 9 6 9 ) .  11.  W. R. C u l l e n , D. F . D o n g a n d J . A . J . T h o m p s o n , C a n . J . C h e m . , 47_, 4 6 7 1 (1 9 6 9 ) .  12.  L. S. C h i a , M . S c 1971 .  13.  W. R. C u l l e n , D. A. H a r b o u r n e , B. V. L i e n g m e a n d J . R. S a m s , I n o r g . C h e m . , 8, 1 4 6 4 ( 1 9 6 9 ) .  14.  W. R. C u l l e n , P. S. D h a l i w a l a n d C. J . I n o r g . C h e m . , 6, 2 2 5 6 ( 1 9 6 7 ) .  15.  J . P. C r o w , W. R. C u l l e n , W. H a r r i s o n a n d J . T r o t t e r , J . A m e r . C h e m . S o c , 9_2_, 6 3 3 9 ( 1 9 7 0 ) ; W. H a r r i s o n a n d J . T r o t t e r , J . C h e m . S o c , A , 1 6 0 7 (1 971 ) .  Thesis, University of British  Columbia,  Stewart,  - 42 -  16.  W. R. C u l l e n , D. A . H a r b o u r n e , B. V. L i e n g m e a n d J . R. S a m s , I n o r g . C h e m . , 9, 7 0 2 ( 1 9 7 0 ) ; B. J . R o b e r t s , B. R. P e n f o l d a n d J . T r o t t e r , I n o r g . C h e m . , 9, 21 37 (1 9 7 0 ) .  17.  W. R. C u l l e n a n d D. A. H a r b o u r n e , I n o r g . C h e m . , 9, 1 8 3 9 (1970) .  18.  P. J . R o b e r t s a n d J . T r o t t e r ,  J . Chem. S o c , ( A ) , 1479  (1971) . 19.  P. J . R o b e r t s a n d J . T r o t t e r ,  20.  F . W. B. E i n s t e i n , W. R. C u l l e n a n d J . T r o t t e r , J . A m e r . C h e m . S o c , 8 8 , 5 6 7 0 (1 9 6 6 ) . F . W. B. E i n s t e i n , A. M. P i l o t t i a n d R. R e s t i v o , I n o r g . C h e m . , 1_0, 1 9 4 7 (1 971 ) . F . W. B. E i n s t e i n , R. D. G. J o n e s , A . C. M a c G r e g o r a n d W. R. C u l l e n , u n p u b l i s h e d r e s u l t s .  21. 22.  ibid.,  3246  (1970).  23.  J . P. C r o w , W. R. C u l l e n , F . I.. H o u , L . Y. Y. C h a n a n d F . M. B. E i n s t e i n , C h e m . Commun., 1 2 2 9 ( 1 9 7 1 ) .  24.  W. R. C u l l e n a n d J . P. C r o w , C a n . J . C h e m . , - 4 9 , (1971).  25.  J . P. C r o w , W. R. C u l l e n 9 , 21 25 (1 9 7 2 ) .  a n d F. L. Hou, I n o r g .  2948 Chem.,  2 6 . ' R. J . A n g e l i c i , F . B a s o l o a n d A . J . P o e , J . A m e r , S o c , 8 5 , 221 5 ( 1 9 6 3 ) . 27.  Chem.  F . W. B. E i n s t e i n a n d J . T r o t t e r , J . C h e m . S o c , ( A ) , 824 ( 1 9 6 7 ) .  -  43  -  Chapter  The  Thermal  R e a r r a n g e m e n t and  Cleavage Reactions  I I I . 1.  of the  the  Mew  Halogen  Complexes  I n t r o d u c t i on  (a) The  Thermal  Rearrangement  When f ^ f a r s F e ^ ( C O ) ^ Q s o l u t i o n , the  major product 1  f farsFe (C0)g 4  III  3  (1).  The  t h a t t h i s c o m p o u n d has mined s t r u c t u r e m o i e t y has  (Figure  in  cyclohexane  i s a compound of 19 H and  little III-l)  been d i s p l a c e d  ture c o n s i s t s of three  i s heated  formula  F n.m.r. d a t a  symmetry.  The  indicate  X-ray  i n d i c a t e s t h a t an  from the  ligand  (2).  deter-  AsMe The  d i s s i m i l a r i r o n atoms and  a r s e n i c atom which form a d i s t o r t e d square p l a n e . c y c l o b u t e n e C=C d o u b l e b o n d i s c o o r d i n a t e d t o o n e B a t o m , Fe .  2  struc-  one The iron  - 45  -  Another ligand rearrangement involving p l a c e m e n t o f AsMe^ g r o u p s o c c u r s f farsCo (C0) 4  has  2  the  empirical  structure a two but  is heated.  6  (3)  Again  2  AsMe  2  t h i s time the cyclobutene system.  The  atoms are a p p a r e n t l y configuration  and  one  two  manganese atoms are  nated the  and  preparation  Mn (C0)-|  observed  4  product. carbonyl  short  sixth  by a h y d r o g e n  0  (see  2  spectrum that g  50%  g  coordination atom.  Figure  11 - 2 ) .  octahedrally  AsMe  section was  2  moiety.  as an  from the  infrared  h hr. a f t e r the  to the  isomeric  final  was  initial  at approximately  i t could  coordi-  it  reaction mixture  reaction, indicating that  The  reaction  of the  of the  in  During  II. 2.(D)),  present  estimated  shell"  group also occurs  2  (see  g  displaced  In f a c t , i t was  2  of a "closed  that the  approximately  that f farsMn (CO )  of f f a r s M n ( C 0 ) 4  2  has  cobalt  of t h i s compound from the thermal  of f f a r s with 4  molecule  carbonyl-bridged  2  by t h e  The  to form a  of i - f f a r s M n ( C 0 )  bridged  ).  r i n g s have u n i t e d  electron  4  yield  displaced,  D i s p l a c e m e n t o f an A s M e  two  i n low  g  The  containing  groups have been  p o s i t i o n around each i s occupied  formation  4  111 - 2.  i t is possible  the  obtained  (f^fars) Co (CO) (2H?  i s shown i n F i g u r e  fold axis.  bicyclobutyl  when a s o l u t i o n  A product  formula  dis-  be a  consisted start  precursor  product.  Although during  the  thermal  reaction of f . f a r s  - 47  with  Re (C0)-j  duct  other  2  a t 1 3 9 ° C t h e r e was  0  than  f farsRe 4  2  (C0)  possible that f farsRe (C0)g 4  heating.  and  2  The  was  g  f^farsRe (C0) 2  halogens  Halogen Cleavage  manganese can  o r HC1  d r y HC1  gas  t r a n s - R e ( C 0 ) ( P M e P h ) X and Cl,  halocarbonyl  Br, or  2  I) ( 5 ) .  dinuclear  2  0  2  halogens  resulted in  the f o r m a t i o n  o f c i s - and  3  2  2  ] Q  d r y HC1  n  gas  (5).  4  An a l t e r n a t i v e way  of preparing  i s b y t h e a c t i o n o f l i g a n d s on M ( C 0 ) X 5  v a r i e t y of t e r t i a r y  )  2  these  (M = R e ,  phosphite  and  the  )C1  2  complexes Mn).  r e a c t i o n s of M(C0)^X with  phosphines,  n  to produce  and  2  (X =  2  trans-Re(C0) (PMePh  s t u d i e s on t h e  complexes.  n  c h l o r o d e r i v a t i v e s , c i s - and  Extensive  of  of r e a c t i o n .  Similarly, Re (CO) _ (PMePh  2  of  Re (CO)^ _ (PMe Ph )  and  ( n = 1, 2, o r 3) r e a c t e d w i t h  3  and  by t h e a c t i o n  trans-Re(C0) (PMe Ph) X  trans-Re(C0) (PMePh ) Cl  both  complexes  reports of t h i s type  Re-Re bond and 4  prolonged  Reactions  of the d i n u c l e a r s p e c i e s  s p l i t t i n g the  on  Chapter.  on 1 i g a n d - s u b s t i t u t e d  ( n = 2 o r 3) w i t h  still  rearrange  be p r e p a r e d  H o w e v e r t h e r e a r e o n l y few Reaction  i t was  were i n v e s t i g a t e d  g  in this  Ligand-substituted r h e n i u m and  present,  pro-  rearrangement reactions of  the r e s u l t s are d e s c r i b e d (b)  no i n d i c a t i o n t h a t  could  2  Thus the thermal  f^farsMn (CO)g  -  a  arsine  - 48  -  l i g a n d s have been r e p o r t e d  (4) and  represented  equation  by t h e g e n e r a l  M(C0) X—  4  (M = Mn,  Re;  3  X =  d e s c r i b e the  preparation  1igand-substituted  halocarbonyl  complexes  dirhenium  obtained  I I I . 2.(B)  1igand-bridged  complexes,  dimanganese  (L-L)M (C0) . 2  g  Materials  The  in Chapter  on  by  Experimental  I I I . 2.(A)  (M = Mn,  [1]  we  the a c t i o n of halogens  I I I . 2.  .....  2  halogen)  In t h i s C h a p t e r , o f s o m e new  be  [1]:  > M(C0J LX — ^ M ( C 0 ) L X  5  and  t h e r e s u l t s may  Re)  new  and II.  c o m p l e x e s f ^ f a r s M , , ( C 0 ) , i - f ^ f a r s M (CO ) g  f farsRe (CO) g  2  The  Thermal  and  ?  used  without  R  (0.5  g ) was  as  g  described  bromine  further  Rearrangement of  f farsMn (C0) A  were prepared  s o l v e n t s , i o d i n e and  commercially  The  g  2  were purification.  f^farsMn (CO) 2  g  r e f l u x e d in m-xylene  - 49 -  for 5 hr. repeated  A f t e r removal  o f the s o l v e n t a t low  c r y s t a l l i z a t i o n o f the product  methane-hexane y i e l d e d l i g h t yellow i-f farsMn (C0) 4  2  spectrum.  III.2.(C)  The Thermal  by i t s i n f r a r e d  Rearrangement o f f^farsRe^(C0)g  - The p r o g r e s s  o f the thermal  rearrangement  i n r e f l u x i n g m - x y l e n e was f o l l o w e d  2  infrared  spectroscopy.  spectrum  showed t h a t ^ 9 0 % o f f - f a r s R e , , ( C 0 )  converted  4  i n CgDg a n d p l a c e d under vacuum.  106.6 and  o  had been  2  Rearrangement of  4  f fars(C0) ReMn(C0) 4  4  The s e a l e d tube  1  0 . 6 0 , 0.50 p.p.m.  was h e a t e d  ( e x t e r n a l TMS).  p.p.m., s i m i l a r t o t h o s e i-f,farsRe (C0) . f i  4  was d i s s o l v e d  4  sealed  t o 156°C f o r  showed f o u r s i n g l e t s a t 1.10,  showed complex p a t t e r n s  9  4  i n an n.m.r. t u b e w h i c h was t h e n  The H n.m.r. s p e c t r u m  spectrum  by  A f t e r 87 h r , t h e i n f r a r e d c a r b o n y l  A sample o f f f a r s ( C 0 ) R e M n ( C 0 )  1.08,  of  to i-f farsRe (C0)g.  III. 2.(D) The Thermal  2 hr.  dichloro-  crystals of  (0.4 g, 8 0 % ) , i d e n t i f i e d  8  carbonyl  f^farsRe (CO)g  from  pressure,  The  centered  observed  1  9  F n.m.r.  a t 102.8 and  for  i-f farsMn (CO) 4  S i n c e o n l y a small amount o f  2  - 50 -  f fars(C0) ReMn(C0) 4  4  its thermally  w a s a v a i l a b l e , no a t t e m p t  4  r e a r r a n g e d p r o d u c t was made.  I I I . 2.(E) The Iodine Cleavage  f farsMn (C0)g 4  dissolved  to isolate  2  Reaction of  f farsMn (CO) 4  2  g  ( 0 . 5 g , 7.5 m m o l ) w a s  i n 5 ml o f d i c h i o r o m e t h a n e .  To t h i s was a d d e d  s l o w l y , w i t h v i g o r o u s s t i r r i n g , a s o l u t i o n o f i o d i n e (0.2 g, 7.0 m m o l ) i n 50 ml o f d i c h i o r o m e t h a n e .  The p u r p l e - c o l o r e d  i o d i n e s o l u t i o n was i n s t a n t a n e o u s l y d i s c o l o r e d . C r y s t a l lization yielded  of the product  from  hexane-dichloromethane  b r o w n c r y s t a l s o f i " f a r s [ M n (C 0 ) ^ I J 4  Anal . Calcd.  2  (0.6 g, 4 3 % ) ;  C, 2 0 . 7 ; H, 1 . 3 ; I , 2 7 . 6 , F o u n d  H, 1 . 2 ; I , 2 8 . 1 .  C, 2 0 . 5 ;  The H n.m.r. s p e c t r u m ( C D C 1 s o l u t i o n ) 19 s h o w e d a s i n g l e t a t 2.02 p.p.m. T h e F n.m.r. s p e c t r u m 1  3  "  i  c o u l d n o t be o b t a i n e d b e c a u s e  no s u i t a b l e s o l v e n t was  found.  bands (CgH^  The i n f r a r e d carbonyl  at 2090(6),2026(9),2010(10),2006 The  X-ray  crystal  2  s o l u t i o n ) were  ( s h ) , 1 972 ( s h ) , 1 9 6 3 ( 6 )  cm" . 1  s t r u c t u r e has been done by E i n s t e i n and  co-worker ( 7 ) . The  i o d i n e c o m p l e x was u n s t a b l e a n d when  f fars[Mn(C0) I] 4  4  2  ( 0 . 5 g , 5.4 m m o l ) w a s r e f l u x e d i n c y c l o -  h e x a n e f o r 1 h r . a new s o l i d w a s o b t a i n e d . from hexane y i e l d e d f.farsMn(COKi  Crystallization  (0.1 g, 3 1 % ) ; A n a l .  Calcd.  - 51 -  C, 2 2 . 0 ; H, 2 . 0 .  Found  C, 2 1 . 8 ; H, 2 . 0 .  T h e 'H n . m . r .  spectrum  ( C D C 1 ^ s o l u t i o n ) showed two s i n g l e t s a t 1.88 a n d 2 . 0 6 p . p . m . T h e 19 F n . m . r . s p e c t r u m (/ C D C l ^ s o l u t i o n \) showed a s i n g l e t a t 1 1 0 . 5 p.p.m. bands  (C H g  The i n f r a r e d c a r b o n y l  s o l u t i o n ) w e r e a t - 2 0 3 6 ( 8 ) ,1 9 7 2 ( 9 ) ,1 9 2 4 ( 1 0 ) c m " . 1  1 2  The m o t h e r  l i q u o r contained Mn(C0)gI,  infrared carbonyl  identified  by i t s  spectrum.  I I I . 2 . ( F ) The I o d i n e Cleavage R e a c t i o n o f f ^ f a r s R e ( C O ) 2  f farsRe (C0) 4  2  8  ( 0 . 1 5 g, 0.16 mmol) was  i n 10 ml o f d i c h l o r o m e t h a n e t o w h i c h (0.045 added  g  dissolved  a solution of iodine  g , 0 . 1 8 m m o l ) i n 15 ml o f d i c h l o r o m e t h a n e w a s dropwise with vigorous s t i r r i n g .  After every  addition,  t h e p u r p l e - c o l o r e d i o d i n e s o l u t i o n was i n s t a n t a n e o u s l y discolored.  C r y s t a l l i z a t i o n o f t h e product from  methane a t d r y - i c e temperature (0.16 g, 8 5 % ) ; A n a l . C a l c d . Found  gave  s i n g l e t a t 1.22 p.p.m.  (CCl^ solution): spectrum  (C H g  1 2  f fars[Re(C0) I] 4  1  1965(sh),1955(sh),1952(5)  2  H n.m.r. s p e c t r u m ( C C l ^ F n.m.r.  s i n g l e t a t 1 0 4 . 8 p.p.m. solution):  4  C, 1 6 . 2 ; H, 1 . 0 ; I , 2 1 . 4 .  C, 1 6 . 2 ; H, 1 . 1 ; I , 2 1 . 6 .  solution):  dichloro-  spectrum  Infrared carbonyl  21 0 5 ( 4 ) , 2 0 2 6 ( 8 ) , 2 0 1 5 ( 1 0 ) , 2 0 1 0 ( s h ) , cm" . 1  - 52 -  When t h e p r o d u c t  f f a r s [ R e (C0.) 1] 4  4  0 . 2 3 m m o l ) was r e f l u x e d i n c y c l o h e x a n e reaction occurred. solid  from  4  y i e l d e d 0.045  and [ R e ( C 0 ) I ]  3  4  i n f r a r e d and mass s p e c t r a . (CgH^  for 3 hr., a  g of a mixture  as i d e n t i f i e d  2  [Re(C0) I]  showed c a r b o n y l  2 0 0 1 , 1 9 6 5 cm  1  4  2  bands ( C g H ^ s o l u t i o n ) a t  [literature values  (CC1^ s o l u t i o n ) ] .  showed t h e p r e s e n c e  [Re(C0) I]  a t 850 f o l l o w e d  groups and t h e parent  I I I . 2.(G) The I o d i n e and  4  Cleavage 2  3  groups.  Reactions  same p r o c e d u r e  of  i-f farsMn (C0)g 4  2  8  when  i - f f a r s R e ( C O ) g were t r e a t e d with 2  carbonyl  p e a k f o r f f a r s R e ( C O ) ' l a t 731  No r e a c t i o n was o b s e r v e d 4  of the  multiplet for  by l o s s o f e i g h t  i-f farsRe (C0) 4  ( 1 6 ) : 2106,2029,  The mass s p e c t r u m  of-the parent  f o l l o w e d by l o s s o f t h r e e c a r b o n y l  and  while  1  2 1 1 3 , 2 0 3 6 , 2 0 0 4 , 1 9 6 8 cm"  spectrum  4  a t 2 0 4 7 ( 7 ),1 9 6 8 ( 1 0 ) , 1 91 7 ( 6 ) c m " ,  mixture  by t h e i r  f farsRe(CO)showed  absorptions 2  of  The i n f r a r e d c a r b o n y l  s o l u t i o n ) o f t h e new c o m p o u n d  4  (0.27 g,  C r y s t a l l i z a t i o n of the r e s u l t i n g  cyclohexane  f farsRe(C0) I  2  i - f f a r s M n ( C O )g 4  2  iodine, using the  as i n I I I . 2.(E) and ( F ) .  - 53  I I I . 2.(H)  The  -  Bromine Cleavage Reaction  f farsRe (C0)g 4  (0.05  2  4  g) was  hexane to which a s o l u t i o n of B r c y c l o h e x a n e was  o f f f a r s R e ( C O )g  dissolved  ( 0 . 0 0 9 g)  2  added dropwise with  A f t e r each a d d i t i o n ,  the  quickly  A s l i g h t excess of Br  discolored.  added to allow the  solvent  the  and  Anal . Calcd. H,  1.1;  Br,  No  C,  in vacuo gave  17.6;  14.9.  H,  1.1;  (external  n.n.m.  6  solution):  1 2  4  i t s infrared carbonyl  minutes.  The  a silica  yielded 2  4  gel  " '"'  C,  17.8;  n.m.r.  F  carbonyl  spectrum:  spectrum  refluxed  in  recorded  Thin  cm" ) 1  and  every  in decomposition of the  (6).  Further  products.  five  indicated layer  n-hexane  as  cm' ), 1  Re(C0) Br  i d e n t i f i e d by t h e i r i n f r a r e d  solution)  cm' .  cyclohexane  (1915,1961,2050  (2116,2035,2003,1961  2  2  solution):  4  plate, using  3  1  (CgH^  of  Found  (CC1  present.  f farsRe(CO) Br  ( 2 0 5 0 , 2 0 1 2 , 1 9 8 7 cm" ) spectra  Evaporation  s p e c t r u m t a k e n a f t e r 15 m i n u t e s  c h r o m a t o g r a p h y on  4  was  4  14.7.  s p e c t r u m was  p r o d u c t s was  [Re(C0) Br]  was  2  that a mixture of  solvent,  solution  2  21 1 2 ( 4 ) , 2 0 2 7 ( 8 ) , 2 0 1 5 ( b r . ) , 1 955 ( b r . )  f^fars[Re(C0) Br] and  was  4  IMS) .  Infrared  stirring.  f fars[Re(C0) Br] .  H n.m.r. s p e c t r u m  1  satisfactory solvent.  (C 'H  Br,  cycloof  solution  2  c o l o r to p e r s i s t .  drying  a t ?. 35  singlet  red  Br  in  i n 5 ml  vigorous  red-colored  2  refluxing  5  carbonyl resulted  1  - 54 -  I I I . 2 . ( 1 ) The I o d i n e C l e a v a g e  A small amount o f f g f a r s R e ( C O ) 2  in cyclohexane.  f farsRe (C0)  Reaction of  g  2  was d i s s o l v e d  g  To t h i s was a d d e d s l o w l y , w i t h  stirring, a solution of iodine.  vigorous  The p r o g r e s s o f t h e  r e a c t i o n was f o l l o w e d b y i n f r a r e d s p e c t r o s c o p y . r e a c t i o n was s t o p p e d  when t h e s o l u t i o n showed  a t 21 1 0 ( 4 ) , 2 0 2 8 ( 8 ) , 2 0 1 (sh) cm" .  4 ( 1 0 ) , 2 0 0 6 ( s h ) , 1 9 7 0 ( 5 ),1 9 5 4 ( 6 ) ,1 9 5 0  4  4  3. R e s u l t s a n d D i s c u s s i o n '  III.  3.(A) The Thermal  Both  converted  Rearrangement  f farsMn (C0) 2  4  to their  isomers  by r e f l u x i n g i n m - x y l e n e . (87 h r . ) i n t h e c a s e  The  those  2  III.  isolation  thermal  absorptions  for f fars[Re(C0) I] .  observed  the  The  These i n f r a r e d absorptions are s i m i l a r to  1  g  4  2  of f farsRe (C0)  8  2  4  as the product Re (C0)^Q 8  formation of f,farsMn (C0)  Q  involve initial  9  Re)  allows  of the  (scheme  2  2  are  i s slower  compound and  production of i-f farsMn (CO) 4  8  (M = Mn,  g  This rearrangement  of the rhenium  4  2  4  i-f farsM (C0)  reaction of f f a r s with  thermal  f farsRe (C0)  and  g  Reactions  III-l).  a l s o seems t o ( s c h e m e 111 - 2 ) .  - 55 -  SCHEME 111-T Reactions  Involving  f g f a r s and  uv i r r a d i a t i o n , a c e t o n e f fars 4  Re (C0)  +  2  1 0  -  ^  j  4  2  f  ^  2  (24 h r . )  f farsRe (C0) 8 1 3 9 ° ( 8 7 hr|) m-xylene 4  2  i-f farsRe (C0)  f fars[Re(C0) I] .81° ^ cyclohexane + f farsRe(C0) I 4  [Re(C0) I]  f  R e ( C 0 ) 10  4  4  4  2  2  no  reaction  3  SCHEME 111 - 2 Reactions m-xylene  Involving  f fars  and  4  Mn (C0)^ 2  (5 h r . ) ( v i a f f a r s M n ( C 0 ) 4  2  Q  8  0 3 9 ° ( 5 hr.)  m-xylene  f fars[Mn(C0) I] 81 ° ^cyclohexane Mn(C0) I + f farsMn(C0) I 4  5  4  4  2  3  i-f farsMn (C0) 4  I* 1  no  2  8  reaction  8  - 56 -  The  kinetic studies of these rearrangement  found  in Chapter  VI.  The t h e r m a l was  s t u d i e d i n CgD  that  at 156°C.  g  of  f^fars(CO) ReMn(C0) 4  It i s i n t e r e s t i n g to  two  Indeed,  n.m.r. s i n g l e t s  p o s s i b l e p r o d u c t s , A and i t was  k i n e t i c study are found in Chapter  The  Halogen  Cleavage  i o d i n e a t room t e m p e r a t u r e  original  singlets  B are formed  in  solution.  and i t s  VI.  Reactions.  Reactions of f^farsM^(CO)g  metal-metal  B, c o u l d  g r a d u a l l y converted to f o u r  More d e t a i l e d d i s c u s s i o n o f t h i s r e a r r a n g e m e n t  I I I . 3.(B)  2  o b s e r v e d t h a t t h e two  i n d i c a t i n g t h a t both p r o d u c t s A and  The  4  note  4  be o b t a i n e d . H  rearrangement  i f t h i s compound r e a r r a n g e s s i m i l a r l y as f f a r s R e ( C 0 ) g  and f ^ f a r s M n ^ ( C O ) g  1  reactions are  (M = R e , Mn)  with  r e s u l t i n the rupture of  the  bonds to g i v e the d e r i v a t i v e sf f a r s [ M ( C O ) ^ I ] •  proposed  4  s t r u c t u r e has been  f fars[Mn(C0) I] 4  4  2  (7) i n which  are s e p a r a t e l y bonded a r s i n o groups  t o two  2  confirmed i n the case t h e two  Mn(C0) I 4  a r s e n i c atoms.  a r e r o t a t e d so t h a t M n ( C 0 ) I 4  The  moieties dimethyl-  moieties  e a c h a r s e n i c a t o m a r e s i t u a t e d on o p p o s i t e s i d e s o f plane of the cyclobutene r i n g . c o o r d i n a t e d c i s to the l i g a n d .  The  i o d i n e atoms  of  are  on the  v  g 7  (00) u^s<  aH  z  z  a\A  7  svv  (00)  (00)  2  3W  7  <00)  uw«— V> S  7  (ob)  2 9W  7  (00)  6  9W  - 58 -  As m e n t i o n e d  e a r l i e r , these cleavage reactions  also occur with t h e parent carbonyls, M (C0).JQ b u t a p p a r e n t l y t h e r a t e s a r e much s l o w e r difficult  to understand  this effect, although  = Re, Mn),  (M  2  (8,9) and i t i s  why a b r i d g i n g l i g a n d s h o u l d i ti s expected  i n M (C0).JQ  that substitution of  b y p o o r e r ir a c c e p t o r s  carbonyl  groups  decrease  t h e M-M b o n d s t r e n g t h ( 1 0 ) . C e r t a i n l y , t h e  2  Mn-Mn b o n d l e n g t h i n f f a r s M n ( C O ) 4  longer than i n M n ( C 0 ) 2  2  should  (2.971(3)A) i s  g  (2.923(3)8)  1 Q  have  ( 7 ) . Because o f  t h i s d i f f e r e n c e between t h e complex and t h e parent carbonyl, the kinetics o f the iodine cleavage o f the M-M b o n d s i n f ^ f a r s M ( C O ) 2  g  (M = R e , M n ) w e r e s t u d i e d  and a r e d e s c r i b e d i n C h a p t e r The  V.  i o d i n e complexes  f^fars[M(C0) I] 4  2  (M = R e ,  Mn) a r e u n s t a b l e a n d , o n h e a t i n g , g i v e m e t a l  carbonyl  iodides and t h e c h e l a t e complexes  3  Mn) ( s e e s c h e m e I I I - l f farsM(C0) I 4  3  a n d 111 - 2 ) .  i s unexpected  f^farsM(C0) I  (M = R e ,  The formation o f  i n view o f t h e f a c t  f g f a r s i s r e l u c t a n t t o form c h e l a t e complexes  that  as  mentioned  in s e c t i o n 11. 3.(A). Reaction o f f^farsRe (CO) 2  temperature  g  w i t h B r a t room  y i e l d s a compound o f f o r m u l a  as i n d i c a t e d by i t s e l e m e n t a l and t h e i n f r a r e d  analysis.  2  f^farsRe (CO) Br , 2  g  2  Both t h e H n.m.r. 1  carbonyl spectra a r e similar t o those  -  for fars[Re(CO) 1]  obtained  4  f farsRe (C0)gBr 4  2  -  59  , suggesting  2  has a s i m i l a r s t r u c t u r e .  2  iodine complex, f ^ f a r s [ R e ( C O ) B r ] 4  to give metal identified  carbonyl  by t h e i r The  temperature  infrared and  4  6  3  spectra.  reaction o ff farsRe (CO ) 2  with  g  g  4  spectrum  I  2  a t room  o f t h e Re-Re  f fars[Re(CO) I ] , as identified  carbonyl  on h e a t i n g  bromides and f farsRe(C0) Br,  infrared carbonyl  2  by i t s '  which shows s i m i l a r p a t t e r n  intensities as that o f f fars[Re(CO) 1 ] . 4  As e x p e c t e d , f.  Like the  rearranges  2  also r e s u l t s i nthe cleavage  bond t o y i e l d  that  or.  t..'  ! r> rs\  !  ..  4  2  no r e a c t i o n was o b s e r v e d n .  •».... \  ..- -  J. .„ „ - J. .- ,?  , : J- U  when - ^ A  I " i ^ji ai si'^i^u ;g \vi — ivc, n 11/ nua «« • c u. t. c u vv i v. • i s i n c e these compounds do not c o n t a i n a metal-metal  ^  IUOIIIC,  bond.  - 60 -  References  1.  W. R. C u l l e n , D. A . H a r b o u r n e , B. V. L i e n g m e a n d J . R. S a m s , I n o r g . C h e m . , 9_, 7 0 2 (1 9 7 0 ) .  2.  F . W. B. E i n s t e i n , A . M. P i l o t t i i b i d . , 1_0, 1 9 4 7 (1 971 ) .  3.  F . W. B. E i n s t e i n , R. D. G. J o n e s , A . C. M a c G r e g o r a n d W. R. C u l l e n , U n p u b l i s h e d r e s u l t s .  4.  T. A. M a n u e l ,  5.  E . S i n g l e t o n , J . T . M o e l w y n - H u g h e s a n d A . W. B. G a r n e r , J . O r g a n o m e t a l . C h e m . , 2J_, 4 4 9 (1 9 7 0 ) ; J . T. M o e l w y n - H u g h e s , A . W. B. G a r n e r , a n d N. G o r d o n , i b i d . , 26., 3 7 3 (1 971 ) .  6.  J . C. H i l e m a n , D. K. H u g g i n s C h e m . , 1; 9 3 3 (1 9 6 2 ) .  7.  J . P. C r o w , W. R. C u l l e n , F . L . H o u , L . Y. Y. C h a n a n d F . W. B. E i n s t e i n , C h e m . Commun., 1 2 2 9 ( 1 9 7 1 ) .  8.  L . I . B. H a i n e s , D. H o p g o o d a n d A . J . P o e , J . C h e m . Soc,  9. 10. 11. 12.  Adva.  Organometal.  a n d R. R e s t i v o ,  C h e m . , 3_, 181 (1 9 6 5 ) .  a n d H. D. K a e s z ,  Inorg.  ( A ) , 421 (1 9 6 8 ) .  L . I . B. H a i n e s a n d A . J . P o e , i b i d . ,  2826  (1969).  C. E . C o f f e y , J . L e w i s a n d R . ' S . N y h o l m , i b i d . , 1 7 4 1 (1964). W. R. C u l l e n a n d D. A . H a r b o u r n e , I n o r g . C h e m . , 9_, 1839 ( 1 9 7 0 ) . F . W. B. E i n s t e i n a n d J . T r o t t e r , J . C h e m . S o c , ( A ) , 824 ( 1 9 6 7 ) .  - 61 -  Chapter  IV  T h e S p e c t r o s c o p i c P r o p e r t i e s o f t h e New  Complexes  IV.1.Introduction (a)  Raman  Spectra The t r a n s i t i o n m e t a l  carbonyls offer a  rich  variety of polynuclear structures f o r the study of metalmetal  bonding.  Much i n t e r e s t a t t a c h e s t o t h e s i m p l e s t M2(C0)^Q  representatives, the dinuclear decacarbony1s, (M = Mn, T c , R e ) , i n w h i c h groups metal  two s q u a r e - p y r a m i d a l  are joined in a staggered orientation bond  M(C0)  by a m e t a l -  (1-3) (Figure IV-1). 0  0  Figure IV-1.  C-M  0  M-C  0  T h e s t r u c t u r e o f M ( C 0 )l O * 9  g  - J  The metal-metal stressed  usefulness  -  2  o f Raman s p e c t r o s c o p y  v i b r a t i o n s i n these  in studying  binuclear molecules  b y G a g e r e t . a l . who r e p o r t e d  the  was  metal-metal  s t r e t c h i n g v i b r a t i o n s o f Mn2(C0).|Q, R e 2 ( C 0 ) ^ Q a n d (C0)- ReMn(C0) 5  frequency  5  i n 1 966 ( 4 ) . S i n c e t h e n  assignments  f o r M^CCOj-jg s p e c i e s  and metal-metal  Raman constants  (5-9).  1  Raman-active fundamentals  They appear  Indeed,  t o be a c h a r a c t e r i s t i c o f  as i n t e n s e  high  Raman i n t e n s i t y  -J(M-M),  owing t c the  l a r g e c h a n g e i n p o l a r i z a b i 1 i t y when t h e bond atoms o f high atomic  t r a s t , v ( M - M ) may p r o v e  between  number i s d e f o r m e d . impossible  infrared  spectroscopy  molecule  i s centrosymmetric  totally forbidden.  v(M-M),  which are often the strongest  features i n the spectrum.  two  In t h e s e  stretching frequencies,  i n t h e r e g i o n 120-200 cm" .  appears  force  have been r e p o r t e d  reports, the metal-metal fall  many  In con-  t o d e t e c t by f a r -  i n b i n u c l e a r M-M  systems where t h e  a n d v(M-M) i s , o f c o u r s e ,  Even when t h e m o l e c u l e  i s hetero-  n u c l e a r , v(M-M) i s f r e q u e n t l y so weak t h a t i t o f t e n escapes  observation  by f a r - i n f r a r e d i n v e s t i g a t i o n .  In t h i s C h a p t e r , stretching (L-L)M (C0) 2  .described.  frequencies 8  This study  metal-metal  i n compounds o f t h e type  (L-L = f f a r s , 4  some Raman  f f a r s ; M = Re, g  was u n d e r t a k e n  Mn) a r e  i n order  to gain  - 63  -  some k n o w l e d g e o f t h e r e l a t i v e m e t a l - m e t a l  bond  strengths  in these compounds compared with the parent metal bonyls, M (C0) 2  (M = R e ,  1 Q  (b) U l t r a v i o l e t  Mn),  Spectra  It has bond i n  car-  M (C0)^Q 2  been r e p o r t e d (10) t h a t the (M = R e ,  the u l t r a v i o l e t r e g i o n .  Mn)  has a  o+a*  metal-metal  transition  in  T h e r e f o r e , the u l t r a v i o l e t s p e c t r a  of the compounds ( L - L ) M ( C 0 ) g  (L-L = f f a r s ,  2  fgfars;  4  M = Re, Mn)  were measured to see i f they have  similar  metal-metal  {o+o*)  of  transition  was  transitions.  also of interest  The  intensity  the  s i n c e i f i t were s t r o n g  enough i t would o f f e r a means o f f o l l o w i n g the i o d i n e cleavage reaction described in Chapter (c) Mass  III.  Spectra Mass s p e c t r o m e t r y  is a very valuable  in the study of organometal!ic  molecules  technique  b e c a u s e by  t e c h n i q u e m u c h i n f o r m a t i o n c a n be o b t a i n e d w i t h extremely  small sample.  The a v a i l a b l e  isotopic cule,  p a t t e r n s , the d e t a i l e d  composition  p a t t e r n and  s t r u c t u r e and  include from  of the  ( i i ) the determination of the r e l a t i o n s h i p  the fragmentation  an  techniques  ( i ) the d e t e r m i n a t i o n of m o l e c u l a r weights and,  this  mole-  between  ( i i i ) the  - 64  determination  of appearance  -  and  ionization potentials  which a i d i n the e s t i m a t i o n of the r e l a t i v e bond of s i m i l a r molecules. t r a n s i t i o n metal  Therefore,  carbonyls  the mass s p e c t r a  f e a t u r e of the  these complexes i s the  (11-14).  fragmentation  stepwise  In t h i s C h a p t e r , 4  2  4  a r e r e p o r t e d and lated with rhenium  their structures. 185  has  composition  two  isotopes,  and  groups  stoichiometry. of  f fars(C0) ReMn(C0) 4  4  patterns are  4  corre-  In p a r t i c u l a r , s i n c e 187 Re,  the i s o t o p i c  as an a i d i n d e t e r m i n i n g  the d e t a i l e d  of the parent  Re a n d  i o n and  its  fragment.  Experimental  The (L-L  8  their fragmentation  p a t t e r n s are used  I V . 2.  2  for  loss of carbonyl  the mass s p e c t r a  f farsRe (C0)  8  The  patterns  w h i c h i s an i n v a l u a b l e a i d i n d e t e r m i n i n g  f fosRe (C0) ,  of  have been i n v e s t i g a t e d  e x t e n s i v e l y o v e r t h e p a s t few y e a r s outstanding  energies  metal  carbonyl  = f f a r s , f f o s , f g f a r s ; M = Re, 4  4  as d e s c r i b e d i n C h a p t e r  II.  equipped  P h y s i c s Model  with a Spectra  (L-L)M (CO)  complexes,  A Cary  2  Mn),  81  were  g  prepared  Spectrophotometer 125  He-Ne l a s e r  o  as a s o u r c e  of e x c i t i n g l i g h t  (x = 6 3 2 8 A ) was  r e c o r d i n g Raman s p e c t r a o f t h e s e  complexes.  used The  for  - 65 -  powdered samples pyrex tubes Visible  were c o n t a i n e d i n " o p t i c a l "  ( 6 mm O . D . ) .  Spectrophotometer  violet  spectra.  A P e r k i n - E l m e r 202  flat  bottom  Ultraviolet-  was u s e d t o o b t a i n t h e u l t r a -  Mass s p e c t r a were measured  MS-9 s p e c t r o m e t e r w i t h d i r e c t  w i t h an AEI  introduction of solid  samples.  IV. 2 . ( A ) Raman S p e c t r a  The m e t a l - m e t a l (L-L)M (C0) 2  stretching frequencies of  ( L - L = f f a r s , f g f a r s ; M = R e , Mn) a r e  8  4  recorded i n Table IV-1.  T a b l e IV-1 The  Raman M e t a l - M e t a l  Compound Mn (C0) 2  1 Q  5  Re (C0) 2  metal-metal stretching , f r e q u e n c y (cm" )  9  (C0) ReMn(C0)  5  1 Q  f farsMn (C0) 4  2  8  f fars(C0) ReMn(C0) 4  Stretching Frequencies  4  4  Reference  160  7  157  7  122  7  168 ± 4  this  work  163 ± 4  this  work  f farsRe (C0)  g  139  ± 4  this  work  fgfarsRe (C0)  8  145 ± 4  this  work  4  2  2  a  Powdered p o l y c r y s t a l 1 i n e sample  - 66 -  IV. 2.(B) U l t r a v i o l e t  Spectra  The u l t r a v i o l e t are  found i n Table IV-2.  for f,fars(CO),ReMn(C0),  metal-metal A typical  Compound Mn (C0) 2  Re (C0) 2  \nax  b 1 0  1 0  fgfars  ultraviolet  spectrum  IV-2  Metal-Metal  9  transitions  i s shown i n F i g u r e IV-2 w h i c h  Table The U l t r a v i o l e t  (a+o*)  ( m  ^  (CT->O*)  ^max  Transitions  Reference  5  342 ( 1 5 , 0 0 0 )  15  310 ( 1 6 , 0 0 0 )  16  265  this  work  f farsMn (C0)  8  365 ( 9 , 7 0 0 )  this  work  f farsRe (C0)  8  330 ( 1 6 , 0 0 0 )  this  work  f farsRe (C0)  8  3 2 7 (1 1 , 0 0 0 )  this  work  340 ( 9 , 9 0 0 )  this  work  4  2  4  2  6  2  f fars(C0) ReMn(C0) 4  a  4  In C H C 1 2  2  4  solvent unless otherwise  specified,  k In glyme s o l v e n t .  also  i n c l u d e s t h e UV s p e c t r u m o f t h e f r e e  ligand  f fars. 4  0.5 O  C  i— o  {/) JQ <  1.0-  fgfars f fars(C0) ReMn(C0) 4  1.5-  250 Figure  IV-2.  4  300 Wavelength ( m i l l i m i c r o n s ) The U l t r a v i o l e t  350  S p e c t r a of f . f a r s and f f a r s ( C 0 ) R e M n ( C 0 ) 4  4  4  4  in CH C1 2  2  - 68 -  I V . 2. ( C ) M a s s S p e c t r a  The mass s p e c t r a and  f fars(C0) ReMn(C0) 4  4  4  o f f ^fosRe,, (C0)g , f f a r s R e ( C O ) 4  2  were r e c o r d e d i n Tables IV-3,  IV-4 and IV-5 r e s p e c t i v e l y .  In t h e c a s e o f t h e f f o s  complex,  which  a computer  the c o n t r i b u t i o n s also from  C,  program,  takes into  f r o m t h e two r h e n i u m  p  •jo  4  "I  H,  -j  i s o t o p e s and  -j g  0 and  0, w a s u s e d t o c a l c u l a t e  the i n t e n s i t i e s f o r the parent m u l t i p l e t . i n t e n s i t i e s were compared ones  account  The  calculated  with the experimentally observed  (Table IV-6). Table Relative  IV-6  Intensities of the Parent  i n t h e Mass Spectrum  m / e  Multiplet  of f fosRe (C0) A  Relative Observed  ?  f i  Intensity Calculated  1088  28.6  28.6  1089  13.1  11.7  1090  100.0  100.0  1091  40.5  40.3  1092  90.5  92.1  1093  35.7  35.5  1094  7.2  7.9  .  - 69 -  Table  IV-  The Mass S p e c t r u m  m/e  Assignment f fosRe (C0)  8  1006  f fosRe (C0)  5  978  f fosRe (C0)  4  950  f fosRe (C0)  3  922  f fosRe (C0)  2  894  f fosRe (C0)  966  f fosRe  847  (f fosRe -F)  (f fosRe -4C H -2F  494(w)  f fos  482  (f fosRe -4C H -4F  475(w)  (f fos-F)  456(w)  (f fos-2F)  +  2  418(w)  (f fos-4F)  +  2  233(w)  (f fos-4F-P(C H )  187  1 8 7  Re  +  185  1 8 5  Re  +  183  ((C H ) P-2H)  108  (C H )P  +  2  4  +  2  4  +  2  4  +  2  4  +  +  2  (f fosRe -C H ) 4  2  6  +  5  712  (f fosRe -2C H )  681(w)  f fos  1 8 7  679(w)  f fos  1 8 5  558  (f fosRe -4C H )  w = weak  4  2  4  4  Assignment  520  4  .  2  (f fosRe -4C H -F)  +  2  4  fosRe (C0)  539  4  4  4  m/e  1090  789  of  6  Re  +  Re  +  4  2  6  +  5  4  2  4  2  + ?  6  5  +  4  2  6  5  +  4  4  4  4  6  6  6  +  5  fragment are  5  4  peaks  peaks c o n t a i n i n g R e  6  multiplets  5  5  2  +  +  5  2  - 70 -  Table  IV-4  The Mass S p e c t r u m m/e 930 846 831 818 803(w) 790 775(w) 762 7 4 7 (w) 734 719 706 691 676(w) 661(w) 616 601 586 563 548 527(w) 510  499.(w) 497(w) 471(w)  w = weak  of  f farsRe (C0)g 4  2  Assignment  m/e  f farsRe (C0) f farsRe (C0) (f farsRe (C0)g-CH ) f farsRe (C0) (f farsRe (C0) -CH ) f farsRe (C0) (f farsRe (C0) -CH ) f farsRe (CO) + (f farsRe (CO) -CH ) f farsRe (C0) (f farsRe^CC0)-CH ) ' f farsRe (f farsRe -CH ) (f farsRe -2CH ) (f farsRe -3CH ) (f farsRe -AsCH ) (f farsRe -As(CH ) ) (f farsRe -As(CH ) ) (f farsRe -As(CH ) -2F) (f farsRe -As(CH ) -2F) ((CH ) As-C=CCF CF Re(C0) ) EB (f farsRe -As(CH ) -4F) (B-C0) (B-2CH ) (B-2C0) +  4  2  8  4  2  5  +  +  4  2  4  2  3  4  +  4  2  4  4  2  3  3  +  4  2  3  3  +  4  2  2  +  4  2  2  3  +  4  2  4  3  4  2  +  4  2  3  4  2  3  4  2  3  4  2  4  2  3  2  4  2  3  3  +  +  +  3  +  +  +  4  2  3  2  4  2  3  3  +  +  3  2  2  2  4  +  d  2  +  +  3  +  3  3  +  443(w) 415(w) 400(w) 385(w) 334(w) 319(w) 300 270 267 261 243 229 215 206 199(w) 196(w) 191 187 185 151 (w) 140(w) 137(w) 124 120 105  peaks  peaks c o n t a i n i n g Re  2  fragment are m u l t i p l e t s  A s s i gnment (B-3C0) (B-4C0) (B-4C0-CH ) (B-4C0-2CH ) f fars (f fars-CH ) +  +  +  3  +  3  +  4  4  +  3  (f fars-As(CH ) ) 4  3  +  2  (f fars-As(CH ) ) (f fars-As(CH ) F) +  4  3  4  4  3  3  Re 185  1 8 7  +  R e +  (As(CH ) ) 3  2  +  +  - 71 -  Table T h e M a s s S p e c t r u m of m/e  f.fars(CO).ReMn(CO)  Ass i gnment  m/e  799  f fars(C0) ReMn(C0)  715  (P-3C0)  700  (P-3C0-CH )  687  (P-4C0)  672(w)  (P-4C0-CH )  659  (P-5C0)  644(w)  (P-5C0-CH )  631  (P-6C0)  603  (P-7C0)  675  (P-8C0) =f farsReMn  560(w)  (f farsReMn-CH )  545(w)  (f farsReMn-2CH )  470  (f farsReMn-As(CH ) )  +  455  (f farsReMn-As(CH ) )  +  417  (f farsReMn-As(CH ) -2F)  396(w)  ((CH ) As-C=CCF CF  w = weak  IV-5  EP  379  (f farsReMn-As(CH ) -4F)  368(w)  (A-C0)  366(w)  (A-2CH )  340(w)  (A-2C0)  334(w)  f fars  319(w)  (f fars-CH )  312(w)  (A-3C0)  +  +  284(w)  (A-4C0)  +  +  269(w)  (A-4C0-CH )  254(w)  (A-4C0-2CH )  229  (f fars-As(CH ) )  +  199(w)  (f fars-As(CH ) )  +  196(w)  (f fars-As(CH ) F)  4  4  4  +  +  +  +  3  +  +  3  +  +  3  +  +  4  4  +  +  3  4  +  3  4  3  4  4  peaks  2  3  2  2  187  3  3  3  A s s i gnment  +  3  2  Mn(C0) ) EA 4  +  +  4  3  3  +  +  3  +  +  4  4  +  3  +  3  +  3  4  3  4  3  4  4  3  185  Re 185  105  (As(CH ) )  1 8 7  2  +  R e +  3  2  +  3  +  H  IV. 3. R e s u l t s a n d D i s c u s s i o n  I V . 3 . ( A ) Raman  The for  Raman m e t a l - m e t a l  (L-L)M (C0) 2  Spectra  8  recorded i n Table  stretching frequencies  (M = R e , M n ; L - L = IV-1.  The assignment  f r e q u e n c i e s t o v(M-M) i s based of  their  fgfars,  fgfars) are  o f these  on the c o n s i d e r a t i o n  low f r e q u e n c i e s , i n t e n s i t i e s ,  with t h e parent metal  carbonyls.  possibility o f their  being metal-carbon  and a  comparison  Although the deformation  b a n d s c a n n o t , bo c o m p l e t e l y r u l e d o u t , t n e h i g h k a m a n intensities frequency  o fthese bands t o g e t h e r with t h e i r low (below  to be metal-metal  170 c m ) make t h e m a l m o s t - 1  stretching frequencies.  From T a b l e decrease  I V - 1 , i t i s noted  i n the order f farsRe (CO) 4  f fars(C0) ReMn(C0) 4  4  that the metal-metal  4  2  < fgfarsRe (C0)g 2  g  < f farsMn (C0) .' 4  2  that the frequencies  g  I t i s also  corresponding parent metal  conslusion  <  noted  stretching frequencies i n the ligand-  substitu.ted complexes are higher than those  metal-metal  certain  carbonyls.  i n the  Although  t h e Raman  s t r e t c h i n g f r e q u e n c i e s do n o t i n d i c a t e t h e t h a t t h e s u b s t i t u t i o n o f two c a r b o n y l  groups  i  - 73 -  by b r i d g i n g b i d e n t a t e the metal-metal by X - r a y  fluorocarbon  bond.  l i g a n d has weakened  This conclusion  c r y s t a l1ographic  determinations  [Mn-Mn = 2.971 ( 3 ) A ] a n d M n ( C 0 ) 2  (17)  1 Q  for f farsMn (CO) 4  4  those  in  (Chapter  2  The ease o f i o d i n e cleavage  of the metal-metal M (C0)-JQ 2  bonds i n ( L - L ) M ( C 0 ) 2  2  [Mn-Mn = 2 . 9 2 3 ( 3 ) A ] •  i n w h i c h t h e Mn-Mn b o n d o f f f a r s M n ( C 0 )  lengthened.  IV.  i s shown  8  8  is  reactions compared  a l s o s u b s t a n t i a t e s t h i s- c o n c l u s i o n  III).  3.(B) U l t r a v i o l e t Spectra  The  u l t r a v i o l e t absorption  bands o f  (L-L  = f g f a r s , f g f a r s ; M = R e , Mn) a r e r e c o r d e d  Table  IV-2.  Figure  4  (L-L)M (C0) 2  in  IV-2 shows t h e u l t r a v i o l e t s p e c t r a  of f f a r s and f f a r s ( C 0 ) R e M n ( C 0 ) . the  with  4  4  4  I t i s noted  that  s p e c t r u m o f t h e l a t t e r d o e s n o t show t h e l i g a n d  absorption  b a n d a t 2 6 5 my.  This  i s b e c a u s e t h e band  a t 2 6 5 my i s d u e t o t h e t r a n s i t i o n o f e l e c t r o n s the a r s e n i c lone o f t h e C=C b o n d present  p a i r s o f f f a r s t o t h e tr* 4  (21) and t h e lone  in f fars(CO) ReMn(CO) 4  atoms a r e c o o r d i n a t e d  4  4  from  orbitals  p a i r s a r e no  longer  i n which the arsenic  t o t h e metal  atoms.  G r a y e t . a l . ( 1 0 ) h a v e made a r i g o r o u s  assign-  8  - 74 -  ment o f t h e band  a t 3 4 0 my i n t h e e l e c t r o n i c  o f Mn (C0).|Q t o a o+a* t r a n s i t i o n  involving  2  from the metal-metal f o rTC  bands  2  (C0).JQ  by a n a l o g y .  interaction.  S i m i l a r l y , t h e a b s o r p t i o n bands  The e n e r g y o f t h e  o+a*  fha  a bonds  o f the metal-metal  bond  2  8  s t r e n g t h assuming  t h e same e n e r g y .  On t h i s  i t i s noted from Table IV-2 t h a t t h e order o f  m « + ? 1 ..  •» 1  Ho  A  <-4-v,or~-?-h  in  f farsRe (C0)  8  > f farsRe (CO)  f farsMn (CO)  8  which  4  i n (L-L)M (CO ) .  t r a n s i t i o n c a n a l s o be t a k e n a s  2  2  4  2  8  f TO  / I _ I ' VM (  6  i n Table  transitions of electrons  c-*cr*  t h a t t h e a* l e v e l s a l l h a v e basis,  Corresponding  2  i nthe metal-metal  a measure  orbitals  a n d Re (C0).jQ were a l s o a s s i g n e d ,  IV-2 a r e a s s i g n e d t o involved  spectrum  „  V  --.y  -  c  > f fars(COj^ReMn(C0) 4  (7,9,15,16).  2  (a-*-c*) t r a n s i t i o n s  i n (L-L)M (C0) 2  those i nthe corresponding  M (C0)^Q 2  g  a r e higher than  indicating  by t h e l i g a n d s h a s w e a k e n e d t h e m e t a l - m e t a l It s h o u l d be mentioned order o f the metal-metal i.e.  >  i s r o u g h l y t h e o r d e r Re-Re > Re-Mn >  Mn-Mn s u g g e s t e d b y t h e R a m a n s t u d i e s o f M ( C O ) -j Q The  4  bond  substitution  bond.  that although the relative  strength i n (L-L  )M (C0) 2  R e - R e > R e - M n > Mn-Mn, a s d e t e r m i n e d b y t h e . -  u l t r a v i o l e t metal -metal  (c-*a*)  t r a n s i t ions ,  p a r a l l e l s trie Raman r e s u l t s o b t a i n e d f o r t h e p a r e n t  8  ,  - 75 -  carbonyls, M (C0) 2  1 Q  the e l e c t r o n impact that the metal-metal  ( M = R e , M n ) ( 7 , 9, 1 5 , 1 6 ) , s t u d i e s (18) have i n d i c a t e d bond s t r e n g t h f o r M (C0).|Q i s i n 2  t h e o r d e r Re-Mn ( 2 . 1 8 e v ) > R e - R e ( 1 . 9 4 e v ) > Mn-Mn (1.08 e v ) .  Other methods  o f o b t a i n i n g t h e bond  strength  include measurements  o f h e a t o f s u b l i m a t i o n [AH(Mn-Mn) =  34 ± 1 3 k c a l m o l e " ]  (19) a n d bond d i s s o c i a t i o n energy  1  [ D ( M n - M n ) = 21 ± 3 k c a l m o l e " ]  (20).  1  metal  bond s t r e n g t h s i n R e ( C 0 ) ^ 2  known b y t h e s e  methods.  IV. ?.(C) M2ss  Spectra  So f a r , t h e  metal-  a n d ReMn(CO)^Q.are n o t  0  The mass s p e c t r a o f t h e r e l a t e d c o m p l e x e s f fosRe (C0) , 4  2  are l i s t e d  8  f fars.Re (C0) 2  4  i nTables  features will  8  f fars(C0) ReMn(C0)  and  4  4  IV-3 t o IV-5 a n d t h e i r  general  now b e d i s c u s s e d t o g e t h e r b e c a u s e o f  their similarities. confirm the general  As expected,  t h e mass  spectra  formulation (L-L)M (C0) 2  8  f ^ f o s , f g f a r s ; M = R e , Mn) a n d show, w i t h i n error o f ±5, parent m u l t i p l e t s due t o the ion.  (L-L = counting  molecular  In the case o f f f o s R e ( C 0 ) , the c a l c u l a t e d  intensities  4  2  8  f o r the parent m u l t i p l e t agree  with the observed  intensities  very well  (Table IV-6), further  4  - 76 -  substantiating the correctness of the formulation. general, the molecules fragment  In  by l o s s o f c a r b o n y l  groups with peaks a t t r i b u t a b l e to [ m o l e c u l a r i o n - n ( C 0 ) ] n = 0,3,4,5,6,7,8).  In a d d i t i o n , t h e mass s p e c t r a show  peaks a t t r i b u t a b l e t o f ^ f o s R e * and ( L - L ) M f ^ f o s , f g f a r s ; M = Re, Mn). l a t t e r peaks  methyl  (L-L =  + 2  The h i g h i n t e n s i t y o f t h e  indicates that the dimetallic  r a t h e r s t a b l e as a r e f l e c t i o n bonds.  +  ions are  of the strong metal-metal  Other f e a t u r e s of the spectra i n c l u d e loss of groups, f l u o r i n e atoms, and a r s e n i c - m e t h y l groups. It i s a l s o i n t e r e s t i n g t o note t h a t  c o n d i t i o n s employed  under  (210°C) t o v o l a t i l i z e the  samples  i n t h e mass s p e c t r o m e t e r , t h e mass s p e c t r a o f f ^ f a r s R e ( C O )g 2  and i - f ^ f a r s R e ^ ( C 0 ) g a r e i d e n t i c a l . of f^farsMn^(C0)g i s identical  with that of i - f ^ f a r s M n ( C O ) . 2  This indicates that f^farsM (CO) 2  S i m i l a r l y the spectrum  g  (M = R e , Mn)  have  rearranged to t h e i r isomers, i - f ^ f a r s M ( C 0 ) , at high 2  temperature  i n t h e mass s p e c t r o m e t e r .  unexpected,  s i n c e i t has been  g  This i s not  found t h a t f ^ f a r s M ( C 0 ) g 2  do r e a r r a n g e t o t h e i r i s o m e r s o n h e a t i n g ( C h a p t e r I I I ) . In t h e c a s e o f f g f a r s ( C O ) R e M n ( C O ) ^ , 4  Of t h e r m a l r e a r r a n g e m e n t  the i n i t i a l  product  i n t h e mass s p e c t r o m e t e r i s  C, s i n c e t h e m a s s s p e c t r u m o f f ^ f a r s ( C O ) ^ R e M n ( C O ) ^ peaks a t t r i b u t a b l e t o A (x = 4 - 0 ) .  No p e a k s  c a n be  shows  g  Me  0  (CO)/  Mn<—As (COh Me  .Re(CO),  AsMe2 F  Mn(CO).  2  2 AsMe,  - 78 -  References  1.  L . F . Da h i , E . I s h i s h i a n d R. E . R u n d l e , Phys., 26, 7150 (1957).  J . Chem.  2.  L . F . D a h l a n d R. E . R u n d l e , 419 ( 1 9 6 3 ) .  3.  M. F . B a i l e y a n d L . F . D a h l , I n o r g . C h e m . , 4, 1 1 4 0 (1965).  4.  H. M. G a g e r , J . L e w i s a n d M. J . W a r e , C h e m . 616 ( 1 9 6 6 ) .  5.  I . J . H y a m s , D. J o n e s a n d E . R. L i p p i n c o t t , J . C h e m . S o c , ( A ) , 1 9 8 7 (1 9 6 7 ) .  A c t a C r y s t . , 16,  Commun.,  6.. D. M. A d a m s a n d A. S q u i r e , J . C h e m . S o c , ( A ) , 281 7 (1 9 6 8 ) . 7.  C. 0. Q u i c k s . a l l a n d T . G. S p i r o , 2363 (1969).  8.  D. M. A d a m s , M. A . H o o p e r a n d A . S q u i r e , J . C h e m . S o c . , ( A ) , 71 ( 1 9 7 1 ) .  9.  J . P. F a w c e t t , A . J . P o e a n d M. V . T w i g g , Commun., 2 6 7 (1 9 7 3 ) .  10.  R. A . L e v e n s o n ,  I n o r g . C h e m . , 8_,  Chem.  H. B. G r a y a n d G. P. C e a s a r , J .  A m e r . C h e m . S o c , 9 2 , 3 6 5 3 (1 9 7 0 ) . 11.  R. B. K i n g , J . A m e r . C h e m . S o c , 8JS, 2 0 7 5  12.  R. E . W i n t e r s a n d R. W. K i s e r , J . P h y s . C h e m . , 6 9 , 1 6 1 8 (1 9 6 5 ) . F . J . P r e s t o n a n d R. I . R e e d . , C h e m . C o m m u n . , 51 (1 9 6 6 ) . J . L e w i s , A . R. M a n n i n g , J . R. M i l l e r a n d J . M. W i l s o n , J . C h e m . S o c . , ( A ) , 1 6 6 3 (1 9 6 6 ) .  13. 14.  (1966).  - 79 -  15.  R. E . D e s s y  a n d P. M. W e i s s m a n , J . A m e r . C h e m . S o c ,  88, 5124  (1966).  16.  G  17.  J . P. C r o w , W. R. C u l l e n , F . L . H o u , L . Y. Y. C h a n a n d F . W. B. E i n s t e i n , C h e m . Commun., 1 2 2 9 ( 1 9 7 1 ) . H. J . S v e c a n d G. A. J u n k , A m e r . C h e m . S o c , 8_9, 2 8 3 6 (1 9 6 7 ) a n d J . C h e m . S o c , ( A ) , 21 02 (1 9 7 0 ) . F . A . C o t t o n a n d R. R. M o n c h a m p , J . C h e m . S o c , 5 3 3 (1960).  18. 19.  v  W. P a r s h a l l , J . A m e r . C h e m . S o c , 8 6 , 361 (1 9 6 4 ) .  20.  D. R. B i d i n o s t i a n d N. S. M c l n t y r e , C a n . J . C h e m . , 48_, 5 9 3 (1 9 7 0 ) .  21.  W.-R.  C u l l e n , D.. C. F r o s t a n d W. R. L e e d e r , J . F l u o r i n e C h e m . , 1, 2 2 7 ( 1 9 7 1 / 7 2 ) .  - 80  -  CHAPTER V K i n e t i c s of Iodine Cleavage  The R e (C 0 j -j 2  0  dimer,  2  produce  M n ( C 0 ) I and  5  bonds.  complexes,  In t h e c a s e o f  of this thesis, t u r e ..to y i e l d  2  prepared  bonds (Chapter  III).  2  metal  i n Chapter. II  metal-  of i n t e r e s t  study the k i n e t i c s of these r e a c t i o n s i n o r d e r t o the mechanisms i n v o l v e d .  tempera-  with cleavage of the  T h u s , i t was  a  occur  r e a d i l y r e a c t w i t h i o d i n e a t room  (L-L)[M(CO)^ I]  the  iodine also produces  H o w e v e r , t h e new  (L-L)M (C0)g,  and  r e s p e c t i v e l y with  [ R e (CO J ^ . I ^ • A l l t h e s e r e a c t i o n s o n l y  slowly at high temperature.  metal  Re(C0) I  5  carbonyl, reaction with  carbonyl  Bonds  r e a c t i o n s of i o d i n e w i t h Mn (C0)-jQ  cleavage of the metal-metal rhenium  of Metal-Metal  to  understand  -  V. 1 .  81  -  I n t r o d u c t i on .  It i s well e s t a b l i s h e d carbonyl  t h a t a d i n u c l e a r metal  compound c o n t a i n i n g a m e t a l - m e t a l  bond  i s cleaved  by h a l o g e n s t o f o r m t h e c o r r e s p o n d i n g h a l o g e n o m e t a l carbonyl  (1).  derivative  preparation o f  [ M ( C 0 )  g  In p a r t i c u l a r , (M  X ]  the standard  = Mn, T c o r R e ; X = C l , B r ,  or I) ( 2 - 4 ) i n v o l v e s the c l e a v a g e o f metal-metal by the halogens.  [M (C0)-|Q] 2  reactions of [Cr (CO) 2  [ { M O ( T T - C  and  5  H  5  ) ( C 0 )  [ ( M ( T T - C  5  H  3  }  2  ]  Other direct halogenation  ] "  [{Fe(CO) PMe } ]  ( 5 ) ,  2  3  ( 8 ) , [ { M ( T T - C  ) ( C 0 ) }  5  ] Q  2  ]  ( 1 4 , 1 5 )  5  H  5  yield  ) ( C 0 )  }  2  2  ]  ( 9 - 1 3 ) ,  [Cr(C0) I]~, 5  (X = C l , B r , o r I ) , [ M O ( T T - C  [M(ir-C H ) ( C 0 )  (M  5  and  2  2  5  [ M ( T T - C  5  H  5  X ]  2  =  F e , Ru,  or  Os;  More r e c e n t l y , t h e r e a c t i o n triosmium with halogens i nrefluxing  bromine complexes  =  Cl,  H  5  ) ( C 0 )  3  I ] ,  Br, orI ) ,  o f dodecacarbonylbenzene  h a s been  i n r u p t u r e o f o n e Os-Os bond  to yield  l i n e a r complexes In a d d i t i o n ,  X  5  (M = N i o r P t ) r e s p e c t i v e l y .  ) ( C 0 ) I ]  shown t o r e s u l t  ( 6 - 7 ) ,  2  2  [{Fe(C0) XPMe > ] 3  bonds o f  0s (C0)^ X 3  2  2  products ( 1 6 ) .  as the i n i t i a l ( 1 7 ) have  Stone a n dco-workers  reported that  o r iodine react with the metal-metal  bonded  [(Me Si)Ru(CO) ] , [(Me Ge)Ru(C0) ] and 3  [(Me^Si)0s(C0) 1 4  [(Me3M)M'.(C0)4X]  4  2  2  i n hexane (M  =  S i or  4  3  2  t o form t h e compounds t r a n s Ge;  M'  =  Ru  or  Os;  X  =  Br  o rI ) .  - 82 -  Despite cleavage  these  reactions  relatively  reports  on t h e h a l o g e n  of metal-metal bonds, there  few m e c h a n i s t i c  in the f o l l o w i n g  V. l . ( A )  numerous  studies.  have  been  These are summarized  sections.  K i n e t i c Study of the Reaction  of  Mn (C0) 2  1 Q  w it h Ig .  H a i n e s , Hopgood the  r e a c t i o n o f Mn (C0).|Q 2  The k i n e t i c  with  iodine  studied  in decalin  ^ 5  rate law:  0  to the rate constant  ^  =  s  ^5  +  a  w n  f o r decomposition  oxygenated s o l u t i o n and the s e c o n d - o r d e r r a t e K , b  i s assumed  to a r i s e from a bimolecular  between i o d i n e and manganese energy f o r the bimolecular  carbonyl. path  i s 31  a r e a c t i o n scheme  which involves  given  [Mn (C0) 2  [Mn(C0) -] 5  5  2  » 2Mn(C0) 5  in  constant,  Kcal/mole. agreement  [1] to [ 3 ] ,  as t h e p r i m a r y  v==*.-[Mn(C0) -]  1 0  ere  The a c t i v a t i o n  in equations  Mn-Mn b o n d f i s s i o n  a  reaction  The r e s u l t s a r e a l l i n q u a n t i t a t i v e with  in detail  r e s u l t s i n d i c a t e that the reaction follows  pseudo-first-order Ka i s equal  and Poe ( 1 8 , 1 9 ) have  step.  [1]  2  » 2Mn  + 10 •  CO [2]  - 83  [Mn(CO) -] 5  The  2  homolytic fission  + i  > 2Mn(C0) I  2  radicals,  in a s o l v e n t cage.  r e a c t i n a v a r i e t y of ways: equation  [1].  a pair  [Mn(C0) '] ,  These  5  which  2  radical  p a i r s then  (i) recombination  as shown i n  ( i i ) d i f f u s i o n out of the s o l v e n t  f o l l o w e d by r a p i d d e c o m p o s i t i o n of carbon  [3]  5  o f t h e Mn-Mn b o n d p r o d u c e s  of manganese pentacarbonyl are trapped  -  cage  i n v o l v i n g complete  m o n o x i d e as shown i n e q u a t i o n  d a t i o n by i o d i n e , as shown i n e q u a t i o n  [2].  loss  (iii)  [ 3 ] , to  oxi-  form  Mn(C0) I . 5  Although  the p o s t u l a t e of a r a d i c a l  chemically satisfying  i n view  the k i n e t i c s themselves  of the nature of the r e a c t i o n s  do n o t r e v e a l a n y t h i n g a b o u t  nature of the s p e c i e s produced  in equation  excited  Mn (C0)-|Q or  product which  re-forms  a c c o r d i n g to f i r s t - o r d e r  2  k i n e t i c s , and which  with i o d i n e according to second-order the data e q u a l l y w e l l . also proposed  in which  pair is  Thus,  [1].  Any  decomposes can  react  k i n e t i c s would f i t  an a l t e r n a t i v e m e c h a n i s m  r e v e r s i b l e metal  migration  atom w i t h a v a c a n t  c o o r d i n a t i o n s i t e at which  ther r e a c t i o n could take place.  T h i s m e c h a n i s m has  was  occurs  to form a c a r b o n y l b r i d g e d i n t e r m e d i a t e A c o n t a i n i n g metal  the  one furthe  -  84  -  0  II  c <CQ>Mn 4  Mn(CO), A  I  advantage  o fp r o v i d i n g a simple e x p l a n a t i o n f o r such  r e a c t i o n s a s the smooth into metal-metal  bonds  i n s e r t i o n o fstannous h a l i d e s (20), as well as being consistent  with the k i n e t i c data then a v a i l a b l e . m e c h a n i s m was  this  c o n s i d e r e d t o be l e s s l i k e l y a t the  by H a i n e s , H o p g o o d and  -V. l . ( B )  However,  time  Poe.  K i n e t i c Study o fthe Reaction o f R e ( C 0 ) 2  w i t h I£ .  1 0  .  More r e c e n t s t u d i e s o f the i o d i n a t i o n o f Re (C0) 2  1 Q  i n d e c a l i n b y H a i n e s and Poe  shown t h a t t h i s  reaction  (21,22)  is better explained in  of the carbonyl b r i d g e d i n t e r m e d i a t e formed  have terms  by r e v e r s i b l e  - 85  metal m i g r a t i o n . described  The  -  homolytic  fission  i n S e c t i o n V. l . ( A ) was  mechanism  considered  less  favourable because a quite unreasonably  high p r o b a b i l i t y  had  of the  t o be a s s i g n e d t o t h e r e c o m b i n a t i o n  radical's i n order to e x p l a i n the o b t a i n e d  free  kinetic  para-  meters. The  r e a c t i o n o f Re^CCOj-jQ w i t h  p s e u d o - f i r s t - o r d e r r a t e law: Ka i s only approximately  K  Q b s  = K  determinable  Q  follows a + K  b  [ I ] where 2  but i t i s  essentially  t h e same as t h e r a t e o f t h e m e t a l - m i g r a t i o n r e a c t i o n . The  a c t i v a t i o n parameters of the b i m o l e c u l a r path are  different  from those  f o r the c o r r e s p o n d i n g  manganese d e c a c a r b o n y l . explained  very  r e a c t i o n of  T h e s e r e s u l t s c a n a l l be  i n t e r m s o f t h e b a s i c scheme shown b e l o w .  Re (C0)-| 2  0  i  *  Excited  The  Intermediate I.  Decomposition-  Re(C0) I + .[Re(C0) I] 5  5ex-ci t e d i n t e r m e d i a t e i s f o r m u l a t e d s p e c i e s , B, w i t h no m e t a l - m e t a l  co-ordinatively  unsaturated  as a c a r b o n y l - b r i d g e d  bond and w i t h one  atom c o - o r d i n a t i v e l y u n s a t u r a t e d .  4  Re  F u r t h e r a t t a c k on  Re a t o m b y i o d i n e l e a d s  the to  2  - 86  -  0  11  c  /  \  R@(CO)  5  B  Re(CO) I  which  r  can  react f u r t h e r to produce  I t s h o u l d be n o t e d tion  in the absence  greater f o r rhenium and  [Re2(C0) I]2 4  carbonyl than f o r  is  decomposi-  relatively manganese.carbonyl,  product of the r e a c t i o n with  i o d i n e i n a d d i t i o n to R e ( C 0 ) I , g  formed  0  t h a t the r a t e of  of other reagents  i s a major  [Re(CO).I] .  whereas only Mn(C0) I i s  d i r e c t l y from the r e a c t i o n with  g  manganese  carbonyl. In t h e m o r e r e c e n t k i n e t i c ' s t u d i e s ( 2 3 , 2 4 ) o f a v a r i e t y of metal-metal workers  have c o n c l u d e d  are compatible with  b o n d e d c a r b o n y l s , Poe  and  that a l l t h e i r r e s u l t s but  initial  r e v e r s i b l e metal  to form carbonyl b r i d g e d i n t e r m e d i a t e s , the  coone  migration exception  - 87  being the h o m o l y t i c f i s s i o n  -  o f t h e Mn-Mn b o n d i n  [Mn(C0) PPh ] . 4  3  2  The  metal  migration hypothesis is  w i t h t h e w e l l known m e t h y l r e a c t i o n s of bases assisted  "methyl  migration process  with CH Mn(C0) 3  There  2  evidence  Re (C0)-|Q due 2  atom and  the  a r e known  bond energy  of  to c r o s s - i n t e r a c t i o n between  the t e r m i n a l carbon  d i r e c t l y bonded to the o t h e r metal  monoxide l i g a n d  atom.  of the above s t r u c t u r a l , t h e o r e t i c a l  and  Thus,  in  kinetic  pentacarbonyl  radical  view  data,  t h e c a r b o n y l b r i d g e d i n t e r m e d i a t e s , shown as A and f a v o u r e d over the metal  (26).  (27) t h a t t h e r e i s  c o n t r i b u t i o n to the metal-metal  M n ( C 0 ) ^ Q and  the s o l v e n t -  Many s t a b l e s t r u c t u r e s  c a r b o n y l s w i t h b r i d g i n g CO g r o u p s  important  in the  migration" successfully explains  is also theoretical  a metal  i n which  5  formation of C H g C O M n ( C O ) ( 2 5 ) . of metal  analogous  B,  are  p a i r s as  the r e a c t i o n i n t e r m e d i a t e s . In t h e i r m o s t r e c e n t k i n e t i c s t u d i e s , h o w e v e r , Poe  and  co-workers  of metal-metal  (28) have found  that several reactions  bonded c a r b o n y l s obey a r a t e law  t e r i s t i c of r e v e r s i b l e homolytic fission metal  bond as t h e f i r s t  reactions  charac-  of the  metal-  stage of the r e a c t i o n .  i n c l u d e the r e a c t i o n of [Re(C0) PPh,] / 1  These 9  with  - 88  -  triphenylphosphine,  decomposition  decalin  and  under argon  (CO) ReMn(CO) 5  5  under a i r , decomposition  i n the presence  r e a c t i o n of [Ru(CO) SiMe-j^ 4  to y i e l d e q u i v a l e n t amount Ru(CO) (PPh ) (SiMe )2. 2  3  2  o f R e 2 ( C 0 ) ^ Q and via carbonyl  V. l . ( C )  The  3  MngCCOj^Q  bridged  of Mn^CCO)^ in  W1  ^  o f o x y g e n , and n  of  the  triphenylphosphine  of Ru(CO) (PPh ) 3  3  and  2  iodine cleavage apparently  can  reactions  still  proceed  intermediates.  K i n e t i c Study  of the Reactions  0s (C0)^2  of  3  wi t h H a l o g e n s .  The  reaction of Os^CCO)^*  cule of c y c l i c Br, and  (D ) 3 h  s t r u c t u r e , with  I i n b e n z e n e has  breakage  been found  trinuclear  a  X , 2  where X = Cl ,  to r e s u l t  of a s i n g l e osmium-osmium bond w i t h  o f 0 s ( C O ) -j 2 2 ' * X  ne  3  mole-,  in  the  production  s t r u c t u r e of which contains a  l i n e a r a r r a n g e m e n t of osmium atoms (16),  unique  X0s(C0) 4  0s(C0) -0s(C0) X. 4  4  The determined apparatus  r e a c t i o n r a t e s i n methylene c h l o r i d e were  spectrophotometrically using a (29)  and  t h e f o l l o w i n g s c h e m e was  to e x p l a i n the k i n e t i c o b s e r v a t i o n s  stopped-flow put  forward  f o r the r e a c t i o n of  -  0s (CO) 3  with C l  1 2  0s (C0) 3  suggested  and  Br,  base  and  Br : 2  fast + X ^==^ [ 0 s ( C 0 )  1 2  The  2  2  3  intermediate  bridged  t h i s cannot  and  2  be e l i m i n a t e d .  the p r o d u c t , The  Kcal/mole  -X ]  >  2  0s (C0) 3  [0s (C0) 'X ]»' 3  1 2  w n e r e  and  =  c  2  0s (C0)-j . 3  x  1 2  a s C was  not  F u r t h e r a t t a c k on  Os a t o m b y X  2  l  acid/  Although  2  X  a considered,  the  would then  2  lead  XOs ( CO ) - 0 s (CO , ) ~ 0 s (CO ) 4 X . 4  4  A H ^ values were found 1 2 . 7 ± 0 . 2 Kcal/mole  respectively, while and  1 2  intermediate such  co-ordinatively unsaturated to  slow  c o u l d be a c h a r g e - t r a n s f e r o r a L e w i s  complex between X  carbonyl  -  89  - 1 4 . 9 ± 1 . 0 e.u.  t o be 1 1 . 8 ± 0 . 7  for C l  2  and  Br  2  the A S ^ v a l u e s were - 1 5 . 9 ± 2 . 4 respectively.  e.u.  - 90  The methylene  r e a c t i o n between 0 s ( C 0 ) - j 3  c h l o r i d e was  kinetically  V. l . ( D )  in great  The  -  complicated  and  2  and  was  not  Mechanism of Halogenation  (C0) ]X  of  both  (R = H o r Me;  3  that these  of Tetracarbonyl-  [ Fe ( TT-RC H ) (CO) X ] 5  4  reactions proceed  v i a two  5  paths  while the  of the  2  observation that these in solution  to form  The  in the formation  the  halide ions  suggests  2  type  that  o f [ Fe ( I T - R C ^ H ^ )  g e n e r a l m e c h a n i s m i s shown i n scheme V - l  i t accounts  of the type  4  (30).  other  r e a c t i o n s and  compounds r e a c t with  [Fe(7r-RCgH )(C0) X]  they are intermediates (C0) X].  these  2  4  parent  F u r t h e r , the i s o l a t i o n of compounds of the 4  f o r the h a l o g e n a t i o n  of a l l compounds  [ { F e ( T r - d i e n y l ) (CO ) > 3 . 2  The  initial  p h i l i c attack of halogen which  [Fe(ir-RC H )  mechanistic  cleavage  2  demonstrates  cleavage  [{Fe (ir-RCgH ) ( C 0 ) > X ] [ a n i o n ] from  and  its Derivatives.  and  2  X = C l , B r , o r I)  i n v o l v e s u l t i m a t e symmetric  2  studied  2  One i n v o l v e s u l t i m a t a a s y m m e t r i c  dimer.  in  of [{FeCiT-RCgH^) ( C 0 ) } ] ,  In t h e h a l o g e n a t i o n formation  2  detail.  bi s-7r-cycl o p e n t a d i eny 1 d i - i ron and  the  I  2  step i n the scheme i s the on t h e i r o n d i m e r ,  i s f o l l o w e d by t h e f o r m a t i o n  of the  electro-  step [1], 'iodonium'  -  dienyl  o  Fe—p  e  o  -  dienyl \  dienyl  \ A /  91  • X-  [1]  v  o o  dienyl /  /  \  —* Fe  y  Fe  /|\ / V  •  o x  o  o  [2] "dienyl  dienyl  dienyl  o  \ / \/  dienyl  x  Fe / \  rs  /  o-7 \  / *  \  \  V  /  [5] dienyl  dienyl 2  Fe o o  • X"  Fe  o  O  o o  decomposition Scheme  V-1  c  o  products  - 92  intermediate,  D,  symmetrically  with  involves  the  the  respect  bridging  to the  asymmetric cleavage  groups of the while  i n which the  -  a l t e r n a t i v e path, of these  [ { Fe ( TT-RCgH^ ) ( CO) 2 ^ X J X of halide ions  on  is  i r o n atoms. of the  situated  Step  bridging  [3]  carbonyl  d i m e r to y i e l d [Fe (ir-RCgH^) (C0),j]X  parent  symmetric cleavage  iodine  step  [4], involves  carbonyl  the  groups to  afford  . Subsequent n u c l e o p h i l i c  t h i s l a t t e r d e r i v a t i v e , step  produces the n e u t r a l  compound  attack  [5],  [ Fe ( I T - R C g H ^ ) ( C O ) X ] . 2  This  p r o p o s e d m e c h a n i s m shows many s i m i l a r i t i e s w i t h  well  established  mechanism f o r the e l e c t r o p h i 1 i c  the  addition  of halogens to o l e f i n s .  V.  2.  Experimental  V.  2.(A)  Starting  The (L-L  metal carbonyl  = f g f a r s , f g f a r s ; M = Re,  described was  Materials.  in chapter  complexes, Mn),  II of t h i s t h e s i s .  grade.  2  y  were prepared  p u r c h a s e d f r o m F i s h e r S c i e n t i f i c Co.  c e r t i f i e d A.C.S.  [(L-L)M (CO) ] as  The  iodine  and  is  used  resublimed  - 93 -  V. 2 . ( B ) L o w - T e m p e r a t u r e Magnetic  K i n e t i c Study  Resonance  by N u c l e a r  Spectroscopy.  0 . 4 4 2 4 g o f C D C l ^ was c o n d e n s e d  i n t o an n.m.r.  tube c o n t a i n i n g 0.0252 g o f f g f a r s R e ( C 0 ) . 2  n.m.r. t u b e , 0.0064 g o f l to -75°C,  was a d d e d .  To t h i s  y  i n 0 . 7 1 1 0 g o f CDC 1 , p r e - c o o l e d  0  3  T h e t u b e was k e p t a t - 7 5 ° C  until  t h e V a r i a n HA-100 s p e c t r o m e t e r was r e a d y t o o p e r a t e a t -60°C.  The sample  t u b e was s h a k e n  into the spectrometer. -60°C  The  and i m m e d i a t e l y  n.m.r. s p e c t r u m  i n d i c a t e d t h a t t h e r e a c t i o n was a l r e a d y  and t h a t o n l y t h e p r o d u c t f g f a r s  [Re(C0) I] 4  S i m i l a r l y , 0.0252 g o f f f a r s i n 0.3824 g o f C H C 1 2  tube c o o l e d t o -75°C. I  2  2  complete was p r e s e n t .  2  To t h i s n.m.r. t u b e , 0.0040 g o f 2  spectrometer which  2  was  added.  and p l a c e d i n t o t h e V a r i a n HA-100 was s e t t o o p e r a t e a t - 6 0 ° C .  t h e H n.m.r. s p e c t r u m , 1  8  was p l a c e d i n t o an n.m.r.  i n 0.6463 g o f C H C 1 , p r e - c o o l e d t o -75°C,  The t u b e was s h a k e n  taken a t  Mn (C0)  4  dissolved  2  placed  Again  i n d i c a t e d t h a t t h e r e a c t i o n had  gone t o c o m p l e t i o n . Therefore, the reactions of I  2  with fgfars  Re (C0),  and f g f a r s M n ( C 0 ) g were t o o f a s t t o be s t u d i e d by t h e 2  n.m.r. t e c h n i q u e .  2  - 94 -  V. 2 . ( C ) D e s c r i p t i o n o f t h e S t o p p e d - F l o w  Apparatus.  Since the reaction of (L-L)M (C0) 2  g  with iodine  c o u l d n o t be s t u d i e d by l o w t e m p e r a t u r e  n.m.r. and o t h e r  conventional  apparatus  techniques, a stopped-flow  was u s e d t o s t u d y t h i s Stopped-Flow  fast reaction.  Spectrophotometer  r a p i d l y m i x i n g two l i q u i d the change i n o p t i c a l  system  The Durrum-Gibson o p e r a t e s by  r e a c t a n t s o l u t i o n s and  absorbance  as a f u n c t i o n o f time  at a s e l e c t e d wavelength  in the ultraviolet  region of the spectrum.  The system  the f a c t t h a t t h e flow o f sample  measuring  or visible  d e r i v e s i t s name  i s stopped  a f t e r mixing to permit o b s e r v a t i o n o f changes  from  immediately in optical  absorbance  without i n t e r f e r e n c e from t u r b u l e n c e or flow  artifacts.  The r e a c t i o n o f t h e s o l u t i o n s i s o b s e r v e d  by p h o t o m e t r i c a l l y m o n i t o r i n g t h e t r a n s m i s s i o n o f l i g h t through a p o r t i n the mixing chamber c u v e t t e . output level  The  s e n s e d by t h e p h o t o m u l t i p i i e r i s a p p l i e d  to a c a t h o d e - r a y o s c i l l o s c o p e , where i t i s d i s p l a y e d a g a i n s t a time base. the photometer  system  Monochromatic so t h a t each  light  i s used i n  r e a c t i o n c a n be s t u d i e d  at i t s optimum a b s o r p t i o n peak. The apparatus  principal  advantage  of the Durrum-Gibson  i s that i t provides a practical  and r e a d i l y -  - 95 -  a v a i l a b l e means f o r m e a s u r i n g  r e a c t i o n r a t e s which are  " i n s t a n t a n e o u s " o r t o o f a s t t o be m e a s u r e d tional  techniques.  by  conven-  Using a p p r o p r i a t e s o l u t i o n s and  operating conditions,  the instrument provides 99.5%  m i x i n g o f two c o m p o n e n t s  i n 2 m i l l i s e c o n d s f o r a 2 0 mm  c u r v e t t e and p e r m i t s o b s e r v a t i o n o f r e a c t i o n h a l f - t i m e s as s h o r t as 5 m i l l i s e c o n d s . The  stopped-flow spectrophotometer  five functional  systems  comprises  (see Figure V - l ) :  (1) t h e m i x i n g chamber which  i s the heart of the stopped-  flow system and c o n t a i n s the sample  flow  system,  e n t r a n c e o p t i c s , and p h o t o m u 1 t i p 1 i e r t h a t p e r m i t sample  m i x i n g and r e a d o u t o f t h e r e s u l t a n t  optical  absorbance. (2) t h e f l o w a c t u a t i n g system which flow system f o r each (3) t h e o p t i c a l  activates the  sample  measurement.  system which  l i g h t by means o f a l i g h t  supplies  monochromatic  source and  monochromator,  and r o u t e s i t t h r o u g h t h e measurement c u v e t t e and into the photomultipiiercontained i n the mixing chamber.  The l i g h t  sten-iodide operation lamp w h i c h  s o u r c e c o n t a i n s a 60-Watt  lamp w h i c h  f u r n i s h e s the continuum f o r  f r o m 3 5 0 t o 8 0 0 nm a n d a 2 5 - W a t t completes  tung-  deuterium  the energy coverage of the  F i g u r e V-1.  Functional  Block Diagram of Stopped-Flow Spectrophotometer System.  - 97 -  short wavelength 375  end o f t h e spectrum  f r o m .185 t o  nm.  (4) t h e t e m p e r a t u r e  c o n t r o l system,  w h i c h i s n o t shown  Haake  thermostat,  i n Figure V - l but maintains a l l  parts of the flow system  at a constant  temperature  to a v o i d t e m p e r a t u r e - g r a d i e n t r e f r a c t i o n  artifacts  t h a t c o u l d make t h e d i s p l a y m e a n i n g l e s s . (5) the e l e c t r o n i c  system which contains the o s c i l l o -  scope d i s p l a y unit oscilloscope),  ( T e k t r o n i x 5B1 ON T i m e B a s e / a m p l i f i e r  power s u p p l i e s f o r t h e l i g h t  source  and p h o t o m u l t i p i i e r tube and t r i g g e r s w i t c h supplies the signal  which  to trigger the h o r i z o n t a l d i s p l a y  sweep i n t h e o s c i l l o s c o p e j u s t b e f o r e t h e sample flow stops i n the sytem. The  f o l l o w i n g m o d i f i c a t i o n s of the apparatus  were found n e c e s s a r y d u r i n g the c o u r s e o f the  experiments.  The d r i v e s y r i n g e s i n t h e m i x i n g c h a m b e r were  originally  e q u i p p e d w i t h two c e r a m i c p l u n g e r s w h i c h w e r e f o u n d n o t s u i t a b l e f o r use with d i c h i o r o m e t h a n e two t e f l o n  solvent.  plungers f i t t e d with special  r i n g s were used  (the original  by t h e m a n u f a c t u r e r  rubber  with the teflon  swollen i n the dichioromethane  Consequently,  i n e r t V i t o n "0"  "0" r i n g s s u p p l i e d p l u n g e r s became  solvent).  I t was  also  found that the i o d i n e s o l u t i o n s s l o w l y decomposed i n the  - 98 -  Tomac d i s p o s a b l e syringes  reservoir syringes  h a d t o be u s e d .  only materials-'which  and g l a s s  After the modifications  came i n t o c o n t a c t  were s t a i n l e s s s t e e l ,  reservoir  with  Teflon, glass, Viton,  the  the samples and  Kel-F  (polytrichlorofluoroethylene).  V. 2 . ( D ) E x p e r i m e n t a l  Procedure.  With appropriate syringes either  were f i l l e d 2  Then, with  settings, the drive  from the r e s e r v o i r syringes  (L-L )M (CO)g or I  solvent.  valve  dissolved  2  valves  time measurement, the flow  in dichloromethane  reset f o r making a r e a c t i o n actuator  i s a c t i v a t e d to cause  the d r i v e u n i t t o f o r c e the d r i v e s y r i n g e slightly.  This  sample with  forces  equal  volumes  t h e 20 mm c u v e t t e )  solutions  to mix i n the mixing  cuvette.  Flow i s a b r u p t l y  reaction turbulence  takes  place  w h i c h was a c t u a t e d plunger, for  plungers  ( 0 . 1 5 ml and  2  minimum  (L-L)M (C0)g 2  j e t and flow  halted  through the  a t that point and the with  a minimum o f  Meanwhile, the t r i g g e r  by t h e movement o f t h e s t o p  has i n i t i a t e d  the horizontal  the oscilloscope display.  obtained  of I  in the cuvette  interference.  containing  switch, syringe  time base sweep  The monochromatic  light  from the monochromator passes through the mixed  -  solution  i n the mixing  99  -  chamber  cuvette  during the  r e a c t i o n and t h e r e s u l t a n t v a r y i n g  intensity light i s  projected  tube.  onto the photomu1tipiier  m u l t i p l i e r output oscilloscope.  drives the vertical  reaction  i n t e n s i t y v s . time,  the reaction begins  has been c o m p l e t e d .  tube can r e t a i n several observation  axis of the  The r e s u l t a n t o s c i l l o s c o p e d i s p l a y  indicates transmitted- 1ight just before  The photo-  before  and ending  after the  The o s c i l l o s c o p e  successive  photographing  traces f o r  the displayed  U s u a l l y , t h e k i n e t i c e x p e r i m e n t s were repeated successive  remaining  The k i n e t i c data  sections of this chapter  average values  o f two s u c c e s s i v e  It should  storage comparative information. and two  t r a c e s o f t h e r e a c t i o n were o b t a i n e d  a Polaroid camera.  starting  presented  by  using  in the  are usually the kinetic  runs.  be m e n t i o n e d t h a t a l l k i n e t i c  runs  were performed under p s e u d o - f i r s t - o r d e r  conditions, i . e .  o n e r e a c t a n t was k e p t  This  because f o r second know t h e i n i t i a l order  to obtain  i n large excess.  order  reactions, i t i s necessary  concentrations  to  of the reactants i n  the rate constants.  reactions, the initial  i s done  concentrations  But i n  of the reactants  a r e n o t a c c u r a t e l y known i f t h e h a l f - l i f e s h o r t and some r e a c t i o n h a s o c c u r r e d  stopped-flow  times are  during  the  mixing  - 100 -  time.  Furthermore,  Stewart  (31) has p o i n t e d o u t that t h e  second o r d e r r e a c t i o n r a t e s measured techniques are distorted  by f i n i t e  path lengths while the f i r s t not so a f f e c t e d .  by s t o p p e d - f l o w flow v e l o c i t i e s and  order reaction rates are  T h i s i s a l l t h e more r e a s o n f o r  p r e f e r r i n g t o work w i t h r e a c t i o n s under pseudo-first-order  behaviour.  For t h e k i n e t i c of (L-L)M2(C0)g,  conditions of  r e a c t i o n s u s i n g an excess  t h e r a t e s were f o l l o w e d by o b s e r v i n g  t h e d i s a p p e a r a n c e o f t h e 1^ a b s o r p t i o n p e a k a t 5 1 0 nm. F o r r e a c t i o n s u s i n g a n e x c e s s o f \^ s o l u t i o n , t h e r a t e s were m o n i t o r e d Re (C0) , 2  8  by o b s e r v i n g t h e d i s a p p e a r a n c e o f f g f a r s  fgfars  Re (C0)g, 2  fgfars  f f a r s Mn2(C0)g a b s o r p t i o n peaks 4  3 3 0 n m,  t o 3 3 0 nm r a n g e nm r a n g e  Normally  4  and  f o r o p e r a t i o n i n t h e 185  a g r a t i n g i s used.  In o r d e r t o a v o i d t h e  o f the d i s p e r s i n g element  (C0) ReMn(C0) 4  a r e used  a p r i s m i s used, w h i l e f o rt h e 330 t o  region during the experiments, f fars  4  a t 3 3 0 nm, 3 2 7 nm,  a l t e r n a t i v e d i s p e r s i n g elements  in the monochromator.  change  4  a n d 3 6 5 nm r e s p e c t i v e l y . Two  800  (C0) ReMn(C0) ,  4  i n the ultraviolet  the disappearance o f  w a s o b s e r v e d a t 3 3 0 nm a n d n o t a t  t h e R e - M n ( a + a * ) a b s o r p t i o n p e a k o f 3 4 0 nm.  - 101  V. 2 . ( E )  -  K i n e t i c s of the Iodine Cleavage  The determined  of f . f a r s  Re (C0), 9  k i n e t i c s o f the c l e a v a g e r e a c t i o n s were  under  c o n d i t i o n s of p s e u d o - f i r s t - o r d e r  b e h a v i o u r by u s i n g e i t h e r e x c e s s  I  2  or f g f a r s  Re (C0) . 2  I n a t y p i c a l s t o p p e d - f l o w e x p e r i m e n t , 0.15 ml o f _q 1.18 x 10 M fgfars Re (C0) in dichloromethane -4 2  r e a c t e d w i t h 0.15  g  ml o f 1.10  x 10  M I  g  was  in dichloro-  2  methane a c c o r d i n g to the e x p e r i m e n t a l procedure d e s c r i b e d in the previous s e c t i o n .  The  I  disappearance  2  f o l l o w e d by o b s e r v i n g t h e a b s o r b a n c e visible  r e g i o n a t 510  i s more s e n s i t i v e  nm,  change i n the  since this absorbance  t h a n t h e a->o* t r a n s i t i o n  the presence of excess f g f a r s The  was  a t 330  change nm  in  Re (C0) . 2  g  f o l l o w i n g r e s u l t s were o b t a i n e d at 25°C  from, t h e o s c i l l o s c o p e t r a c e : Table V-l Reaction of Excess t (msec)  fgfars  Re (C0) 2  g  with  concentration of U (arbitrary unit)  0  6.2  ±  0.1  5  4.7  ±  0.1  10  3.6  ±  0.1  l^.  - 102  Table Reaction  V-l  of Excess t  -  (cont'd)  fgfars  (msec)  Re2(C0)  with  y  c o n c e n t r a t i o n of I, (arbitrary unit)  15  2.9  ±  0.1  20  2.1  ±  0.1  25  1.7  ±  0.1  30  1.3  ±  0.1  A graph of l o g [ ^ l ^ , where C ^ ^ t concentration t was  of ^  at time  p l o t t e d ( F i g u r e V-2)  t during  the  ^  s  t n e  reaction,  to g i v e a s t r a i g h t  line,  i n d i c a t i n g t h a t the r e a c t i o n i s p s e u d o - f i r s t - o r d e r I  0  2  concentration  with  t, i s t h e  varying life  x 10 s e c  time  - 1  and  t, =  reaction half-life of ^  time. had  rate  13  constant  Furthermore,  no e f f e c t on t h e  half-  o f t h e r e a c t i o n w h i c h r e m a i n e d a t 13 m s e c .  Thus  i s d e f i n i t e l y Rate = k'[I„] s i n c e t  initial  result  pseudo-first-order  the c o n c e n t r a t i o n  r a t e law the  = 5.34  in  h  m s e c , w h e r e k' i s t h e and  k"  vs.  concentration  is only  x  the  i s independent  f o r a f i r s t - o r d e r r e a c t i o n and  true for a f i r s t - o r d e r reaction.  The r e a c t i o n b e t w e e n and f g f a r s R e 2 ( C 0 ) was r e p e a t e d , u s i n g an e x c e s s o f ^ t h i s t i m e . 0.15 ml -4 o f 9.18 x 10 M I2 s o l u t i o n was r e a c t e d w i t h 0.15 ml o f y  this  of  - 103 -  - 104  1.26  x 10"  M fgfars  was  followed  4  by o b s e r v i n g  Re^CCOjg, i . e . t h e region  Re^(CO)  a t 330  were obtained  nm  -  solution  g  the  a b s o r b a n c e change i n the  was  followed.  The  at 25°C from the  Reaction of f g f a r s t (msec)  oscilloscope  g  plotted that  the  Re2(C0)  g  with  +  0.1  10  2.6  +  0.1  20  1.7  +  0.1  30  1.1  +  0.1  40  0.8  +  0.1  50  0.5  +  0.1  60  0.3  +  0.1  i s the  t  at time t during (Figure reaction  results trace:  V-2  4.0  [fgfars Re (C0) ] 2  fgfars  Excess  l^-  concentration of f g f a r s R e ^ K O ^ (arbitrary unit)  A graph of log  Re (C0)  reaction  ultraviolet  following  0  g  the  disappearance of  Table  2  and  V-3)  [fgfars  Re (C0) ] 2  g  where  t  concentration  of  fgfars  the  vs.  t  to g i v e  reaction, a straight  is pseudo-first-order  line,  was indicating  in f f a r s Re (CO) A  ?  - 105  -  0.6  0.3  0  0.3  t(msec) F i g u r e V-3.  Graph of 1 6 g [ f f a r s R e ( C 0 ) ] vs. t f o r the Reaction of f f a r s R e ( C O ) with I 4  2  4  8  2  t  Q  2 >  -106-  concentration.  Therefore, combining  this with  the  p r e v i o u s r e s u l t , t h e r a t e law i s  Rate = k  o 5 s  [f fars Re (C0)g][I ]. 4  2  2  The e f f e c t o f t e m p e r a t u r e  variation  observed bimolecular rate constant, k over the temperature given in Table  o b s  r a n g e 19 t o 3 5 ° C .  The  4  results  are  with I^.  2  Temperature  Dependence  T° (K)  k  obs  ^  of  3.40  x  10  4  298  4.52  x  10  4  303  5.69  x  10  4  308  7.17  x  10  4  The e x p e r i m e n t a l e n e r g y o f Kcal mole" , 1  Q b s  o f a c t i v a t i o n , AH^  vs. j = 6.9  was  0  s  )  1  activation,  obtained from  (Figure V-4). ± 0.3  k b -  mole^sec"  £  292  graph of log k  studied  V-3  Reaction of f f a r s Re (C0)g  ± 0.3  the  V-3:  Table  E a = 7.5  , was  on  The  Kcal mole , - 1  the  enthalpy was  calculated  - 108  from  the  equation  AH  =  1  E  a  where R i s t h e gas AS^  =. - 1 3 . 8  ± 1.0  AH^  w h e r e AG^  -  RT  constant. e.u.,  =  AG^  was  +  k  obs  h  A 1.86 was  a t 327  was nm.  from  of  the  activation, equation  the  relationship  e e  RT  c o n s t a n t and  h is Planck's  of Iodine Cleavage  x 10'  5  r e a c t e d w i t h a n 8.84  reaction  found  from  where K i s Boltzmann's  Kinetics  entropy  1  £  s  The  TAS "  is calculated  k  V. 2 . ( F )  -  of f f a r s  x 10  M I  Re (C0) ,  g  M solution -4  of fgfars  2  solution  constant  2  Re (C0)g 2  and  f o l l o w e d by o b s e r v i n g t h e a b s o r b a n c e The  results  g  at 25°C are given i n Table  the change V-4.  - 109  -  Table  V-4  Reaction of f g f a r s t (sec)  4.9  +  0.1  0.1  3.8  +  0.1  0.2  2.8  +  0.1  0.3  2.1  +  0.1  0.4  1.6  +  0.1  0.5  1.2  +  0.1  0.6  0.9  +  0.1  V-5)  was  I  2  was  fgfars Since the  plotted  that  the  Re (C0)g  [fgfars  reaction  reaction  Re (C0)  8.84  and  8  an  a straight  x 10~^ x 10"  2  2  a t 510  r e s u l t s were obtained  oscilloscope  t  vs.  t  line,  is pseudo-first-order  Re (C0)g solution  disappearance of I  following  2  between f g f a r s a 9.40  fgfars  Re (C0)g]  to give  repeated, using 2  2  in  concentration.  2  The  I  2  0  indicating fgfars  2  concentration of f g f a r s Re (C0) (arbitrary unit)  A graph of log (Figure  Re (C0)g with Excess  trace:  5  was nm  Re (C0)g 2  M solution M solution  of  in excess this was  followed.  at 25°C from  the  and of I 2  time, The  0 . 6  CO  o  0 3  CJ CM  cu  s-  ra  co «*-  I  I  cn o  0 . 4  0 . 2  t(sec) Figure  V-5.  Graph of  log[f farsRe (.C0) ] 6  the Reaction of  2  g  t  f farsRe (CO) g  2  - Ill -  Table  V-5  R e a c t i o n o f E x c e s s fgfars R e ( C 0 ) 9  0  7.9  ±  0.1  0.1  5.6  ±  0.1  0.2  4.2+0.1  0.3  3.1  ±  0.1  2.4  ±  0.1  0.5  "1.7 ±  0.1  0.6  1.3  0.1  •  The g r a p h o f l o g [ I - ] 2  gave a s t r a i g h t  line,  indicating  also p s e u d o - f i r s t - o r d e rin I  2  vs t  ±  '  t  (  F  l  9  o b s  r  e  v  " ) 6  c o n c e n t r a t i o n . Thus, y  the  with  is  [f fars Re (C0) ][I ]. 6  2  g  The e f f e c t o f t e m p e r a t u r e was  u  t h a t the r e a c t i o n i s  r a t e law f o r the r e a c t i o n o f f g f a r s R e 2 ( C 0 )  Rate = k "  I  c o n c e n t r a t i o n o f 1^ (arbitrary concentration)  t (sec)  0.4  with  B  s t u d i e d over the temperature  results are given in Table  V-6:  2  variation  on  r a n g e 22 t o 3 3 ° C .  k  Q b s  The  -112  —I  -  4->  CsJ  O  0.2 Figure  V-6.  0.4  t(sec) Graph of l o g [ I ] vs. t f o r the f f a r s R e ( C 0 ) with I . 2  6  2  8  t  2  06 Reaction  - 113 -  Table Reaction  V-6  of fgfars Re^tCOjg with I  Temperature Dependence of k , . T°(K)  '  k  obG  s e c  "  )  3  298  3 . 7 5 x 10 3 4 . 8 8 x 10 3  301 306  The A r r h e n i u s  entropy  m o 1 e  2.72 x 1 0 3 . 1 8 x 10 3  295  enthalpy  ^  r a t e p l o t ( F i g u r e V-7) gave  o f a c t i v a t i o n o f 9.3 o f a c t i v a t i o n was  ± 0.9  Kcal m o l e  - 1  .  c a l c u l a t e d . t o be - 1 1 . 1  an  The ± 3.0  e.u.  by t h e m e t h o d d e s c r i b e d i n t h e p r e v i o u s s e c t i o n .  V. 2 . ( G ) K i n e t i c s o f I o d i n e C l e a v a g e o f f f a r s ( C 0 ) 4  4  ReMn(C0) . 4  ReMn(C0)  4  was  r e a c t e d w i t h an 8.84  T h e r e a c t i o n was of f f a r s 4  (o+a*)  x 10"  H  f o l l o w e d by o b s e r v i n g t h e  (C0) ReMn(C0) 4  4  V-7:  disappearance  a t 3 3 0 nm a n d n o t a t t h e R e - M n  a b s o r p t i o n p e a k o f 3 4 0 nm.  are given i n Table  M  4 solution.  The r e s u l t s a t 23°C  - 115 -  T a b l e ' V-7 Reaction  The  o f f . f a r s (CO).ReMn (CO),  Excess I  t (sec)  c o n c e n t r a t i o n o f f g f a r s (CO)^ReMn(CO) (arbitrary unit)  0  3.0 ± 0.1  1  2 . 3 ± 0.1  2  1.6 ± 0.1  3  1.2 ± 0.1  4  0 . 8 ± 0.1  5  0.6 ± 0.1  6  0.4 ± 0.1  graph o f l o g [ f f a r s 4  V-8)  with  (C0) ReMn(C0.) ] 4  4  t  vs. t  (Figure  indicated that the reaction i s pseudo-first-order  in f f a r s (CO) ReMn(CO) 4  4  The  4  concentration.  r e a c t i o n was r e p e a t e d  a t 23°C by u s i n g  a 4.36 x 1 0 " M s o l u t i o n o f f f a r s ( C 0 ) R e M n ( C 0 ) -5 4  4  a 4 . 4 2 x 10  M I  2  solution.  4  From t h e a b s o r b a n c e  a t 5 1 0 nm, t h e f o l l o w i n g t a b l e  (Table  4  and change  V-8) i s obtained.  - 1 1 6  -  - 117 -  Table  V-8  Reaction of Excess f . f a r s  (CO). ReMn(CO). with I concentration of I (arbitrary unit)  t (sec) 0  6.5  +  0.1  2  4.0  +  0.1  4  2.7  +  0.1  6  1.9  +  0.1  8  1 .4  +  0.1  10  1.0  +  0.1  12  0.7  +  0.1  The graph o f l o g - [ I 3 2  that the reaction tration.  t  v s . t ( F i g u r e V-9) a g a i n  is pseudo-first-order in  indicated  ^concen-  T h e r e f o r e the r a t e law i s  Rate = k  o b s  [f fars 4  (CO) ReMn(CO) ][ I ] . 4  The e f f e c t o f t e m p e r a t u r e was s t u d i e d o v e r t h e t e m p e r a t u r e The  0  4  variation  2  on k  r a n g e 21 t o 3 1 ° C .  r e s u l t s a r e g i v e n i n T a b l e V-9:  - 118  -  0.9  0,6  CM  cn  o  -0.3  4  Figure  V-9,  8  12  t(sec) Graph of 1o g [ 1 l vs. t f o r the of f f a r s ( C 0 ) R e M n ( C 0 ) with I 2  4  4  Reaction  t  4  2 >  - 119 -  Table Reaction  of f f a r s  V-9  (C0) ReMn(C0)  4  4  Temperature Dependence T°(K)  k 0  entropy  ^  m  o  1  of k e  e  4.00  301  5.89 x  10  2  304  7.59  10  2  found  4  r e a c t e d w i t h an 8.84  in the stopped-flow  ~  x 10  2  )  Kcal mole" . ± 3.2  of f f a r s  4  apparatus. found  M I  Mn (C0) .  4  4  t h e r e a c t i o n , h o w e v e r , was  e.u.  2.(E).  M solution of f f a r s x 10"  The  1  t o be 1.4  V. 2 . ( H ) K i n e t i c s o f I o d i n e C l e a v a g e  x"10"  2  _.  r a t e p l o t ( F i b u r e V - 1 0 ) g a v e an  o f a c t i v a t i o n was  A 1.50  10  x  h  c  296  o f a c t i v a t i o n o f 1 4 . 2 ± 0.9  2  2  g  Mn (C0) 2  g  s o l u t i o n at 22°C  The h a l f - l i f e  time  t o be l e s s t h a n  which i s the l i m i t of the instrument. r e a c t i o n was  s  3.40 x  by t h e m e t h o d d e s c r i b e d i n V.  was  "'  294  The A r r h e n i u s enthalpy  b3  with I  4  Since  of  2 msec  this  t o o f a s t t o be f o l l o w e d e v e n b y t h e  stopped-  - 120 -  - 121 -  f l o w t e c h n i q u e , no a c t i v a t i o n  parameters  V. 2 . ( 1 ) K i n e t i c s o f I o d i n e C l e a v a g e in the Presence  were o b t a i n a b l e .  of fgfars  of Free Radical  Re (C0)g 2  Scavengers.  25 mg o f 2 , 6 - d i - t e r t - b u t y 1 - p - c r e s o l was a d d e d t o 5 ml  o f 1.86 x 1 0 "  4  M fgfars  Re. (Cb) 2  solution  g  -4 w h i c h was t h e n a l l o w e d t o r e a c t w i t h 8 . 8 4 solution  i n the stopped-flow  the f r e e r a d i c a l  x 10  spectrophotometer.  s c a v e n g e r a b s o r b s a t 3 2 7 nm,  d i s a p p e a r a n c e o f i o d i n e a b s o r p t i o n a t 5 1 0 nm observed.  M I  T h e r e a c t i o n r a t e was  2  Since  the was  f o u n d t o be t h e same  as i n t h e a b s e n c e o f t h e s c a v e n g e r . In a n o t h e r e x p e r i m e n t ,  a second  free  s c a v e n g e r , 2 , 2 - d i p h e n y l - 1 - p i c r y ! h y d r a z y l , was  radical  used.  H o w e v e r , i t was f o u n d t h a t t h i s s c a v e n g e r a b s o r b s s t r o n g l y i n b o t h 3 2 7 nm a n d 5 1 0 nm r e g i o n . of i o d i n e with fgfars  Therefore, the r e a c t i o n  Re (C0)g in the presence of this  free radical  scavenger  stopped-flow  technique.  2  c o u l d n o t be s t u d i e d by t h e  - 122 -  V. 2 . ( J ) T h e I o d i n e C l e a v a g e Presence  o f Sodium  of fgfars Re (C0) 2  in the  y  Tetraphenylborate.  25 mg o f N a B P h ~ w a s a d d e d t o 30 ml  of  +  4  CgHg w h i c h  c o n t a i n e d 25 mg o f I ^ .  8 0 mg o f f f a r s R e ( C 0 ) 4  stirred  2  g  f o r 5 minutes.  To t h i s s o l u t i o n ,  was a d d e d .  No p r e c i p i t a t e was i s o l a t e d .  V. 2 . ( K ) P h o t o l y s i s o f f g f a r s R e ( C 0 ) g 2  A degassed / fgfars  Re (C0)g  in Tetrahydrofuran.  tetrahydrofuran solution of -3  \%1 x 10  2  T h e s o l u t i o n was  M) i n ' a n e v a c u a t e d  n.m.r. t u b e was i r r a d i a t e d w i t h a 1 0 0 - W a t t lamp e q u i p p e d 5 hrs. solution  with  mercury  a 3 3 4 nm i n t e r f e r e n c e f i l t e r f o r  No c o l o r c h a n g e w a s o b s e r v e d . remained  sealed  The i r r a d i a t e d  yellow after the addition of a  dilute s o l u t i o n of 2 ,2-diphenyl -1-pi cry!hydrazyl i n THF.  - 123 V. 3. R e s u l t s  and  V. . 3 . ( A ) K i n e t i c  The (L-L(CO)g technique.  Discussion. Results.  kinetics of the reaction of iodine  was f i r s t  s t u d i e d by low t e m p e r a t u r e  i n t h i s way.  Therefore,  Stopped-Flow Spectrophotometer fast reaction.  Using  the Durrum-Gibson  was u s e d  appropriate  s o l u t i o n s and o p e r a t i n g  concentrations  of  instrument  half-life  times  be m e n t i o n e d t h a t a l l k i n e t i c  experiments  were p e r f o r m e d  ultraviolet  and v i s i b l e  interfere with  i n dich1oromethane.  spectra  the absorption  peaks o f i o d i n e and o f bond.  i s no r e a c t i o n b e t w e e n t h e r e a c t a n t s  room t e m p e r a t u r e  dichloromethane The were found law i s  and a l s o t h e r e a c t a n t s  in this solvent. a suitable  A l l these  order  In a d d i t i o n ,  and the solvent have  good  reasons  make  solvent.  reactions of iodine with  t o be f i r s t  The  o f t h i s s o l v e n t do n o t  t h e o+o* t r a n s i t i o n o f t h e m e t a l - m e t a l  solubility  as s h o r t  seconds. It s h o u l d  rate  this  a p r a c t i c a l and r e a d i l y a v a i l a b l e means f o r  a s 5 mi 1 1 i  at  to study  conditions, this  measuring f a s t reactions with  there  n.m.r.  H o w e v e r , t h e r e a c t i o n was t o o f a s t t o be  monitored  provides  with  i n both  (L-L)M (C0)g  reactants,  2  i.e. the  - 124  Rate =  The a c t i v a t i o n rized in Table  k  o b s  -  [(L-L')M (C0) ][I ]. 2  8  2  p a r a m e t e r s a n d r a t e c o n s t a n t s a r e summaV-10:  ^  Table  V-10  Results of K i n e t i c Study of the Reactions of Iodine with (L-L)M (C0) 2  Reaction  and  g  M (C0) 2  kobs (£mole ^sec )  A H ^ ( K c a l m o l e ) AS^(e.u.) - 1  1  f . f a r s R e „ ( C 0 ) + I-  6.9 ± 0.3  -13.8  ±1.0  4.52 x 1 0 a t 25°C  4  fgfars Re (C0) + I  9.3 ± 0.9  -11.1 ± 3.0  3.18 x 1 0 a t 25°C  3  14.2 ± 0.9  1.4 ± 3.2  3  2  g  2  f f a r s (C0) ReMn(C0) 4  4  f f a r s Mn (C0)g + I 4  2  Re (C0) 2  Mn (C0) 2  1 Q  1 Q  + I  2  + I  2  4  + I  ?  Too f a s t t o be measured  g  16.9 ± 1.2  The p a r a m e t e r s of R e ( C 0 ) 2  1 Q  and M n ( C 0 ) 2  for comparison purposes. these activation  (18,19,21,22)  4  +10  f o r the  are also included  1 0  2  >10 a t 22°C  -26.1 ± 1.8  31  4.00 x 10 ' a t 23°C  3.19 x 1 0 " a t 150°C  2  9.0 x 1 0 " a t 115°C  3  iodination  in Table  V-10  I t s h o u l d be p o i n t e d o u t h e r e  parameters were c a l c u l a t e d  by u s i n g o n l y  the second-order rate c o n s t a n t f o r the b i m o l e c u l a r path s e c t i o n s V. 1 ( A ) a n d  IB)).  that k  b  (see  - 125 -  The r e a c t i o n o f i o d i n e w i t h was t o o f a s t t o be f o l l o w e d e v e n technique.  t r u e AH  1  by t h e  stopped-flow  that the a c t i v a t i o n para-  T a b l e V-10 a r e o n l y a p p r o x i m a t i o n s and AS  v a l u e s used two t e r m s ,  values.  1  half-life  2 milliseconds.  I t s h o u l d be n o t e d Yh  2  T h i s r e a c t i o n , a p p a r e n t l y , has a  time o f l e s s than  meters  fgfars Mn (C0)g  This i s because  in the Arrhenius i.e.k  Q b s  to the  the  k  Q b s  plots actually include k  = k^K w h e r e K =  .  (The d e r i v a -  t i o n o f t h i s r e l a t i o n s h i p i s f o u n d i n S e c t i o n V. 3 . ( B ) ) T h e r e f o r e , the a c t i v a t i o n e n t h a l p i e s c a l c u l a t e d from the s l o p e s o f the A r r h e n i u s  plots are the  o f two e n t h a l p i e s , A H ! a n d A H .  combination  Since the r a t i o -j^-  0  1  only gives a small c o n t r i b u t i o n to the slope of the Arrhenius  p l o t , AH° i s small  c a l c u l a t e d from  r e l a t i v e to AH| which  t h e s l o p e c o n t r i b u t e d by k^.  Thus  AH^ v a l u e s a r e good a p p r o x i m a t i o n s  experimental  S i m i l a r l y , experimentally obtained entropy the combination  o f two t e r m s .  is  to AH|.  values are  I f we a s s u m e P q e v a l u e f o r k a  (1.30  x 10"  5  sec"  can g i v e a rough term to A S  1  f o r the reaction of Re (C0) with I at 150°C) k estimate f o r ^ , the contribution of this 1  is small.  2  1 Q  k-x  However, because  of the influence of  s o l v a t i o n on a c t i v a t i o n e n t r o p i e s , t h e e x p e r i m e n t a l values provide only a very rough the t r a n s i t i o n  states.  ?  estimate  AS^  of the order of  - 126  V. 3 . ( B )  Possible Reaction  -  Mechanisms.  Four r e a c t i o n mechanisms are c o n c e i v a b l e the i o d i n e cleavage  reactions of (L-L)M (C0) . 2  f o u r , the f r e e r a d i c a l ,  the carbonyl  These  g  bridged  inter-  m e d i a t e , the f o u r - c e n t e r e d t r a n s i t i o n  s t a t e , and  iodonium intermediate mechanisms w i l l  now  separately experimental  to determine  first  considered  i f they are c o n s i s t e n t with  the  mechanism i n v o l v e s the homolytic  s i o n o f the m e t a l - m e t a l  bond o f ( L - L ) M ( C 0 ) 2  radical. (L-L)["(CO/4•] •  g  [ 1 ] , which  by i o d i n e a t t a c k on t h e f r e e r a d i c a l  to produce the product  (L-L)M (C0) I , 2  k (L-L)M (C0) 2  g  2  by  is intermediate  equation  (L-L)[M(C0) -] 4  k 4  the  [2].  r  g  (L-L)[M(C0) -]  fis-  to form  This is represented  2  the r e v e r s i b l e e q u i l i b r i u m , equation followed  be  the  findings. The  free  for  + I  2  [1]  2  ?  (L-L)[M(C0) I]  2  4  2  [2]  The  r a t e law  is  d[(L-L)[M(C0)-I] ^  4  ?  — =  k [(L-L)[M(C0) .] ][I ] [3] 2  4  2  2  - 127 Using  the steady  -  state approximation,  the c o n c e n t r a t i o n of the f r e e r a d i c a l  intermediate  k,[(L-L)[M(C0), [(L-L)[M(C0) -] ] = J : k_! + k [I ] 4  4  T h u s , by s u b s t i t u t i n g e q u a t i o n  : k  Equation  [5] can  C a s e 1.  I f k_  2  1  -l  to k , 2  —  +  4  [4] i n t o equation  k  2  [ I  2  —1  [3],  <<  k  2  2  —  [5]  ]  be s i m p l i f i e d  b y c o n s i d e r i n g two  [ I ] , I.e.,  k_^ i s slow  2  cases  relative  then  Rate = k  C a s e 2.  2  becomes  Rate =  to k ,  [4]  2  ?  2  t h e r a t e law  then  I f k_  1  >>  C(L-L)[M(C0) I] ].  1  4  k  2  2  [ I ] , i . e . , k_ 2  is fast  1  then  Rate = = k  k K[(L-L)[M(CO) I] ][I ] 2  o b s  4  2  2  [(L-L)[M(C0) I] ][I ] 4  2  2  r e l a t i ve  -128  where K  -  equilibrium constant for equation  [1]  k,  k -1 and  kobs It i s obvious t h a t w h i l e case 1 does  agree with the e x p e r i m e n t a l l y found r a t e  Rate = k  o b s  not  law  [(L-L)[M(C0) I] ][I ], 4  2  2  case 2 i s i n agreement with the e x p e r i m e n t a l  results.  Although  activation  the e x p e r i m e n t a l l y found entropy of  (Table V-i0)  suggests t h a t the t r a n s i t i o n  random than the s t a r t i n g  r e a c t a n t s and  stale  is less  is associative  in nature, i t i s not i n c o n s i s t e n t with the  proposed  d i s s o c i a t i v e mechanism, s i n c e the d i s s o c i a t e d f r e e radical two  i n t e r m e d i a t e i s not c o m p l e t e l y random and  halves of the f r e e r a d i c a l  are s t i l l  by t h e b r i d g i n g ( L - L ) l i g a n d . the presence of the f r e e r a d i c a l of fgfars R e ( C 0 ) 2  y  the  held together  In an a t t e m p t  to c o n f i r m  intermediate, solutions  containing a free radical  scavenger  were r e a c t e d w i t h i o d i n e i n the s t o p p e d - f l o w s p e c t r o photometer.  These experiments,  because the f a i l u r e  however, were i n c o n c l u s i v e  to o b s e r v e any e f f e c t o f the  on t h e r e a t i o n r a t e s d o e s n o t n e c e s s a r i l y i m p l y  scavenger the  - 129  absence of the  free radical  Recently, chemical and  there  intermediate.  have been r e p o r t s  homolysis of the metal-metal  Re (C0) 2  tively.  (33)  1 Q  In a f u r t h e r a t t e m p t t o d e t e c t  2  (the  o-*a*  f g f a r s R e ( C 0 ) g i s 330  nm).  2  intermediate of the  was  observed  the  proposed solution  a  2  334  respec-  5  4  t r a n s i t i o n of the  addition  Re-Re bond i n  H o w e v e r , no since there  o f a d i l u t e THF  diphenyl-1-picrylhydrazyl. production reported  As  of Mn(C0)g*, Hallock that the y e l l o w  was  free radical no  color  s o l u t i o n of  evidence and  for  Wojcicki  change  even 2,2-  the (32)  Mn (C0)-jQ s o l u t i o n changed 2  o r a n g e a f t e r i r r a d i a t i o n and  a d d i t i o n of the  i n THF  r a p i d o r a n g e '•*• v i o l e t -* g r e e n - * y e l 1 ow  changes.  gous to the  color  proposed free r a d i c a l mechanism i s reversible homolytic  proposed f i r s t  by Poe  and  r e a c t i o n of iodine with  fission  2  Detailed  of t h i s mechanism i s found in Section  produced  analo-  mechanism  co-workers (18,19) f o r  Mn (C0)-|Q.  to  irradiated  s o l u t i o n to 2 , 2 - d i p h e n y l - 1 - p i c r y l h y d r a z y l  The  of  nm u l t r a v i o l e t  i r r a d i a t e d s o l u t i o n which remained yellow  a f t e r the  photo-  Re(C0) -  (L-L)[M(C0) •] »  i r r a d i a t e d with  the 2  5  f g f a r s R e ( C 0 ) g was  on  bonds i n Mn (C0).|Q  t o y i e l d M n ( C 0 ) ' and  free radical intermediate,  light  -  the  discussion  V. l . - ( A ) .  (32)  -130  A second formation  p o s s i b l e mechanism involves the  o fthe carbonyl  r e v e r s i b l e metal  -  bridged intermediate by  migration.  This i s represented by  equation [ 6 ] . 0 i  (L-L)M (C0) * 2  11  • (C0) M ' M*(C0) L L /  8  k  3  w h e r e M* i s a . c o - o r d i n a t i v e l y u n s a t u r a t e d The metal  metal  a t t a c k by i o d i n e on t h e co-ord.i n a t i v e l y atom i s shown b y e q u a t i o n  the product  (L-L)[H(C0) I] 4  2  .... [ 6 ]  X  4  atom.  unsaturated  [7] w h i c h t h e n  produces  as s h o w n b y e q u a t i o n [ 8 ] .  0  H  + l  (COKM."^ ^ M * ( C 0 K U  9  .L k,  (C0) M  M*(C0)  4  L  ---C\ (C0) M 4  J  *MJC0) ' T  3  k. —2->  3  ....  [7]  ..  [8]  _L \  S.  I  (C0) M 4  I  I  M(CO)  4  - 131 -  The r a t e law i s  d[(L-L)[M(CO),I] ] —^ i — ^ = ?  k [(L-L)(C0) M(C0)M*(C0) -I ] 3  4  Applying steady state approximation (L-L) ( C 0 ) M ( C 0 ) M * ( C 0 ) 4  2  to the intermediate,  and (L-L) (CO) 'M(CO  3  3  4  )M*(CO  )• 1 , 3  2  then  Thus, t h e r a t e law  Rate  =  becomes  k k [I ][(L-L)M (C0) ] : -l 2 2 1  2  k  2  2  +  k  [ I  g  ]  T h i s r a t e l a w c a n be s i m p l i f i e d Case 1 .  I f k_-j << k ' [ I ] , 2  Rate  C a s e 2.  I f k_  =  1  2  by c o n s i d e r i n g two  then  k [(L-L)M (C0) ]. 1  2  >> k [ I ] , 2  2  then  8  cases  - 132  Rate  where K  -  =  k K[I ][(L-L)M (C0) ]  =  k  2  2  o b s  2  g  [I ][(L-L)M (C0) ] 2  2  equilibrium constant  8  for equation  [6]  k  and  kobs  k K. 2  While mental  case  r a t e law,  Although  1 doesn't  case  the formation  agree  with the e x p e r i -  2 i s in agreement with i t . of the carbonyl  bridged  inter-  mediate i n v o l v e s the breaking of the metal-metal  bond,  t h i s d i s s o c i a t i o n i s not i n c o n s i s t e n t with the e x p e r i mentally  found  entropy  of a c t i v a t i o n (Table V-10),  during this dissociative fission the metal-carbon molecule  bond tends  together.  b e t w e e n t h e two  Also the  Furthermore, mechanism i s analogous Haines  to h o l d the t r a n s i t i o n (L-L) l i g a n d s t i l l carbonyl  bridges  order to the t r a n s i t i o n  this carbonyl  bridged  to t h a t proposed  of state  groups  and state.  intermediate  by P o e  (21,22) f o r the r e a c t i o n of i o d i n e with  in d e c a l i n . found  step the formation  halves of the metal  t h i s p r o v i d e s r e s t r a i n t and  since  and Re (C0)-jQ 2  D e t a i l e d d i s c u s s i o n of t h i s mechanism i s  i n t h e I n t r o d u c t i o n s e c t i o n V. l . ( B ) .  There  is  - 133 -  also t h e o r e t i c a l evidence  (27)that a terminal  monoxide l i g a n d on one metal metal  i n t h e metal-metal  the undisturbed metal evidence  i s attracted t othe other  bond t o some d e g r e e ,  carbonyl.  for the carbonyl  comes from  the thermal  Other  bridged  [Mn(C0) I]  4  4  2  rearrangement  c  y  c  1  ^  e  x  a  n  e  >  + f.fars  [Re(C0) I]  f fars 4  4  o  c  y  c  *  o  h  e  x  a  n  even i n  corroborating  intermediate  e  + f fars 4  mechanism  o ff g f a r s  (M = R e , M n ) i n r e f l u x i n g c y c l o h e x a n e  f fars  carbon  [M(C0) I], 4  (Chapter I I I ) :  Mn(C0) I 5  Mn(C0),I  ^  [Re(C0) I] 4  2  Re(CO) I 3  a very p l a u s i b l e intermediate  i nt h e above  ments i s t h e c a r b o n y l  bridged  intermediate  explain the formation  o ft h e c h e l a t e complex f f a r s M(C0)  and  t h e metal  carbonyl  E which  iodides very well. corroborating evidence  b r i d g e d i n t e r m e d i a t e comes from  work on s t e r e o c h e m i c a l l y n o n r i g i d organometal compounds b y Cotton  would  4  Further important the carbonyl  rearrange-  and co-workers.  for  some r e c e n t carbonyl  Theidea that t h e  -134 -  Me.As*—»M(CO) I Q  /  >c=o /  •  -As—»M(CO),I Me 4  0  carbonyl  l i g a n d s i n a p o l y n u c l e a r metal  compound might be a b l e t o m i g r a t e  from  carbonyl terminal t o  b r i d g i n g p o s i t i o n s and v i c e v e r s a was f i r s t Cotton  (34) i n 1966.  L a t e r i n 1972,  s i t e exchange was again suggestion  terminal-bridge  (35), with  t h a t i t can be r a p i d and thus  basis f o r fluxional behaviour  proposed  o rother  i n p o l y n u c l e a r metal  e  ^4  '  r a  P  l c  carbonyls.  Specifically, o f di(penta-  di carbonyl  ' l y i n t e r c o n v e r t a t room  ture v i a the bridge-termina1  the  s t e r e o c h e m i c a l l.y n o n r i g i d  haptocyclopentadi enyl)di(y-carbonyl) 5  the e x p l i c i t  afford  i t was shown t h a t t h e c i s and t r a n s i s o m e r s  (7z -C,-Hj- )'2^ 2  proposed by  carbonyl  exchange.  diiron, temperaI n 1972,  - 135 -  0 II  Fe—Fe  —-  Fe—Fe  ' ?=i  Gansow and c o - w o r k e r s . ( 3 6 ) , i n t h e i r i n v e s t i g a t i o n o f 13 the  C n.m.r. s p e c t r a o f t h e same compound i n t h e  carbonyl  region, confirmed directly that bridge-  terminal  s i t e exchange  as would  have  earlier  o fthe c a r b o n y l groups do o c c u r ,  been e x p e c t e d from t h e pathway  (35) f o r the i n t e r c o n v e r s i o n o fisomers.  recently,  doubt  Very  in the plenary lecture t othe 6th International  Conference i n Organometal1ic Cotton  proposed  Chemistry i n 1973,  (37) e m p h a t i c a l l y s t a t e d t h a t "There can be no that s t e r e o c h e m i c a l n o n r i g i d i t y , which i m p l i e s  rapid m i g r a t i o n o fcarbonyl groups a v a i l a b l e and from one metal atom  among t h e s i t e s t oanother, i s a  - 136 -  general design  p r o p e r t y o f p o l y n u c l e a r metal  The  and i n t e r p r e t a t i o n o f a l l r e a c t i o n s i n v o l v i n g  p o l y n u c l e a r metal proper  carbonyls.  account  c a r b o n y l s m u s t be c o n d u c t e d  of stereochemical  taking  n o n r i g i d i t y and i t s  consequences". Thus, i n view o f t h i s statement k i n e t i c , t h e o r e t i c a l and chemical bridged one  evidence,  intermediate mechanism i s a very  centered  third  k  i  + 1 2 ^ = *  1 The  >  2  The r e a c t i o n pathway i s as  (L-L)(C0) M4  -i k  reasonable  p o s s i b l e mechanism i n v o l v e s a four-  transition state.  (L-L)M2(C0)8  the carbonyl  (L-L)M (C0)g.  f o r the reaction of iodine with The  and t h e  . • | i-  (L-L)[M(C0) I] 4  M(C0)4 i  i  I  ....  2  [9]  rate law i s d[(L-L)[M(C0) I]J — ^—^ dt 4  Applying  the steady  of the four-centered  = k [(L-L)M2(C0) .-I ] 2  state approximation, intermediate i s  8  2  the concentration  - 137  k [(L-L)M (CO).][I ]  [(L-L)M (CO) -I ] 1  ?  8  R  1  = -1  ?  9  1  k  r a t e law t h e n  R a t  e  =  It i s obvious  k K  2  k k,[(L-L)M (C0) ][I ]. ?  _LJ  2  k  o b s  W  ?  +  1  f i  k  ?  ?-  2  [(L-LJM (C0) ][I ] 2  that equation  mentally found  +  becomes  k_ =  -l  ?  . .  2  K  The  -  r a t e law.  8  [10]  2  [10] agrees with the e x p e r i -  In a d d i t i o n , t h i s  four-centered  t r s n s i t i c r i s t a t e rri G c h a n i s rn i s c o n s i 31 G n t w i t h experimental transition  AS^  values  (Table V-10), since  the  the  s t a t e i s a s s o c i a t i v e i n n a t u r e and p r e d i c t s  a negative entropy of  activation.  I t s h o u l d be p o i n t e d o u t h e r e t h a t t h e w e l l known b i m o l e c u l a r r e a c t i o n b e t w e e n H thought  I , previously  by m o r e r e c e n t e x p e r i m e n t a l  n o r a l l o w e d by m o l e c u l a r o r b i t a l The  2  data  (39),  symmetry r u l e s (40).  "iodonium" intermediate in which  iodine is situated symmetrically with  t h e two  state (38),  f o u r t h p o s s i b l e mechanism i n v o l v e s the  f o r m a t i o n o f an  to  and  to occur v i a a f o u r - c e n t e r e d t r a n s i t i o n  is not supported  bridging  2  metal  atoms.  the  respect  Subsequent n u c l e o p h i l i c attack  - 138-  on t h e " i o d o n i u m "  intermediate by the iodide i o n product ( L - L ) [ M ( C O ) I ] . The  produces  the neutral  reaction  p a t h w a y i s shown a s f o l l o w s : (L-L)M (C0) 2  4  k,  •+ I  8  v = f ^ (LrL)(C0) M- — - M ( C 0 )  2  (L-L)(C0) M  ^4  4  rate  4  —1  M(C0)  n  \  4  \  +.1  4  \ +  ( L - L ) [ M ( C 0 )  The  2  4  [11]  I ]  2  law i s  [ ( L - L ) [ M ( C 0 ) i» I— ]i ] =  k [ r ] [ ( L - L ) ( C 0 ) M ( I, ) M ( C 0 ) ] +  9  3  4  4  dt Using the steady state approximation f o rthe intermediates (L-L)(C0) M(I )M(C0)  and (L-L)M (CO)g-I  +  4  4  2  , the rate law  2  becomes k k,[(L-L)M (C0) ][I ] —: • -l 2 2  2  Rate  =  k  =  k  o b s  8  +  2  k  [(L-L)M (C0) ][I ] 2  8  2  -139-  Thus, this analogous  "iodonium"  to that proposed  for the halogenation dienyldi-iron  intermediate  by H a i n e s  mechanism,  and co-workers  o f t e t r a c a rbonyl bi s-Tr-cycl openta-  a n d i t s d e r i v a t i v e s [ s e c t i o n V.  l.(D)],  gives a rate law c o n s i s t e n t with the experimental law a n d \ n v o l v e s  (29)  an a s s o c i a t i v e t r a n s i t i o n  rate  state  which  p r e d i c t s a n e g a t i v e AS^ v a l u e a l s o c o n s i s t e n t w i t h t h e experimental  f i n d i n g s ( T a b l e V-10 ).  In an e f f o r t mediate, was  to v e r i f y the "iodonium"  the reaction of iodine with  carried out i n a non-polar  the p r e s e n c e Although  o f sodium  f fars 4  inter-  {^(CCOg  solvent, benzene, i n  tetraphenylborate  (Na BPh ~). +  4  no p r e c i p i t a t e o f t h e k i n d [ i o d o n i u m  intermediate]  [ B P h ^ ] was o b s e r v e d ,  t h i s does n o t r u l e o u t t h i s mechanism  V. 3 . ( C ) C o m p a r i s o n s  of Kinetic Results.  From T a b l e V-10, i t i s n o t e d  that the  e n t h a l p i e s o f a c t i v a t i o n and t h e r e a c t i o n r a t e s c o n s i d e r a b l y from iodination  f o rthe  c a r b o n y l s , . MngtCOj-jg  and  T h e s m a l l e r AH^ a n d f a s t e r r a t e s f o r  2  ?  values obtained  o f the parent metal  Re (C0)^Q. (L-L)M (C0)  those  differ  f i  c o m p l e x e s c a n be e x p l a i n e d by t h e w e a k e r  entirely.  - 140  metal-metal  -  b o n d s i n them as a r e s u l t o f s u b s t i t u t i o n  o f two  carbonyl groups  carbon  ligand.  fgfars  l i g a n d and  by b r i d g i n g b i d e n t a t e  Specifically,  t h e b i t e s o f f g f a r s and  their poorer ir-acceptor properties  are r e s p o n s i b l e f o r the weakening bonds.  This i s because  A s d i s t a n c e s ( e . g . 4.02 2  g  atoms f a r t h e r a p a r t and  metal  bonds.  these  ligands also decrease  & f o r As  i n which  8  is longer than i n M n ( C 0 ) 2  f o r e , as a c o m b i n a t i o n donor-acceptor  -rr-acceptors,  the metal-metal  t h e Mn-Mn b o n d 1 Q  (2.923  bond  (42).  2  are weaker than  4  Re (C0)g  metal-  in  M (C0)-JQ, 2  complexes.  (see T a b l e V-10)  the i o d i n e cleavage r e a c t i o n r a t e s f o r i n c r e a s e i n the order f f a r s  There-  f a s t e r rates f o r the  iodine cleavage reactions of these It i s a l s o obvious  (L-L)M (C0)g  (C0) ReMn(C0) 4  that while 2  4  < f g f a r s Re,(C0)  < f f a r s Mn (C0)g, the enthalpies of 4  2  (41)  f a c t o r s and  p r o p e r t i e s of the l i g a n d s , the  bonds i n ( L - L ) M ( C 0 ) g  2  (.3) A)  (2.971  ( 3 ) A)  of the geometric  l e a d i n g t o s m a l l e r AH^ v a l u e s a n d  4  metal-  C e r t a i n l y , t h e s e e f f e c t s are shown i n  2  < f fars  As  thus weakens the  In a d d i t i o n , as p o o r e r  f fars Mn (C0)  metal  intra-  (41 ) ) t e n d t o f o r c e t h e  metal  strengths.  metal-metal  atoms, t h e i r l a r g e  distance in fgfars Mn (C0)  4  of the  t h a t w h i l e t h e l i g a n d s do  bridge between the metal l i g a n d As —  fluoro-  - 141  activation fgfars  -  decrease i n the order f f a r s  (C0) ReMn(C0)  4  Re (C0) 2  Comparisons  > f fars  8  Re (C0)  4  2  4  > f fars  8  Mn (C0) .  4  2  o f t h e s e r a t e s and e n t h a l p i e s o f  their correlation  with the metal-metal  g  activation,  bond s t r e n g t h ,  and t h e e f f e c t o f r e p l a c e m e n t o f f f a r s by f g f a r s  ligand  4  will  now  >  4  be d i s c u s s e d .  V. 3 . ( C ) . ( a ) C o m p a r i s o n and f f a r s  of Results f o r f f a r s  Mn (C0)  4  2  g  Re (C0) .  4  2  g  . S i n c e Raman. ( 4 3 ) , m a s s s p e c t r o m e t r i c ( 4 4 ) , electrochemical indicate  (45) and t h e o r e t i c a l  that the metal-metal  (27) s t u d i e s a l l i n R e ( C O ) -j Q i s  bond  2  s t r o n g e r than t h a t i n Mn (C0)-|Q, i t i s e x p e c t e d t h a t 2  this  i s also true f o r the metal-metal  f fars 4  Re (C0) 2  g  and f f a r s M n ( C 0 ) . 4  b y t h e o+o* t r a n s i t i o n ultraviolet region: are  3 0 , 3 0 0 cm"  1  2  surprising weaker  2  g  bonds  the e n e r g i e s of these for f fars  1  4  respectively.  strength in  This is confirmed  g  of the metal-metal  and 2 7 , 4 0 0 cm"  and f f a r s M n ( C 0 ) 4  bond  i n the  transition Re (C0) 2  g  T h e r e f o r e , i t i s not  to f i n d t h a t the i o d i n e cleavage of the  metal-metal  bond  in f f a r s Mn (C0)  q u i c k l y than t h a t i n fgfars  4  2  Re (C0) . 9  Q  g  o c c u r s more  In f a c t ,  the  - 142  -  c l e a v a g e r e a c t i o n r a t e i s so f a s t that i t cannot  f o r t h e Mn  be f o l l o w e d b y t h e s t o p p e d - f l o w  Consequently,  no a c t i v a t i o n  parameters  However, the e n t h a l p y of a c t i v a t i o n s m a l l e r t h a n 6.9  Kcal m o l e  t h e c o r r e s p o n d i n g Re  V.  3.(C).(b)  were  technique.  obtained.  is expected  AH^  be  compound.  fgfars  The  to  , the value obtained f o r  - 1  Comparison of Results f o r fgfars  and  with  compound  Re (C0)g 2  Re (C0) . 2  g  value f o r the r e a c t i o n of f g f a r s  Re (C0)g 2  i o d i n e i s g r e a t e r than the corresponding r e a c t i o n  of f f a r s  Re (C0)  4  2  with i o d i n e (Table V-10).  8  i n c r e a s e c a n be a c c o u n t e d tions. based  The  first  and  f o r b y two  This  possible explana-  the most p r o b a b l y e x p l a n a t i o n i s  on t h e d i f f e r e n c e o f t h e b i t e s o f t h e l i g a n d s  f g f a r s and  fgfars.  The  b i t e of the former  t o be s m a l l e r t h a n t h a t o f f g f a r s . the 5-membered r i n g  is  expected  This i s because  t h e d e c r e a s e d C=C  bond s t r a i n  in tends  t o make t h e e x o c y c l i c C=C-As a n g l e s m a l l e r t h a n t h a t i n the 4-membered r i n g . structures of f a r s f. fars 4  Co (C0) 2  6  T h i s has Ru (CO) 3  (48) and  b e e n shown by t h e (46 ) , ( f f a r s )  1 Q  [Rh ( f  4  g  f  X-ray  Ru (C0)g  2  3  (47),  os ) ] [ c i s - (CO) R h C l J " (49 ) +  2  2  2  - 143 -  in which the e x o c y c l i c and  C=C-As a n g l e s  138° i n t h e 4-membered  a r e between 132°  rings while  i t is  approxi-  *  m a t e l y 120° i n t h e 5-membered As  ring.  a result of the expected smaller  C=C-As a n g l e i n t h e 5-membered than i n t h e 4-membered strated fgfos  by X - r a y data  Fe(N0)  2  ring.  ring, i t s bite i s This  has a l s o  on [ R h ( f g f o s ) ]  fgfars ligand  been  demon-  2  (50) and f f a r s M n ( C 0 ) 4  smaller  [cis-(CO) RhCl ]~  +  2  2  Thus, i n complexes o f the type bridging  exocyclic  2  (41) (Table  8  (49),  V-ll).  (L-L ) R e (C0)g, the 2  i s not e x p e c t e d t o weaken t h e  Re-Re bond as much a s t h e f g f a r s l i g a n d w h i c h t e n d s t o lengthen bite.  t h e Re-Re d i s t a n c e The s t r o n g e r  explains  the higher  mere because o f i t s l a r g e r  Re-Re bond i n f g f a r s R e ( C 0 ) g  then  2  AH^ v a l u e  f o r the iodination  of this  compound. The increased *  second possible  inductive  explanation  involves  e f f e c t o f t h e two e x t r a  the  fluorine  S i n c e no X - r a y d a t a o n f f a r s l i g a n d i s a v a i l a b l e , t h e e x o c y c l i c C=C-P a n g l e f r o m t h e a n a l o g o u s p h o s p h o r o u s ligand fgfos i s taken f o r comparison purpose here. I t s h o u l d be n o t e d t h a t f g f o s a c t s as a c h e l a t i n g l i g a n d i n t h e c a t i o n [ R h ( f g f o s ) 2~\ w h i l e f f a r s a c t s a s a bridging ligand i n fgfars Ru (C0)-j , (f fars) Ru (C0) and f f a r s C o ( C 0 ) g . 6  +  4  3  4  2  0  4  2  3  8  144  Table V - l l Intra-1igand  P---P  o r As  As  Distance  intra-1igand P—P o r As As d i s t a n c e  Compound  [Rh(f fos) ] [cis-(CO) RhCl ]' +  6  2  2  •fgfos  2  Fe(NO  f fars  Mn (C0)  4  2  8  f g f o s a c t s as a c h e l a t i n g  11  [Rh(fgfos) ]  and  +  2  .-.X-ray d a t a ligand  on  P---P  fgfos  bridging distances  l i g a n d in the  Fe(N0) 2  In t h e  3.11  A  3.08  A  4.03  A  cation absence  of  f g f a r s complexes, these  intra-  are  purpose  used f o r comparison  here.  atoms in f g f a r s . expected  to i n c r e a s e  ligand, leading and  The  a decrease  metal atoms.  t o an  electron-withdrawing  fluorine  -rr-acceptor  of  the  increase  strength  i n Re + As  in electronic repulsion Thus there  is a greater  back  between increase  are  this donation the  in  the  - 145  Re-Re bond s t r e n g t h fgfars  in fgfars  Re2(C0)g.  is required  bond i n the  former.  fgfars  the  t o be  too  can  u s e d as  strength  second explanation entire  increase  i n AH^  i s due  in the  bites  of the  ligand  to the  i s not  v a l u e s f o r the  reaction  -rrexpected  and  indicators  fgfars.  of  Thus, for  More l i k e l y , . t h e major  the the the  increase  i . e . the  difference  In o t h e r w o r d s , t h e  i s more i m p o r t a n t than the substituent  numbers  carbonyl.stretching  sensitive  ligands.  Re-Re  wave  increased  over fgfars  geometric factor,  e f f e c t of the  of  of  cannot adequately account  i n AH^.  of the  bands  s l i g h t l y higher  of f g f a r s  to  c l e a v a g e of the  ( C h a p t e r I I ) , the  of f g f a r s  be  enthalpy  carbonyl  s i g n i f i c a n t , i f the  frequencies ir-acceptor  at only  Re2(C0)g  acceptor strength  for iodine  infrared  Re^CCOjg are  than f g f a r s  R e 2 ( C 0 ) g as c o m p a r e d  Consequently, higher  activation  Since  -  inductive  groups i n a f f e c t i n g the of iodine  with  bite AH^  (L-L)Re (C0) . 5  Q  - 146  V.  3.'(C)-. ( c ) C o m p a r i s o n and f f a r s  -  of Results for f f a r s  (C0) ReMn(C0) -  4  4  4  T h e AH^ v a l u e f o r t h e i o d i n a t i o n f fars  (C0) ReMn(C0)  f fars  Re (C0)g  4  4  4  2  Re(C0)g  4  of  i s g r e a t e r than' t h a t of  4  (Table V-10).  This i s unexpected  v i e w o f t h e e n e r g i e s o f a+a* a b s o r p t i o n s o f t h e metal  bonds i n the u l t r a v i o l e t  region.  The  for f fars  1  4  respectively. transitions  These  (CO) ReMn(CO) 4  4  f fars 4  and  - 1  and f f a r s  c a n be u s e d t o g i v e s o m e m e a s u r e o f  Re (CO)g 2  2  bonds,  the  t h e Re-Re  bond  i s s t r o n g e r t h a n t h e Re-Mn b o n d  (C0) ReMn(C0) . 4  Re (C0)  4  v a l u e s i n d i c a t e t h a t , i f t h e a->a*  r e l a t i v e strength of metal-metal in f f a r s  4  metal-  experimen-  t a l l y o b s e r v e d o+o* t r a n s i t i o n s a r e 2 9 , 4 0 0 c m 3 0 , 3 0 0 cm"  in  T h e r e f o r e , one w o u l d  4  in  expect a  greater AH^ value f o r the  i o d i n e cleavage of the  metal  However, t h i s t r e n d i s not  bond  observed.  of the former.  Instead, the i o d i n a t i o n  of the  metal-  latter  compound r e q u i r e d h i g h e r A H ^ . A s i m i l a r a n o m o l y was and c o - w o r k e r s  (51).  They  also observed  found that although  r e l a t i v e force constants f o r metal-metal (C0) ReMn(C0) 5  bond  5  and T c ( C 0 ) 2  1 0  by  Poe  the  vibrations in  s u g g e s t t h a t t h e Re-Mn  i s s t r o n g e r than the Tc-Tc  bond which  is in  - 147  agreement with t h e i r k i n e t i c a-*•<?* t r a n s i t i o n s  suggest  data are a less r e l i a b l e  V.3.(C) (d)  (L-L)M '(C0) 2  metal-metal  bonds".  The  No a c t i v a t i o n  has  o  -11.1  4  a r e 6.9  ± 3.0  parameters  of f farsMn (CO)g 2  enthalpies  o  ± 0.3,  9.3  ± 0.9,  and  1.4  ± 3.2  14.2  values  0.9  are  e.u. r e s p e c t i v e l y .  were o b t a i n a b l e f o r the r e a c t i o n  w i t h i o d i n e b e c a u s e i t has  apparatus  used.  a of  Four p o s s i b l e r e a c t i o n  mechanisms f o r these cleavage r e a c t i o n s are  proposed.  In v i e w o f t h e k i n e t i c d a t a and o t h e r t h e o r e t i c a l  involving  ±  time of l e s s than 2 msec which i s the l i m i t  the stopped-flow  chemical  been  f o r f . f a r s R e r . ( C 0 ) . f - f a r s R e ( C 0 ) „ and 4 c • 8' o Z o  r e s p e c t i v e l y while the entropy  1  ±1.0,  half-life  technique.  reactions of  Mn)  4  4  4  U.V.  strengths  k i n e t i c s of the i o d i n e cleavage  f fars(C0) ReMn(C0)  -13.8  of bond  ( L - L = - f g f a r s , f f a r s ; M = Re,  8  of activation  kcal mole"  To e x p l a i n  t h a t " p o s s i b l y the  indication  by t h e s t o p p e d - f l o w  4  ultraviolet  Summary  The  studied  data, the  the o p p o s i t e o r d e r .  this anomoly, they suggested  of unsymmetrical  -  evidence a l r e a d y d i s c u s s e d , the  and  mechanism  the bridged-carbonyl i n t e r m e d i a t e i s favoured.  -148  -  References P. C a n d l i n , K. A . T a y l o r a n d D. T. 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S o c , ( A ) ,  -151  -  Chapter VI K i n e t i c s o f The Thermal  Rearrangement o f (L-L)M (C0)g 2  V I . 1. I n t r o d u c t i o n During complexes,  t h e p r e p a r a t i o n o f t h e new m e t a l  i t was observed  complexes f f a r s M ( C 0 ) g 4  2  carbonyl  that the f1uorocarbon-bridged  (M = R e , M n ) s l o w l y r e a r r a n g e d t o  t h e i r isomers  a f t e r r e f l u x i n g i n m-xylene (Chapter I I I ) .  The  o fthese  formation  esting  isomers,  i-f fars'-' (C0) , i s inter4  i n that i tinvolves the breaking  bond and t h e i n s e r t i o n o f t h e M ( C 0 ) arsenic-carbon reactions 3  f f a r s C o (C0-) 4  2  1 0  6  (1,2) (3,4)  easi ly-'Studied  4  2  8  into one o f t h e  Other  rearrangement  o ff farsFe^(CO)g  4  (see Chapter  2  4  g  from  I I I . 1. I n t r o d u c t i o n ) .  I n view  and f fars(CO) ReMn(CO) 4  from  4  a r e not quantitative and a r e  kinetically.  the k i n e t i c s o f t h e thermal were  o ft h e metal-metal  moiety  f a c t t h a t a s e r i e s o f s i m i l a r compounds , f farsRe (C0)  g  and ( f f a r s ) C o ( C 0 ) ( 2 H ? )  However, these c o n v e r s i o n s not  4  bonds o f t h e l i g a n d .  include the formation  -f farsFe (C0') 4  2  4  4  rearrangement  o fthis, and the f farsMn (CO)g, 4  2  were o b t a i n a b l e , o fthese  compounds  s t u d i e d i n order t o e l u c i d a t e t h e mechanism o f these  conversions experimental strengths.  and s e e i f t h e r e i s a c o r r e l a t i o n between t h e a c t i v a t i o n parameters  and the metal-metal  bond  - 152  V I . 2.  -  Experimental  VI. 2.(A)  Starting Materials  The metal  (L-L')M2'(C0)g  carbonyl complexes,  ( L - L = f g f a r s ; M = Re, Mn),  were p r e p a r e d as d e s c r i b e d i n  Chapter  The  II o f t h i s t h e s i s .  s o l v e n t s CDClg,  CgHg  and  C g D g w e r e p u r c h a s e d f r o m M e r c k S h a r p & Dohme o f C a n a d a L t d . and F i s h e r S c i e n t i f i c are of C e r t i f i e d m-xylene  Company r e s p e c t i v e l y .  Spectrananalyzed grade.  0.3 of m-xylene  was it.  The s o l v e n t  i s also purchased from F i s h e r S c i e n t i f i c  V I . 2•••(B) U n s a t i s f a c t o r y K i n e t i c  bottom  They  Study  g o f f f a r s R e ( C O ) g was 4  w h i c h was  2  then added  dissolved  into a 2-necked  flask equipped with a reflux condenser.  deoxygenated  Company.  i n 50 ml round The s o l v e n t  by p a s s i n g a s t r e a m o f n i t r o g e n t h r o u g h  T h e f l a s k was  "then h e a t e d t o r e f l u x i n g  (139°C) under n i t r o g e n atmosphere  temperature  and the p r o g r e s s o f the  c o n v e r s i o n o f f ^ f a r s ^ 2 ( C O ) g i n t o i - f g f a r s Re2 ( C O ) g f o l l o w e d by i n f r a r e d  spectroscopy.  This kinetic  h o w e v e r , p r o v e d t o be u n s a t i s f a c t o r y b e c a u s e , to the e x p e c t e d thermal  rearrangement,  was  study,  in addition  t h e r e was c o n s i d e r a b l e  - 153 -  decomposition of oxygen.  o f t h e r e a c t a n t p r o b a b l y due t o t h e p r e s e n c e  Therefore, the k i n e t i c s of the thermal  rearrangement  o f f ^ f a r s R e ^ ( C 0 ) was s t u d i e d w i t h  complete  y  e x c l u s i o n of oxygen,  u s i n g n.m.r. s p e c t r o s c o p y t o m o n i t o r  the r e a c t i o n . T h i s i s d e s c r i b e d next.  V I . 2. ( C ) E x p e r i m e n t a l  Procedure  In g e n e r a l , a s a m p l e  of (L-L)M (C0)g 2  w a l l e d n.m.r. t u b e was c o n n e c t e d 0.5 g o f b e n z e n e w a s c o n d e n s e d  to a vacuum l i n e and  into the tube.  c o n t e n t s o f t h e tube were degassed vacuum.  and s e a l e d  The under  T h e n.m.r. t u b e was t h e n p l a c e d i n a c o n s t a n t  temperature  bath and the progress of the thermal  m e n t was f o l l o w e d b y r e c o r d i n g t h e its contents at regular intervals. c o n d i t i o n s were s t r i c t l y meter  in a thick-  observed  so t h a t the o b t a i n e d  rearrange-  n.m.r. s p e c t r u m  of  The f o l l o w i n g i n running the specto-  n.m.r. i n t e g r a t i o n s were  accurate and r e p r o d u c i b l e : (1)  T h e V a r i a n T - 6 0 s p e c t r o m e t e r was l o c k e d on  t h e b e n z e n e s i g n a l w h i c h was o p t i m i z e d t o i t s maximum . 1evel. (2)  During a given series of a kinetic experi-  m e n t , t h e ^H n.m.r. s p e c t r u m  amplitude, spinning rate,  - 154 -  sweep w i d t h , f i l t e r throughout  the  a n d RF p o w e r l e v e l w e r e k e p t t h e s a m e  experiment.  (3)  T h e s p e c t r u m was r e c o r d e d o n l y a f t e r t h e  sample had been warmed temperature  up t o t h e o p e r a t i n g s p e c t r o m e t e r  and had been s p i n n i n g f o r f i v e (4)  T h e s w e e p w i d t h was r e d u c e d t o 1 0 0 Hz  o r 50 Hz i n o r d e r t o o b t a i n s a t i s f a c t o r y without i n t e r f e r e n c e from adjacent  VI. 2.(D) K i n e t i c s o f the Thermal f farsMn (C0) 4  2  The  procedure  rearrangement  0.0206 g o f f ^ f a r s M n , , ( C O )  0.5402 g o f CgHg i n an n.m.r. to 139°C.  g  In a  typical  was d i s s o l v e d i n  tube and the tube  The p r o g r e s s o f t h e t h e r m a l  was  rearrange-  m e n t w a s f o l l o w e d b y t a k i n g t h e H n .m.r. s p e c t r u m 1  15 m i n u t e s .  w e r e o b t a i n e d f r o m t h e n.m.r. ?  R  every  n.m.r.  The f o l l o w i n g r e s u l t s i n t e g r a t i o n o f one o f t h e  two i - f f a r s M n ( C 0 ) p e a k s ( T a b l e V I - 1 ) . 4  1  F i g u r e V I - 1 s h o w s t h e c h a n g e i n ^H  spectra with respect to time.  of  by t h e e x p e r i m e n t a l  described i n Section VI. 2.(C).  experiment,  heated  Rearrangement of  8  were determined  2  integration  peaks.  kinetics of the thermal  f farsMn (CO)g 4  minutes.  cn  V  ****  0  min. F i g u r e VI-1.  15  min  30  min.  Ihr.  The l H n.m.r. S p e c t r a o f t h e T h e r m a l of f f a r s M n ( C 0 ) . 4  2  8  2hr Rearrangement  - 156 -  T a b l e VI-1 The  Thermal  Conversion  into  / 1  of  i-f farsMn (CO).  t ( m j n.)  9  Q  f^farsMn,,(CO) at  139°C.  Concentration of i-f farsMn (CO) f r o m i t s n.m.r. i n t e g r a l ( a r b i t r a r y um'TJ 4  15  17.5  30  26.0  45  36.0  60  40.0  75  44.0  90  46.0  105  47.0  120  50.0  Since the thermal into i-f^farsMn (CO ) 2  8  g  c o n v e r s i o n from  was c o m p l e t e  f farsMn (CO) 4  2  and i r r e v e r s i b l e (see  Figure VI-1), the concentration of f farsMn (C0)g 4  the r e a c t i o n c a n be c a l c u l a t e d of. i - f ^ f a r s M n ( C O ) g . 2  of f^farsMn (CO)g 2  with  from  2  t h e n.m.r.  during  integral  .Table VI - 2 shows t h e c o n c e n t r a t i o n respect to time.  - 157  Table The  Thermal  Conversion  -  VI-2 o f f ^ f a r s M n , , (CO ),  into i-f farsMn (C0) A  t(min.)  9  at  Q  139°C.  C a l c u l a t e d Concentration of f.farsMn (CO) ~~ (arbitrary unit) g  0  50  15  32.5  30  24.0  45  14.0  60  10.0  75  6.C  90.  4.0  105  3.0  120  0  A graph  of 1o g [ f f a r s M n ( C 0 ) g ] , 4  2  [ f ^ f a r s M n (CO ) g ] ^ . i s t h e c o n c e n t r a t i o n 2  at time VI-2)  t during  t h e r e a c t i o n , v s . t was  to g i v e a s t r a i g h t l i n e ,  conversion  is f i r s t order  wi t h k = 3.00  x 10"  2  where  t  of  f^farsMn (C0)g 2  plotted  indicating that  in f^farsMn (CO)g 2  min" . 1  (Figure  the  concentration  - 159  -  The e f f e c t o f t e m p e r a t u r e experimental temperature  r a t e c o n s t a n t k was range  given in Table  131°C  variation  studied over  to 147°C.  The Thermal 4  The r e s u l t s  Temperature  y  x  10"  2  412  3.00  x  10"  2  420  5.92  x  10  ± 2.0  Kcal mole , - 1  was  ( F i g u r e VI - 3 ) . Kcal m o l e , - 1  =  - 2  activation,,  o b t a i n e d from the  graph  The e n t h a l p y o f a c t i v a t i o n , ' was  equation.  AH^  k.  - 1  1.07  ± 4.5  into  k(min )  404  of l o g k vs. j = 36.8  y  Dependence of  The e x p e r i m e n t a l e n e r g y o f  AH^  are  VI-3  T° (K)  = 37.6  the  Conversion of f^farsMn^(C0)  i-f farsMn2(C0) .  a  the  VI-3.  Table  E  on  E a - RT  calculated  from  the  - 161 -  where R i s t h e gas c o n s t a n t .  The e n t r o p y o f a c t i v a t i o n ,  A S * = 1 5 . 0 ± 4.7 e . u . , w a s f o u n d f r o m t h e e q u a t i o n  AH*  " =  AG*  +  TAS*  w h e r e AG* i s c a l c u l a t e d f r o m t h e r e l a t i o n s h i p _ (AG*.) K  obs  h  where K i s Boltzmann's  V I . 2 .'(E)  Kinetics  e  c o n s t a n t and h i s Planck's  o f the Thermal  f farsRe (C0) 4  (a) CDC!  3  2  Rearrangement  constant  cf  8  as s o l vent  0.0320 g o f f f a r s R e ( C 0 ) 4  0 . 7 1 7 6 g o f CDC 1 . 3  The sample  2  v 8  was  dissolved in  was s e a l e d i n a t h i c k -  w a l l e d n.m.r. t u b e w h i c h was t h e n h e a t e d t o 1 4 8 ° C constant temperature  T h e ^H n . m . r .  heating bath.  s p e c t r a w h i c h w e r e t a k e n e v e r y 30 m i n u t e s  showed t h a t t h e  e x p e c t e d p r o d u c t , i - f f a r s R e ^ ( C O ) , was a b s e n t . 4  two p e a k s external  in a  8  Instead,  a t 2.1.2 a n d 2 . 1 0 p . p . m . ( w i t h r e s p e c t t o T M S ) w e r e o b t a i n e d a f t e r 36 h r s . T h e n . m . r .  - 162 -  t u b e was o p e n e d  a n d 0. 2 7 2 0 g o f C D C !  t u b e was a g a i n h e a t e d t o 1 4 8 ° C spectrum p.p.m. 2156, 1947  still  was a d d e d .  3  f o r 2 hours.  s h o w e d t h e same two p e a k s  The i n f r a r e d  spectrum  The  The  n.m.r.  a t 2.12 a n d 2.10  showed c a r b o n y l bands  at  2115, 2048, 2024, 2016, 2010, 1984, 1967, 1953, a n ^ ! 9 1 6 cm"  1  indicating that a mixture of three  products, f f a r s [ R e ( C 0 ) C l ] , f f a r s R e ( C 0 ) C l and Re(C0) Cl 4  4  was p r e s e n t . gave  The graph  2  4  2  first-order  8  4  2  that the conversion of  i n ttie p r e s e n c e o f e x c e s s C D C l ^  i s . pseudo-  in f f a r s R e ( C 0 ) g concentration with a 4  2  o b s e r v e d r a t e c o n s t a n t o f 2.56 x 1 0 ~ (b) Benzene  5  of log [f farsRe (C0)g]j. vs. t  a s t r a i g h t 1ine , i n d i c a t i n g  f^f arsRe (C0)  3  J  combined  min  as s o l v e n t  The  k i n e t i c s o f thermal  conversion of f farsRe (CO) 4  2  i n t o i - f f a r s R e ( C O ) g were a g a i n s t u d i e d , u s i n g benzene 4  solvent.  2  0 . 0 2 9 0 g o f f f a r s R e ( C O ) g was d i s s o l v e d i n 4  2  0 . 4 4 5 0 g o f C^Hg a n d s e a l e d i n an n.m.r. t u b e . was h e a t e d by  as  to 193°C  tube  a n d t h e t h e r m a l c o n v e r s i o n was f o l l o w e d  n.m.r. s p e c t r o s c o p y .  Table VI-4.  The  The r e s u l t s a r e found i n  - 163  Table The Thermal into  VI-4  Conversion  of  f^farsRe (CO)g 2  i - f f a r s R e ( C 0 ) g at 4  t(min.)  2  A  70  15  65  30  57  60  48  90  40  105  36  135  30  202  21  240  15  a straight  193°C.  Concentration of f farsRe (C0) (arbitrary unit)  0  The  The  -  graph  line  of T o g [ f f a r s R e ( C 0 ) g ] 4  ( F i g u r e VI-4)  e f f e c t of temperature  over the temperature  range  a r e g i v e n i n T a b l e VI - 5.  2  2  t  w i t h k = 6.93  v a r i a t i o n o n k was 193°C  to 202.5°C.  vs. t gave x 10"  3  min" . 1  studied The  results  I00r  1  I  i  60  I  120  1S0  240  1(mi Figure VI-4.  —J  I  I  300  n)  Graph of 1 o g [ f f a r s R e ( C O ) ] 4  2  Q  Conversion of f,farsRe (C0) 9  R  t  vs. t f o r the into  i-f,farsRe (CO) 9  - 165  Table The  Thermal  Conversion  i-f^farsRe (CO) . 2  -  V1-5 of f^farsRe^(C0)g  Temperature  p  into  Dependence of  k.  k(min" ' )  T°(K),  \ 6.93  x  10  470  1.09  x  10  475.5  1 .87  x  10  466  The enthalpy entropy  v  Arrhenius  r a t e p l o t ( F i g u r e VI - 5) g a v e  o f a c t i v a t i o n o f 46.8 o f a c t i v a t i o n was  ± 0.5  Kcal m o l e  - 1  .  c a l c u l a t e d t o be 23.2  an The  ± 1.1  e.u.  by t h e m e t h o d d e s c r i b e d i n t h e p r e v i o u s s e c t i o n . I t s h o u l d be m e n t i o n e d s t u d i e s of the thermal i-f farsRe (C0)g 4  observed  2  integration  conversion  decomposition  to occur.  t h a t d u r i n g the  I t was  kinetic  of f^farsRe (CO)g  of the r e a c t a n t  estimated  from  the  was n.m.r.  t h a t 10 t o 2 0 % o f r e a c t a n t d e c o m p o s e d  the temperature  range  plotted over this small  193°C to 202.5°C. temperature  into  2  F i g u r e VI - 5  range.  over was  - 166 -  215  210 Y  Figure  VI-5.  x  io  3  1  Graph of log k v s . i- f o r the Thermal Conversion of f f a r ^ R e ( C O ) o into ' l-f.farsRe-tCO):. . a  7 d  a  - 167 VI. 2.(F) K i n e t i c s o f the Thermal f fars(C0) ReMn(C0) 4  4  Rearrangements  4  0.0460 g o f f f a r s ( C 0 ) R e M n ( C 0 ) 4  4  was d i s s o l v e d  d  i n 0.7280 g o f CgDg i n an n.m.r. t u b e w h i c h s e a l e d under  vacuum.  of the thermal  4  4  ( F i g u r e V I - 6) s h o w e d t h a t t h e o r i g i n a l 4  two  s i n c e a p p r o x i m a t e l y 10% o f  o b t a i n e d a f t e r 2 0 6 m i n . was i d e n t i c a l 19 The  (with  T h e c o n v e r s i o n , h o w e v e r , was f fars(CO) ReMn(CO) 4  a f t e r - p r o l o n g e d h e a t i n g (95 m i n . ) .  a f t e r 95 mm.  was  gradually converted to four  r e s p e c t to e x t e r n a l TMS).  remained  4  singlets  s i n g l e t s a t 1 . 1 0 , 1 , 0 8 , 0.60 a n d 0.50 p.p.m.  not complete  156°C  The o b t a i n e d s p e c t r a  1  4  to  of f fars(C0) ReMn(C0)  f o l l o w e d by i t s H n.m.r. s p e c t r u m .  4  then  h e a t i n g bath and the k i n e t i c s  rearrangement  f fars(C0) ReMn(C0)  was  T h e s e a l e d t u b e was h e a t e d  in a constant temperature  of  4  4  The s p e c t r a  to that obtained  F n.m.r. s p e c t r u m  of the products  showed c o m p l e x p a t t e r n s c e n t e r e d a t 1 0 2 . 8 a n d 106.6 p.p.m., s i m i l a r to those observed f o r i - f f a r s M n ( C O ) g and 4  2  i-f farsRe (C0)g. 4  2  The  rate of disappearance of  was f o l l o w e d by i t s  straight line  initially  4  n.m.r. i n t e g r a l  The g r a p h o f l o g [ f f a r s ( C O ) R e M n ( C O ) ] 4  f fars(CO) ReMn(CO) ~  4  4  4  4  (Table VI-6). t  v s . t gave a  ( F i g . V 1 - 7 ) w i t h k = 8.98 x 1 0 "  2  min" . 1  00  1 0.75  Omin. F i g u r e VI-6.  i—i—i  I 1 1 1.10 0.750.50  1.10 075 0.50  9 min.  2 2 min.  The H n.m.r. Spectra of f fars(C0) ReMn(C0) . 4  4  4  i—i—i  i — r — i 1.10 0.75 0.50  3 0 min.  95 min.  1.10 075 0.50  the Thermal  Rearrangement  of  - 169 -  Tab!e V I - 6 The T h e r m a l  Rearrangement o f  f fars(C0) ReMn(C0) 4  4  t (mi n. )  4  a t 156°C.  C o n c e n t r a t i on o f f f a r s (C0) ReMn(C0") ( a r b i t r a r y . u-ni t ) 4  4  0  50  4  37  9  "  25  13  17  22  10  30  8  Temperature v a r i a t i o n gave t h e f o l l o w i n g  4  over t h e range 153.5°C t o 162°C  results  ( T a b l e VI - 7) :  Table VI-7 The Thermal f fars(CO) ReMn(CO) . 4  4  4  Rearrangement o f Temperature Dependence o f k  T°(K)  k(min" )  426.5  6.93 x 1 0 "  2  429  8.98 x 1 0 "  2  435  1.68 x 1 0 "  1  1  —Jjj  20  30  t(min) Figure VI-7 .  Graph of 1 o g [ f f a r s ( C 0 ) R e M n ( C 0 ) ] 4  the  Conversion 4  t  vs. t f o r  of f fars(C0) ReMn(C0) 4  4  i-f fars(C0) ReMn(C0) . 4  4  4  4  4  ,into  - 171 Over  this small temperature  the A r r h e n i u s r a t e p l o t  range o f 153.5°C  to  162°C,  ( F i g u r e V I - 8 ) gave an e n t h a l p y o f  a c t i v a t i o n o f 3 9 . 2 ± 5.2 K c a l m o l e  - 1  .  The e n t r o p y o f  a c t i v a t i o n was c a l c u l a t e d ' t o be 2 0 . 9 ± 2.8 e . u .  VI. 2.(G) K i n e t i c s o f t h e Thermal \  f^farsMn (CO) 2  Radical  8  Rearrangement  i n the Presence  2  4  2  was d i s s o l v e d i n 0.0073 g o f 3 , 5 - d i r  T h e n.m.r. t u b e was  the kinetics of the thermal  f farsMn (CO)g  y  T o t h i s was a d d e d  tert-butyl-0-benzoquinone. and  of a Free  Scavenger.  0.0125 g o f f ^ f a r s M n ( C O ) 0.6492 g o f CgHg.  of  rearrangement  was s t u d i e d by r e c o r d i n g t h e  s p e c t r a e v e r y 10 m i n .  heated  of n.m.r.  The o b t a i n e d r a t e c o n s t a n t s were  t h e same as i n S e c t i o n V I . 2 . ( D ) .  V I . 3.  R e s u l t s and D i s c u s s i o n  V I . 3. ( A ) K i n e t i c  The  Results  kinetics of the thermal  f f a r s M ( C 0 ) ( M = Re, 4  2  8  Mn)  rearrangement  of  - 173 -  Me  (CO),  9  As*—»M(CO), / i 4  •AsMe,  v  'As—»M(CO), Me  was  As—>M.(CO)  A  Me  0  s t u d i e d b y u s i n g H n.m.r. s p e c t r o s c o p y w h i c h  provided  1  a f a s t a n d c o n v e n i e n t way  to f o l l o w e i t h e r the  ance o fr e a c t a n t o r appearance  o fproduct  y  4  2  disappear-  without  i n t r o d u c i n g a i r i n t o the r e a c t i o n mixture. ( a ) The  Thermal  Rearrangement of  f^farsMn (CO)g. 2  Using t h i s technique, the thermal of f^farsMn (C0)g 2  was  found  t obe f i r s t  r e a c t a n t w i t h a r a t e c o n s t a n t k = 3.00 Temperature yielded  v a r i a t i o n over the range  the AH^and  AS^  values  rearrangement  order in this -2 -1 x 10  131°C  t o 147°C  ( T a b l e VI - 8 ) .  be n o t e d t h a t o v e r t h i s t e m p e r a t u r e  range  min .  the  It should thermal  - 174 -  table Results Thermal  VI-8  o fKinetic Studies  o f The  Rearrangements o f f f a r s M ( C O ) 4  * ' , -1\ A H ^M(KKcc aa ll m mooll e ) f.farsMn (C0) 2  f  2  4  solvent  ± 4.7  46.8  ± 0.5  2 3 . 2 2 ± 1 -1  39.2  ±5.2  20.9  C H 6  6  o  4  2  occurs  o  c  into i-f farsMn (C0) 4  f farsRe (C0)  i n the s o l v e n t  8  was  this temperature,  ± 2.8  H  CgDg  first  with  100%  conversion  CgHg.  f farsRe (C0) . 4  2  k i n e t i c s o fthe thermal g  C  o  Thermal Rearrangement of The  ^ 66 6  4  / 1  2  15.0  ±"2.0  rearrangement o ff farsMn (C0)  4  u )  P  A S ' ^ . U . ;  36.8  8  fars('C0) MnRe(C0)  (b) The  *cTr  g  8  f farsRe (C0) 4  2  studied  the expected  g  rearrangement o f  in CDC1  3  product,  at 148°C. A t i-f farsRe (CO) , 4  2  was  not obtained.  Instead,  the  two  p e a k s a t 2.10  and  p.p.m., i n d i c a t i n g t h a t  2.12  n.m.r. s p e c t r u m  8  showed either  the e q u i 1 i brium t . f farsRe (C0) 4  2  148°C  V  YbTTJ 4 f  8  f a r s [ R e ( C 0 )  4  C 1 ]  2  H.3  - 175 -  occurred  or the conversion  fgfars[Re(COJ^CI]  of f^farsRe (CO) 2  was n o t c o m p l e t e d u e t o i n s u f f i c i e n t  2  amount o f CDCl^ s o l v e n t . possibility,  into  To e l i m i n a t e  the l a t t e r  t h e n . m . r . t u b e w a s o p e n e d a n d m o r e CDC 1 ^  was a d d e d .  Further  two peak^s.  Thus t h e e q u i l i b r i u m shown by e q u a t i o n  is responsible heating  heating  f o r t h e two n.m.r. s i g n a l s .  [1]  After  prolonged  o f t h e sample, t h e i n f r a r e d spectrum showed  the product  of equation  into f farsRe(C0) Cl 4  3  fgfars Rc'C0) . 4  o f t h e t u b e s h o w e d t h e same  L  CDC1Q  148°C  [1] reacts f u r t h e r being  and R e ( C 0 ) C l  that  converted  as shown by e q u a t i o n [ 2 ] .  5  f .f a r s [ R e (CO ) - C l ] 4  L  9  148°C •i/  f farsRe(C0) Cl 4  From t h e graph o f l o g [ f f a r s R e ( C 0 ) g ] 4  2  version of f farsRe (C0)g 4  presence order  4  observed  2  rate constant The  f^farsRe (CO) 2  using  CDC 1^ w a s f o u n d  in f farsRe (C0)g  8  t  5  vs. t , the  into fgfars[Re(CO)^Cl]  2  of excess  + Re(C0) Cl  3  2  ...  coni n the  t o be p s e u d o - f i r s t -  concentration with a combined -3 -1 o f 2 . 5 6 x 10  min  k i n e t i c s of the thermal  conversion  into i-f^farsRe (CO)  was f u r t h e r  benzene as s o l v e n t .  2  g  Over the temperature  of studied, range  [2]  - 176  193°C  to 202.5°C,  -  t h e c o n v e r s i o n was  found  t o be  o r d e r i n f ^ f a r s R e ^ ^ ( C O ) g c o n c e n t r a t i o n , w i t h AH^ 46.8  ± 0.5  VI - 8 ) .  Kcal mole"  1  but a l s o thermal ( c ) The T h e r m a l  The  Rearrangement  thermal  thermal  rearrangement,  two  of  fgfars(COJ^ReMn(CO)^.  of  s t u d i e d i n CgDg o v e r t h e t e m p e r a t u r e It is interesting  0  4  A  4  range  to  to note t h a t the product of  the  i-fgfars(COJ^ReMn(CO) , 4  (CO),  Mn«— As (CO) Me  f fars(CO)^ReMn(CO) 153.5°C  p o s s i b l e s t r u c t u r e s , A and  Me  rearrangement  o f up t o 2 0 % o f t h e r e a c t a n t ,  rearrangement  162°C.  2  (Table  kinetic  showed not o n l y thermal  decomposition  =  ± 1 .1 e . u .  I t s h o u l d be n o t e d t h a t d u r i n g t h e  s t u d i e s , the sample  was  a n d AS ' = 2 3.2  1  first  B.  can  A l t h o u g h A and  have B  (CO), Re£  Me As  As Me  »Mn (CO)  2  B  cannot  9  4  4  -  -  177  1  19  be d i s t i n g u i s h e d o n t h e b a s i s o f t h e i r  H and  spectra,  s t r u c t u r e i s more  i t i s p o s s i b l e t odecide which  l i k e l y from  t h e mass s p e c t r u m  f fars(C0) ReMn(C0) . 4  4  been found  o fthe reactant  This i s because  4  f farsMn (CO) 4  2  t orearrange t o i - f f a r s M n ( C O )  spectrometer  4  (Chapter  IV).  F n.m.r.  2  i n t h e mass  g  Since f farsRe (C0) •rearranges 4  s i m i l a r l y i n t h e mass s p e c t r o m e t e r ,  2  g  f fars(C0) ReMn(C0) 4  4  is also expected t oconvert t o i-f fars(CO) ReMn(CO) u n d e r t h e same c o n d i t i o n s . B e c a u s e r h e n i u m h a s t w o 187 185 4  isotopes and  Re a n d -  has  g  4  4  4  Re w i t h n a t u r a l a b u n d a n c e o f 6 3 %  37% r e s p e c t i v e l y , the f r a g m e n t a t i o n p a t t e r n s o f A and  B should look q u i t e d i f f e r e n t S p e c i f i c a l l y , fragments  i n t h e mass  spectrum.  C a n d D (X = 4-0) s h o u l d  AsMe,  offer  .Re(COX  2  F  Mn(CO).  AsMe,  D  - 178 -  a c l u e as t o which  structure i-fgfars(CO)^ReMn(CO) i s . 4  In f a c t , a f t e r c a r e f u l of f f a r s ( C 0 ) R e M n ( C 0 ) 4  4  e x a m i n a t i o n o f t h e mass  (Chapter I V ) , i t i s concluded  4  that f fars(C0) ReMn(CO) 4  spectrum  4  4  t o s t r u c t u r e A t h a n t o B. s t r u c t u r e B i s the major  will  more l i k e l y  rearrange  However, the p o s s i b i l i t y product in solution  cannot  that be  completely ruled out. In f a c t , t h e H n.m.r. s p e c t r a ( F i g u r e VI - 6) 1  s u g g e s t t h a t b o t h p r o d u c t s , A a n d B, a r e f o r m e d in e q u i l i b r i u m with f f a r s ( C 0 ) R e M n ( C 0 ) . 4  n.m.r. peaks  4  4  for f fars(C0) ReMn(C0) 4  4  4  and a r e  Thus, the  do n o t d i s a p p e a r  c o m p l e t e l y even a f t e r p r o l o n g e d h e a t i n g ( t h e H n.m.r. s p e c t r a o b t a i n e d a f t e r 95 m i n u t e s  a n d 206 m i n u t e s a r e  i denti cal). The m a j o r  p r o d u c t a s s o c i a t e d w i t h t h e two  singlets  a t 1 . 1 0 & 0 . 6 0 p.p.m.  i s assigned to structure A f o r  reasons given above.  On t h i s b a s i s , t h e o t h e r t w o  singlets B.  a t 1 . 0 8 a n d 0 . 5 0 p.p.m.  The proposed  assignments  ;  i s assigned to structure  e q u i l i b r i u m and t h e a p p r o p r i a t e n.m.r.  are given i n equation [ 3 ] .  - 179 -  Me  (CO), .Re  Me (CO), ' .As—»Re  (CO)/  9  2  4  Mn<— As (CO) Me 4  H  n.m.r. peaks  0 min  ^As—»Mn Me (CO) 2  2  1.10 and 0.60 p.p.m.  206 min  4  initial  rearrangement i s almost Me  0  4  kinetics o f  However, s i n c e the  entirely 2 CCO), A t^o Re 4  M e  s  A  10%  rearranges  v  4  B  V  (CO),  Mn<—As (CO), Me,  >Mn (CO)  0%  t o two p r o d u c t s , t h e d e t a i l e d  this rearrangement i s complicated.  2  1.08 and 0.50 p.p.m.  10%  Because fgfars(CO ) ReMn(CO) reversibly  As Me  4  100%  80%  2  -{»]  0.72 and 0.80 p.p.m.  0%  Me As  a  As—>Mn Me (CO) 2  4  - 180  o b t a i n A H ^ and A S ^ v a l u e s ( T a b l e VI-8)  one can s t i l l this  rearrangement In  by u s i n g t h e i n i t i a l  1  H n.m.r.  summary, the k i n e t i c s o f the  rearrangements  of f farsMn (CO) 4  f fars(C0) ReMn(C0) 4  -  4  2  were s t u d i e d .  4  2  2  rearranges to i - f f a r s M n ( C 0 ) c o m p l e t e l y 4  f farsRe (CO) 2  parameters  g  shows some d e c o m p o s i t i o n  g  rearrangement  2  t o i - f f a r s R e ( C 0 ) . The 4  2  f o r these thermal  Table VI-8.  g  4  4  thermal  rearrangement  A & B.  The a c t i v a t i o n p a r a m e t e r s  Table  4  undergoes  are found in reversible products,  f o r the i n i t i a l  rearrange-  into A are a l s o found in  P o s s i b l e Rearrangement of  be d i s c u s s e d . radical  and  M e c h a n i s m s and  Comparisons  K i n e t i c Res u l t s .  Three  possible rearrangement The f i r s t  mechanisms w i l l  now  two m e c h a n i s m s i n v o l v e t h e f r e e  the c a r b o n y l b r i d g e d i n t e r m e d i a t e s which  have  d i s c u s s e d f o r the i o d i n e cleavage r e a c t i o n s in  C h a p t e r V.  The  t h i r d mechanism i n v o l v e s the o x i d a t i v e  a d d i t i o n ' o f an A s - C metal  while  VI-8.  VI. 3.(B)  been  4  g  activation  w i t h f o r m a t i o n o f two  ment o f f f a r s ( C O ) R e M n ( C O ) 4  4  and  in i t s thermal  rearrangements  f fars-(C0) ReMn (C0)  g  f farsMn (CO) 4  integrals.  thermal  , f farsRe (CO) 4  for  carbonyl  bond to a c o - o r d i n a t i v e l y u n s a t u r a t e d  moiety.  - 181  The f r e e r a d i c a l homolytic step.  -  mechanism  (Scheme VI-1) has t h e  f i s s i o n of the metal-metal  Free r a d i c a l  E undergoes the cleavage  bond and the f o r m a t i o n f o r m s a new A s - M  bond as t h e  o f a n M-C  a bond to y i e l d  first  o f an  As-C  bond to g i v e F which the f i n a l  then  product  i-f farsM (C0) 4  2  The b r e a k i n g i s an i m p o r t a n t formation M-C  of the normally  s t e p a n d i s f a c i l i t a t e d by t h e  o f t h e new  M-C  bond.  The f o r m a t i o n  double  bond i n bonding  (L-L)Fe (C0) 9  f i  4  moiety  to a metal  complexes (5).  Me .As  first. i s well  bond  partial of the  b o n d c o u l d i n v o l v e t h e c o o r d i n a t i o n o f t h e C=C  of the l i g a n d to the -M(C0)  in  s t r o n g As-C  new  bond  Use o f t h e substantiated  -182  Scheme V I - 1 .  P o s s i b l e Rearrangement Mechanism f o r f f a r s M 2 ( C 0 ) g . 4  Me  Me ^As^—»M(CO)  9  , A S ^ - H > M ( C O )  F  -  4  2  4-  As—»M(CO), Me.  Me As^-»M(CO), 9  'M«-—AsMe, (CO) '4  - / N  „  As—i M(CO), Me N  0  Me? As^—»M(CO),  M< (CO),  AsMe,  4  - 183  -  In s u m m a r y , t h e o v e r a l l r e a r r a n g e m e n t viewed  as i n v o l v i n g t h e h o m o l y t i c  fission  of the  b o n d f o l l o w e d by t h e i n s e r t i o n o f t h e M ( C 0 ) one  o f the As-C The  bonds of the second  intermediate  unsaturated  M(C0)  3  t h e As-C formation  moiety.  The  AsMe  second  o f t h e M-C  f o l l o w e d by t h e b r e a k i n g  bridged  bond w i t h  intermediate  bond c o u l d f i r s t  involve  new  As -> M d a t i v e The  t h i r d and  The  a simpler mechanism  5  the  formation  of  ( S c h e m e V I - 3)  o f t h e As •->• M d a t i v e b o n d a s  o x i d a t i v e a d d i t i o n o f the As-C  co-ordinatively unsaturated  *M(C0)^ moiety  F i n a l l y the s h i f t of the AsMe produces  M(C0)  bond.  i n v o l v e s the breaking step.  a bond and  the  changing  2  As ->- M d a t i v e b o n d t o an A s - M  Again,  Finally  i - f f a r s M ( C 0 ) g i s f o r m e d as a r e s u l t o f 4  of  the  K.  bond of the l i g a n d to the  one  first  the  unsaturated  a s d i s c u s s e d . e a r l i e r f o r S c h e m e V I -1 .  product  carbonyl  step is  group to the  2  t h e m a k i n g o f t h e M-C  c o o r d i n a t i o n o f t h e C=C moiety  of a  G which contains a c o - o r d i n a t i v e l y  of the. c a r b o n y l  the formation  into  mechanism  the formation  This i s then  bond and  M-M  moiety  4  p o s s i b l e rearrangement  coordination of another M(C0)2 moiety.  be  ligand.  ( S c h e m e V I - 2 ). i n v o l v e s f i r s t bridged  can  the product,  2  4  i s a n a l o g o u s "to t h a t p r o p o s e d  bond  produces  g r o u p i n t o t h e M-M  i-f farsM (C0)g. 2  This  by G r a h a m a n d  the to I. bond  mechanism Hoyano  (6)  - 184 -  Scheme V I - 2 .  P o s s i b l e Rearrangement Mechanism f o r f f a r s M ( C 0 ) g . 4  Me, As—»M(Cd)/ I  2  Me As^M(CO),  H  3  C=0 v  As—»M(CO),  AsMe-  Me As^-»M(CO), 2  As—-»M(CO),  M  As Me  ^M(COL 5  As\ > ^c=o A  M (CO),  0  H  Me As—>M(CO), 2  F  •M(CO),  2  M<  AsMe  <C0)  4  9  185 Scheme V I - 3 .  P o s s i b l e Rearrangement Mechanism f o r f f a r s M 2 ( C 0 ) g . 4  Men  As^—5>M(C0),  'AsMe,  M(CO)/  Men • As  v  * M(CO),  As—-»M(CO), Me 4  0  (CO),  Me  M < «  A S  As Me  I  2  (CO),  9 2  - 186  for  -  the r e a c t i o n between Re (C0).]Q  and  2  All s i n c e they  the proposed  agree with  Rate  =  not produce  m e c h a n i s m s a r e p o s s i b l e •'.,„•,•  the e x p e r i m e n t a l l y found r a t e  4  2  8  d i d not change the r a t e of the  and  thermal  the p h o t o l y s i s of f f a r s R e ( C O ) 4  a free radical  mechanism seems l e s s The  law:  of the f a c t t h a t the a d d i t i o n of a f r e e  scavenger  rearrangement  3  k[f farsM' (C0)" ]  However, i n view radical  H S i C1 .  second  (Chapter  2  V), the  did  g  first  likely. mechanism i n v o l v i n g a  bridged intermediate cannot  carbonyl  be e l i m i n a t e d a n d m u s t  be  considered e s p e c i a l l y sinee this mechanism best f i t s iodine cleavage  reactions of f f a r s M ( C 0 ) g 4  2  the c o n v e r s i o n of f f a r s [ M ( C 0 ) I ] 4  M.(C0)gI ( C h a p t e r which  III).  the order f f a r s M n ( C 0 ' ) 4  f farsRe (C0)g.  metal  4  In a d d i t i o n , t h i s  values  2  2  s  (Table VI-8)  3  which  and  • bond  as  experimentally increase in  4  T h i s i s a l s o the o r d e r found  4  < for  o f t h e u l t r a v i o l e t o+o* t r a n s i t i o n s ' o f t h e bonds of these compounds which  and  mechanism,  < f fars(C0) ReMn(C0) 4  V)  into f farsM(C0) I  consuming step, agrees with the  obtained enthalpy  energy  2  r e q u i r e s t h e b r e a k i n g o f the. m e t a l - m e t a l  an e n e r g y  4  4  (Chapter  the  c a n be t a k e n  the metalto  - 187 -  indicate the relative Although  metal-metal  bond  t h e r e a r e no d i r e c t  the t h i r d mechanism, the experimental a l s o seem t o f a v o u r i t . the thermal  experiments to support enthalpy  to this  values  mechanism,  r e a r r a n g e m e n t o f f ^ f ars-Mng ( C 0 ) g a n d  fgfars(C0) ReMn(C0) 4  similar  According  strength.  As—>Mn  approximately  4  involves the breaking of a very  d a t i v e bond.  The A H * v a l u e s  be t h e same, p r o v i d e d t h a t l a t e r  do n o t m a k e s i g n i f i c a n t This i s indeed  found  should steps  contribution to the AH* values.  t o be t r u e e x p e r i m e n t a l l y  (Table  VI-8). The tetrahedral  kinetics  o f racemization o f the pseudo-  compound, J , have been s t u d i e d r e c e n t l y by  Mn  0 J  - 188 -  H n.m.r. a n d p o l a r i m e t r i c t e c h n i q u e s  (7,8).  of a c t i v a t i o n f o r the loss o f the phosphine is the rate determining 31.1  Kcal/mole.  enthalpy  f farsMn (C0) 4  2  ligand,  a n d f ' f a r s ( C 0 ) R e M n ( . C 0 ) ..which 4  4  high entropy  e x p l a i n e d by t h e f o r m a t i o n  values  of  involves  4  t h e b r e a k i n g o f an As—>-Mn bond as an i m p o r t a n t  mediates  which  i s c o n s i s t e n t with our  (Table VI-8) f o r the rearrangement  g  The  enthalpy  step f o r the racemization, i s  This value  values  The  step.  ( T a b l e V I - 8 ) c a n be  of the d i s s o c i a t i v e inter-  i n v o l v e d i n the thermal  rearrangement.  This  is e s p e c i a l l y true i n the case o f the o x i d a t i v e a d d i t i o n mechanism which one  a r s i n e group  from  involves the d i s s o c i a t i o n of  t h e metal  atom.  V I . 3 . ( C ) Summary The f farsM (CO) 4  2  k i n e t i c s o f the thermal  (M = R e , Mn) h a s b e e n s t u d i e d b y H 1  8  spectroscopy. 2  of  n.m.r.  The e n t h a l p i e s o f a c t i v a t i o n f o r  f farsMn (C0) , 4  rearrangements  8  f farsRe (C0) 4  2  g  and  f fars(CO) ReMn(CO) 4  4  4  a r e 3 6 . 8 ± 2 . 0 , 4 6 . 8 ± 0.5 a n d 3 9 . 2 ± 5.2 r e s p e c t i v e l y while the entropy 20.9  v a l u e s a r e 1 5 . 0 ± 4 . 7 , 2 3 . 2 ± 1.1 a n d  ± 2.8 e . u . r e s p e c t i v e l y .  enthalpy values  The o r d e r o f these  i s i n agreement with the r e l a t i v e  order  - 189 -  of the metal-metal determined  i n these  complexes as  by t h e u l t r a v i o l e t m e t a l - m e t a l  transitions, Chapter  bond s t r e n g t h  (a->a*)  i . e . , R e - R e > R e - M n > Mn-Mn ( s e e  IV).  Three p o s s i b l e mechanism f o r the  ment r e a c t i o n s a r e d i s c u s s e d  and the o x i d a t i v e  mechanism i s favoured.  i s because that  This  to this mechanism the rearrangement o f and  fgfars(C0) ReMn(C0)  very should  4  similar  according  4  2  involves the breaking  be t h e same.  experimentally.  addition  f farsMn (C0)g  A s -* Mn d a t i v e b o n d a n d t h e AH*  approximately  t o be t r u e  4  rearrange-  of a  values  This i s indeed  found  - 190 -  References  1.  F. W. B. E i n s t e i n , A. M. P i l o t t i a n d R. I n o r g . C h e m . , 1_0, 1 9 4 7 (1 971 ) .  Restivo,  2.  W. R. C u l l e n , D. A . H a r b o u r n e , B. V. L i e n g m e a n d J . R. S a m s , i b i d . , 9 , 7 0 2 (1 9 7 0 ) .  3.  J . P. C r o w a n d W. R. C u l l e n ,  4.  F . W. B. E i n s t e i n , R. D. G. J o n e s , A . C. M a c G r e g o r a n d W. R. C u l l e n , u n p u b l i s h e d r e s u l t s . W. R. C u l l e n , D. A . H a r b o u r n e , B . V . L i e n g m e a n d J . R. S a m s , I n o r g . C h e m . , 8 , 95 (1 9 6 9 ) . J . K. H o y a n o a n d W. A. G. G r a h a m , I n o r g . C h e m . , 11 , 1265 (1972).  5. 6.  i b i d . , ]_0, 21 65 (1 971 ) .  7.  H. E r u n n e r , A n g e w C h e m . I n t e r n a t .  8.  H. B r u n n e r a n d H. D. S c h i n d l e r , 2 4 6 7 (1 971 ) .  E d n . , 10, 249 Chem. B e r . , 1 0 4 ,  -191  -  Appendix I Reactions  o f Some F l u o r i n a t e d A c e t y l e n e s  with  Tetrakis(triphenylphosphine)platinum(0)  A l t h o u g h a number o f complexes have been prepared a c e t y l i d e s a r e known.  platinum-acetylene  ( 1 - 8 ) , o n l y a few  platinum  C h a t t a n d Shaw ( 2 ) f i r s t  some a c e t y l i d e s o f t h e t y p e t r a n s - ( P ( C H g ) ) 2  3  2  prepared  Pt(CHCR)  (R = H, CH-j, C g H g ) b y t h e r e a c t i o n o f t h e s o d i u m  acety-  1ide with c i s - ( P ( C H ) ) P t C l i n l i q u i d ammonia. 2  5  3  similar bisacetylide, was i s o l a t e d  2  trans-(P(C H ) ) Pt(C=CCF ) , 2  reaction of trans-(P(C H ) ) P t C l 2  also prepared  A  2  5  by Stone and c o - w o r k e r s  magnesium i o d i d e .  5  3  2  2  3  2  3  2  (4) from the  with trif1uoropropyny1 -  R e c e n t l y , R o u n d h i l l and co-workers  a platinum  (5)  bi'sacetyl i d e h y d r i d e by t h e  reaction of tetrakis(triphenylphosphine)pi atinum(0), with  2  1-ethynylcyclohexanol.  A,  - 192 -  Harbourne  and Stone  (3) have r e p o r t e d t h a t t h e TT-  3,3,3-trifluoropropyne reacts with A to yield bonded  complex  (P(CgHg ) ) P t ( C F C H ). 3  2  3  In t h i s  2  we r e p o r t t h a t t h i s r e a c t i o n a f f o r d s t h e complex  appendix,  o-bonded  c i s - ( P ( C g H ) ) P t ( C = C C F ) , B, i n l o w y i e l d i f 5  3  2  3  2  e x c e s s ^pVopyne i s used and i f t h e r e a c t a n t s a r e l e f t f o r longer periods.  A similar product  (P(CgHg) ) Pt(CHCC Fg) , 3  2  2  C, i s o b t a i n e d w h e n A a n d 3 , 3 , 4 , 4 , 4 - p e n t a f 1 u o r o b u t y n e  2  react  at 20°. The  s t r u c t u r e o f B f o l l o w s from i t s i n f r a r e d  and ^ F n u c l e a r m a g n e t i c  resonance  (n.m.r.) s p e c t r a . _i  f o r m e r shows a b s o r p t i o n s a t 2115 and c h a r a c t e r s t i c of C=CCF  3  2060  groups a-bonded  The  cm ' w h i c h a r e  to a metal  (4,9,10).  T h e p r e s e n c e o f t w o C=C s t r e t c h i n g f r e q u e n c i e s s u g g e s t s that the f l u o r o c a r b o n groups a r e c i s to each other i n t h i s 19 compound.  The  F n.m.r. s p e c t r u m c o n f i r m s t h i s s t e r e o -  c h e m i s t r y and shows a t r i p l e t o f d o u b l e t s c e n t e r e d a t 44.2  p.p.m. [ J .  2 9 . 8 H z ; J - - 3.8 H z ] . T h e Pt-CE3 ' 3 chemical s h i f t and Pt-CF coupling constant are s( iP m(iCl aHr ) t)o Ptth (o Cs eE C fC oF u n) d f( o4 r) ,a wn ha il co hg o ussh o wb si ,s a ch oe wt ey vl eird,e ta r a n s 19 1 Q C  i y b  D  r r  P  L h  3  2  5  3  2  triplet of triplets  3  2  in i t s  F n.m.r. s p e c t r u m  the f l u o r o c a r b o n groups a r e t r a n s t o each o t h e r .  becaus< The  -  spectrum  of B arises  193 -  because  only one phosphorus  is s i g n i f i c a n t l y coupled t o the C F group.  Since i t  3  has been  found  g r e a t e r than • J  (3,6,11) D  '.'  r c  that J  p  t r a n s  _rjp  i s usually  . -i t seems r e a s o n a b l e t o a s s i g n  the c o u p l i n g i n B t o the i n t e r a c t i o n groups  atom  and the phosphorus  between the C F  atoms t r a n s t o them.  3  However,  t h e v a l u e o f 3 . 3 Hz f o u n d f o r t r a n s - - ( P ( C H g ) ) P t (C = C C F ) 2  (4)  one  2  3  2  1 ess, certain.  makes t h i s a s s i g n m e n t Although  3  (P(CgHg ) ) P t ( C = C C F g ) 3  2  2  C=C s t r e t c h i n g a b s o r p t i o n a t 2125 c m  , C, shows o n l y  2  - 1  ,this i s not  sufficient evidence to assign a trans structure. 19  Unfortunately, the due  F n..m.r. s p e c t r u m v/ss n o t o b t a i n a b l e  to its-.low-solubility.'  procedure as B a c i s geometry Additional correctly  S i n c e C w a s made b y t h e same seems more  likely.  evidence that C i s formulated  i s p r o v i d e d b y i t s mass s p e c t r u m  a p a r e n t m u l t i p l e t a t m/e  =1000  ±10.  which  shows  The c a l c u l a t e d  p a r e n t m u l t i p l e t , m/e = 1 0 0 5 , f o r C i s w e l l w i t h i n c o u n t i n g error.  Furthermore,  the observed  the p a r e n t m u l t i p l e t a r e i n good  relative  intensities of  agreement with the  c a l c u l a t e d v a l u e s a s shown i n T a b l e 1. A d d i t i o n a l multiplets are observed the molecule fragments fluorocarbon andphenyl  i nthe spectrum  indicating  that  by loss o ft r i p h e n y l p h o s p h i n e , groups.  -  194  -  Table 1 Relative intensities  i n the parent m u l t i p l e t o f  t h e m a s s . s p e c t r u m o f (P(C HcK)oPt(C = CC Fr ) fi  Relative m/e  ?  Intensity  Observed  Calculated  1002  2.2  1 .55  1003  2.4  0.77 65.71  1004  61  1005  100  1006  91  91.89  1007  35  34.55  1008  22  21.92  8.7  1009  ?  1u u  8.29  T h e r e a c t i o n o f h e x a f 1 u o r o b u t y n e -2 w i t h A produces  ( P ( C H ) ) P t ( F g C C g C F g ) , D, w h i c h h a s  obtained  p r e v i o u s l y by d i f f e r e n t routes  g  5  3  2  (6,7).  been This  c o m p o u n d i n w h i c h t h e a c e t y l e n e m o i e t y i s ir-bonded w a s i d e n t i f i e d by m i c r o a n a l y s i s , a n dby i t s i n f r a r e d a n d n.m.r. s p e c t r a .  - 195 -  Experimental  All  r e a c t i o n s were c a r r i e d  atmosphere and v o l a t i l e  out under a n i t r o g e n  r e a g e n t s were m a n i p u l a t e d  s t a n d a r d vacuum system.  M e l t i n g p o i n t s were  in evacuated c a p i l l a r i e s  and a r e u n c o r r e c t e d .  in a  determined Infrared  s p e c t r a w e r e r e c o r d e d on a P e r k i n - E l m e r 457 s p e c t r o p h o t o m e t e r , m a s s s p e c t r a o n a n A E I MS-9 and n.m.r. eters.  spectrometer,  s p e c t r a on V a r i a n T-60 a n d HA-100  Chemical  spectrom-  s h i f t s a r e g i v e n i n p.p.m. d o w n f i e l d  f r o m e x t e r n a l TMS a n d u p f i l e d  from e x t e r n a l CFCl^.  M i c r o a n a l y s e s were performed  b y M r . P. B o r d a o f t h i s  department. 3 ,3,3-Tri fl uoropropyne  was p r e p a r e d by t h e  dechlorination of 1,1,2-trichioro-3,3,3-trif1uoropropene with zinc dust i n dimethylformamide P e n t a f l u o r o b u t y n e was a g i f t  (12).  f r o m D r . M.C.  3,3,4,4,4Waldman.  H e x a f 1 u o r o b u t y n e - 2 w a s p u r c h a s e d f r o m P e n i n s u l a r Chem Research  Inc. and p o t a s s i u m t e t r a c h l o r o p l a t i n i t e  from  P l a t i n u m C h e m i c a l s, I n c . Preparation of c i s - ( P ( C H ) ) P t ( C H C C F ) , g  5  3  2  3  2  B.  Tetrakis(triphenylphosphine)piatinum(0),  A,  was p r e p a r e d b y t h e a c t i o n o f a n a q u e o u s s o l u t i o n o f 0.4 g  -196-  of sodium  b o r o h y d r i d e on an aqueous  oftriphenylphosphine  (0.83 g, 2 mmol).  A, was f i l t e r e d  50 ml o f h o t b e n z e n e ,  into t h e Pyrex tube.  tube.  ( 1 . 4 g , 15 m m o l ) w a s t h e n  condensed  nil  i i t  a u i i u  A f t e r 5 months a t room  reduced  washed with pentane crystallized  nitrogen, dissolved in  pressure.  L. t ^ - ^ r \ \j ^ti  m.p. 1 8 0 ° ( d e c ) .  / ^ j ^ i \,  -  alkyne  T h e r e s i d u e was  and ethanol and t h e crude  twice from d i e t h y l  H, 3 . 3 ; F , 1 2 . 6 .  temperature,  and the s o l v e n t and excess  were removed under  was  under  The p r e c i p i t a t e d  and t r a n s f e r r e d i n t o a Pyrex  3,3,3-Trifluoropropyne  t h e t u b e was o p e n e d  solution  (2.1 g, 8 mmol) a n d p o t a s s i u m  tetrachloroplatinite complex.  alcoholic  product  ether a t -78° t o give  t 2 J 2  \ v . \ u  y,  z io i y  Anal . Calcd. f o r C ^ H ^ F g P ^ t : Found:  n.m.r. s p e c t r u m  C, 5 5 . 7 ;  C, 5 5 . 4 ; H, 3 . 3 ; F , 1 2 . 4 .  The  ( a c e t o n e s o l u t i o n ) showed a m u l t i p l e t  a t 7.00 p.p.m. a n d t h e i n f r a r e d  spectrum  showed t h e f o l l o w i n g a b s o r p t i o n s :  (CHCl^ s o l u t i o n )  2990(br), 2115(s ),  2 0 6 0 ( s h ) , 1 590 ( w ) , 1 4 8 0 ( w ) , 1 4 3 5 ( w ) , 1 4 2 0 ( s h ) , 1  335(w),1 300(sh) ,  1220(br),1097(s),1030(sh),998(w),905(w),867(w),610(w), 522(m),504(sh),435(w)  cm' . 1  Preparation of (P(C H g  A benzene butyne  5  ) ) . P t (C = C C F g ) C . 3  2  solution of  2  2  3,3,4,4,4-pentafluoro-  ( 2 . 2 g , 16 m m o l ) a n d A ( 2 . 5 g\ 2 mmol ) w a s s e a l e d  - 197 -  in a Pyrex tube. for  5 months.  T h e t u b e was l e f t a t r o o m  A f t e r opening t h e tube, t h e s o l v e n t and  e x c e s s a l k y n e were removed under  reduced  r e s i d u e was w a s h e d w i t h m e t h a n o l . dichloromethane ,(C=CC F- ) 2  for  5  C44H  a t - 7 8 ° gave  F  3 0  1 0  Crystal 1ization  from  (P(C H ) g  (dec).  (CHC1  (fii), 1 000  n.m.r. s p e c t r u m  ( w ) , 520  and i n f r a r e d  (w)  cm  Preparation of (P(CgH ) ) Pt(CF C CF ), 3  2  Hexaf1uorobutyne-2 (2.5 g, 2 mmol) i n benzene 20°.  A f t e r removal  2  3000(br),2125(m),  ( s ) , 51 0 ( s h ) , 4 3 4  5  ) Pt-  Found:  1 585(w),1480(w),1 435(w),1 338(w),1176(s),1098(m),1 1 02S  3  I t showed a m u l t i p l e t a t  solution) at:  3  g  Anal . C a l c d .  2  p.p.m. i n i t s  absorptions  The  P P t : C, 5 2 . 5 ; H, 3 . 0 ; F , 1 8 . 9 .  C, 5 2 . 4 ; H, 2 . 9 ; F , 1 8 . 6 . 7.17  pressure.  a white solid  ( 0 . 1 0 g , 5 % ) ; m.p. 2 2 0 °  2  temperature  3  2  3  1  072 (m),  .'  D.  ( 2 . 6 g , 16 m m o l ) a n d A w e r e r e a c t e d f o r 14 d a y s a t  o f s o l v e n t and excess alkyne the  c r u d e r e s i d u e was e x t r a c t e d w i t h d i c h l o r o m e t h a n e a n d c r y s t a l l i z e d at -78° to y i e l d white crystals of (P(C H ) ) Pt(F CC CF ) 6  value  5  3  2  3  2  (6) 215-216°).  C, 5 4 . 5 ; H, 3 . 4 .  ( 0 . 7 0 g , 4 0 % ) , m.p. 2 1 6 ° ( l i t .  3  Anal . C a l c d . f o r C  Found:  4 0  C, 5 4 . 8 ; H, 3 . 3 .  H  3 0  F P Pt: g  2  -198-  References  1.  J . C h a t t , G. A . Rowe a n d A . A . W i l l i a m s , P r o c . C h e m . S o c , 2 0 8 (1 9 5 7 ) .  2.  J . C h a t t a n d B. L . S h a w , J . C h e m . S o c , 4 0 2 0  3.  D. A . H a r b o u r n e a n d F . G. A . S t o n e , J . C h e m . S o c , ( A ) , 1765 ( 1 9 6 8 ) . M. I . B r u c e , D. A. H a r b o u r n e , F . W a u g h a n d F . G. A . S t o n e , i b i d . , 3 5 6 (1 9 6 8 ) . J . H. N e l s o n , H. B. J o n a s s e n a n d D. M. R o u n d h i l l , I n o r g . C h e m . , 8, 2 5 9 1 ( 1 9 6 9 ) .  4. 5.  (1959).  6.  J . L . B o s t o n , S. 0. G r i m a n d G. W i l k i n s o n , J . C h e m . S o c , 3 4 6 8 (1 9 6 3 ) .  7.  E . 0. G r e a v e s , C . J . L . L o c k a n d P. M. Can.  0.  Chem., 4 6 , 3879  Maitlis,  (1968).  8.  A . « D . A l l e n a n d C. D. C o o k , i b i d . , 4 2 , 1 0 6 3 ( 1 9 6 4 ) .  9.  W. R. C u l l e n a n d W..R. L e e d e r , I n o r g . C h e m . , 5, 1 0 0 4 (1 9 6 6 ) . W. R. C u l l e n a n d M. C. W a l d m a n , J . F l u o r i n e C h e m . , 1, 41 ( 1 9 7 1 / 7 2 ) . B. C l a r k e , M. G r e e n , R. B. L . O s b o r n a n d F . G. A . S t o n e , J . Chem. S o c , ( A ) , 167 ( 1 9 6 7 ) .  10. 11. 12.  W. G. F i n n e g a n a n d W. P. N o r r i s , J . O r g . C h e m . , 2 8 , 1139 ( 1 9 6 3 ) .  - 199  Appendix The  -  II  Reaction of Bis(trif1uoromethyl)diazomethane with Bis(trimethylsi1y1 )acety1ene .  Although prepared  a number of c y c l o p r o p e n e s  have  c o n t a i n i n g a s i n g l e sigma-bonded metal  or  m e t a l T o l d s u b s t i t u e n t ( 1 , 2, 3 ) , n c e x a m p l e s w e r e w h e r e two  o r m o r e o f t h e s u b s t i t u t e n t s on t h e The  been  known  cyclopropene  were of t h i s  nature.  diazomethane  with b i s ( t r i m e t h y l s i l y l ) a c e t y l e n e under  influence of ultraviolet  r e a c t i o n of bis(trif1uormethy1)  irradiation  produces  l,2-bis(tri-  methylsilyl)3,3-bis(trifluoromethyl )cyclopropene in (6%)  the  low  yield.  *  (CH„),Si  [1]  - 200  The  -  same m e t h o d has b e e n u s e d  (trifluoromethyl)cyclopropenes (R  =  H,  CF ,  (CH ) Sn,  3  3  3  acetylenes give mainly a d d i t i o n which  yield  (CH ) Ge) 3  The  the cyclopropenes  by n i t r o g e n  i n the i n t i a l  C F  H o w e v e r some c y c l o p r o p e n e reaction.  3  C E C R  "organic"  1,3-dipolar  i n t e r m e d i a t e i s o p y r a z o l e was of eq.  (2).  3  3,3-bis  the a c e t y l e n e s  i s o p y r a z o l e s by  e l i m i n a t i o n on- h e a t i n g . produced  from  to p r e p a r e  No e v i d e n c e  o b t a i n e d from  is  f o r an  the r e a c t i o n  [1]• The s t r u c t u r e o f t h e p r o d u c t f o l l o w s f r o m i t s 1 1 9 F n.m.r. s p e c t r a , w h i c h  have the  the  "double-bend"  singlet  H and  chemical  s h i f t v a l u e s , and  stretching frequency 1946  o r 1928  cm . - 1  strong  (4) i n the i n f r a r e d This frequency  recorded for a cyclopropene the p r e v i o u s l y observed  and  expected  spectrum  i s one o f t h e  i s unexpected  at highest  i n view  trend that electropositive  in the v i n y l i c p o s i t i o n lower the frequency  of  groups  (2).  Experimental  All  v o l a t i l e reagents  in a s t a n d a r d vacuum system. r e c o r d e d on a P e r k i n - E l m e r magnetic  resonance  457  and  p r o d u c t s were  manipulated  I n f r a r e d s p e c t r a were spectrophotometer.  Nuclear  s p e c t r a were r e c o r d e d u s i n g a V a r i a n  T60  - 201  instrument.  -  M i c r o a n a l y s e s w e r e p e r f o r m e d b y Mr.  Borda of this  Department.  • B i s ( t r i m e t h y l s i1 y l ) a c e t y l e n e  ( 0 . 8 5 g , 5.0  (5) and b i s ( t r i f l u o r o m e t h y l ) d i a z o m e t h a n e (6) were s e a l e d i n a P y r e x t u b e and Watt  ultraviolet  The  less volatile  lamp  (20% SF-96  identified.  acetylene  irradiated with a  F, 3 5 . 6 . spectrum  The  (CCl  the l a t t e r c  4  C, 4 1 . 3 ;  collected  t h e c y c l o.proper.e (0..G91 i  H  H, 5 . 7 3 ;  F  ;  C  F, 3 5 . 3 .  '  4 1  The  *  2 ;  ]  H  solution) consisted of a singlet at  F spectrum consisting  upfield  Only  f o r m e r p r o v e d t o be u n r e a c t e d  p.p.m. d o w n f i e l d f r o m i n t e r n a l 19 a  c o u l d be  from external  in  chromato-  at 140°) into eleven components.  Anal . C a l c d . f o r i i i s ^ 2 6  Found  200  contents of the tube which condensed  ( 0 . 4 0 g.) a n d  5.7% y i e l d ) .  mmoles)  a t a d i s t a n c e o f 10 cm f o r s i x d a y s .  the s e v e n t h and e l e v e n t h f r a c t i o n s and  mmoles)  ( 1 . 0 g , 5.6  a t r a p a t - 7 8 ° , w e r e s e p a r a t e d by v a p o r p h a s e graphy  Peter  TMS.  The  The  the f o l l o w i n g a b s o r p t i o n s ( l i q u i d  infrared film):  '  5  -  6 2 ;  n.m.r. 0.29  same s o l u t i o n  o f a s i n g l e t a t 57.5  CFCl^.  H  g,  gave  p.p.m.  spectrum  showed  2975(m),2905 (w),  1 9 4 6 ( s ) , 1 9 2 8 ( s ) ,1 3 9 6 ( s ) ,1 3 3 2 ( s ) ,1 3 0 0 ( m ) , 1 2 5 8 ( s ) , 1 1 6 0 ( s , b r . ) , 1020(w),970(s),860(s,br.),822(m,sh),768(m),712(s),700(m,sh.), 688(m,sh.),650(w) ,620(m) cm" . 1  .  - 202 -  References  1.  W. R. C u l l e n ,  2.  W. R. C u l l e n a n d M. C. W a l d m a n , C a n . J . C h e m . 4 8 , 1885 ( 1 9 7 0 ) .  3.  W. R. C u l l e n a n d M. C. W a l d m a n , J . F l u o r i n e in  Fluorine  Chem. R e v i e w s ,  3_, 73 (1 9 6 9 ) .  Chem.  press.  G. L . G l o s s ,  5.  R. W e s t a n d L . C. Q u a s s , J . O r g a n o m e t a l . C h e m . 1 8 , 55 (1 9 6 9 ) . D. M. G a l e , W. J . M i d d l e t o n , a n d C. G. K r e s p a n , J . A m e r . C h e m . S o c . 88 , .361 7 (1 9 6 6 ) .  6.  Advan.  Alicyclic  C h e m . 1,  4.  53  (1963).  

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