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Sulfoxide complexes of rhodium and iridium and their potential use as asymmetric hydrogenation catalysts Morris, Robert Harold 1978

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SULFOXIDE COMPLEXES OF RHODIUM AND I R I D I U M AND THEIR POTENTIAL USE AS ASYMMETRIC HYDROGENATION CATALYSTS  by  ROBERT HAROLD MORRIS B.Sc.(Hon.), U n i v e r s i t y  o f W a t e r l o o , 1975  A T H E S I S SUBMITTED I N P A R T I A L FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY  in  THE FACULTY OF GRADUATE STUDIES Department o f Chemistry  We a c c e p t t h i s to  The  t h e s i s as conforming  the required  University  standard  of B r i t i s h  Columbia  November, 1978 ©  Robert Harold M o r r i s ,  1978  In  presenting  this  an a d v a n c e d  degree  the  shall  I  Library  f u r t h e r agree  for  scholarly  by  his  of  this  written  at  thesis  make  that  freely  may It  is  University  gain  Oct IT!, f ? 7 ?  Columbia,  British  by  shall  m  British  of  for  Columbia  r  the  that  not  requirements I  agree  r e f e r e n c e and copying  t h e Head o f  understood  C^-^ ' s l V y of  of  for extensive  permission.  of  fulfilment  available  be g r a n t e d  financial  2075 Wesbrook P l a c e Vancouver, Canada V 6 T 1W5  Date  it  permission  purposes  for  in p a r t i a l  the U n i v e r s i t y  representatives.  Department The  thesis  of  or  that  study.  this  thesis  my D e p a r t m e n t  copying  for  or  publication  be a l l o w e d w i t h o u t  my  ii  ABSTRACT  Efficient  preparative  routes to several  some i r i d i u m compounds c o n t a i n i n g Chiral  sulfoxide  sulfoxide  new r h o d i u m c o m p l e x e s a n d  ligands  complexes o f rhodium were t e s t e d  are described.  as p o s s i b l e  catalysts  f o r t h e homogeneous a s y m m e t r i c h y d r o g e n a t i o n o f p r o c h i r a l o l e f i n s . t e s t e d were c h i r a l  s u l f o x i d e - i r i d i u m complexes as p o t e n t i a l  f o r H2 t r a n s f e r f r o m i s o p r o p a n o l The  sulfoxides  tetramethylene diphenyl p-tolyl  sulfoxide  used i n c l u d e :  t h e monodentate l i g a n d s (NPSO), m e t h y l p h e n y l  (DPSO); t h e m o n o d e n t a t e c h i r a l  (S,R)-methyl s u l f o x i d e  sulfoxide  (MSE),  (+)-(R)-methyl(TBPTSO),  ligands  ( P T S E ) , and ( - ) - ( 2 R , 3 R ) - 2 , 3 - 0 - i s o p r o p y l i d e n e - 2 , 3 - d i h y d r o x y (DIOS).  (diene=l,5-cyclooctadiene facile  [Rh(diene)(PPh )L] 3  +  coordination complexes  TBPTSO) h a v e b e e n s y n t h e s i z e d ;  The  ligands  (R,R)-1,2-bis(p-tolyl  Displacement of the l a b i l e acetone l i g a n d  form.  (MPSO), a n d  (MBMSO); a n d t h e p o t e n t i a l l y c h e l a t i n g  1,4-bis(methyl sulfinyl)butane  SbFg ) a l l o w s  (DMSO),  (OTPTSO), a n d ( + ) - ( S ) - 2 - m e t h y l b u t y l -  meso-l,2-bis(methyl sulfinyl)ethane  (acetone)]A  dimethyl  (MPTSO), ( + ) - ( R ) - t - b u t y l - p - t o l y l s u l f o x i d e  (-)-(S)-o-tolyl-p-tolyl  sulfinyl)ethane  catalysts  t o p r o c h i r a l o l e f i n s and ketones.  (TMSO), d i - n - p r o p y l  sulfoxide  Also  Diaryl sulfoxides  upfield shifts  from  [Rh(diene)(PPh^)  (COD), n o r b o r n a d i e n e  of d i a l k y l or d i a r y l  ( N B D ) ; A=PF^ ,  s u l f o x i d e s , and  (L=DMSO,TMSO,NPSO,MBMSO,MPSO,MPTSO, a n d compounds w i t h  a n d DIOS c o o r d i n a t e ,  L=AsPh.j,py a n d ( C O ) 2 a l s o b u t no s o l i d s w e r e i s o l a t e d .  of the s u l f o x i d e resonances  (^"H n m r ) ,  reflecting  s h i e l d i n g by t h e a d j a c e n t p h e n y l groups o f P P h , and t h e d e c r e a s e i n q  i i i  v(SO)  on c o o r d i n a t i o n , a r e i n d i c a t i v e o f O-bonding i n a l l c a s e s .  NMR d a t a o n t h e o l e f i n i c d i e n e  protons  suggest the occurrence  o f some  d i s p r o p o r t i o n a t i o n o f t h e m i x e d l i g a n d c o m p l e x e s t o [ R h ( d i e n e ) ( P P h ^ ) 2]"*" and  [Rh(diene)(L)2] >  and  5-coordinate  d e p e n d i n g on L, and t h e p r e s e n c e o f  +  ( f o r diene=NBD o n l y )  intermediates.  The  3-coordinate, hydrogenation  o f i t a c o n i c a c i d u s i n g c a t a l y s t s w i t h L=R-MPTSO o r DIOS r e s u l t e d i n no asymmetric i n d u c t i o n i n t h e a-methyl s u c c i n i c a c i d product  because of  d i s p r o p o r t i o n a t i o n and c a t a l y s i s v i a t h e b i s ( t r i p h e n y l p h o s p h i n e ) Efficient  hydroformylation  (PPh^)(CO)2j  as c a t a l y s t  +  of 1-alkenes i s e f f e c t e d using  system.  [Rh(diene)  precursors.  A q u e o u s i s o p r o p a n o l s o l u t i o n s o f RhC^^-SH^O s u l f o x i d e s p r o v i d e an e f f i c i e n t  on t r e a t m e n t  r o u t e t o R h C ^ L ^ complexes  with  (L=DMSO,  R-MPTSO,MPSO,TMSO) t h a t c o n t a i n i n s o l u t i o n , a t l e a s t f o r t h e f i r s t t h r e e s y s t e m s , two S-bonded s u l f o x i d e s t r a n s t o a c h l o r i d e , a n d a n 0-bonded l i g a n d .  The 0-bonded s u l f o x i d e i s d i s p l a c e d b y a m i d e s , a m i n e  o x i d e s , and p h o s p h i n e o x i d e s The  t o g i v e mer-RhCfc^(DMSO)^(OL) c o m p l e x e s .  DMSO c i s t o OL i n RhC£^(DMSO)^(OL) o r R u C £ ( D M S O ) ( O L ) c a n b e 2  identified OPPti^Me. yield  i n t h e nmr b y u s i n g t h e r i n g c u r r e n t s h i e l d i n g e f f e c t s o f RhC^L^ react with  Rh(I)  (1:1) i n base promoted r e a c t i o n s t o  presumably v i a undetected  RhC^.SH^O  r  e  a  c  t  s  dimer  Rh(III)-H  (indirect  [RhC£(DPSO) J • 2  evidence)  2  T  h  e  cation.  2  as t h e  r e a c t i o n w i t h NPSO  and a R h ( I I I ) p r o d u c t ,  [H(NPSO) ][RhC£^(NPSO) ] c o n t a i n i n g a s y m m e t r i c a l 2  species.  w i t h DPSO i n i s o p r o p a n o l t o g i v e R h ( I )  chloride-bridged species a Rh(I)  3  gives  i s o l a t e d as  hydrogen-bridged  A c r y s t a l s t r u c t u r e o f t r a n s - [ H ( D M S O ) ] [RhC£^(DMSO) ] r e v e a l s  the s h o r t oxygen-oxygen d i s t a n c e  (^2.45A) i n t h e c a t i o n e x p e c t e d f o r  iv  s t r o n g H - b o n d s . S u c h c a t i o n s d i s p l a y i n t e n s e v (OHO) b a n d s a t 1 7 0 0 di  1100  a n d 900-600 c m " . 1  The a i r - s e n s i t i v e c o m p l e x e s [RhC£(DIOS) ] 2  ligand  [RhC£(C H,.)(DPS0)]_,  and [RhC£(MPSO)(PPh )] ,  2  3  s o l u t i o n s , contain very  [RhC£(DMS0)„].,  0  i s o l a t e d from  2  [RhC£(cyclooctene)  ] ^  l a b i l e Rh-S b o n d s t h a t do n o t a p p e a r t o  i n v o l v e Rh(diT)+S (d-rr) b a c k b o n d i n g . Attempts a t generating H  2  hydride  complexes by o x i d a t i v e a d d i t i o n o f  o r HC£ t o R h ( I ) r e s u l t e d n o r m a l l y  sulfoxide reduction; complications The compound  i n e i t h e r metal formation or  even i n t h e p r e s e n c e o f p r o c h i r a l o l e f i n s  occurred  rather  than c a t a l y t i c  asymmetric  these  hydrogenation.  [ R h ( M S E ) ] P F ^ was i s o l a t e d f r o m t h e r e a c t i o n o f H 2  with  2  [ R h ( N B D ) ] P F , a n d 2 MSE i n a l c o h o l s o l u t i o n s . / o 0  The compounds m e r - I r C £ ( H ) ( D M S 0 ) ^ w i t h 2  IrC£(H) (DMSO)^ w i t h 2  c i shydrides,  trans  were obtained  c h l o r i d e s , and merfrom o x i d a t i v e a d d i t i o n  r e a c t i o n s i n v o l v i n g HC£ a n d E^, r e s p e c t i v e l y , w i t h DMSO.  The f o r m e r c a t a l y z e s t h e e f f i c i e n t  unsaturated  aldehydes t o t h eunsaturated  synthesis using A simple and  2  Attempts a t asymmetric  sulfoxide mixtures  2  bent M-K)=L v i b r a t i o n a l model i s used t o e s t i m a t e  v(S0) the force constants  F.„ a n d F „ u s i n g d a t a MO OL DMSO, DMSO-d,, a n d TMSO c o m p l e x e s o f s e v e r a l m e t a l s . o T  2  s e l e c t i v e r e d u c t i o n o f a,$alcohols.  a s c a t a l y s t s IrCi^.3H 0/chiral  [IrC£(CgH^) ] i n  failed.  from v(M0)  f o r s e v e n t y 0-bonded The c o r r e l a t i o n  o  F„=-(1.24±0.12)F .+(8.78±0.12) OL MO w  complexes excepting  mdyne/A a p p e a r s t o h o l d  t h o s e o f g r o u p I V A a n d VA e l e m e n t s .  f o r a l l metal  V  TABLE OF CONTENTS  ABSTRACT TABLE OF CONTENTS L I S T OF TABLES L I S T OF FIGURES ABBREVIATIONS ACKNOWLEDGEMENTS CHAPTER 1.  Introduction 1.1 1.2 1.3  1.4 CHAPTER 2.  1  The I m p o r t a n c e o f C a t a l y t i c A s y m m e t r i c S y n t h e s i s Aim C a t a l y t i c P o t e n t i a l o f Rh, I r S u l f o x i d e Complexes 1.3.1 H y d r o g e n a t i o n o f O l e f i n s 1.3.2 Solvent Transfer Hydrogenation of Ketones and A l d e h y d e s 1.3.3 Oxidation Reactions 1.3.4 Homogeneous A s y m m e t r i c H y d r o g e n a t i o n S u l f o x i d e s as Ligands  1 4 5 5 14 15 15 19  Apparatus and G e n e r a l E x p e r i m e n t a l P r o c e d u r e s  22  2.1 2.2 2.3 2.4  22 23 23 25 25 26 26 27 27 29 29 29 29 29 30 30 30 30 31  2.5 2.6  Instrumentation Gas-Uptake Apparatus Gas-Uptake E x p e r i m e n t a l Procedure M o d i f i c a t i o n s o f Gas-Uptake Apparatus 2.4.1 Gas I n l e t B u b b l e r 2.4.2 T e f l o n Stopcocks 2.4.3 Convenient Ampoules 2.4.4 Low T e m p e r a t u r e U p t a k e V e s s e l Work-Up o f H y d r o g e n a t i o n s o f I t a c o n i c A c i d Starting Materials .2.6.1 G a s e s 2.6.2 Solvents 2.6.3 Silver Salts 2.6.4 Rhodium S t a r t i n g M a t e r i a l s 2.6.4.1 [ R h ( n o r b o r n a d i e n e ) ] P F 2.6.4.2 [ R h ( c y c l o o c t a d i e n e J ] S b F 2.6.5 I r i d i u m S t a r t i n g Complexes 2.6.6 Sulfoxides ' 2.6.6.1 ( R ) - ( + ) - M e t h y l - p - t o l y l s u l f o x i d e , 18 2.6.6.2 ( R , R ) - ( l , 2 ) - b i s ( p - t o l y l s u l f i n y l ) e t h a n e , jL4_ 6  2  6  32  vi  2.6.6.3 ( M e s o ) - ( l , 2 ) - b i s ( m e t h y l s u l f i n y l ) ethane 2.6.6.4 ( S ) - M e t h i o n i n e - ( S ) - s u l f o x i d e , _16 CHAPTER 3.  35  Mixed S u l f o x i d e - T r i p h e n y l p h o s p h i n e C a t i o n i c Complexes of Rhodium(I)  38  3.1  38 38 38 39 39 44 44 45  Syntheses and S p e c t r o s c o p i c P r o p e r t i e s 3.1.1 I n t r o d u c t i o n 3.1.2 Experimental 3.1.2.1 [Rh ( d i e n e ) ( P P h o ) ( a c e t o n e ) ] A 3.1.2.2 [ R h ( C O D ) ( P P h ) ( D M S O ) ] P F 3.1.2.3 [ R h ( C O D ) ( D M S O - d ) ] S b F 3.1.2.4 [ R h ( N B D ) ( P P h ) ( p y ) ] S b F 3.1.2.5 [ R h ( d i e n e ) ( P P h ) ( A s P h ) ] P F : diene=COD,NBD 3.1.2.6 [ R h ( d i e n e ) ( P P h ) ( C O ) ] P F : diene=COD,NBD 3.1.2.7 [ R h ( d i e n e ) ( P P h ) ( D I O S ) ] P F : diene=COD,NBD 3.1.3 R e s u l t s and D i s c u s s i o n 3.1.3.1 A c e t o n e C o m p l e x e s 3.1.3.2 S u l f o x i d e C o m p l e x e s . 3.1.3.3 DMSO a n d TMSO C o m p l e x e s 3.1.3.4 O t h e r S u l f o x i d e C o m p l e x e s . 3.1.3.5 O t h e r M i x e d L i g a n d C o m p l e x e s The R e a c t i o n s o f t h e M i x e d L i g a n d C o m p l e x e s w i t h Hydrogen 3.2.1 Introduction 3.2.2 Experimental 3.2.2.1 The nmr S p e c t r u m o f [ R h ( N B D ) ( P P h ) ( D I O S ) ] P F + 2.5 H 3.2.3 R e s u l t s a n d D i s c u s s i o n Attempts a t the Asymmetric Hydrogenation of Prochiral Olefins Hydroformylation Reactions Using [Rh(NBD)(PPh )(CO^] 3.4.1 Introduction 3.4.2 E x p e r i m e n t a l and R e s u l t s 3.4.3 D i s c u s s i o n 3  6  6  2  6  3  6  3  3  3  6  2  6  3  3.2  6  3  3.3 3.4  CHAPTER 4.  34  t o Rhodium  3  2  3  2  77 78 79 79 85 86 86 87 88  89 89 90 90  6  3  54 54 66 67 74 76 77  89  S y n t h e s i s and S p e c t r o s c o p i c P r o p e r t i e s 4.1.1 Introduction 4.1.2 Experimental 4.1.2.01 R h C £ L ; L=DMS0, D M S 0 - d , TMSO, MPSO, R-MPTSO 4.1.2.02 R h C £ ( D M S 0 ) ( 0 L ) ; (0L)=DMF,NFP 4.1.2.03 R h C £ ( D P S O ) ( H O C H ( C H ) ) 4.1.2.04 [H(NPS0) ][RhC£ (NPSO) ] 4.1.2.05 [H(DMS0) ][RhC£ (DMSO) ] 3  54  2  3  Sulfoxides Sulfur-Bonded 4.1  6  45  3  2  2  4  2  2  4  2  .  92 92 92 93  vii  4.1.2.06 4.1.2.07  [NEt ][RhC£ (DMSO) ] ' [P.S.H][RhC£ (DMSO) ]5 P.S.= " P r o t o n Sponge", l , 8 - b i s ( d i m e t h y l amino)naphthalene 4.1.2.08 [RhC£(DPSO) ] 4.1.2.09 [RhC£(DPS0)(cyclooctene)] 4.1.2.10 [RhC£(DMSO) ] 4.1.2.11 [RhC£(DIOS) ] 4.1.2.12 [RhC£(MPS0)(PPh )] 4.1.3 R e s u l t s and D i s c u s s i o n 4.1.3.1 N e u t r a l R h ( I I I ) Complexes from Isopropanol Solutions 4.1.3.2 D i p h e n y l s u l f o x i d e Complexes 4.1.3.3 A n i o n i c R h ( I I I ) Complexes 4.1.3.4 Rhodium(I) Complexes from [RhC£(olefin) ] 4.1.3.5 The N a t u r e o f R h o d i u m - S u l f u r B o n d i n g i n S u l f o x i d e Complexes R e a c t i o n s o f R h o d i u m - S u l f o x i d e Complexes w i t h Hydrogen; A t t e m p t s t o Form M e t a l - H y d r i d e Complexes 4.2.1 Introduction 4.2.2 Experimental 4.2.2.1 Reactions of RhC£ L 4.2.2.2 P r e p a r a t i o n o f [P.S.H][RhC£ (DMS0) ] 4.2.2.3 Reaction of RhC£ (DMS0) w i t h P r o t o n Sponge u n d e r A r 4.2.2.4 P r e p a r a t i o n o f [Rh(MSE) ]PF :MSE= meso-1,2-bis(methyl s u l f i n y l ) e t h a n e 4.2.3 R e s u l t s and D i s c u s s i o n 4.2.3.1 The H e t e r o l y t i c C l e a v a g e o f H b y RhC£ (sulfoxide) Complexes 4.2.3.2 Oxidative A d d i t i o n Reactions of Rh(I) S u l f o x i d e Complexes 4.2.3.3 The R e a c t i o n s o f P r o t o n Sponge w i t h RhC£ (DMS0) Attempts a t C a t a l y t i c Asymmetric Hydrogenation 4.3.1 Introduction 4.3.2 E x p e r i m e n t a l 4.3.3 R e s u l t s and D i s c u s s i o n 4  4  2  4  2  2  2  2  2  2  2  2  3  2  4.2  2  3  2  3  2  3  2  6  2  109 110 118 120 123 123 123 123 123 124 130 131 131  3  3  4.3  94 95 96 96 98 98 98  2  3  3  93 94  134 136  3  CHAPTER 5. H y d r i d o i r i d i u m S u l f o x i d e C o m p l e x e s  145  5.1. P r e p a r a t i o n a n d S p e c t r o s c o p i c P r o p e r t i e s 5.1.1 Introduction 5.1.2 Experimental 5.1.2.1 T r a n s - [ H ( D M S O ) ] [ I r C £ ( D M S O ) ] 5.1.2.2 Cis-[H(DMS0) ][IrC£4(DMSO) ] 5.1.2.3 T r a n s - d i c h l o r o - m e r - t r i s ( D M S O ) h y d r i d o iridium(III) 5.1.2.4 Chloro-cis-dihydrido-mer-tris(DMSP) iridium(III) 2  2  138 138 139 139  4  2  2  145 145 145 146 146 147 150  viii  5.1.2.5 5.1.2.6  5.2  5.3  A t t e m p t e d P r e p a r a t i o n o f [IrC£(DMSO) ]2 Attempted P r e p a r a t i o n of IrCJc^I^; L=MPSO,DPSO,MBMSO,TBPTSO,OTPTSO 5.1.3 D i s c u s s i o n Attempts a t t h e Asymmetric Hydrogenation o f P r o c h i r a l Ketones and O l e f i n s u s i n g I r i d i u m - C h i r a l S u l f o x i d e Complexes 5.2.1. I n t r o d u c t i o n 5.2.2 E x p e r i m e n t a l 5.2.3 R e s u l t s a n d D i s c u s s i o n Solvent Transfer Hydrogenation of a,^-Unsaturated Aldehydes t o t h e Unsaturated A l c o h o l s Catalyzed by H y d r i d o i r i d i u m S u l f o x i d e Complexes 5.3.1 Introduction 5.3.2 E x p e r i m e n t a l 5.3.3 R e s u l t s a n d D i s c u s s i o n 2  CHAPTER 6. V i b r a t i o n a l A n a l y s i s o f O x y g e n - B o n d e d S u l f o x i d e C o m p l e x e s 6.1 6.2 6.3  Introduction Calculations R e s u l t s and D i s c u s s i o n  CHAPTER 7. C o n c l u s i o n s 7.1  7.2 7.3  and Recommendations  Coordination Chemistry 7.1.1 P r e p a r a t i o n o f S u l f o x i d e Complexes o f Rhodium and I r i d i u m 7.1.2 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 S u l f o x i d e Complexes Attempts a t t h e C a t a l y t i c Asymmetric Hydrogenation of P r o c h i r a l O l e f i n s and Ketones Other C a t a l y t i c Reactions  BIBLIOGRAPHY:REFERENCES FOR CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER CHAPTER  1 2 3 4 5 6 7  152 152 152 156  156 157 159 162  162 162 162 166 166 167 172 183 183 183 188 191 192 194 201 203 • 206 211 213 216  ix  L I S T OF TABLES  T a b l e Number  Page  3.1  A n a l y t i c a l D a t a f o r t h e Rhodium(I) Complexes  40  3.2  I n f r a r e d Data  41  (cm" ) f o r [ R h ( d i e n e ) ( P P h ) L ] P F , 1  0  Complexes 3.3  1  H nmr D a t a f o r [ R h ( C O D ) ( P P h ) L ] P F ,  j Complexes 3.4  42  0  1  o  a t 35°C  H nmr D a t a f o r [ R h ( N B D ) ( P P h ) L ] P F 3  43  6  Complexes 3.5  Some I n f r a r e d D a t a  ( c m " ) f o r [Rh(COD) ( P P h ) L ] P F . 70 1  0  J  L=DMS0 a n d DMSO-d^ 6 3.6  Some L i g a n d V i b r a t i o n s o f [ R h ( d i e n e ) ( P P h ) L ]  3.7  S t o i c h i o m e t r y o f Hydrogen U p t a k e by 3  4.1  1  i n Degassed  CH C& 2  H nmr D a t a f o r R u C £ ( D M S O ) + 0 L 2  3  (4.2)  • P h y s i c a l D a t a f o r S u l f u r - B o n d e d DMSO A d d u c t s "4l nmr D a t a f o r t h e R e a c t i o n o f P r o t o n S p o n g e w i t h RhCJt- (DMSO) 3  4.6  106  4  RuCJl (DMS0) (0L)+DMS0  4.5  (4.1)  2  2  3  100  103  3  1  83  2  H nmr D a t a f o r RhCSl^(DMSO) +0L 3  71  Complexes  RhC£ (DMSO) (OL)+DMSO  4.4  +  S o l u t i o n I n f r a r e d Data f o r Rhodium S u l f o x i d e Complexes  4.3  6  3  [Rh(diene)(PPh )L]A  4.2  /  i n CD C£ 2  2  122 126  ''  Hydrogen Uptake Data f o r Rhodium-Sulfoxide  132  Complexes 4.7  Attempts a t C a t a l y t i c Hydrogenation using Rhodium-Sulfoxide  Complexes  142  X  T a b l e Number 5.1  Page The R e d u c t i o n o f K e t o n e s C a t a l y z e d b y I r ( I I I ) Sulfoxide  5.2  Complexes.  The R e d u c t i o n o f O l e f i n s Sulfoxide  160  C a t a l y z e d by I r ( I I I ) -  161  Complexes  5.3  Hydrogenation of a,^-Unsaturated Aldehydes  164  6.1  Infrared  168  D a t a f o r 0-Bonded DMSO and TMSO  Complexes 6.2  V i b r a t i o n a l Data f o r Sulfoxide  Complexes  6.3  V i b r a t i o n a l Data f o r Other S u l f o x i d e  6.4  V i b r a t i o n a l D a t a f o r Group  Complexes  I V A and VA C o m p l e x e s  173 175 181  xi  L I S T OF  FIGURES  F i g u r e Number 1.1  Page Amino A c i d P r e c u r s o r s : S u b s t r a t e s Used i n C a t a l y t i c Asymmetric  3  Hydrogenation  1.2  L i g a n d s f o r C a t a l y s t s o f t h e Type [ R h ( C O D ) P ]  1.3  C h i r a l Sulfoxide Ligands  6  1.4  R h , I r S u l f o x i d e Complexes i n t h e L i t e r a t u r e  7  2  up 1.5  to  Simplified  The  3  1978 Schemes o f Homogeneous  Hydrogenations 1.6  +  9  Involving Platinum Metals  Proposed Mechanism f o r S o l v e n t T r a n s f e r  12  H y d r o g e n a t i o n o f C h a l c o n e C a t a l y z e d by IrCJL (H)L ,L=DMSO 2  3  1.7  Cis-PtC£ (S-MPTSO)(Olefin) D i a s t e r e o m e r s  16  1.8  The  20  2  S t r u c t u r a l and  S p e c t r o s c o p i c Data f o r  DMSO C o m p l e x e s 2.1  Constant P r e s s u r e Gas-Uptake Apparatus  24  2.2  C o n v e n i e n t Ampoule T e c h n i q u e s  27  2.3  Low  28  2.4  100 MHz  Temperature 1  H  nmr  (p-tolyl 2.5  100 MHz  3.01  60 MHz  1  H  Spectrum  of  (R,R)-(1,2)-bis  33  s u l f i n y l ) e t h a n e , 1A_  """H nmr  (methyl  Uptake V e s s e l  Spectrum  of  (Meso)-(1,2)-bis  36  sulfinyl)ethane  nmr  Spectrum  SbFJ i n CDC£ 6 3 0  of  [Rh(COD) (DMSO) ] +"  46  xii  F i g u r e Number 3.02  1 0 0 MHz H nmr S p e c t r u m  of  1  [Rh(COD)(PPh )(AsPh-)]PF, j j o n  ( C D ) C O a t -50°C 3  3.03  2  1 0 0 MHz H nmr S p e c t r u m in CD C£ 2  3.04  a t -50°C  1  3  1  CO i n C D C £  1  3  1  of  of  [Rh(NBD)(PPh_)(acetone)]PF,  J  of  6  [Rh(COD)(PPh_)(acetone)]PF, 3 6  a t 35°C  60 MHz •'"H nmr S p e c t r u m 3  a t a ) -30°C b ) 35°C  a t -50°C  60 MHz H nmr S p e c t r u m 3  [Rh(NBD)(PPh,,)(acetone)]PF, -> 6  [Rh(NBD)(PPh_)(acetone)]PF, J 6 a t 35°C  1  i n CDC£ 3.11  3  of  of  100 MHz H nmr S p e c t r u m  i n CDC£ 3.10  3  60 MHz H nmr S p e c t r u m  + DIOS i n C D C £ 3.09  0  [Rh(COD)(PPh.)(acetone)]PF, J 6 a t 35°C  1  + DIOS i n C D C £ 3.08  3  1 0 0 MHz H nmr S p e c t r u m + DIOS i n C D C £  3.07  o f [Rh(COD)(PPh )(C0)„]PF, -J 2 6  a t 35°C  100 MHz H nmr S p e c t r u m under  3.06  2  100 MHz H nmr S p e c t r u m i n CDC£  3.05  o f [Rh(NBD)(PPh.,)(AsPh„)]PF, J J O  1  o f [Rh(NBD) ( P P h ) ( a c e t o n e ) ] P F , 0  J  a t 35°C  60 MHz H nmr S p e c t r u m 1  of  6  [Rh(NBD)(PPh_)(acetone)]PF -> 6  i n a c e t o n e - d , a t 35°C 6 3.12  100 MHz "hi nmr S p e c t r u m  of  [Rh(NBD)(PPh_)(acetone)]PF, J 6  i n a c e t o n e - d , a t -60°C 6 3.13  60 MHz H nmr S p e c t r u m 1  i n CDC£ 3.14  3  a t 35°C  100 MHz "Si nmr S p e c t r u m i n CDC£  3  o f [Rh(NBD)(PPh„)(DMSO)1SbF, J 6  a t -30°C  of  [Rh(NBD)(PPh )(DMSO)1SbF, 3 6 0  xiii  F i g u r e Number 3.15  Page 60 MHz  1  H nmr S p e c t r u m o f [ R h ( C O D ) ( P P h ) ( D M S O ) ] S b F 3  i n CDC£ 3.16  a t 35°C  3  The I n f r a r e d S p e c t r a a Nujol mull;  3.17  of [Rh(COD)(PPh )(L)]PF 3  ( a ) L=DMS0, ( b ) L=DMS0-d  The I n f r a r e d S p e c t r a  of [Rh(COD)L ]SbF 2  6  3.18  [ Rh ( d i e n e ) ( P P h J ( D I 0 S ) ] P F ,  3.19  100 MHz  as  72  6  73  6  75  nmr S p e c t r u m o f [ R h ( N B D ) ( P P h ) ( a c e t o n e ) ] P F 3  + DIOS R e a c t e d O v e r n i g h t ( a ) 100 MHz H i g h F i e l d (acetone)]PF,  4.01  g  as a  N u j o l M u l l ; ( a ) L=DMS0, ( b ) L=DMS0-d  3.20  68  6  with H  2  80  6  i n (CD^CO  """H nmr S p e c t r u m o f [Rh(NBD) ( P P h ) 81 3  + 2.5 H„ i n DMA  (b) S p e c t r u m o f [Rh(NBD)(PPh„)„]SbF, + 3H„ i n DMA J I D /  81  (a) I n f r a r e d Spectrum Using  97  Nujol Mull of  [RhC£ (DMSO) ] .DMSO 2  (b) N u j o l M u l l o f [ R h C £ ( D M S 0 - d ) ] 6  2  97  2  4.02  T h e L o c a l E n v i r o n m e n t o f Rh i n m e r - R h C & ( D M S O ) ( O L ) 2  99  4.03  6 3 . 8 - 2 . 3 R e g i o n o f 100 MHz "Si  nmr S p e c t r a u s i n g  104  3  CDCi>  3  o f (a) RhC£ (DMSO) 3  (c) RhCi! (DMSO) 3  4.5  3  3  + 3DMF ( b ) R h C £ ( D M S 0 )  + 2 0PPhMe  3  2  ( d ) RhCX- ( D M S 0 ) 3  3  3  +  0PPh Me 2  4.04  The L o c a l E n v i r o n m e n t o f Ru i n R u C £ ( D M S 0 ) ^  105  4.05  6 3 . 8 - 2 . 5 R e g i o n o f 100 MHz  107  2  CDC£  3  H nmr S p e c t r a  using  o f ( a ) R u C £ ( D M S O ) + 6DMF ( b ) R u C £ ( D M S O ) 2  (c) RuC£ (DMSO) 2  4  1  0PPh Me 2  4  4  + 4 0PPhMe  2  2  (d) R u C £ ( D M S O ) 2  4  +  4  xiv  The M a i n P r o d u c t  from t h e S e l e c t i v e Exchange  Reaction  o f RhC£„(DMS0)„ w i t h DMSO-d, i n CHC£„ 3 3 o 3 Infrared  Spectrum of a N u j o l M u l l of  [H(NPSO) ][RhC£ (NPSO) ] 2  Infrared  4  2  S p e c t r u m o f a N u j o l M u l l o f [H(DMSO)]+"  [RhC£ (DMSO) ] 4  -  2  The C o n t e n t s o f a U n i t C e l l  i n Crystalline  [H(DMSO) ][RhC£ (DMSO) ] I n c l u d i n g 2  4  Bond D i s t a n c e s ,  Selected  2  Corrected  f o r Thermal  Librations  The R a n g e o f B o n d i n g Modes f o r S-bonded  Sulfoxides  (a) The H y d r o g e n U p t a k e o f R h C £ ( D M S O >  + 2  3  Sponge i n 1 , 2 - C H C £ 2  4  Proton  a t 30°C  2  (b) A n o t h e r E q u i v a l e n t  3  o f R h C £ ( D M S O ) was A d d e d a t Th 3  3  Point 100 MHz "*"H nmr S p e c t r u m o f 0.8 P r o t o n RhC£ (DMSO) 3  100 MHz  i n CH C£  3  2  a t 38°C a f t e r l l h .  2  nmr S p e c t r u m u s i n g  Crystals  from the Reaction  0.8 P.S. + R h C £ ( D M S O ) 3  CD C£ 2  2  3  from the Reaction 6  o f Orange 2  of  3  2  RhC£ (DMSO-d )  2  i n CH C£  100 MHz "'"H nmr S p e c t r u m u s i n g C D C £ Crystals  Sponge +  2  o f t h e Orange  o f 0.8 P.S. +  3  100 MHz """H nmr S p e c t r u m o f I r C £ H ( D M S O > .DMSO 2  in  CDC£  100 MHz "Si  3  3  nmr S p e c t r u m o f  + HC£.DMA i n C D C £  n  IrC£H (DMS0) 2  3  XV  Figure  Number  5.3  Page T h e F o r m a t i o n a n d Some R e a c t i o n s o f I r - S u l f o x i d e Hydride  6.1  Complexes  P l o t o f Frequency of  154  S h i f t o f v(SO) on C o o r d i n a t i o n  0-bonded S u l f o x i d e  169  v s . v(MO)  6.2  B e n t MOL M o d e l  6.3  C o r r e l a t i o n of Force Constant Data  f o r TMSO C o m p l e x e s  176  6.4  C o r r e l a t i o n o f Force Constant Data  f o r TMSO, DMSO,  179  and 6  -  5  DMS0-d  170  6  Complexes  C o r r e l a t i o n o f Force Constant Data  f o r DMSO a n d DMS0-d  C o m p l e x e s o f Some G r o u p I V A a n d VA  elements.  (  182  XVI  ABBREVIATIONS  A  anion,SbF, ,PF, 6 6  Ac  acetyl  Anal.  analysis  BDIOS  (2R, 3 R ) - 2 , 3 - 0 - i s o p r o p y l i d e n e - 2 , 3 - d i h y d r o x y - l , 4 bis(benzyl sulfinyl)  Bu  butane  n-butyl c o n c e n t r a t i o n i n g/100 g s o l v e n t  1,2-C H C£ 2  C  8 14 H  4  2  1,2-dichloroethane cis-cyclooctene  Calcd  calculated  Cat*  chiral  COD  1,5-cyclooctadiene  d  doublet  DDIOS  ( 2R, 3R) - 2 , 3 - d i h y d r o x y - 1 , 4 - b i s ( m e t h y l s u l f i n y l ) b u t a n e  DIOP  (2R,3R)-2,3-0-isopropylidene-2,3-dihydroxy-l,4-bis  catalyst  (diphenylphosphino)butane DIOS  (2R,3R)-2,3-0-isopropylidene-2,3-dihydroxy-l,4-bis (methyl s u l f i n y l ) b u t a n e ,  s e e f i g u r e 1.3  DMA  N,N-dimethylacetamide  DMF  dimethylformamide  DMS  dimethylsulfide  DMSO  oxygen-bonded d i m e t h y l s u l f o x i d e  DMSO  sulfur-bonded dimethylsulfoxide  DMSO-d,  hexadeutero  dimethylsulfoxide  xvii  DPSO  diphenyl  sulfoxide  DSS  sodium  EA  ethyl  e.e.  enantiomeric  Et  ethyl  2,2-dimethyl-2-silapentanone-S-sulfonate atropate excess  o  F  force  F  average f o r c e  G.C.  gas-liquid  h  hours  HOMO  highest occupied molecular  HSAB  Hard and S o f t A c i d s and Bases  [HCP^SO)2]"^"  sulfoxides  I  nuclear  I.A.  constant  (mdyne/A) constant  chromatography  orbital  b r i d g e d v i a t h e oxygens by h y d r o g e n bonds  spin  ' i t a c o n i c a c i d , H C=C(COOH) ( C ^ C O O H ) 2  ir  infrared  L  ligand  LUMO  lowest unoccupied  m  multiplet  M  molarity;  MBMSO  (-)-(S)-2-methyl butyl-(S,R)-methyl  Me  methyl  ME  2-methoxyethanol (-)-menthoxy  MET  (S)-methionine minute  orbital  metal  Men  min  molecular  sulfoxide  xviii  m.p.  melting  point  MPSO  methyl phenyl  MPTSO  (R)-methyl-p-tolyl  MSE  meso-(1,2)-bis(methyl  mV  millivolts  NBD  norbornadiene  sulfoxide sulfoxide sulfinyl)ethane  NFP  N-formyl  NPSO  di-n-propyl  OL  oxygen-donating  ligand  OTPTSO  o-tolyl-p-tolyl  sulfoxide  P .  tertiary  PBS  phenyl benzyl  Ph  phenyl  ppm  parts  P.S.  " P r o t o n Sponge",  [P.S.H]  +  piperidine sulfoxide  phosphine sulfide  per m i l l i o n  protonated Proton  1,8-bis(dimethylamino)naphthalene Sponge  PTSE  (R,R)-(l,2)-bis(p-tolyl sulfinyl)ethane  py  pyridine  PyNO  pyridine  q  quartet  qu  quintet  N-oxide  r  bond  length  R  alkyl,  s  singlet(nmr);  S  styrene  sec  second  t  time  aryl strong(ir)  xix  T  temperature  TBPTSO  (R)-t-butyl-p-tolylsulfoxide  THF TMS  tetrahydrofuran tetramethylsilane  TMSJD  oxygen-bonded t e t r a m e t h y l e n e  tu  thiourea  V  volume  &  asymmetric  a  8 6  d e f o r m a t i o n mode  chemical s h i f t  (ppm f r o m  partial  positive  A  crystal  field splitting  X  normal  +  mode  =C  olefin  v X  •  frequency  (cm ^)  electronegativity  TMS)  charge  frequency  r o c k i n g mode :  sulfoxide  energy  XX  ACKNOWLEDGEMENTS  I w i s h t o e x p r e s s my g r a t i t u d e t o P r o f e s s o r B. R. James f o r h i s e x p e r t a d v i c e and f l e x i b l e g u i d a n c e  i n g e n e r o u s l y accommodating f o r  a n y d i g r e s s i o n s I made f r o m t h e m a i n a i m o f my S i n c e r e thanks  i s a l s o extended  i n t r o d u c t i o n t o Schlenk tube D r . A. W i l l i s  project.  t o D r . K. J . R e i m e r f o r a n  t e c h n i q u e s and rhodium  chemistry, to  a n d P r o f e s s o r F. W. B. E i n s t e i n f o r p r e l i m i n a r y r e s u l t s  o f a c r y s t a l s t r u c t u r e d e t e r m i n a t i o n , a n d t o D r . R. B a l l J.  T r o t t e r f o r an attempted  structural  and P r o f e s s o r  s t u d y on t h e m y s t e r i o u s  Proton  Sponge c o m p l e x . I acknowledge w i t h thanks Engineering Research  support from  t h e N a t u r a l S c i e n c e s and  C o u n c i l o f C a n a d a i n t h e f o r m o f summer s t u d e n t -  s h i p s and p o s t g r a d u a t e  scholarships.  I am i n d e b t e d t o A n n a Wong f o r h e r d i l i g e n c e i n t y p i n g t h i s manuscript. Finally  I w i s h t o t h a n k C o l l e e n , whose encouragement i n s u r e d t h e  r a p i d p r o g r e s s o f my w o r k ; o u r i m p e n d i n g  w e d d i n g was a g r e a t  incentive.  -11.  1.1  Introduction  The I m p o r t a n c e o f C a t a l y t i c A s y m m e t r i c I f one were t o s t e p  one  would soon d i s c o v e r  our  lives.  The food  Synthesis  "Through t h e L o o k i n g G l a s s "  1  as A l i c e  did,  the e s s e n t i a l r o l e c h i r a l molecules play i n  and p h a r m a c e u t i c a l s  t h e r e w o u l d be u s e l e s s  o r even  p o i s o n o u s t o t h e human s y s t e m b e c a u s e n a t u r a l enzymes may n o t i n t e r a c t w i t h , o r may e v e n b e i n h i b i t e d b y , m i r r o r  image p r o t e i n s ,  n u c l e i c a c i d s , a l k a l o i d s e t c . . And t h e m i r r o r synthesize  carbohydrates,  chemists with a l l our  present  knowledge c o u l d  asymmetrically  only a few of t h e  correct  e n a n t i o m e r s one w o u l d need t o s u r v i v e i n t h e i r l o o k i n g  world.  W i t h o u t t h e a i d o f enzymes o r c a t a l y s t s , a t t e m p t s a t s u c h  glass  s y n t h e s i s w o u l d r e q u i r e t h e u s e o f l a r g e i m p r a c t i c a l amounts o f c h i r a l resolving  agents.  However t h i s  situation  i s changing w i t h  homogeneous a s y m m e t r i c s y n t h e s i s  t h e advent o f e f f e c t i v e  catalysts (Cat*).  L i k e some e n z y m e s  these s o l u b l e c a t a l y s t s a r e comprised of c h i r a l molecule(s) a t r a n s i t i o n metal that can s t i l l normally  accommodate t h e b i n d i n g  a m o l e c u l e X-Y a n d a p r o c h i r a l u n s a t u r a t e d  the metal a c t i v a t e s t h e r e a c t i o n , t h e c h i r a l substrate  so t h a t  unsaturate, favoured.  bonded t o of reactants,  substrate.  While  ligand interacts with the  t h e a d d i t i o n o f X-Y t o o n e d i a s t e r e o t o p i c f a c e o f t h e  and hence t h e f o r m a t i o n  o f one o p t i c a l  isomer of product, i s  I n t h i s f a s h i o n a s m a l l amount o f c h i r a l c o m p l e x c a n e f f i c i e n t l y  generate c a t a l y t i c a l l y  a h u g e amount o f o p t i c a l l y  active  product.  -2-  Cat* + X-Y -> >  X - C  X-Y=H  asymmetric 3 4 hydrogenation '  R R  1  2  (1.01)  X=H, Y="C(0)H"(CCH-H )  R  2  (1.02)  asymmetric hydroformylation^ R,  Cat* C = 0  + X-Y  X >  v  . Y C - 0  X-Y=H V.  asymmetric  A  «-•  3  hydrogenatxon  R  X=H;  Y=SiR  '  (1.03) 6  (1.04)  3  asymmetric R  hydrosilylation  3,6  A d e c a d e o f r e s e a r c h i n t o a g r e a t number o f c a t a l y s t s f o r r e a c t i o n s (1.01-1.04) has y i e l d e d  some i n s i g h t  and most i m p o r t a n t l y h a s r e s u l t e d  into  t h e cause o f asymmetric  i n t h e d e v e l o p m e n t o f some  induction,  chiral  p h o s p h i n e - r h o d i u m c o m p l e x e s f o r e f f i c i e n t homogeneous h y d r o g e n a t i o n . complexes a c t as c a t a l y s t s , synthesis v i a equation of S - " L " - a l a n i n e R-"D"-alanine  These  a t ambient t e m p e r a t u r e and p r e s s u r e , f o r t h e  (1.01) o f 85-100%  o p t i c a l l y p u r e amino  acid  derivatives  ( s u b s t r a t e 1 _ w i t h c a t a l y s t w i t h | o r 1 0 , f i g u r e s 1.1, 1 . 2 ) ,  (1 w i t h 9 ) , S - p h e n y l a l a n i n e  (3 w i t h 7 , 8 , 1 0 , 1 1 , 1 2 , o r  (-)-13)  -3F i g u r e 1.1. Amino a c i d p r e c u r s o r s : s u b s t r a t e s u s e d i n c a t a l y t i c asymmetric hydrogenation.  for  alanine  for  phenylalanine  for  leucine  for  phenylalanine  H  F i g u r e 1.2.  Ligands  for catalysts  o f t h e type  [Rh(COD)P,J . +  {+)-{RhZ'  Ph P 2  9 (S,S>9  PPh,  P h  2  p  v  /  -pph  2  >H (R>10  9  PPhg  PPhc  PPhg  —N  <+)-&.R}-13  12  -4-  and  (4_ w i t h 8 ) , R - p h e n y l a l a n i n e  8^ o r 1 0 ) , R - l e u c i n e tyrosine  (3 w i t h 9_ o r  (+)-13),  (2 w i t h 9) , S - t y r o s i n e (5 w i t h 10 o r 12) ,  (5 w i t h 9),  and  (6 w i t h J7_,_8,jL0, o r 1 2 ) .  L-DOPA, a d r u g V a r i o u s Rh  1  It  i s c l e a r f r o m t h e numerous r e v i e w s  other m e t a l - c h i r a l ligand catalysts  1.04), that the i n t e n s e i n t e r e s t  specificity.  ' '  1.3)  s t e p by  future catalysts w i l l facilitate  '  for reactions result  i n the  l i k e l y be  t h e i r recovery  although methyl  g e n a t e d t o 90%  s u r f a c e and  s i t e s t h a t c a n be  t e t h e r e d t o an  i n s p e c i a l cases.  The  use  of  '  Altering  spectroscopy  _ , Rh,  27  These 20 '  heterogeneous approach; hydro-  of  a  a r e much m o r e  able to  supply  i n the l o o k i n g g l a s s world,  of c h i r a l phosphine-rhodium  systems, i n c l u d i n g Rh-amides  I r - S c h i f f bases  at  catalysts.  some s t r a n g e f o o d s  w i t h some n a t u r a l n u t r i e n t s . 1.2 Aim Due p r o b a b l y t o t h e s u c c e s s ligand  routinely  '  the chemistry  C e r t a i n l y c h e m i s t s , u s i n g t h e s e d e v e l o p m e n t s , w i l l be  other c h i r a l  will  p r e c u r s o r s have been  f o l l o w i n g the r e a c t i o n s by  d i d swallow  enantio-  developed  i s a less promising  amino-acid 21 22  t h a n s t u d y i n g homogeneous  A l i c e , who  discovery  i n s o l u b l e support  from the products.  a c e t o a c e t a t e and  e.e.  (1.01-  t h e a p p l i c a t i o n o f an a s y m m e t r i c c a t a l y s t . 18 19  c a t a l y s t s modified with c h i r a l molecules  difficult  '  rhodium-phosphine  c a t a l y z e d w i t h t h e same h i g h  l i n k a g e s as l a t e n t c h i r a l  a l a t e r convenient  26  figure  Perhaps i n the f u t u r e s y n t h e t i c organic chemists  leave unsaturated  amines  disease  17  i n t h i s area w i l l  o f o t h e r t r a n s f o r m a t i o n s t h a t c a n be  metal  (15b,  of s t u d i e s of  3 ^\ 15 16  to  R-  t o combat P a r k i n s o n ' s  complexes of DI0P  (2^ w i t h  _ 13,14 effective.  are also  and  S-leucine  , Ru-carboxylates  23 28  , Co-amines , and  catalysts, 24  '  25  , Pt-  .. 29,30,31 Ru-sulfoxides 1 f  -5-  h a v e r e c e i v e d much l e s s a t t e n t i o n e v e n t h o u g h t h e y may different  ligand-substrate interactions.  This  involve  completely  i s a m a i n r e a s o n why  chiral 31  sulfoxides coordinated and  why  this  iridium,  the  led  to ruthenium were f i r s t  to the study  s u b j e c t of t h i s  of  their  successfully is  ( f i g u r e 1.3)  and  f u n c t i o n a l groupings.  i n asymmetric hydrogenation:  the a c e t a l cleaved  e.e.  c o o r d i n a t i o n to rhodium  2  2  3  g a v e 1.5%  and up  to!6%,  RuCft,, ( D I O S ) ( D D I O S ) , w h e r e DDIOS  t o 25.2%  e.e.(ref.31,  diastereomers  at s u l f u r .  b e t t e r r e s u l t s c o u l d be  The 1978  synthesized using sequently utilize 1.3 1.3.1  an  aim  obtained  228);  page  o f S,S  to f i n d  7.2%  202).  and  out  S,R  whether  w i t h o p t i c a l l y p u r e 14,16,18,19,20 on  a  center.  relatively  ( f i g u r e 1.4),  t h e r e f o r e of i n t e r e s t  in  page  r e s p e c t i v e l y ( r e f . 31,  c a t a l y s t s contain ligands which are mixtures I t was  ones  Some h a v e a l r e a d y b e e n u s e d  Both of these  rhodium or i r i d i u m  as w e l l a s  d e r i v a t i v e o f DIOS, g a v e S - N - a c e t y l a l a n i n e  R - m e t h y l s u c c i n i c a c i d w i t h up  [RuCil (MBMSO) l  and  w i t h s t r u c t u r e s analogous  s u c c e s s f u l c h e l a t i n g p h o s p h i n e s shown i n f i g u r e 1.2,  with quite different  laboratory  thesis.  S u l f o x i d e s have been developed to the  s t u d i e d i n our  few  apart the  s u l f o x i d e c o m p l e x e s o f Rh from those  s u l f o x i d e as  o f t h i s w o r k was  of t h i s  C a t a l y t i c P o t e n t i a l o f Rh, Hydrogenation of  I r reported  up  to  t h e s i s , were g e n e r a l l y  the s o l v e n t or to devise routes  a minimum o f t h e v a l u a b l e c h i r a l  and  i n great  excess.  to complexes  Con-  that  reagents.  I r S u l f o x i d e Complexes  Olefins  H y d r o g e n a t i o n s u s i n g homogeneous p l a t i n u m m e t a l c a t a l y s t s h a v e b e e n found to occur  mainly  through the  two  types  o f schemes e x e m p l i f i e d  in  -6Figure  (R,R)-l,2-bis(p-tolylsulflnyl)ethane  O  1.3  3 2  ( P T S E ) 14 c f . 8  H -R -R  H R=(R,S)-S(0)CH  3  .31 2R,3R-(-)-DIOS 15a;  gives  (S)-methionine-(S)-sulfoxide  33  R=PPh  2  g i v e s 2 R , 3 R - ( - ) - D I O P 15b  (METO) 16  ( + ) - ( S ) - 2 - m e t h y l b u t y l - ( R , S ) - m e t h y l s u l f o x i d e ( M B M S O ) 17 3 1  MPTSO 18 (+)-(R)-methylp-tolyl sulfoxide  TBPTSO 19  3 0  '  3 4  (+)-(R)-t-butylp-tolylsulfoxide  OTPTSO  3 4  20  (-)-(S)-o-tolylp-tolylsulfoxide ^ 3  -7-  Figure  Rh, I r S u l f o x i d e  RhOO  1.4  C o m p l e x e s i n t h e L i t e r a t u r e up t o 1 9 7 8 ^  RhC£(DMS0)(PPh  )  3 5  ,  RhC£(CO)(DMSO)  ,  3 6  [Rh(COD) (DMSO) J B F — 2 4 23 3  z 21 I  [Ir(CO)(DMSO)(PPh„)„]CJl0 J 2 4 24  ( D  r  22  7  3 8  —  RMID  Rh (0 CR) .2R S0 2  2  4  3 9  2  '  4 0  25  Rh( L(im  mer-RhC£ ( R S 0 ) ( R ^ O ) ' 26 4 1  3  2  '  4 2  2  m e r - R h C £ (DMSO) ( p y r i d i n e ) 3  4 3  , trans-Na[RhC£ (R^O) . 27  ]  4  4 2  5  ,  R h C £ (DMSO) ( e n )  4  1  '  4  4  4 6  3  28  29  [RhC£(DMSO) ][C£0 ] 5  4  4 7 2  30 [H(DMSO) ) [ R h C £ (DMSO) ] , 4 8  2  4  2  [Rh ( M e ^ p ) (DMSO) ] [ P F ] 3  31 I  r  (  I  I  I  )  50  2  4  2  [ I r ( M e ^ p ) (DMSO) ] [ P F ]  33  3  5 0 3  ,  34 IrC£ (DMSO) (DMSO) , 5 0  3  2  35  36  IrC£(H) (DMS^0) 2  T~ST\T\  i L i m  IrC£ (DMS0) 4  12.  5  9  2  0  2  50 3  r M- i , [H(DMSO) ] [IrC£ ] M  2  IrC£ (H)(DMSO)  6  4  37  38 51 51  9  32  cis,trans-[H(DMSO) ][IrC£ (DMSO) ] ,  IrC£ (DMSO)  4  6  2  40  2  6  (a) n o t i n c l u d i n g t h o s e o f t h i s tL hu ce os ii os .. 0 n d JS w a emu o mean mean r e s p e c t i v e l y 0- a n d S- b o n d i n g of the s u l f o x i d e . Me Cp means pentamethyl cyclopentadienyl.  -8-  3 15 f i g u r e 1.5. '  T h e schemes  d i f f e r mainly  i n t h e mode o f h y d r o g e n  a d d i t i o n t o t h e complex; they have been t h o r o u g h l y  reviewed  by  3 15 52 53 others  '  '  '  , a n d h e n c e o n l y some r e c e n t f i n d i n g s a l o n g  r e l e v a n t examples w i l l  be mentioned  here.  The o x i d a t i o n s t a t e o f t h e m e t a l throughout  ligand  and H  +  v i a equation  substitutes into  the hydrogenation  the metal  of acrylamide  the "hydride route" reaction  i n scheme I d o e s n o t c h a n g e  t h e v a r i o u s c y c l e s because t h e  cleaved t o H  (1.05),  (1.05) and i n d e e d  c o o r d i n a t i o n sphere.  A d d i t i o n o f base  i n t h i s case without  a c e t y l e n e by IrC£ (H) (DMS0) H_C, 2  D i r e c t evidence  5  6  A  >  H  /  =  37.. C,H  3 >  /  t h a t goes v i a  promotes  substrate present, f o r the protonolysis  i n the hydrogenation  of diphenyl-  T h e a l k e n y l i n t e r m e d i a t e 52^ c o u l d b e C,H C,H  — • > \^ HC£ IrC£ (DMSO) 52 1 1 6  An example i s  i n DMA b y [RuCJl^ (DMSO)^] 31  o f a n a l k y l ^6_ v i a ( 1 . 1 0 ) was o b t a i n e d  37 + C H,C=CC,H + — 6 5 6 5  i s heterolytically  (1.05) o r (1.08) and t h e h y d r i d e  (1.06).  h y d r i d e s a r e d e t e c t e d b y rimr..  with  5  9  i s o l a t e d and then t r e a t e d w i t h a c i d  Kl  Z >  H  t o g i v e t h e reduced  6  5  + _35  v  H  product  and 3 5 ,  54 a p r e c u r s o r t o t h e h y d r i d e _3_7.  T h e h y d r o g e n o l y s i s o f t h e a l k y l 46  ( e q u a t i o n 1.11) i s e x e m p l i f i e d b y R h H ( C O ) ( P P h ^ ) ^ s y s t e m s ( r e f . 1 5 , p a g e 402), I n scheme I I , t h e o x i d a t i o n s t a t e a n d c o o r d i n a t i o n number o f t h e m e t a l c h a n g e b y t w o when h y d r o g e n i s o x i d a t i v e l y added"'"' ( 1 . 1 2 , when t h e s a t u r a t e d p r o d u c t  i s e l i m i n a t e d (1.16).  Wilkinson's  1.15) a n d  catalyst,  -9Figure  1.5  S i m p l i f i e d Schemes o f Homogeneous Hydrogenations i n v o l v i n g Platinum Metals  * L may b e v a r i o u s l i g a n d s o r s o l v e n t s . R i s a a-bonded a l k y l . s t e p s w i l l be r e v e r s i b l e . Charges on t h e complexes have been  Some ignored.  -10-  RhC£(PPh ) , i s thought to f o l l o w both the hydride 3  and  3  the unsaturate  that  the  route  (1.13),  former predominates.  coordinate  because of  the  route  (1.15) a l t h o u g h r e c e n t ^*  studies  Intermediate  large trans  i n f l u e n c e of  (1.12),  48 may  (1.14) indicate  be  five-  the h y d r i d e s ,  and  5 6 if  s o , _50 w o u l d t h e n b e  to allow  favoured.  R e a r r a n g e m e n t t o j j l may  t r a n s f e r of b o t h h y d r i d e s  to the  substrate.  evidence t h a t a c i s o r i e n t a t i o n of h y d r i d e mediate to a l k y l  formation,  (51)  i s the  inter-  since a c i s , c i s complex^IrH (COD) (PPh^Me)^]^ 60 2  now  the  c i s - h y d r i d e trans-phosphine isomer e q u i v a l e n t  and  could  via  necessary  T h e r e i s good  olefin  has  The  b e e n o b s e r v e d and  and  be  studied  a t low  temperature.  In  t o _50 was  contrast, more  stable  be i s o l a t e d . ^ O s b o r n - t y p e c a t a l y s t s , J54, _55,  derived  from  [Rh ( d i e n e ) L ^ ] ,  53,  +  equations(1.18),(1.19), [Rh(diene)L ]  +  n  +  3H  2  ->- a l k a n e +  [H RhL (solvent) ] 2  n  53 54  (1.18)  +  x  54  v  -1 H  +  +  \HRhL ( s o l v e n t ) n y  (1.19) .  55 L = PR ,AsR 3  3  n=2  h y d r o g e n a t e o l e f i n s and hydride  of  I, ^2,  can  or 3  x,y=l,2 or  acetylenes  by  3  b o t h schemes s i n c e t h e  interconvert with  the d i h y d r i d e  of  a c t i v e mono-  I I , 48^,  via  53 equation  (1.19=1.17 i n scheme I I ) .  a d d i t i o n of  e x c e s s a c i d o r b a s e , i t was  h y d r o g e n a t i o n and genation  and  By  f o r c i n g one  regime through  d e d u c e d t h a t _55_ was  a very  the good  i s o m e r i z a t i o n c a t a l y s t whereas was g o o d f o r h y d r o 53 poor f o r i s o m e r i z a t i o n . Of i n t e r e s t , t h e c a t i o n i c  -11-  diphosphines  [ R h ( d i e n e ) L ] , L = d i p h o s , DIOP, and +  l i g a n d s o f f i g u r e 1.2,  do  not  f o r m d i h y d r i d e s and __  the unsaturate  so l i k e l y  certain criteria  i n f i g u r e 1.5.  splitting  strength to thermodynamically  t h e e n e r g y gap  (1) They m u s t be  support  the  of s u f f i c i e n t  follow  catalysis  crystal  field  favour hydride formation  b e t w e e n t h e HOMO a n d  LUMO ( A ) o f t h e m e t a l  t h e h y d r i d e b o n d i n g e l e c t r o n i s e a s i l y promoted t o an  orbital  other  61,62  described  low,  the  r o u t e o f scheme I I .  Only l i g a n d s f u l f i l l i n g  if  probably  -  i s too  antibonding  and  t h e h y d r i d e becomes t o o l a b i l e - b u t n o t so s t r o n g t o r e n d e r 52 the hydride k i n e t i c a l l y i n e r t . I r i d i u m ( I I I ) c a t a l y s t s t e n d t o be l e s s a c t i v e t h a n t h o s e o f R h ( I I I )  because of the i n c r e a s e i n A , i n going  from the second to the t h i r d  row  of  52 the p e r i o d i c t a b l e  and  hence the decrease  in lability  of Ir-H.  This  i n c r e a s e i n s t a b i l i t y , h o w e v e r , a l l o w s the i s o l a t i o n of i n t e r e s t i n g mediates such  a s _52.  L o w e r v a l e n t I r ( I ) and  Rh(I)  tend  inter-  t o be more r e a c t i v e  because of the lower A v a l u e s . (2)  Good s i g m a d o n o r a n c i l l a r y  hydrido o l e f i n  i n t e r m e d i a t e s 44^ and _5_1, e s p e c i a l l y  g e n a t i o n where s u b s t r a t e s such (3)  (1.14).  species f o r steps  Bulky  l i g a n d s may  labile  (1.05),  have t h i s  to y i e l d  (1.06),  ligands which favour the R h ( I I I ) , I r ( I I I ) five coordinate I r ( I ) ,  s o l v a t e d h y d r i d e s j>4_ a n d 5_5 f u l f i l J  the  hydrogroups.  reactive, coordinatively  (1.07), 63  (1.08),  (1.13)  and  property.  O x i d a t i v e a d d i t i o n r e a c t i o n s ( 1 . 1 2 ) and  favour four over  i n asymmetric  as 1 t o 6 have e l e c t r o n w i t h d r a w i n g  Some o f t h e l i g a n d s m u s t be  unsaturated  (4)  ligands are required to " a c t i v a t e "  (1.15) a r e promoted  s t a t e (PPh >C0) and  Rh(I).~^  3  Clearly  these requirements,  by  which  the r e a c t i v e  having strongly  -12-  bonded good a d o n o r s The  ( L ) and l a b i l e s o l v e n t  ligands.  f e w r e p o r t s o n s u l f o x i d e s a n d s u l f i d e s o f I r a n d Rh a s o l e f i n  hydrogenation  c a t a l y s t s suggest  that these  s u l f u r l i g a n d s do h a v e  c a t a l y t i c p o t e n t i a l d e s p i t e t h e i r r e p u t a t i o n as poisons  of heterogeneous  64 catalysis.  T h e I r s u l f o x i d e c o m p l e x e s 3 3 , 3 5 , 3 6 , a n d _37_ ( f i g u r e 1.4)  c a t a l y z e t h e B.^ t r a n s f e r f r o m b o i l i n g ketones and a c e t y l e n e s respectively."* '^ 4  isopropanol  to a,6-unsaturated  t o g i v e s a t u r a t e d k e t o n e s and c i s o l e f i n s ,  Under s i m i l a r c o n d i t i o n s c h l o r o i r i d i u m complexes  66 go  t o metal.  T h e common r e a c t i v e b u t i s o l a b l e c o m p l e x f o r t h e  s u l f o x i d e s y s t e m s i s IrCZ^(H) with substrates  to yield  (figure 1.6)^;  this  (1.06),  (1.10).  (1.09),  formation  (DMSO)^, _37_, s i n c e i t r e a c t s  the isolable alkyl  intermediates  directly _5_2 a n d 56  i s a n a l o g o u s t o a p a t h w a y o f scheme I : ( 1 . 0 5 ) , T h u s DMSO f i t s  and c r i t e r i o n  criterion  (1) f o r h y d r i d e  (3) f o r complex l a b i l i t y , where s u l f u r - b o n d e d F i g u r e 1.6 The P r o p o s e d M e c h a n i s m f o r S o l v e n t T r a n s f e r H y d r o g e n a t i o n o f C h a l c o n e C a t a l y z e d b y I r C £ ( H ) L , , L=DMS0; X may b e L o r s o l v e n t . 9  57  -13-  DMSO m u s t d i s s o c i a t e i n s t e p s for  isopropanol  (1.20) and p o s s i b l y (1.22) t o a l l o w  coordination.  R e p o r t s i n v o l v i n g Rh s u l f o x i d e ' c a t a l y s t s a r e s c a r c e . w o r k e r s g i v e no d e t a i l s as  i ntheir  I r ( I I I ) complexes, a r e i n e r t  c l a i m t h a t RhCJi^ (DMSO) ,  Russian  _26, a s w e l l  3  a s homogeneous h y d r o g e n a t i o n a n d 67  i s o m e r i z a t i o n c a t a l y s t s , and  t h a t 2j5 g o e s t o m e t a l u n d e r H^.  With  t h e a d d i t i o n o f 6 NaBH^ p e r Rh i n DMSO, c o m p l e x 26_ i s r e d u c e d t o w h a t is  s a i d t o be a n a c t i v e Rh(I)-DMS0 complex f o r pentene r e d u c t i o n and 68 i s o m e r i z a t i o n a t 20°C, a l t h o u g h l i t t l e e v i d e n c e i s p r e s e n t e d . Formed 69 in situ  from hot  solvent)  DMSO a n d R h C £ ( H 0 ) 3  2  3  , _26 d o e s h y d r o g e n a t e DMSO  t o d i m e t h y l s u l f i d e a n d w a t e r a t 80°C a n d 1 a t m . ^ (cf.  scheme I,42-»47) was t h o u g h t t o d e a c t i v a t e t h e c a t a l y s t . i n DMSO c a t a l y z e s b o t h DMSO a n d m a l e i c the  solvent r e a c t i o n discouraged  (ref. path  7 1 , page 180).  via  3  obtained  using  of the o l e f i n  reduced t o a Rh(I)  route  3  2  3  although system  r e d u c t i o n o f cinnamic  i n DMA a t 70°and 1 atm.  s p e c i e s , by l o s i n g a s u l p h i d e  cleaving H  2  v i a (1.05) t o a R h ( I I I ) - H  Hydrogenation then proceeds  s o l u t i o n s o f [RhC£(cyclooctene) ] 2  f i n d i n g s (Chapter  o l e f i n such as maleic  species  in situ,  6 i n r e f . 71).  acid  acid,  Here t h e R h ( I I I )  o f scheme I I : ( 1 . 1 3 ) , ( 1 . 1 5 ) ,  to generate s i m i l a r Rh(I) these  2  t h a t decomposes t o 47.  the u n s a t u r a t e  data  f u r t h e r study  and then by h e t e r o l y t i c a l l y  intermediate  3  a c i d r e d u c t i o n a t 80°C,  f o r the RhC£ (Et S)  a c i d , and e t h y l e n e  complex i s i n i t i a l l y ligand  RhC£ (Et S)  P r e s u m a b l y t h i s o l e f i n r e d u c t i o n f o l l o w s t h e same  as that considered  maleic  A reactive  7  R h ( I I I ) - H was p o s t u l a t e d , a n d a s l o w r e d u c t i o n t o R h ( I )  (the  (1.16). 2  Kinetic  a n d 4 E t S i n DMA, 2  a r e i n good agreement w i t h  I n t h e absence o f a s t a b i l i z i n g  (but n o t c y c l o o c t e n e ) , such i n s i t u  Rh(I)  -14-  s o l u t i o n s d i s p r o p o r t i o n a t e t o R h ( I I ) a n d Rh m e t a l whether under  o r N^.  This i s a l s o t h e case f o r t h e corresponding  SPh^ and S C C H ^ P h ^ s y s t e m s . as phosphines i n removing  Clearly  (criterion  i nactivating  49_ t o w a r d  oxidative  (4)), since the chlororhodate(I)/maleic  acid/DMA s y s t e m i s f i v e t i m e s more 1.3.2  these l i g a n d s a r e not as e f f e c t i v e  e l e c t r o n d e n s i t y from R h ( I ) and t h e y a r e a l s o  not as e f f e c t i v e as c h l o r i d e s addition of  ( r e f . 7 1 , page 134)  72  active.  Solvent T r a n s f e r Hydrogenation o f Ketones  and A l d e h y d e s  66 73 B o t h IrC£ H(DMSO)° , 3 7 , a n d R h C £ ( D M S O ) ( P P h ^ ) , 21> c a t a l y z e 2  equilibrium  2  (1.23).  To d r i v e t h i s r e a c t i o n t o t h e r i g h t  R^R CO m u s t b e e a s i e r t o r e d u c e t h a n R^R^CO b y a b o u t 2  R R C=0 + R ^ C H O H 1  if  2  secondary a l c o h o l s  1 0 0 mV  74  , although  R ^ C H O H + R R C=0 3  a p r o d u c t i s c o n t i n u o u s l y removed  d i f f e r e n c e c a n be l e s s . and  s v  (98% products),  (1.23)  4  (e.g. acetone) t h i s  potential  The s p r e a d o f o x i d a t i o n p o t e n t i a l s i s 3 0 0 mV; t h i s r a n g e  a l c o h o l s w i t h e l e c t r o n d o n a t i n g groups w i t h e l e c t r o n w i t h d r a w i n g groups  includes  f o r primary  secondary  (60-160), secondary  alcohols  (160-360), and p r i m a r y a l c o h o l s  with  74 e l e c t r o n w i t h d r a w i n g groups donating groups  (200-300).  Hence, 2 - p r o p a n o l w i t h  electron  i s a c o n v e n i e n t r e d u c t a n t o f most k e t o n e s and a l d e h y d e s .  Chloroiridate(III) species i n refluxing DMSO/isopropanol^  or  H P 0 / i s o p r o p a n o l ^ reduced c y c l o h e x a n o n e s a t a h i g h e r r a t e , and w i t h 3  3  a much h i g h e r a x i a l  t o e q u a t o r i a l a l c o h o l product r a t i o , t h a n  ponding phosphine systems.  W i t h DMSO, t h e a c t i v e s p e c i e s  corresIrC& H(DMS0) , 2  3  -15-  37,  i s thought t o be formed a l o n g w i t h acetone by c o o r d i n a t i o n o f t h e  i s o p r o p a n o l as an a l k o x i d e l i g a n d , f o l l o w e d by 3-hydride The  ketone s u b s t r a t e i sthought t o coordinate  formation,  and r e a c t a f t e r  s i n c e no a s y m m e t r i c s y n t h e s i s o f a c h i r a l  p r o c h i r a l k e t o n e was d e t e c t e d  using  (-)octan-2-ol  reductant.^  On t h e o t h e r  the concerted  intramolecular hydride  to coordinated  hand,RuC£ (PPh ) 2  k e t o n e ^ , and t h i s  3  3  a l c o h o l from a  i s thought t o mediate  t r a n s f e r from c o o r d i n a t e d  saturated ketones using  t h i s ruthenium complex and a  ketones t o c h i r a l glucofuranose  donor.^  E v e n i n t h e p r e s e n c e o f e x c e s s DMSO a n d k e t o n e ,  [NH,]„[RhC£,] i s H  reduced t o metal i n r e f l u x i n g 21, w i t h  suggesting 1.3.3  3  2  ; i n a range o f R h C ^ P P h ^ ^ L  Reactions  2  o x i d a t i o n o f DMSO t o ( 0 ) S ( M e ) , a n d O S ( P h ) 2  hydrides, M(III)-H,  2  are considered  Organic s u l f i d e s were not  stable Rh(III) sulfides.  that mixtures  0  the  i n v o l v e m e n t o f a R h ( I I I ) h y d r i d e was s u g g e s t e d .  The  3  Homogeneous A s y m m e t r i c designing  2  to (0) S(Ph)^. 2  o x i d i z e d due t o t h e f o r m a t i o n o f  James e t a l ^ r e p o r t e d  o x i d i z e DMSO w i t h R h C £ ( H 0 )  2  isopropanol  t o be i n v o l v e d i n t h e  and  1.3.4.  on R h ( I ) .  I r a n d Rh a c i d s 33 a n d 3_1 ( f i g u r e 1.4) i n h o t a q u e o u s  Intermediate  2  D  However, RhC£(DMSO)(PPh^) , 73  t h a t s u l f u r b o n d e d DMSO i s e l e c t r o n w i t h d r a w i n g  catalyze the0  process.  3  w a s m o s t a c t i v e a n d L=CO a n d DMSO, 2 1 , w e r e l e a s t a c t i v e ,  Oxidation The  2-propanol.  66  2 - p r o p a n o l does r e d u c e c y c l o h e x a n o n e s  complexes,L=PPh  alkoxide  i s s u b s t a n t i a t e d by t h e r e p o r t o f t h e  o f p r o c h i r a l a,3-unsaturated  alcohol  hydride  as s o l v e n t and  asymmetric hydrogenation  d e r i v a t i v e as c h i r a l  abstraction.  3  of H  2  as c a t a l y s t p r e c u r s o r , and again  Hydrogenation  of asymmetric s y n t h e s i s systems t h a t g i v e  products  -16-  with of  a high enantiomeric excess  the factors  involved  i n the discriminating  l i g a n d b e t w e e n t h e two p o s s i b l e olefin  - i.e. a diastereotopic  be d i v i d e d and  (3)  (e.e.) r e q u i r e s  a detailed  interaction of the c h i r a l  enantiomers of the coordinated discrimination.  prochiral  This i n t e r a c t i o n can  i n t o t h r e e components: (1) l i g a n d - o l e f i n , (2) m e t a l - o l e f i n ,  ligand-metal.  A study of cis-PtC& (S-MPTSO)(Olefin) complexes, 2  sulfoxide aryl  understanding  i s d e s i g n a t e d as S on c o o r d i n a t i o n ) ,  substituents  (R-methyl  p-tolyl  where s i m p l e a l k y l and  on t h e o l e f i n w e r e n o t e x p e c t e d t o i n t e r a c t w i t h t h e 78  metal  ( i n t e r a c t i o n ( 2 ) ) , was c o n d u c t e d b y B o s n i c h e t a l .  t o what e x t e n t c h i r a l the  olefin  sulfoxide ligands  to determine  were capable o f d i s t i n g u i s h i n g  e n a n t i o m e r s shown i n f i g u r e 1.7. Figure  1.7  Cis-PtC£~(S-MPTSO)(Olefin) D i a s t e r e o m e r s  s  S c e n t e r on o l e f i n S c e n t e r on s u l f o x i d e  R c e n t e r on o l e f i n S center on s u l f o x i d e  -17-  Crystals  of  the  R ^ C H ^ H . ^ , 5 8 , C H ( C H ) , 5 9 , and 3  w e r e i s o l a t e d i n 100%  S f o r m , and  C(CH )  2  3  3 >  a crystal structure  60,  of  derivatives  the  isopropyl  79 c o m p l e x _5_9_. as  showed t h a t  i n f i g u r e 1.7.  H o w e v e r , on  m e r s t a k e s p l a c e by to the  o l e f i n of  although the C^H^,  and  2  in solution with the  55/44 f o r 58, not  66/34 f o r 59  and  have e q u i l i b r a t e d .  derivatives,  3  r a t i o s of  61,  62  and  63_,  4 4 / 5 6 , 2 5 / 7 5 , and  s t y r e n e d e r i v a t i v e , j>2,  sulfoxide,  d i s s o l u t i o n , slow e q u i l i b r a t i o n of  o l e f i n d i s s o c i a t i o n t o g i v e S/R  l a t t e r may  OCH CH  t h i s b u l k y g r o u p p o i n t e d away f r o m t h e  i s e x p l a i n e d by  ratios with  100/0  f o r 60  prefer 25/75.  respect  at  S t r a n g e l y the  the  diastereo-  30°C,  R^=CH , 3  the  R  configuration  The  R preference  phenyl i n t e r a c t i o n  of  with 80  the  sulfoxide  p - t o l y l group, c l e a r l y observed i n the  The  R o l e f i n i s rotated  aromatic rings  180°  from the  to f a c e each other.  the  R enantiomer, whereas the  S one,  the  authors f e e l that  sulfoxides unity  of  the  are  the  r a t i o s , but  "washed o u t " .  dynamic v a l u e s .  T h e r e may  i t m u s t be  be  a larger  structure.  to allow  the  propene d e r i v a t i v e ,  sulfoxide  poor c h i r a l d i s c r i m i n a t o r s  S/R  f i g u r e 1.7  1-butene s p e c i e s ,  because of  o l e f i n i s nearly  of  Since the  likes  p r e f e r e n c e of  one  crystal  _58,  61,  prefers  the  r o t a t i o n , the  chiral  They c o n c l u d e  that  j u d g i n g from the v a l u e s  emphasized t h a t  near  these are  kinetic discrimination  as  thermoolefin  b i n d i n g o c c u r s , a s i n t h e c a s e o f 60. The same g r o u p d i d n o t i c e a d r a m a t i c k i n e t i c e f f e c t i n v o l v i n g o l e f i n rotation.  A l t h o u g h s t y r e n e , t - b u t y l e t h y l e n e , and 78  olefins, an  odd  do  fashion  Rotation  rotate  '  , even a t since  R^  50°C, \58,  _59 and  c a n n o t p a s s by  S - o l e f i n i s f o u n d t o be much e a s i e r  R enantiomer because of  groups of  the  substituted  81  ( f i g u r e 1.7)  f o r the  than f o r the tolyl  not  higher  sulfoxide  i n the  the  l o c a t i o n of  61  the  do  oscillate in  bulky c i s  chloride.  (the b a r r i e r  i s lower)  t h e m e t h y l and  different transition states  for  p-  -18-  78 r o t a t i o n o f t h e two i s o m e r s . I n c o n c l u s i o n , t h i s study p o i n t s out two t y p e ( 1 ) i n t e r a c t i o n s : ' ( i ) b u l k y g r o u p s p o i n t away f r o m t h e s u l f o x i d e a s i n f i g u r e 1.7  except i n the case of  (ii)  the  olefin-  ligand phenyl-phenyl interaction. The  latter  specific  i n t e r a c t i o n may f i g u r e 1.2,  d i p h e n y l p h o s p h i n e s 7-13, and  S - a l a n i n e i n h i g h e.e.  cannot  be i m p o r t a n t f o r t h e  but the p r o d u c t i o n of S - l e u c i n e  i n v o l v e phenyl groups.  a p p e a r s t o be t h e b u l k y and c h i r a l a r r a n g e m e n t 8 9 n a t i v e l y " e d g e and  face"  Instead i t  of the phenyls  ' '  around  the rhodium c e n t e r t h a t l e a d s t o These e f f e c t i v e phosphines  t h e p h e n y l s i n t h i s c o n f i g u r a t i o n by p " ^ ( 8 , 9 , 1 0 , 1 1 , 1 2 ) , P^b(7_,8) c h e l a t i o n t o r h o d i u m  (all  P~N  i n t e r m e d i a t e , j>l_ ( f i g u r e 1 . 5 ) , w h e r e t h e l i g a n d The  lock  (12?,13)  and  type(3) i n t e r a c t i o n s ) , although i t  c h e l a t i o n i s p o s s i b l e i n the dihydride  coordination sites.  alter-  82  t h e i m p o r t a n t t y p e (1) i n t e r a c t i o n .  i s n o t c l e a r how  chelating  olefin  i s allowed only  two  importance of l o c k i n g the carbons j o i n i n g  the  phosphorus  a t o m s i n t o one c o n f o r m a t i o n b y u s i n g m e t h y l g r o u p s h a s a l s o 9 been demonstrated. Another c r u c i a l f a c t o r i s the a b i l i t y of substrates L t o 6^ t o c h e l a t e t o r h o d i u m b y t h e o l e f i n and t h e e n a m i d e o x y g e n a s d e m o n s t r a t e d by  31  P nmr  i n t e r a c t i o n enhances s o l v e n t and  83  , and a c r y s t a l s t r u c t u r e .  84  Thus a t y p e ( 2 )  the c h i r a l d i s c r i m a t i o n of t y p e ( 3 ) .  t e m p e r a t u r e on c h i r a l  The  effect  of  induction i s poorly understood.  T h e s e p o i n t s , many o f w h i c h w e r e r e p o r t e d d u r i n g t h e c o u r s e o f t h e studies i n this  t h e s i s , c o n f i r m e d our thoughts that c h e l a t i n g  1 4 - 1 6 , w e r e p r o m i s i n g l i g a n d s t o t r y on Rh o r I r .  sulfoxides,  I n t e r m e d i a t e _56  ( f i g u r e 1 . 6 ) , i n h y d r o g e n a t i o n s i n v o l v i n g I r C ^ ^ D M S O ) ^ shows a good t y p e ( 2 ) i n t e r a c t i o n and  therefore a catalyst  containing chiral  ligands  -19-  m i g h t be  1.4  q u i t e e f f e c t i v e i f t h e h y d r o g e n a t i o n p r o c e e d s by  Sulfoxides Both the  as  a s u l f o x i d e t o a c t as  so  +  with  The  only  cases of l i n k a g e and  2  A v a r i e t y of s p e c t r o s c o p i c the  two  modes o f b o n d i n g .  o x y g e n 2p  electrons  absorption on  The  i r .  by  and  nmr  r(S0).  S-0  The  distinguishes  are  (figure  donation an  of  intense  t h i s pi-bonding i s decreased  increased  on  S-coordination,III, and  length  characteristically  of methyl protons a to the case of  of  as  the  i n the v a l u e SO  group  s u l f u r than f o r  Electron spectroscopy for chemical analysis I from I I I .  1.4). ;  o r b i t a l s creates  f o r the  35,  distinguishes between  t h i s change i n s t r e n g t h  Deshielding  inorganic  IrC£^(DMSO)^,  m u l t i p l e b o n d c a u s e d by  amount o f  i s g e n e r a l l y much g r e a t e r  coordination.  87  techniques r e a d i l y  b o n d i s r e f l e c t e d d r a m a t i c a l l y and  v(S0)  coordination  m e t a l s , [Fe(CN)^(DMSO)]  i s o m e r s o f c o m p l e x 34  ( f i g u r e 1.8,1), or  a f u n c t i o n o f t h e m e t a l , M; SO  (platinum  isomerism  i n t o empty s u l f u r 3d  band i n the  0-coordination  85  Sulfur  enabling  o x y g e n a d d u c t s a r e much m o r e common i n  I r C £ ( D M S O ) ( D M S O ) , 36, 3  p a i r of e l e c t r o n s  ambidentate Lewis base.  f o r some c l a s s b a c i d s  3  86  oxygen have a l o n e  an  C r ( 0 ) , M n ( 0 ) , C H ) and chemistry.  route.  Ligands  s u l f u r and  i s observed only  this  of  observed oxygen  (E.S.C.A.) a l s o  88 89  The  d o r b i t a l s of a s u l f u r coordinated 2+  s u c h as  [Ru(NH )^] 3  these adducts are  the  case of  ligands  and  2  [Fe(CN)^] from the  on M n ( C 0 ) ( C p ) L was 2  2  4  can  Hence, use  The  The  spectroscopic  SO b o n d o r d e r  of only  ir-acceptor a b i l i t y  o r d e r e d as of  accept metal d electrons  oxygen.  c o n s i s t e n t w i t h an  free sulfoxide,II.  i—i 90 SEt =S(CH ) .  groups  3-  expense c f p i e l e c t r o n s of  t o good b a c k - b o n d i n g  0SPh >0S~(CH ) 2  2  4  at  properties two  as  of v a r i o u s =  the  in  sulfur  OS(CH^) SPh =  s u l f o x i d e s i n s t e a d of s u l f i d e s i n  >  2  2  the  3—  ,  -20-  F i g u r e 1.8  The S t r u c t u r a l a n d S p e c t r o s c o p i c D a t a f o r DMSO C o m p l e x e s  © Bonding  CH  0  © CH  3  > = Q.  >-6:  ^  CH  3  v(S0) cm"  Structural  r(S0)A  1.56-1.53  6(-CH )  3.1-2.6  1  H  nmr  E.S.C.A. ( 0 -S j-s zp  3  1  860-1000  ( b )  )e.v. 365.8±.3  1055  ( b )  '  (  ( b )  1.531  ( b )  d  )  2.57  ©  3  > = 0 :  in  II  ir  (a)  ( b )  1060-1198  ( c )  1.53-1.41  ( c )  3.1-3.6  ( b )  ( c )  365.0±.3  ( e )  '  ( d )  ( e )  3 / 2  (a)  T h e v a l u e s f o r a l l known DMSO c o m p l e x e s f a l l  (b)  S e e c h a p t e r s 3,6.  (c)  S e e c h a p t e r 4.  (d)  These ranges  (e)  See r e f e r e n c e 88.  i nthe ranges  exclude cases o f magnetic s h i e l d i n g  »  given.  by neighbouring  groups.  -21-  catalytic more  reactions  discussed  might be expected t o s t a b i l i z e R h ( I )  effectively. Sulfoxides  OS(CH ) 2  are strong  oxygen donor p r o t o n i c  = OSBu >OS(CH ) >OS(CH )Ph>OSPh .  4  2  3  s e r i e s f o r such ligands  2  3  bases i n the order: The s p e c t r o c h e m i c a l  9 1  2  oxygen-bonded t o t r a n s i t i o n  metals  parallels  92 this  ordering.  Oxygen-bonded s u l f o x i d e s  (e.g.[Co(DMSO)(NH ) ][C£0 1 3  4  5  QT  i n general  are l a b i l e  and c i s - [ P t ( D M S O ) ( D M S O ) ^  7 J  3  2+ 94s  1, a n d  £  t h i s may b e a n i m p o r t a n t f a c t o r i n t h e r e a c t i v i t y  o f c a t a l y s t s such as  R h C & ( D M S O ) ( D M S O ) , 2 6 , i n DMSO. 3  2  Sulfur coordinated (kinetic  s u l f o x i d e s have a pronounced  e f f e c t ) when c o o r d i n a t e d  a f a c t o r i n Rh(I)  catalysis.  toPt(II)  95  However t h e r e  trans-effect  a n d t h i s a l s o may b e  i s disagreement whether  96 they have a s t r o n g references The using  Rh a n d I r c o m p l e x e s p o i n t  reduction  (pro:  c h i r a l a t the sulfur.  and o x i d a t i o n o f s u l f o x i d e s  outa l i m i t a t i o n of sulfoxide  where such redox r e a c t i o n s  these reactions  mization  a thermodynamic e f f e c t  97,98,99,100,101; m i x e d v i e w : 102; c o n : 45, 104, 105, 106).  aforementioned c a t a l y t i c  Conditions since  trans-influence,  would destroy  ligands.  o c c u r must be a v o i d e d , e s p e c i a l l y  the optical  a c t i v i t y of ligands  Otherwise sulfoxides are quite  over a wide range o f c o n d i t i o n s .  103  inert  t o race-  -22-  2.  2.1  A p p a r a t u s and G e n e r a l  Experimental  Procedures  Instrumentation S y n t h e t i c p r o c e d u r e s and s o l u t i o n measurements were  under argon atmosphere by u s i n g Infrared spectrometer.  standard  s p e c t r a were r e c o r d e d  Schlenk tube  i n Nujol or  hexachlorobutadiene  F o r s o l u t i o n s , 0.1 mm NaCJl c e l l s f i t t e d w i t h  c a p s w e r e u s e d w i t h CECi^,  CH^CSL^,  o  CH^Br^; t h e l a s t  r  h a v e u s e f u l w i n d o w s f r o m 1 2 0 0 - 1 0 0 0 a n d 1 0 7 0 - 8 5 0 cm {4l NMR s p e c t r a w e r e r e c o r d e d using  techniques.  o n a P e r k i n E l m e r 457 g r a t i n g  S o l i d s were r u n as m u l l s  between C s l p l a t e s .  conducted  1  serum  two s o l v e n t s  respectively.  o n a V a r i a n T60 o r X L 1 0 0  spectrometer  t e t r a m e t h y l s i l a n e a s a r e f e r e n c e w i t h s o l v e n t s CC& , C D C ^ J  CD2C&2*  4  C^CJ^*  ( C D ^ ^ C O and ( C D ^ ^ S O , and u s i n g  5-sulfonate  (D.S.S.) w i t h  sodium  2,2-dimethyl-2-silapentanone-  D 0. 2  C o n d u c t i v i t y m e a s u r e m e n t s w e r e made i n n i t r o m e t h a n e a t 25°C u s i n g a Thomas S e r f a s s  conductivity bridge  and a c e l l  that allows purging  with  argon. O p t i c a l r o t a t i o n s were d e t e r m i n e d on a P e r k i n Elmer 141 p o l a r i m e t e r a t room t e m p e r a t u r e u s i n g  a one d e c i m e t e r  Gas c h r o m a t o g r a p h i c a n a l y s e s grammable H e w l e t t  Packard  were used  were c o n d u c t e d on a t e m p e r a t u r e  5750 w i t h a t h e r m o c o n d u c t i v i t y  e i g h t h i n c h columns packed w i t h Specialities  m i c r o c e l l w i t h a 1 ml volume.  detector.  less  than  9 carbons,  and columns  with  1 0 % C a r b o w a x 20M o n 60-80 mesh C h r o m o s o r b W f o r u n s a t u r a t e d  and  aldehydes.  department.  One  "Durapak" s u p p l i e d by C h r o m a t o g r a p h i c  f o rolefins with  C,H,N, a n d CI a n a l y s e s  pro-  ketones  w e r e p e r f o r m e d b y M r . P. B o r d a o f t h i s  -23-  2.2  Gas-Uptake The  and  Apparatus  constant pressure apparatus,  for stoichiometric  nected a c a p i l l a r y flask  experiments.  d r i v e n by an o f f s e t w h e e l  shaken  connected  bucket.  The  The  h i g h v a c u u m m e t e r i n g v a l v e , M,  capillary  perspex water  bath.  was  and  electric  connected  to  r e s e r v o i r E a n d a 10  ml  connected  v i a an  to the gas-handling p a r t of the  m a n o m e t e r and  con-  reaction  t o a Welch v a r i a b l e speed  g a s b u r e t t e was  T h i s p a r t c o n s i s t e d of a mercury The  tube  by means o f a p i s t o n - r o d  b u r e t t e c o n s i s t i n g of a mercury  p i p e t t e o f known d i a m e t e r .  kinetic  reaction flask  The m a n o m e t e r D c o n t a i n e d n - b u t y l p h t h a l a t e and was  a gas m e a s u r i n g  for  manometer D a t t a p C t o a p y r e x two n e c k e d  t h e r m o s t a t t e d i n a n o i l b a t h and  G.  used  A f l e x i b l e glass s p i r a l  e q u i p p e d w i t h a d r o p p i n g s i d e arm  motor.  ( f i g . 2 . 1 ) , was  m a n o m e t e r F, g a s  i n l e t Y,  Edwards  apparatus.  a n d v a c u u m pump  g a s b u r e t t e w e r e t h e r m o s t a t e d @ 25°C i n a  T h e r m o s t a t i n g o f t h e o i l b a t h and w a t e r b a t h  was  c o n t r o l l e d by Jumo t h e r m o - r e g u l a t o r s and M e r c t o M e r c r e l a y c o n t r o l cuits,  w i t h h e a t i n g a c c o m p l i s h e d b y a 40 w a t t  baths were w e l l s t i r r e d , held in  t o ±0.05°C.  t i m e was  Gas-Uptake E x p e r i m e n t a l In  a typical  gas-uptake  25 m l r e a c t i o n f l a s k .  the o i l bath i n s u l a t e d .  filled  The  The  temperature  f o l l o w e d t h e gas  recorded w i t h a Labchron  1400  was  uptake  timer.  Procedure e x p e r i m e n t , 5 m l o f s o l v e n t was  placed i n the  Weighed . s u b s t r a t e s w e r e a d d e d t o t h e s o l v e n t  and w e i g h e d c a t a l y s t v i a t h e b u c k e t flask  elongated l i g h t bulb.  A v e r t i c a l mounted c a t h e t o m e t e r  t h e b u r e t t e , and  2.3  and  cir-  w i t h r e a c t a n t gas.  after  Degassing  pumping on t h e s o l v e n t w h i l e s h a k i n g .  t h e s o l v e n t was f o r DMA  s o l v e n t was  For h i g h e r vapour  t h e f r e e z e t h a w u n d e r s t a t i c v a c u u m t e c h n i q u e was  degassed  directly  and  effected  the by  pressure solvents  employed.  For  both  Figure 2 . 1 .  Constant pressure gas-uptake apparatus  25-  methods a d e g a s - r e f i l l  c y c l e was  t h e r e a c t i o n f l a s k was  filled  less  than that required  repeated three times.  w i t h r e a c t a n t g a s a t a p r e s s u r e somewhat  f o r the experiment,  t a p s C and p. w e r e t h e n c l o s e d and spiral  d i s c o n n e c t e d f r o m 0 and  w h o l e s y s t e m up M open.  t o t a p C was  Reactant  g a s was  Initially  a t 0,  ( f i g . 2.1).  The  the r e a c t i o n f l a s k complete  with  a t t a c h e d t o H and  the shaker rod.  t h e n pumped down w i t h t a p s H,  K,  L,J  admitted to t h i s p a r t of the system i n the r e a c t i o n f l a s k but l e s s than  desired  After  f l a s k was  attained  whole system of  gas  (-15  thermal e q u i l i b r a t i o n of the  m i n . ) , t a p C was  o p e n e d and  a t t h e r e a c t i o n p r e s s u r e (-5  t a p s K and L a n d  starting  ference i n o i l levels into  changes i n mercury of  the timer.  i n m a n o m e t e r D.  min.).  An  experimental run  G a s - u p t a k e was  levels  s h a k i n g r a t e s and  inlet  balanced  dif-  by  Corresponding  to volume changes  time.  a large indented reaction  Inlet Bubbler:  a s shown i n f i g u r e 2.1  closing  i n d i c a t e d by a  i n the p i p e t t e N were t r a n s l a t e d  M o d i f i c a t i o n s of Gas-Uptake Gas  was  the shaker,  The manometer was  D i f f u s i o n c o n t r o l o f t h e r e a c t i o n s was  2.4.1  introduction  t h e b u r e t t e t h r o u g h t h e m e t e r i n g v a l v e M.  gas r e a c t e d , per u n i t  2.4  the  t h e n done t o s a t u r a t e t h e s o l v e n t  t h e n s t a r t e d by d r o p p i n g t h e c a t a l y s t b u c k e t , s t a r t i n g  a d m i t t i n g gas  reaction  Y.  S h a k i n g o f t h e r e a c t i o n v e s s e l was w i t h gas  that  the p r e s s u r e of  a d j u s t e d t o t h e d e s i r e d r e a c t i o n p r e s s u r e by  through  and  at a  pressure greater than that f o r the r e a c t i o n .  The  Y a t a p r e s s u r e o f 1000  mm.  fast  flask.  Apparatus  A mercury  so t h a t gas  e l i m i n a t e d by u s i n g  b u b b l e r was  connected  to tap Y  c o u l d be c o n t i n u o u s l y c i r c u l a t e d The  advantages  of t h i s  system  past  over  -26-  s i m p l y c o n n e c t i n g a gas  cylinder  resulting  i n the upset  the i n l e t  t u b i n g i s e a s i e r , and  maintained  to tap Y are that pressure b u i l d u p s  o f manometer F a r e a v o i d e d , t h e gas  inlet  the purging  system  of  to tap M can  a t a maximum p o s i t i v e p r e s s u r e d u r i n g a n u p t a k e  experiment.  However, t a p Y must be opened c a r e f u l l y t o a v o i d s u c k i n g m e r c u r y the  into  system. 2.4.2  right  T e l f o n Stopcocks;  Since the s e c t i o n of the apparatus  o f t a p M i n f i g u r e 2.1  1 atm,  Kontes t e f l o n  taps are s u p e r i o r to greased  o f g a s e s when s e t t i n g  loaded, greased  t a p s a r e b e s t f o r H,  o p e n e d and t h e gas  2.4.3  Convenient  were s e n s i t i v e uptake  Ampoules:  onto  K,  t h e y do n o t  b u l b was  filled  I n s t e a d a b u l b was  p l a c e d i n t h e s t e m and  w i t h s a m p l e and  using the hydrogenation  alter  The  closed.  work i n the  b l o w n on a g l a s s  a g l a s s r o d was latter  rapidly  the volumes of  s t a t e t o h y d r o g e n so t h a t t h e b u c k e t  breakage of the ampoule.  spring-  L, J b e c a u s e t h e y a r e more  t h e bottom of the b u l b t o weaken i t .  guarantee  than  However  S e v e r a l of the complexes i n t h i s  c o u l d n o t be u s e d .  t u b e , a c o n s t r i c t i o n was  the  They a l s o a l l o w  t e f l o n o n e s do when t h e y a r e o p e n e d and  i n the s o l i d  procedure  ones.  t h e p r e s s u r e i n F.  c l o s e d t h a n t e f l o n o n e s and  b u r e t t e s , which  to  i s n o r m a l l y under a p r e s s u r e g r e a t e r  easier metering  to  be  t r i c k was  melted essential  A f t e r being t e s t e d f o r l e a k s , the  then sand,  and  then s e a l e d o f f under  argon  b a l l o o n t o r e g u l a t e t h e p r e s s u r e as i n f i g u r e  These p r e c a u t i o n s m i n i m i z e  gas  uptake  when t h e a m p o u l e b r e a k s .  The  2.2.  glass  -27-  Figure  w  2.2  Hydrogenation Rubber vacuum  Balloon  tubing Hook f o r m e d during seal-off  Seal-off Glass  tube  Sand Sample Glass  should  be  rod  s e a l e d o f f i n t h e s h a p e o f a h o o k ( f i g u r e 2.2)  can be hooked t o t h e b u c k e t d r o p p e r o f t h e u p t a k e 2.4.4  Low  Temperature  Uptake  Vessel:  many o f t h e e x p e r i m e n t s t o be d e s c r i b e d by u s i n g to  l a r g e q u a n t i t i e s of ^SO^  design  tube  so t h e ampoule  flask.  Rhodium m e t a l w h i c h formed c a n o n l y be r e m o v e d f r o m  a t 150°C.  I t was  glass  therefore necessary  a n u p t a k e v e s s e l t h a t c o u l d be f i t t e d w i t h a d i s p o s a b l e  ( f i g u r e 2.3).  The  f e r i n g w i t h the s t i r r e r .  gauze p r e v e n t s t h e b u c k e t o r ampoule from T h i s assemblage  was  immersed i n a  test inter-  constant  t e m p e r a t u r e b a t h b u t t h e r e s t o f t h e u p t a k e p r o c e d u r e i s t h e same. uptakes at temperatures  lower than ambient  in  were measured u s i n g  Gas  this  apparatus.  2.5  Work Up The  The  of Hydrogenations  of I t a c o n i c A c i d  r e a c t i o n s o l u t i o n s were f i r s t  r e s i d u e was  pumped t o d r y n e s s a t 0.2  d i s s o l v e d i n 25 m l o f 1 0 % NaOH s o l u t i o n a n d  mm  filtered  pressure. through  -28-  Figure  Low  Reaction Solvent  Stainless Steel Gauze o r Flattened G l a s s Rod  2.3  Temperature Uptake V e s s e l  -29-  Celite.  T h e f i l t r a t e was e x t r a c t e d w i t h 25 m l c h l o r o f o r m t o r e m o v e  any  f r e e s u l f o x i d e a n d t h e n made j u s t  was  extracted  from t h e aqueous phase w i t h d i e t h y l  d r i e d o v e r MgSO^. 2.6  Starting 2.6.1  a c i d i c w i t h 1 0 % HC£.  The p r o d u c t  e t h e r (5x25 m l ) and  T h e e t h e r was r e m o v e d t o y i e l d p r o d u c t a n d s u b s t r a t e .  Materials  Gases:  Purified  hydrogen  a n d C. P. g r a d e  carbon monoxide were  o b t a i n e d f r o m t h e M a t h e s o n Gas Co., w h i l e p u r i f i e d n i t r o g e n and a r g o n were from t h e Canadian  Liquid A i r Ltd.  Deoxo H y d r o g e n P u r i f i e r b e f o r e u s e . through a CaC&  2  d r y i n g tower.  further sieves  Solvents:  Argon and N  ^  passed  c o n d i t i o n s were  m o l e c u l a r s i e v e s was e m p l o y e d .  an<  S p e c t r a l grade  through a  were n o r m a l l y  2  When m o r e r i g o r o u s a n h y d r o u s  r e q u i r e d , a m i x t u r e o f f r e s h ^2^5 2.6.2  H y d r o g e n was p a s s e d  s o l v e n t s were n o r m a l l y used  without  p u r i f i c a t i o n and were s t o r e d where a p p r o p r i a t e o v e r m o l e c u l a r (BDH, t y p e 5 A ) .  They w e r e vacuum-degassed b e f o r e u s e .  Where n e c e s s a r y , t h e f o l l o w i n g d r y i n g s t e p s w e r e p e r f o r m e d . A l c o h o l s were r e f l u x e d  and t h e n d i s t i l l e d  a l k o x i d e s under N 2  from,  t h e n vacuum 2.6.3  or  E t h e r a n d THF w e r e s t i r r e d  s o d i u m / b e n z o p h e n o n e u n d e r N^.  vacuum d i s t i l l e d . and  from t h e i r c o r r e s p o n d i n g magnesium  Silver  2.6.4  distilled  DMSO was d r i e d w i t h KOH a n d t h e n  DMA s u p p l i e d b y F i s h e r was s t i r r e d w i t h C a H  2  overnight  distilled. S a l t s : AgSbF^ and AgPF^ were s u p p l i e d by A l p h a  Cationics Ltd.  was m i n i m i z e d .  i n , and t h e n  Exposure  of these s a l t s  t o a i r ( m o i s t u r e ) and l i g h t  These compounds, even a s s o l i d s ,  etch glass  Rhodium S t a r t i n g M a t e r i a l s : R h o d i u m ( I I I )  as t h e t r i h y d r a t e f r o m J o h n s o n ,  Matthey  Chemicals  Limited.  rapidly.  t r i c h l o r i d e was o b t a i n e d L i t e r a t u r e methods were  -30-  u s e d f o r t h e s y n t h e s i s o f [RhC£(cyclooctene)^] [RhC£(l,5-cyclooctadiene)] except f o r the l a s t shaken;  3 2  , [RhCil(CO) ] 2  2  , [RhC£(C H  )^\  2  2 ,  4 5 , a n d [RhC£(norbornadiene) ] ,  compound w h e r e t h e i n g r e d i e n t s w e r e s t i r r e d , n o t  t h e method r e p o r t e d by Osborn e t a l  complex r e s u l t e d  1 2  f o r the norbornadiene  i n a low y i e l d .  The  p r e p a r a t i o n s o f [ R h ( n o r b o r n a d i e n e ) - ] P F , a n d [Rh(l,5-cyclooctadiene)„]• z o I SbF^ w e r e a d a p t e d f r o m one r e p o r t e d by O s b o r n , e t a l . / 2.6.4.1 [ R h ( n o r b o r n a d i e n e ) ] P F ^ : 2  o f 0.43 g [ R h C £ ( N B D ) ] i n 1 ml of acetone. and  2  The o r a n g e  v o l u m e was r e d u c e d t o 4 m l .  s o l u t i o n was t h e n f i l t e r e d  suspension  f r o m t h e AgC£,  Red c r y s t a l s p r e c i p i t a t e d  The c r y s t a l s w e r e r e c o v e r e d b y d e c a n t i n g o f f t h e s o l v e n t ,  R h C H P F : C , 3 8 . 9 1 ; H,3.73. 1 6  6  Yield  Z  followed.  Yield,  0.6 g ( 7 5 % ) .  Anal.  washing  Calcd f o r  F o u n d : C , 3 9 . 0 9 ; H.3.93.  2.6.4.2 [Rh(cyclooctadiene)„]SbF,: t o 0.19 g o f [ R h C £ ( C 0 D ) ]  as t h e  P r e c i p i t a t i o n was c o m p l e t e d b y a d d i n g 4 m l  w i t h e t h e r and d r y i n g i n vacuo. 1 4  degassed  i n 20 m l a c e t o n e w e r e a d d e d 0.51 g A g P F g d i s s o l v e d  0.21 m l n o r b o r n a d i e n e w e r e a d d e d .  ether.  To a s t i r r e d ,  —D  A g S b F , ( 0 . 2 7 g ) i n THF was a d d e d O  i n 4 m l o f THF; t h e m e t h o d o f 2.6.4.1 was  2  7 5 % . C a l c d f o r RhC, , H S b F , : C , 3 4 . 6 2 ; H,4.36. I D 44 o 0 /  then  Found:  C , 3 4 . 6 6 ; H,4.28. 2.6.5  I r i d i u m S t a r t i n g Complexes: Hydrated I r C l ^  f r o m E n g e l h a r d I n d . [NH ] [IrC£g] 4  Matthey L i m i t e d . octene) ] 2  2.6.6  2  was  2  ( 5 6 % I r ) was  purchased  and I r C J l ^ w e r e s u p p l i e d by J o h n s o n ,  T h e " I n o r g a n i c S y n t h e s e s " p r e p a r a t i o n f o r [IrC£(cyclo-  followed.  Sulfoxides:  1  A p a r t f r o m t h e d r y i n g o f t h e DMSO, n o  o f t h e s u l f o x i d e s was p e r f o r m e d .  purification  S u p p l i e r s were: A l d r i c h f o rt e t r a m e t h y l e n e  -31-  sulfoxlde  (TMSO), E a s t m a n f o r d i p h e n y l s u l f o x i d e ( D P S O ) , a n d K a K L a b s  for n-propyl  (NPSO) a n d m e t h y l  s u p p l i e d b y KaK L a b s Corporation  phenyl  (MPSO) s u l f o x i d e .  (2,5-dithiahexane)  (L-methionine).  S u l f i d e s were  and N u t r i t i o n a l  Biochemicals  (S)-(+)-2-Methylbutyl-(S,R)-methyl  s u l f o x i d e a n d (-)-DIOS w e r e p r e p a r e d  b y R.  McMillan.  (R)-t-Butyl  p - t o l y l s u l f o x i d e , and ( S ) - o - t o l y l - p - t o l y l s u l f o x i d e were d o n a t e d b y B. B o s n i c h 2.6.6.1  a n d H. B o u c h e r  (U. o f T o r o n t o ) .  ( R ) - ( + ) - M e t h y l - p - t o l y l s u l f o x i d e ,18.  p a r a t i o n has been p u b l i s h e d . ^  kindly  The m e t h o d o f p r e -  The s y n t h e t i c r o u t e , w h i c h a l s o  applies to the other s u l f o x i d e s c h i r a l a t s u l f u r ,  i soutlined  i n scheme  (2.1).  18  An e f f e c t i v e method f o r r e m o v i n g t h e y e l l o w i m p u r i t y t h a t t h e c r u d e MPTSO ( 1 0 g ) i s a S o x h l e t  e x t r a c t i o n u s i n g 50 m l o f ACS  hexanes, t h e s o l v e n t used f o r r e c r y s t a l l i z a t i o n impurity  i sleft  contaminates  o f MPTSO.  The y e l l o w  i n t h e t h i m b l e a n d when t h e h e x a n e i s a l l o w e d  to cool,  25° white  crystals  This avoids  o f pure s u l f o x i d e separate;  [a]  D  =148°  (C=l, acetone).  t h e r e p e t i t i v e use o f a c t i v a t e d c h a r c o a l suggested  originally.  -32-  A recent c a n be  report  achieved  shows t h a t h i g h e r by  r e p l a c i n g the Grignard  organocopper l i t h i u m 2.6.6.2  y i e l d s and  cleaner product  mixtures  r e a g e n t i n scheme ( 2 . 1 )  with  reagents.  (R,R)-(l,2)-Bis(p-tolylsulfinyl)  e t h a n e , 14.  The  following 13  p r e p a r a t i o n was  b a s e d on  the  sketchy  T h e y s u c c e e d e d i n c o u p l i n g two s u l f o x i d e s by to y i e l d  methyl s u b s t i t u t e d e n a n t i o m e r i c a l l y pure  the copper promoted o x i d a t i v e c o u p l i n g of the  the o p t i c a l l y  J§f^ 9  pure s u b s t i t u t e d ethane, r e a c t i o n  BAS6>0K STRONG^  C H  3  9  18  Recently  communication of Mislow et a l .  C  H  u  S 2  2^ r — ^ |  C  a-carbanions  (2.2).  "I j  W  I  -  C  H  2  -  (2.2)  67  t h e methane a n a l o g u e has  b e e n made w i t h 1 0 0 %  optical purity 14  by  r e a c t i n g the a-carbanion M e t h o d : The  67_ w i t h t h e m e n t h y l e s t e r ,  strong base, l i t h i u m diethylamide  adding dropwise a standardized o f 1.37  M  i n h e x a n e ) t o 4.8  s o l u t i o n was  transferred  1  cooled  2  d i s s o l v e d by  a d d i n g 10 m l  ml  two  ( R ) - p - t o l y l m e t h y l s u l f o x i d e i n 150  ml  d r y THF  6.8  added p o r t i o n w i s e .  g of anhydrous CuC£  2  by  ml  Ar. the ml  n e c k f l a s k c o n t a i n i n g 6.5  After agitating  (prepared  (34  d r y THF,  s y r i n g e t o a 125  t o a 250  b a s e was  by  t o -78°C u n d e r d r y  u s i n g an a i r t i g h t  equalizing funnel attached  prepared  s o l u t i o n " ' of n - b u t y l l i t h i u m  ml N H E t  A f t e r p r e c i p i t a t e d b a s e was  was  66.  a t -78°C u n d e r A r . the  s o l u t i o n f o r 20  r e f l u x i n g CuC£ .2H 0 w i t h 2  2  g  The minutes,  S0C£ ) 2  F i g u r e 2.4  ( a ) 100 MHz  H nmr  spectrum of ( R , R ) - ( l , 2 ) - b i s ( p - t o l y l e t h a n e , 14.  (b) S i m u l a t e d s p e c t r u m o f m e t h y l e n e  region.  sulfinyl)-  -34-  was  added w i t h t h e r e s u l t i n g s p e c t a c u l a r f o r m a t i o n of a b l u e c o l o u r  ( p r e s u m a b l y C u ( I ) ) and LiC£. a t -78°C, t h e s o l u t i o n was  A f t e r s h a k i n g f o r a n o t h e r 15  warmed t o room t e m p e r a t u r e and  w i t h oxygen  f o r 15 m i n u t e s .  m i x t u r e was  extracted  After hydrolysis  ( 1 x 1 5 0 , 3 x 5 0 m l CHCil^) , a n d t h e c o m b i n e d  e v a p o r a t e d t o a brown o i l .  c o n t a i n i n g 500 m l o f s i l i c a g e l / C H C ^ . w i t h no o p t i c a l a c t i v i t y . and a b r o w n b a n d m i x e d column.  The  T h i s was  B r o w n i m p u r i t y was  0.7  g  °3'  column  3  yielded  the product  also l e f t  on  d e s i r e d f r a c t i o n s were e v a p o r a t e d t o a brown o i l .  s t a l l i z a t i o n from hot t o l u e n e y i e l d e d  C 2  e l u t e d a brown band  3  600 m l o f 5% E t O H i n C H C £  together.  K  added t o a  300 m l C H C £  the  extracts  dried with  2  and  saturated  (450 m l o f 1 0 % t ^ S O ^ ) ,  w e r e w a s h e d w i t h 200 m l d i l u t e NH^OH, 2 x 1 0 0 m l H 0 , filtered,  minutes  (11%) y e l l o w i s h  the  Recry-  crystals  25 [a]  D  =220°.  (0.5g)  R e c r y s t a l l i z a t i o n f r o m CHC£ /heptane y i e l d e d w h i t e  [ a ] J = + 2 7 0 ° ( l i t e r a t u r e : + 2 7 8 ° , C=0.044, C H O H ) . 5  1 3  3  f o r C, ,HL S 0 : o  crystals  3  o  o  0 , 6 2 . 6 0 ; H,5.90.  67.35 ( m , 8 , a r o m a t i c ) ; 2.42 spectrum of the methylene  Anal.  F o u n d : C,62.70; H,5.92. nmr  ( s , 6 , C H ) ; F i g u r e 2.2 3  resonances  Calcd  (CDC£„)  shows a s i m u l a t e d  (an AA'BB' p a t t e r n ) b a s e d on p a r a -  meters  f r o m r e f e r e n c e 17: 6 =2.75, 6 =3.31, J . . ^J.,.,,^3.4, J . =J. ^ , = - 1 2 . 0 , A B AA BB ' AB A B J ^=J ^ =11.2 Hz. Agreement'with the o b s e r v e d spectrum i s good. AtS A Jo 2.6.5.3 ( M e s o ) - l , 2 - b i s ( m e t h y l s u l f i n y l ) e t h a n e o r 2 , 5 - d i t h i a h e x a n e - 2 , 5 -  d i o x i d e , 68.  MSE:  I n v i e w o f t h e s m a l l y i e l d o f P T S E , 1A_, f r o m t h e p r e v i o u s  p r e p a r a t i o n , i t was  d e s i r a b l e t o u s e a m o r e r e a d i l y o b t a i n a b l e compound f o r  exploratory experiments.  MSE,  J58, c a n be s y n t h e s i z e d i n a p u r e  chiral  18 form  b u t t h e p r o c e d u r e i s l a b o r i o u s and  chiral  i s o m e r o f MSE  was  chosen.  the y i e l d v e r y low.  Thus a  non-  -35-  The  original preparation,  w i t h H^O^, y i e l d s a m i x t u r e The  i n v o l v i n g t h e o x i d a t i o n o f 2,5  of sulfides,  higher  melting  diastereomer  19  20 2 1 ' ' • A cleaner  j-|22  .,  dl  19  This  , 18  u n t x l more r e c e n t  by  preparation  (75% y i e l d ) i s t h e a c i d c a t a l y z e d  e x c h a n g e f r o m DMSO t o t h e s u l f i d e .  be  s u l f o n e s , and s u l f o x i d e s .  meso a n d d l f o r m s o f t h e d i s u l f o x i d e c a n b e s e p a r a t e d  fractional recrystallizations.  work  dithiahexane 19 20 '  repeated of the oxygen  i s o m e r was t h o u g h t t o b e  • . , , and a c r y s t a l  21  , .  structure  showed i t t o  meso. Method: A m i x t u r e  and  o f 10.4 g o f 2 , 5 - d i t h i a h e x a n e ,  0.18 g o f 12 M HC£ was  Erlenmeyer f l a s k . with  stirred  a n d h e a t e d a t 100° o v e r n i g h t  A f t e r c o o l i n g , t h e p r e c i p i t a t e was f i l t e r e d ,  3 m l benzene, and r e c r y s t a l l i z e d  Anal.  Calcd  for  C  H 4  S 1  0  0 2  2  163-164°C. nmr (CDC£ ) . 2.6.6.4  20 m l o f DMSO,  :  C  three  i n an washed  t i m e s f r o m EtOH. Y i e l d ,  9 g.  > 1 - 1 3 ; H,6.53. F o u n d : C . 3 1 . 0 1 ; H,6.70. m.p. 3  52.63  ( S , 6 , C H ) ; 3.10 ( m , 4 , C H ) ; 3  (S)-Methionine-(S)-sulfoxide,  oxidation of methionine to 1 6  2  16:  ( f i g u r e 1.3),  s e e f i g u r e 2.5.  A simple s t e r e o s p e c i f i c  by u s i n g  chloroauric acid 23  (HtAuCJt.^]) a s t h e s t o i c h i o m e t r i c o x i d a n t The  has r e c e n t l y been communicated.  a s y m m e t r i c i n d u c t i o n may a r i s e f r o m a p r e f e r r e d c h e l a t e d  configuration  of t h e s u l f i d e on t h e g o l d . Four attempts a t reproducing by N u t r i t i o n a l B i o c h e m i c a l s Co. (approximately resulted gold  t h e i r procedure using methionine  supplied  o r E a s t m a n K o d a k L t d . a n d HlAuCic-^] .xH^O  3 1 % A u ) s u p p l i e d b y A l p h a C h e m i c a l s o r B.D.H. C h e m i c a l Co.  i n p r o d u c t s c o n t a i n i n g l a r g e amounts o f c o n t a m i n a n t s o f c o l l o i d a l  or gold  salts  t h a t were n o t r e a d i l y removed i n p u r i f i c a t i o n  M e t h o d : A s t o i c h i o m e t r i c amount o f ( S ) - m e t h i o n i n e o f H^O was a d d e d t o a s t i r r e d  s o l u t i o n o f HfAuCJt-^] (0.8  (0.33  attempts.  g ) i n 20 m l  g ) i n 20 m l o f t ^ O .  jl  (methylsulfInyl)ethane.  -37-  Th e o r a n g e s o l u t i o n went t u r b i d , and t h e n f a d e d d e p o s i t i o n o f some g o l d , a l t h o u g h should  stay c l e a r f o r hours.  i t was r e p o r t e d  that the s o l u t i o n  23  A f t e r 30 m i n u t e s o f s t i r r i n g , by  to yellow with the  attempts to p r e c i p i t a t e the  a d j u s t i n g t h e pH t o 4 ( a q u e o u s KOH  product  o r NH^OH) a n d a d d i n g a c e t o n e a n d  23 ethanol  , resulted i n the p r e c i p i t a t i o n of c o l l o i d a l  i n o r g a n i c compound, a n d t h e p r o d u c t , still  present  after  through c e l i t e , Yellow  s o l i d mixture  g o l d compounds  However p u r p l e  Purple  contaminants were  was r e d i s s o l v e d i n H^O,  c a n be e x t r a c t e d f r o m t h e o r i g i n a l  by r e p e t i t i v e t r e a t m e n t s  w i t h ether  gold p r e c i p i t a t e s .  yellow  t o 4.  f o r 16 h o u r s m o s t o f t h e  The s o l u t i o n was t h e n b r o u g h t t o pH 4 ( a q u e o u s  t h r o u g h c e l i t e a n d t h e n a d d e d t o 100 m l o f  (V/V=l).  filtered  (8x20 m l ) .  c o n t a m i n a n t s r e a p p e a r when t h e pH i s a d j u s t e d  the yellow r e a c t i o n s o l u t i o n i s l e f t  filtered  purple  and r e p r e c i p i t a t e d .  reaction mixture  If  this  16.  gold, a  The p r o d u c t ,  KOH),  acetone-ethanol  a white  p o w d e r was c o l l e c t e d b y f i l t r a t i o n , 25 w a s h e d w i t h a c e t o n e a n d d r i e d i n v a c u o : [ c ] ^ =+60° (C=0.8, I N HC&; 23 l i t e r a t u r e g i v e s +132°).  R e p r e c i p i t a t i o n from  d i d not a l t e r  25 [ a ] ^ =+60°.  (Due t o t h e h i g h s u r f a c e  tension of these  solutionsa i r  b u b b l e s had t o be removed f r o m t h e p o l a r i m e t e r m i c r o c e l l w i t h a The nmr  i n D^O  i s c o n s i s t e n t w i t h t h e s t r u c t u r e o f JL6.  62.71  syringe)  (s,3,CH ); 3  3.03 ( m , 2 , S - C H ) ; 2.30 (m,2,C-CH -C); 3.81 ( t , l , N - C H ) . A n a l . C a l c d f o r 5 11°3 ' - ; » - ; N,8.47. F o u n d : C.19.03; H,3.46; N,4.37. T h i s i m p u r e compound was n o t s t u d i e d f u r t h e r . 2  C  H  S N :  c  3 6  2  3 4  H  6  7 1  -38-  3.  Mixed  3.1  S u l f o x l d e - T r i p h e n y l p h o s p h i n e C a t i o n i c Complexes of Rhodium(I)  S y n t h e s i s and  3.1.1.  Spectroscopic Properties.  Introduction  C a t a l y s t s d e r i v e d from the complexes cyclooctadiene  (COD), n o r b o r n a d i e n e  [RhCdiene)]^]A, _5_3,- (diene=l,5-  (NBD); L= n e u t r a l d o n o r l i g a n d ;  a n i o n ) a r e known t o b e u s e f u l f o r t h e h y d r o g e n a t i o n o f a v a r i e t y unsaturated organic s u b s t r a t e s . reactions  The  1  s e l e c t i v i t y and  (e.g., hydrogenation vs. isomerization) e a r  t h e n a t u r e o f L, t y p i c a l l y a t e r t i a r y p h o s p h i n e that c a t a l y t i c  of  e f f i c i e n c y of  l i k e l y dependent  o r a r s i n e , and  typically prepared  suggest •  1  C o m p l e x e s s u c h as J53 a r e  b y t h e a d d i t i o n o f e x c e s s L t o [RhC£(diene)]^, a  procedure  n o t a p p l i c a b l e t o t h e s y n t h e s i s o f 6 9 ; b u t we h a v e f o u n d 1 2 t h e l a t t e r a r e e a s i l y o b t a i n e d f r o m [ R h ( d i e n e ) L ( a c e t o n e ) ] A , 70. t h i s chapter the u t i l i t y  be d e s c r i b e d .  An a p p r e c i a t i o n 12  t h e e l e c t r o n i c and  and  that  o f 70_ a s a s y n t h e t i c p r e c u r s o r f o r  [Rh(diene)(PPh^)(sulfoxide)]A species w i l l  of  on  2  p r e c u r s o r s , [ R h ( d i e n e ) L L ] A , 69_.  In  such  s e l e c t i v i t y m i g h t be f u r t h e r c o n t r o l l e d by u s i n g m i x e d 1  ligand  A=  s t e r i c requirements  of the  the p r o p e r t i e s of s u l f o x i d e d e r i v a t i v e s  +  [Rh(diene)L L ]  ( e . g . , 0-vs  cation  S-bonding) i s  e s s e n t i a l f o r a n e v a l u a t i o n o f s u c h compounds a s p o t e n t i a l  catalysts.  D u r i n g t h e c o u r s e o f t h i s work, C r a b t r e e r e p o r t e d t h e use o f [Rh(COD)+ 3 ( P P h g ) ( p y ) ] , _71> f o r t h e h y d r o g e n a t i o n o f 1 - a l k y n e s t o 1 - a l k e n e s , and + 4 5 the use of [ I r ( C O D ) ( p h o s p h i n e ) ( p y ) ] f o r the r e d u c t i o n of o l e f i n s . ' 3.1.2.  Experimental  Synthetic procedures an a r g o n a t m o s p h e r e .  and  s o l u t i o n measurements were conducted  V i b r a t i o n a l d a t a a r e r e p o r t e d i n cm  1  .  The  under phenyl  -39-  r e s o n a n c e s o f t h e P P h ^ c o m p l e x e s come a t 67-8 i n t h e nmr b u t t h e d a t a for  this  region yield  little  i n f o r m a t i o n and a r e n o t t a b u l a t e d .  P r e p a r a t i o n o f t h e Complexes 3.1.2.1. a CH C£ 2  2  [Rh(diene)(PPhJ(acetone)]A; 3  s o l u t i o n (15 m l ) o f P P h  diene=COD,NBD;A=PF , S b F , : To b  ( 0 . 4 0 9 g , 1.56 mmol) a n d [ R h C £ ( C 0 D ) ]  3  (0.384 g , 0.774 mmol) was a d d e d d r o p w i s e , w i t h  AgC£  A f t e r 10 m i n t h e b r i g h t o r a n g e s o l u t i o n was f i l t e r e d  and c o n c e n t r a t e d  to 5 ml.  Gradual a d d i t i o n of ether  w h i c h were c o l l e c t e d , washed w i t h e t h e r , and d r i e d . was o b t a i n e d  f r a c t i o n s were combined, d i s s o l v e d i n an equivolume  Solvent  precipit-  under argon  gave orange Additional  and c r y s t a l l i z e d  of c r y s t a l l i z a t i o n  was r e m o v e d b y p r o l o n g e d  2  evacuation. similarly.  3.1.2.2..[Rh(COD)(PPh )(DMS0)]PF,: J  b  0  [Rh(COD)(PPh )(acetone)]PF (3 m l ) a n d s t i r r e d  &  DMSO ( 2 1 u £ , 0.29 mmol) a n d  ( 0 . 2 0 g, 0.29 mmol) w e r e d i s s o l v e d i n C H C £  f o r 15 m i n .  w h i c h were r e c r y s t a l l i z e d  (yield=80%).  u s u a l l y found i n samples so o b t a i n e d ,  2  The NBD compound was p r e p a r e d  3  The  acetone/dichloro-  by t h e a d d i t i o n o f e t h e r  (CH C£ ),  crystals product  upon f u r t h e r c o n c e n t r a t i o n , and a d d i t i o n o f e t h e r .  methane m i x t u r e ,  2  A d d i t i o n of ether  gave y e l l o w  from dichloromethane/ether,  o f t h e s u l f o x i d e complexes  washed w i t h  from t h e a p p r o p r i a t e Tables  3.2-3.4 l i s t  ( t a b l e 3.1) w e r e s i m i l a r l y  acetone precursor. t h e i r a n d nmr d a t a  Y i e l d s were t y p i c a l l y f o r these  compounds.  2  crystals ether,  and d r i e d i n v a c u o f o r s e v e r a l h o u r s . All  2  s t i r r i n g , A g P F ^ (0.395 g,  .1.56 mmol) d i s s o l v e d i n a c e t o n e ( 1 0 m l ) ; f l o c c u l e n t w h i t e ated.  b  prepared 80-90%.  T a b l e 3.1  A n a l y t i c a l data f o r the rhodium(I)  complexes  Analysis  %C  %H  Decomposition point(°C)  Found  Calculated  [Rh(COD)(PPh.)(acetone)]PF. j 6 [Rh(NBD)(PPh )(acetone)]PF, 3 0  148-150  51.53  51.49  4.89  4.92  145-150  50.71  50.93  4.41  4.43  [Rh(NBD)(PPh )(acetone)]SbF  145-148  44.84  44.77  3.97  3.89  179-180  48.67  48.28  4.80  4.77  [Rh(NBD)(PPh.)(DMSO)]SbF,  139-140  42.02  42.04  3.70  3.79  [Rh(COD)(PPh )(TMSO)]PF, J 6  173-175  49.46  49.87  4.66  4.88  [Rh(COD)(PPh )(NPSO)]PF*  119-121  48.43  48.37  5.22  5.26  [Rh(COD)(PPh )(MBMSO)]PFg  57-59  50.75  51.07  5.50 •  5.50  [ R h ( C O D ) ( P P h . ) ( M P S O ) ] P F J°  96-98  50.58  50.62  4.68  4.50  137-139  52.56  52.85  5.00  4.83  140-143  54.75  54.55  5.20  5.30  Complex  Found  Calculated  c  0  3  [Rh(COD)(PPh )(DMSO)]PF, 0  J  0  J  0  Q  0  J  0  3  J  0  [Rh(COD)(PPh )(MPTSO)]PF 3 6 0  r  [Rh(COD)(PPh )(TBPTSO)]PF, Q  ->  D  6  a  The c a l c u l a t e d a n a l y s i s i n c l u d e s  0.7 C H C 1 ; nmr shows a p p r o x . 0.6  CH C1  b  The c a l c u l a t e d a n a l y s i s i n c l u d e s  0.4 C H C 1 ; nmr shows a p p r o x . 0.5  CH C1  c  Uncorrected, i n a i r .  2  2  2  2  2  2  -41-  T a b l e 3.2  Infrared data  (cm  ) f o r[Rh(diene)(PPh )L]PF  v(CO) o r v(SO) - ' -  L  acetone acetone  complexes-  P (CH ) -'r  3  Av(SO) -  1658 s , b r (NBD)  1663 s , b r  DMSO  958 s , b r ( 9 4 7 s , b r )  DMSO (NBD)  922 s , b r ( 9 4 5 s , b r )  TMSO  935 s , b r ( 9 3 8 s , b r )  84  TBPTSO  947 s , b r ( 9 4 0 s )  97  NPSO  942 s , b r ( 9 4 7 s , b r )  70  L  v ( 9 0 0 - 1 0 0 0 cm  bands)  992s 983s  (983s) (985s)  108 110  Av -  MBMSO  937m, 9 6 7 s  (965s,br)  65  MPSO  958s,  942s  (959s, 945sh)  9 1 , 105  MPTSO  957s,  939s  (959s, 943sh)  8 8 , 104  a.  D i e n e = COD, u n l e s s i n d i c a t e d o t h e r w i s e .  b_  N u j o l m u l l s ; values i n parentheses f o r C E ^ B ^ solutions.  c_  s = s t r o n g , b r = b r o a d , m = medium, s h = s h o u l d e r  cl  Defined as [v(S0) f o r f r e e l i g a n d - v(S0) coordinated l i g a n d ]  e^  Defined as v(S0) f o r f r e e l i g a n d - v i n s o l u t i o n .  i n CH^Br  -42-  T a b l e 3.3  1  H nmr d a t a ^ 3  1  f o r [Rh(COD)(PPh,)L]PF, c o m p l e x e s a t J  35°C.  0  5 diene(oleflnlc) L  6 .coordinated L  «P  \  acetone  5.20  3.AO  2.05(s , C H - )  DMSO  5.15  3.15  2.20(s,S-CH )  NPSO  5.13  3.17  2.50(m,S-CH ),1.58(tq,-CH -),  ( d )  3  3  2  2  0.90(t,CH -). 3  MPSO  5.18  3.18  2.38(s,S-CH )  MPTSO  5.17  3.17  2.38 (s , S-CH ) , 2.38 (s , p - C l ^ - )  TBPTSO  5.18  3.15  0.98(s,S-C(CH ) ),2.37(s,p-CH -)  MBMSO  5.15  3.17  2.22(s,s-CH  3  3  3  )^  3  e )  3  ,  1.2(m,methine),  0.80(m,CH CH +C-CH ). 3  2  3  (a)  Measured i n pptn (downfield p o s i t i v e ) from TMS i n CDCH^i phenyl resonances o m i t t e d ; s = s i n g l e t , m=multiplet, t = t r i p l e t , t q = t r i p l e t o f q u a r t e t s .  (b)  TMSO complex  (c)  Appear as broad s i n g l e t s ; Hp and H = o l e f i n i c p r o t o n s t r a n s t o PPhj and L r e s p e c t i v e l y ; methylene resonances appear as m u l t i p l e t s a t 61.8-2.5.  (d)  T h i s i s t h e p o s i t i o n o f f r e e acetone.  (e)  S-CH, resonance obscured.  insufficiently  soluble. L  T a b l e 3.4  1  H nmr d a t a ^  f o r [Rh(NBD) (PPh„)L]PF Complexes O D 6 diene(olefinic)  Solvent CDC£  T°C  L  K  35  acetone  (CD ) CO  35  acetone  (CD ) CO  -60  acetone  3  3  2  3  2  CDCJ> CDC£  3  3  CD C£ 2  2  35  DMSO  -30  DMSO  -50  AsPh  h. l\ \ \  (3.3)  (b)  6 diene (CH )  6L  2  4.4  4.4  4.4  3.7?  4.2-3.8  1.4  2.3 ? 2  4.5  4.5  4.5  4.5  4.0  1.43  2.05  5.4  3.2  4.6  4.1  3.9  1.34  2.10  3.9  3.9  4.4  4.1?  3.9  1.35  2.45  0.06 >  5.3  3.2  4.5  4.3  4.0  1.4  2.55  0.2< >  4.2  4.7  4.4  4.5  4.0  1.45  7.4-7.0  o.i  (  d  )  (d  d  3  6 diene (methine)  (  )  I 00  I  (a)  Measured  (b)  T h i s g i v e s a complex, There  i n ppm d o w n f i e l d f r o m TMS; p h e n y l r e s o n a n c e s o m i t t e d . c o n c e n t r a t i o n dependent  i s a l s o an u n i d e n t i f i e d  spectrum.  These a r e n o t f i r m  species with 6(olefinic)=6.2-5.9,  (c)  S i g n a l may b e d u e t o [ R h ( N B D ) ( a c e t o n e ) ] .  (d)  E r r o r i n K d e t e r m i n a t i o n e s t i m a t e d t o b e ±40%.  +  2  assignments,  6(methine)=3.15.  -44-  3.1.2.3.  [Rh(COD)(DMSO-d ) ]SbF : 6  2  To a s u s p e n s i o n o f [RhC£ (COD) ]  6  2  ( 0 . 2 4 g , 0.47 mmol) i n 15 m l o f a c e t o n e was a d d e d w i t h s t i r r i n g ( 0 . 3 4 g , 0.97 mmol) d i s s o l v e d was  filtered  i n5 ml of acetone.  from the y e l l o w s o l u t i o n under Ar.  After  After  AgSbF^  5 m i n t h e AgC£  the a d d i t i o n of  DMSO-d, ( 0 . 1 8 m l , 2.4 m m o l ) , t h e s o l u t i o n was c o n c e n t r a t e d  t o 2 ml.  Ether  O  (10 m l ) was g r a d u a l l y a d d e d u n t i l o f 20 u £  DMSO-d^ a t t h i s p o i n t  Y i e l d was 5 0 % . A n a l . Found: p  Calcd  induced slow formation of y e l l o w  for RhSbFgS^C^D^H^:  C, 2 3 . 4 3 ; H, 4 . 1 2 . i r ,  C, 2 3 . 4 3 ; H+D, 4 . 4 2 .  63.93 ( m , 4 ,-C=C-H); 2.40(m,4,CH )  r  d i e n e peaks as above; c f .  3  3  f i g u r e 3.01;  resulted  instead  The c o r r e c t s t o i c h i o m e t r y o f  of crystal precipitation.  DMSO  The u s e o f impure AgSbF^  i n decomposition of t h er e a c t i o n s o l u t i o n  possibly containing  473s,  62. 75 ( s , 6 ,DMS0) ;  r e a c t a n t s used f o r t h i s p r e p a r a t i o n i s e s s e n t i a l s i n c e excess caused o i l  1020s;  1.65  v(S0) 950s; v(Rh-0)  4 6 5 s ; 6 ( C H ) 1 3 2 7 s , 1 3 2 0 s ; P ( C H ) 9 8 5 s , 9 7 0 s . nmr(CDCJ!, ) 3  crystals.  3  P r o p e r t i e s o f t h e DMSO a d d u c t : i r ,  2  addition  v(S0) 950s; v(Rh-0) 443s, 435s; 6(CD )  (CD„) 8 3 2 s , 7 6 7 s . n m r ( C D C O  (m,4,CH ).  t h e s o l u t i o n was a l m o s t t u r b i d ;  t o a green  Rh(II) formed by an o x i d a t i o n r e a c t i o n .  solution, No p r o d u c t  c o u l d b e i s o l a t e d when THF was u s e d a s t h e s o l v e n t , p r e s u m a b l y b e c a u s e the l a t t e r  i s a s t r o n g e r 0-donor  3.1.2.4. added  than acetone.  [Rh(NBD) ( P P h ) ( p y ) ] S b F : P y r i d i n e 3  6  (12  0.15 mmol) was  t o [ R h ( N B D ) ( P P h ) ( a c e t o n e ) ] S b F ^ ( 0 . 0 9 6 g , 0.13 mmol) i n 1 m l C H C £ 3  2  Addition of ether t o t h i s very a i r - s e n s i t i v e crystals. Found: a t 1603  Anal. Calcd  for RhSbPNF C  C, 4 6 . 8 2 ; H, 3.80; m.  6  3 0  N, 1.54. i r ,  H  2 g  solution yields yellow  : C, 4 6 . 6 6 ; H, 3.65;  characteristic  micro-  N, 1 . 8 1 .  pyridine  2 >  vibration  -45-  3.1.2.5.  [ R h ( d i e n e ) ( P P h ) ( A s P h ) ] P F ; d i e n e = C O D , NBD: 3  3  6  [ R h ( C O D ) ( P P h ) a c e t o n e ] P F g ( 3 3 mg, 0.05 mmol) a n d A s P h ( 1 5 mg, 3  mmol) w e r e m i x e d i n 0.5 m l o f C D C £ of  t h e CDC£  3  f o r a n nmr s a m p l e .  s o l v a t e d e p o s i t e d a f t e r one day ( 7 0 % ) .  3  0.05  3  RhP„F,AsC.,H,„.CDC£„: z o 44 4 z -j  Orange  Anal.  C, 5 1 . 7 2 ; H, 4.05; C£, 1 0 . 1 8 .  crystals  Calcd f o r  F o u n d : C,  51.80;  H, 3 . 9 1 ; C£, 1 0 . 4 9 . i r , c h a r a c t e r i s t i c b a n d s o f A s P h : 3 3 0 s , 3 2 5 s a n d 3  315s;  bands o f P P h : 1103s, 1098s, 527s, 511s. nmr(CDC£ ) 3  64.87(m,1.7,  3  C=C-H); 4.30(m,1.6,C=C-H); 4.68(m,0.3,C=C-H), 4.53(m,0.3,C=C-H); 2.67-1.95 (m,8,CH ).  An i d e n t i c a l  2  s p e c t r u m was o b t a i n e d i n C C I ^ ^ C O a t -50°C  (figure  3.02). The NBD a n a l o g u e p r e c i p i t a t e s nmr i n C D C £ 2  f r o m CDC&  b u t c a n be o b s e r v e d by  3  n m r ( C D C £ , 3 5 ° C ) . 64.53(m,4,C=C-H); 4 . 0 3 ( m , 2 , m e t h i n e ) ;  2  2  2  I . 5 6 ( m , 2 , C H ) . nmr (CD CJ> ,-50°C) , 64. 71 (m, 1. 5, C=C-H) ; 4.22(m,1.5,C=C-H) ; 2  2  2  4.50(m,0.5,C=C-H); 4.36(m,0.5,C=C-H); 3 . 9 8 ( m , 2 e t h i n e ) ; 1 . 4 2 ( m , 2 , C H ) . > m  2  See f i g u r e 3.03. 3.1.2.6.  [ R h ( d i e n e ) ( P P h ) (CO) J P F , ; d i e n e = C 0 D , NBD: j z o  The c o m p l e x e s  0  p r e c i p i t a t e d when e t h e r was a d d e d t o C O - s a t u r a t e d C H C £ 2  acetone cations.  Anal.  C a l c d f o r t h e COD d e r i v a t i v e :  solutions  2  of the  C, 5 0 . 1 8 ; H, 4 . 2 1 .  F o u n d : C, 5 0 . 2 5 ; H, 4.40. i r ( N u j o l ) , v ( C 0 ) 2 0 2 9 ; i r ( C H C £ ) , v ( C 0 ) 2 0 5 0 , 3  1 9 8 3 . nmr  ( C D C £ , 35°C), 3  5.56(m,4,C=C-H);  3.0-2.2(m,8,CH  ).  See f i g u r e  3.04. A n a l . C a l c d f o r t h e NBD d e r i v a t i v e :  C, 4 9 . 2 6 ; H, 3.52.  F o u n d : C,  49.36;  H, 3.75. i r ( N u j o l ) , . v ( C 0 ) 2 0 8 0 s b . i r ( C H C £ ) , v ( C 0 ) 2 0 8 0 s , 2 0 4 5 s . nmr 3  35°C, u n d e r A r o r CO)  3  64.23(m,4,C=C-H); 3 . 7 6 ( m , 2 , m e t h i n e ) ; 1 . 4 2 ( m , 2 , C H ) . 2  n m r ( C D C £ , -30°C, u n d e r CO) 4.07(m,4,C=C-H), 3 . 7 4 ( m , 2 , m e t h i n e ) , 3  ( m , 2 , C H ) , s e e f i g u r e 3.05. n m r ( C D C £ 2  (CDC£ ,  3  , -20°C, u n d e r A r )  4.50(m,0.3,C=C-H), 4.36(m,0.3,C=C-H), 4.08(m,3,C=C-H);  1.40  65.7(m,0.3,C=C-H),  3.74(m,2,methine);  F i g u r e 3.01.  60 MHz  H nmr s p e c t r u m o f [Rh(COD)(DMSO) ] S b F  i n CDC£  (a)!  oI (b)  I ppm F i g u r e 3.05.  100 MHz H nmr s p e c t r u m o f [ R h ( N B D ) ( P P h ) ( a c e t o n e ) ] P F u n d e r CO i n CDC«, a t a ) -30°C, ( b ) 35°C. 1  3  7  5 Figure 3.06.  ppm  3  100 MHz "4 nmr spectrum of [Rh(COD)(PPh.)(acetone)]PF +DI0S i n CDC£ at 35°C. Impurity at 6375, 1.2 i s ether.  1  F i g u r e 3.07.  60 MHz H nmr s p e c t r u m o f [ R h ( N B D ) ( P P h . ) ( a c e t o n e ) ] P F +DI0S a t 35°C i n CDCJ> .  5 F i g u r e 3.08.  ppm  100 MHz -""H nmr s p e c t r u m i n C D C £ a t -50°C. 3  3 o f [Rh(NBD) ( P P h . ) ( a c e t o n e ) ] P F , + D I 0 S  -54-  1.42(m,2,CH2).  A g a s u p t a k e i n DMA,  a CO/Rh s t o i c h i o m e t r y o f 3.1.2.7.  using  t h e ampoule  3  diene=COD,NBD: A t t e m p t s a t  6  complexes f a i l e d .  In situ  Rh a c e t o n e c a t i o n g a v e t h e f o l l o w i n g s p e c t r a . nmr(CDC£ ),DIOS: 6 4 . 1 9 - 3 . 9 5 ( m , 2 , m e t h i n e ) ; 3  (s,1.9,CH -S), 2.41(s,3.2,CH -S), 3  CH -C).  3  n m r ( C D C £ ) ,, COD:  3  3  2.45  2.39(s,0.9,CH -S); 3  1.42-1.39(m,6,  3.06.  d e r i v a t i v e : nmr(CDCJ> , 35°),DIOS: 64.4-3.9 (m, 2 , m e t h i n e ) ; 3  2.95(m,broad,4,S-CH );  2 . 5 5 ( s , b r o a d , 6 , S - C H ) ; 1.30(s,6,C-CH ).NBD:  2  3  (m,4,C=C-H); 3 . 8 2 ( m , 2 , m e t h i n e ) ; 4.4-3.9(m,2,methine); 3  F o r t h e COD d e r i v a t i v e : 2  2  ( m , 6 , C H - C ) . NBD:  one DIOS p e r  65. 39 (m, 2 ,C=C-H),3. 23 (m, 2, C=C-H) ; 2.58-2.30  2  t h e NBD  systems u s i n g  3.1-2.8(m,4,CH "S);  (m,4,CH ), 2.2-1.8(m,4,CH ), r e f e r t o f i g u r e For  yielded  1.9.  [Rh(diene)(PPh )(DIOS)]PF ;  i s o l a t i o n of these  technique,  4.13  3  1 . 3 0 ( m , 2 , C H ) . nmr(CDC& ,-50°C)>DI0S: 2  3  3.1-2.8l(m,4,CH^-S);2.54(s,broad,CH^-S);  1.36  5.22(m,2,C=C-H), 3.29(m,2,C=C-H); 4.34(m,0.5, [ R h N B D ( P P h ) ] ) ; +  3  3 . 9 9 ( m , 2 , m e t h i n e ) , 1.24(m,2,CH ) . F i g u r e 3.07  and f i g u r e 3.08  show nmr  spectra  a t 35° a n d - 5 0 ° , r e s p e c t i v e l y . 3.1.3.  R e s u l t s and  Infrared data anions SbF^  Discussion f o r a l l o f t h e c o m p l e x e s r e p o r t e d h e r e show t h a t t h e  are uncoordinated,  s i n c e o n l y t h e c h a r a c t e r i s t i c bands o f PF^  a r e o b s e r v e d a t 8 4 0 v s , 5 6 0 s , a n d 6 5 8 v s , 290s cm 3.1.3.1.  Acetone  and  respectively.^'''  Complexes  8—12 F a c i l e cleavage  of the c h l o r i d e bridge  L e w i s base L \ can g i v e a monomeric excess reactant s o l v e n t may  ( e s p e c i a l l y where L  d i s p l a c e the l a b i l e  o f [RhCJt ( d i e n e ) J  2  by a  d e r i v a t i v e [RhC£(diene)L ] , _7_2, b u t 1  1 =  phosphine or arsine) i n a polar  c h l o r i d e forming  [Rh(diene)L ^]^. 1  1 3  '  1 4  2  -55-  The  r e m o v a l of c h l o r i d e as a s i l v e r  c o o r d i n a t i o n of acetone, r e a c t i o n s 3.1  and  salt  a w e a k and  f r o m 7_2 f a c i l i t a t e s  the  easily displaced ligand "'; 1  3.2.  [RhC£(diene)]  2  + 2L  -> 2 [ R h C J l ( d i e n e ) L , ]  1  (3.1)  1  72. [•RhCjKdienejL ]  + AgA  1  ^  (3.2)  CH C£ /acetone 2  2  [Rh(diene)L (acetone)]A 1  + AgC£  70  A l t h o u g hu a v a r i•e t y o f* li -i g a n Jd s s u c hT, a s a m i• n e s 10,11 , a r s i n e s 12 , p h o s p h m e s 8,9 , g halides our  , e t c . , h a v e b e e n u s e d t o e f f e c t r e a c t i o n 3.1,  initial  we  have c o n f i n e d  i n v e s t i g a t i o n to triphenylphosphine d e r i v a t i v e s .  a s y n t h e t i c a d v a n t a g e , as c r y s t a l l i n e  Table  3.1  gives m i c r o a n a l y t i c a l data.  of other r e a c t i v e acetone complexes i s r e a d i l y Solid 3.2),  one  The  1  o f t h e f r e e l i g a n d a t 1710  i n CH C£ . 2  present evidence  2  Furthermore,  i n t h e "'"H nmr  cm  2  synthesis  the replacement  The  (table  1  extreme  of t h i s band  by  f i g u r e 3 . 0 9 ) , and  is  t h e r e i s no  In c o n t r a s t , w i t h the c a t i o n i c  complexes  , M=Rh, I r , t h e c o o r d i n a t e d a c e t o n e s i n g l e t  to diamagnetic  lability  during the r e c o r d i n g of s o l u t i o n i r  s p e c t r a ( t a b l e 3.3,  [M(C0)(acetone)(PPh^) ]  in situ  o n l y a s i n g l e t a t 62.05 f o r f r e e l i g a n d  of coordinated acetone.  a t 6 1 . 6 - 1 . 8 , due  1  derived sulfoxide  a t V L 6 6 0 cm  c o n s i s t e n t w i t h a c o o r d i n a t e d acetone moiety. "' i s d e m o n s t r a t e d by  70,  accomplished.  s t a t e i r m e a s u r e m e n t s on _70 show v ( C 0 )  of the acetone l i g a n d  provides  samples of the acetone c a t i o n ,  a r e e a s i l y o b t a i n e d when L ^ P P h ^ , a s a r e t h e s u b s e q u e n t l y complexes.  This  s h i e l d i n g by  the c i s phosphines  appears  (references  F i g u r e 3.09.  60 MHz a t 35°C.  H nmr s p e c t r u m o f [ R h ( C O D ) ( P P h ) ( a c e t o n e ) ] P F 3  &  i n CDC£  -57-  13,  15,  and  see  b e l o w ) , and  f r e e acetone i s detected  only a f t e r several  hours. The  d i s s o c i a t i o n of acetone suggests the  three-coordinate  species.  t o be  solvated  CHC^  t° P t ( I I ) h a s  18 systems.  Although such species  four-coordinate  square planar  been demonstrated  for three-coordinate  formation  intermediates  17  of  formally  are u s u a l l y  considered  ( t h e weak b i n d i n g  ) , e v i d e n c e has g  been  of  presented  i n r e a c t i o n s of d , organometal  19 '  U n s y m m e t r i c a l T-  and  Y-  shaped  c o n f i g u r a t i o n s were  19 favoured  and  account f o r the  the  former, or s o l v a t e d  inequivalence  system.  Two  solution  ( t a b l e 3.3,  f o r t h e NBD 3.4,  o f t h e COD  f i g u r e 3.09).  analogue but  complex,  a t -50°C t h e below).  two The  the 20  [RhXPPh^)^]ClO^  are  sets are  by  observed  i n CDCJt.^  f r o z e n out  i s o l a t i o n of  present  s i g n a l i s observed  p r o b a b i l i t y of a  (see  table  3-coordinate  the T-shaped  s i t e with a phenyl carbon,  c r y s t a l structure a n a l y s i s , could  s o c i a t i o n o f a c e t o n e f r o m _70_.  could  3-  , c h a r a c t e r i z e d a f t e r our work  c o m p l e t e d ; i n t e r a c t i o n o f t h e v a c a n t Rh observed i n the  3.4  species,  protons i n the  A single olefinic  i s f u r t h e r s u b s t a n t i a t e d by  coordinate  olefinic  s e t s o f r e s o n a n c e s a t <55.2 and  f i g u r e s 3 . 1 0 - 3 . 1 2 , and  species  four-coordinate  a l s o e x p l a i n the  However a t t e m p t s t o i s o l a t e s u c h a  was as dis-  species  r e p r e c i p i t a t i o n o f 7_0_ i n C ^ C J t ^ adding ether f a i l e d , since r e a c t i o n 1 2 3.3 i s f a v o u r e d , L = P P h L = a c e t o n e , and t h e l e a s t s o l u b l e c o m p l e x , 2[Rh(diene)L L ] ^ ' ^ [RMdiene)! ] " + [Rh(diene)L ] (3.3) o n  3 >  1  2  [Rh(diene) ( P P h ^ ^ l P F ^  +  3  13  3  , crystallizes  1  4  i n s t e a d of the p o s s i b l e  2  +  three-  -61-  c o o r d i n a t e one.  Hence samples  presence of excess When p u r e  o f 70_ m u s t be r e c r y s t a l l i z e d  i n the  acetone.  [Rh(COD) ( P P h _ ) ( a c e t o n e ) ]PF,. i s d i s s o l v e d J  0  3  a s m a l l amount o f d i s p r o p o r t i o n a t i o n by o l e f i n r e s o n a n c e s  i n CDC£ ,  O  (K^ <0.01) o c c u r s and i s s i g n a l l e d 3  of v e r y low i n t e n s i t y of the bisphosphine c a t i o n  • 13 (at  64.6)  and b i s a c e t o n e c a t i o n  ( a t 64.0) i n t h e nmr, f i g u r e  e q u i l i b r i u m 3.3 m u s t be s l o w o n t h e nmr t i m e s c a l e b e c a u s e of  t h e COD  inequivalent olefinic  resonances  3.09;  broadening  i s n o t o b s e r v e d a t 35°C.  E q u i l i b r i u m 3.3 i s a l s o s l o w a n d l i e s  very f a r to the l e f t  [Rh(COD)(PPh^)(sulfoxide)]  s y n t h e s i z e d , as w e l l as f o r a l l  the  mixed  and  [Rh(COD)(amine) ]  complexes  +  f o r a l l the  ligand  complexes, [Rh(COD)(phosphine)(amine)]PF^, r e c e n t l y 21 + p r e p a r e d by C r a b t r e e e t a l . t h r o u g h t h e r e a c t i o n o f [Rh(COD)(phosphine)^] 2  In  contrast,  +  v i a reaction  t h e new  was s y n t h e s i z e d , a n d f o u n d e q u i l i b r i u m 3.3 i n CDCil^ [Rh(COD)(PPh ) ] 3  and  2  +  a  3.3.  c r y s t a l l i n e complex,  +  to disproportionate extensively according to  t 35°; i n t h i s c a s e o l e f i n i c  and [ R h ( C O D ) ( A s P h ) ] 3  4.68 r e s p e c t i v e l y , a n d a K  3  3  2  +  1  3  r e s o n a n c e s due t o  were c l e a r l y  o b s e r v e d a t 64.53  =0.10±0.04 c o u l d be c a l c u l a t e d .  same c o n s t a n t i s o b t a i n e d f r o m t h e nmr s p e c t r u m m e a s u r e d a t -50°C ( f i g u r e  [Rh(COD)(PPh^)(AsPh^)] ,  About t h e  of a sample i n ( C D ) C O , 3  2  3.02).  We a r e c o n f i d e n t t h a t t h e [ R h ( d i e n e ) L J s p e c i e s o b s e r v e d i n t h e +  2  nmr s p e c t r a o f [ R h ( C O D ) ( P P h ) ( A s P h ) ] , +  3  3  w i t h diene=NBD t o b e d e s c r i b e d , r e s u l t impurities co-precipitated with  and t h e mixed  ligand  complexes  from e q u a t i o n (3.3) and a r e n o t  t h e d e s i r e d complex.  I t would  great a c o i n c i d e n c e that such i m p u r i t i e s a r e present always  be t o o  i n equimolar  -62-  amounts i n s o l u t i o n ( t o a g r e e w i t h (to give  t h e c o r r e c t a n a l y s i s and g i v e  samples), e s p e c i a l l y considering of  t h e nmr d a t a ) a n d t h e s o l i d  t h e two d i s p r o p o r t i o n a t i o n  [Rh(COD)(PPh ) ] 3  the great  crystalline  difference  i n solubility  p r o d u c t s i n c e r t a i n c a s e s - e.g.  i s much l e s s s o l u b l e  +  2  good l o o k i n g  state  i n CH C£ 2  2  than  [Rh(COD)(acetone) ] . +  2  4 R e c e n t l y C r a b t r e e and M o r r i s intermolecular  l i g a n d exchange r e a c t i o n  1 with  have p r e s e n t e d good e v i d e n c e t h a t t h e (3.3) i n v o l v i n g i r i d i u m complexes  2  L =phosphine, L = p y r i d i n e ,  coordinate  intermediates.  three-coordinate  a h d d i e n e = C O D , p r o c e e d s b y way o f  The d i s p r o p o r t i o n a t i o n  r e a c t i o n and t h e proposed  b e h a v i o u r o f [Rh(COD)(PPh„)(acetone)]PF, d i s c u s s e d 3  this  t h e s i s support the g e n e r a l i z a t i o n that  intermediates  allows  to operate.  If L  intermediates  1  the formation  i s a h a l i d e , then ligand—bridged,  NBD d e r i v a t i v e s g i v e m o r e c o m p l e x s p e c t r a (3.3),  possibly  p r e s e n t a t room t e m p e r a t u r e .  assigned  ligand  ones have sometimes been  3  +  disproportion-  are equivalent  is  are also believed to  Evidence f o r the existence  b y v a r i a b l e t e m p e r a t u r e nmr a s f o l l o w s .  to [Rh(NBD)(PPh )L]  because  involving 3-coordinate intermediates,  a l w a y s o b s e r v e d , and 5 - c o o r d i n a t e f l u x i o n a l s p e c i e s  i s provided  five-coordinate  8  ation v i a equation  be  of 3-coordinate  t o be t h e s o u r c e o f such  exchange r e a c t i o n s , a l t h o u g h t h r e e - c o o r d i n a t e  The  in  b  t h e l i g a n d exchange r e p r e s e n t e d by e q u i l i b r i u m (3.3)  have been p o s t u l a t e d  implicated."'"  three  of such  The o l e f i n i c  species  resonances  a t 35°C b u t c a n b e f r o z e n t o  i n e q u i v a l e n c e a t l o w t e m p e r a t u r e ( t a b l e 3.4, f i g u r e s 3 . 1 0 - 3 . 1 4 ) . P r e v i o u s _ ,. 1 7 , 1 8 , 2 2 , 2 3 . , . , , . . , j j studies i n v o l v i n g n e u t r a l and c a t i o n i c • m i x e d donor complexes o f I r a n d Rh h a v e d e m o n s t r a t e d t h a t NBD c o m p l e x e s u n d e r g o r e a r r a n g e m e n t s  -63-  more r e a d i l y  t h a n COD a n a l o g u e s .  Five coordinate  intermediates  •22  ,  e v e n c o n t a i n i n g w e a k l y b o n d e d c h l o r i n a t e d hydrocarbons"*"^, a p p e a r t o b e involved; recently a f i v e coordinate  p y r i d i n e adduct of a  (diene)  ( p e n t a n - 2 , 4 - d i o n a t o ) r h o d i u m ( I ) c o m p l e x was i s o l a t e d b y e m p l o y i n g a norbornadiene with is  that  electron  f o r [Rh(diene)L ]  24  withdrawing substituents.  Also  relevant  c o m p l e x e s , n may b e 3 f o r NBD, b u t o n l y  +  2for  13 COD s y s t e m s .  The s t r o n g e r  fr-backbonding p r o p e r t i e s  o f NBD h a v e b e e n  23 invoked  to rationalize  the r e a c t i v i t y  pattern.  T h e r e a r e a l s o p e a k s i n t h e 35° s p e c t r a that  c a n be a s s o c i a t e d  (3.3).  with  ( f i g u r e s 3.10 a n d 3.13)  the disproportionation products of equilibrium  R e s o n a n c e s t h a t do n o t a p p e a r t o b e b r o a d e n e d o r a v e r a g e d b y e x -  c h a n g e , a r e o b s e r v e d f o r [Rh(NBD) (V"Ph^)^]  +  i n the spectrum of  [ R h ( N B D ) ( P P h ) ( D M S O ) ] , and [ R h ( N B D ) ( a c e t o n e ) ] +  3  [Rh(NBD)(PPh )(acetone)]  2  +  3  (see t a b l e 3.4).  p r o d u c t s a r e masked by o t h e r  peaks.  +  i n the spectrum of  Resonances o f t h e other  Thus, l i k e  t h e COD  these complexes appear t o exchange l i g a n d s v i a equation t h e nmr t i m e s c a l e , a n d a g a i n of K^  3  3  ^  c a n be e s t i m a t e d  derivatives, (3.3) s l o w l y  on  3 - c o o r d i n a t e s p e c i e s may b e i n v o l v e d .  Values  ( s e e t a b l e 3.4) f r o m t h e l o w t e m p e r a t u r e  spectra  ( f i g u r e s 3 . 1 2 , 3.14) w h e r e t h e p r o d u c t s o f e q u i l i b r i u m ( 3 . 3 ) a r e c l e a r l y visible. I n s u m m a t i o n , three-, four-, a n d f i v e - c o o r d i n a t e c o m p l e x e s may b e g e n e r a t e d when [ Rh (NBD) ( P P h ) ( a c e t o n e ) ]"*" i s d i s s o l v e d , w h e r e a s 3  three-and four-coordinate COD  system.  d e r i v a t i v e s normally  only  appear f o r t h e analogous  i ON i  i  i  i  i  I  7.0  I  I  I  I  I  I  I  I  I  I  6.0 F i g u r e 3.13.  5.0  I  I  '*'  PPM  I  I  I  4.0  I  I  I  I  1  3.0  1  1  L  2.0  60 MHz HH nmr 60 nmr ssppeeccttrruumm ooff [Rh(NBD)(PPh„)(DMSO) [Rh(NBD)(PPh„)(DMSO)]SbF, i n 1  3  CDC2.- a t 35°C.  The i m p u r i t y a t 6 2 . 1 i s a c e t o n e .  6  -66-  3.1.3.2.  Sulfoxide  Complexes  D e s p i t e t h e somewhat c o m p l e x s o l u t i o n b e h a v i o u r o f  such  s o l u t i o n s r e a c t w i t h a n e q u i v a l e n t o f a s u l f o x i d e t o g i v e y e l l o w (COD) or yellow-orange  (NBD) c r y s t a l l i n e p r o d u c t s .  A n a l y t i c a l data a r e  p r e s e n t e d i n T a b l e 3.1. The complexes a r e r e a s o n a b l y a i r - s t a b l e solid  state.  I n s o l u t i o n t h e NBD d e r i v a t i v e s a r e v e r y  w h i l e t h e COD d e r i v a t i v e s show r e a c t i v i t y For -2 85 mho cm  [Rh(COD)(PPh )(DMSO)]A  air-sensitive,  several  (A=PF ,SbF ) a molar  3  i sobserved  only after  6  i nnitromethane  hours.  conductance o f  6  identical  i n the  t o that f o r  13 [Rh(COD)(PPh ) ]PF , 3  2  a known 1:1 e l e c t r o l y t e .  6  However, s o l u t i o n i r  s p e c t r a o f t h e s e DMSO c o m p l e x e s i n n i t r o m e t h a n e  [ R h ( C O D ) ( P P h ) ( M e N 0 ) ] : v (SO)  species i s probably cm  1  show t h a t  +  3  2  the solution  i s d e t e c t e d a t 1055  , t h a t o f f r e e DMSO. The  signals  "*"H nmr s p e c t r a f o r t h e COD d e r i v a t i v e s  f o r thenon-equivalent o l e f i n i c  a t 6^5.2 i s a s s i g n e d t o t h e p r o t o n s 25 previous  protons.  i n CDC£  3  show t w o  The d o w n f i e l d  resonance  (Hp) t r a n s t o P P h , c o n s i s t e n t w i t h 3  4 and recent  assignments  f o r t h e n e u t r a l compounds  [MC£(C0D)PPh ]  M=Rh,Ir; i n t h e s e , t h e s i g n a l due t o t h e p r o t o n s t r a n s t o c h l o r i d e a t 6^3, s i m i l a r ligands  (table The  PPh  3  t o that  found here  f o r those  down- a n d u p - f i e l d  shifts  positions of the equivalent o l e f i n i c [Rh(COD)(PPh ) ] 3  The m e t h y l e n e  appears  ( H ) opposite the sulfoxide Li  3.3).  of o l e f i n i c  and s u l f o x i d e , r e s p e c t i v e l y , a r e f u r t h e r  cations  3  2  +  1  3  diene protons trans to  supported by t h e r e s p e c t i v e  p r o t o n s a t 6 4 . 6 a n d 3.9 f o r t h e  and [ R h ( C O D ) ( D M S O ) ] .  protons o f t h e d i e n e appear  +  2 3  2  as a broad  signal  between  -67-  61.8-2.5.  T h e """H nmr r e s o n a n c e s  of the o l e f i n i c  protons of the diene  i n t h e N B D - s u l f o x i d e compounds a r e c o m p l e x a t room t e m p e r a t u r e , a s discussed  above.  All  t h e s u l f o x i d e c o m p l e x e s c o n t a i n 0-bonded s u l f o x i d e  Although theligand  (see below).  e x c h a n g e p r o c e s s e s o b s e r v e d b y nmr a s d e s c r i b e d  above occur i n s o l u t i o n s o f a l l t h e s e complexes,  no f r e e s u l f o x i d e i s  detected i nt h e s o l u t i o n i r s p e c t r a (see t a b l e 3.2). 3.1.3.3. A sharp (DMSO)]  1  DMSO a n d TMSO C o m p l e x e s H nmr s i n g l e t  appears  +  d u e t o DMSO m e t h y l p r o t o n s o f  a t 62.2 ( f i g u r e 3 . 1 5 ) ,  [Rh(COD)(PPh^)-  compared t o 62.6 f o r t h e f r e e  s u l f o x i d e a n d 62.8 f o r [Rh(COD) (DMSO) J B F . , a n d [Rh (COD) (DMSO) J S b F , . Z 4 Z D 2 3  ( f i g u r e 3.01).  Downfield s h i f t s  o f u p t o 1 ppm a r e u s u a l l y  o f S-bonded DMSO, w h i l e t h e 0-bonded c o m p l e x e s ,  i n which  characteristic  the protons a r e  f u r t h e r r e m o v e d f r o m t h e m e t a l show c o n s i d e r a b l y l e s s v a r i a t i o n f r o m t h e f r e e v a l u e s ( r e f . 26 a n d f i g u r e 1.8, c h a p t e r 1 ) . T h e p r o x i m a l p h e n y l r i n g s o f PPh^ must be r e s p o n s i b l e f o r t h e u p f i e l d and n o t e d space  previously  2 7  f o r [Ir(CO)(DMS0)<PPh ) ]C£0 2  f i l l i n g models suggest  where a p h e n y l group  4  observed  (61.8).  here,  Indeed,  t h a t t h e most f a v o u r a b l e o r i e n t a t i o n i s one  presents a ring: center t o the adjacent  l i g a n d , and such a c o n f o r m a t i o n w i l l of r o t a t i o n a l  shifts  likely  sulfoxide  persist during themajority  motion.  A d d i t i o n o f e x c e s s DMSO t o a s o l u t i o n o f [ R h ( C O D ) ( P P h ) ( D M S O ) ]  +  3  i n CDCA^ g i v e s a s h a r p r e s o n a n c e coordinated scale.  a t a w e i g h t e d mean p o s i t i o n o f f r e e a n d  ligand, suggesting that  t h e e x c h a n g e i s f a s t o n t h e nmr t i m e  I n t e r e s t i n g l y , t h e COD (-CH=) r e s o n a n c e s  a r e n o t broadened  which  -69-  again implies 3-coordinate behaviour.  F a c i l e exchange  o f 0-bonded  s u l f o x i d e s , l e s s so f o r S-bonded , has been noted by o t h e r s ^ ' 2 8  and  this,  2  t o g e t h e r w i t h t h e o t h e r nmr a n d i r e v i d e n c e ( s e e b e l o w ) , i s  c o n s i s t e n t w i t h t h e 0-bonded n a t u r e o f DMSO i n t h e p r e s e n t The  instance.  position of thesulfur-oxygen stretching v i b r a t i o n  n o s t i c o f t h e b o n d i n g mode; S - b o n d i n g t o about  2 9  1 1 0 0 cm \  whereas a s h i f t  i n d i c a t i v e o f d o n a t i o n from oxygen  usually  i s diag-  causes an i n c r e a s e o f v(SO)  t o a lower range  ( 1 0 0 0 - 9 0 0 cm ^) i s  ( f i g u r e 1.8, r e f e r e n c e s 2 6 , 2 8 , 3 0 ,  c h a p t e r 6 ) . H o w e v e r , a s s i g n m e n t s o f v ( S 0 ) f o r 0-bonded s u l f o x i d e s a-methyl  groups  a r e c o m p l i c a t e d by t h e presence o f m e t h y l  v i b r a t i o n s which a r e s i m i l a r  i n energy  B a n d s a t 983 a n d 947 cm of  [Rh(COD)(PPh )(DMSO)]A. 3  1  t o t h e S-0 s t r e t c h  with  rocking (see chapter6 ) .  a r e observed i nt h e C T ^ B ^ s o l u t i o n i r  The h i g h e r f r e q u e n c y band i s a b s e n t i n t h e  s p e c t r u m o f t h e DMSO-d,. a n a l o g u e  ( t a b l e 3.5) i n d i c a t i n g  that t h e major  b  c o n t r i b u t i o n t o t h i s b a n d i s a m e t h y l r o c k i n g mode. By c o m p a r i s o n o f t h e i r s p e c t r a o f t h e p r e s e n t compounds w i t h t h o s e o f o t h e r r h o d i u m d i e n e s p e c i e s we h a v e a s s i g n e d v ( R h - 0 ) f o r t h e TMSO ( 4 3 2 c m " ) a n d DMSO ( 4 5 0 c m " ) compounds. 1  be s h i f t e d  1  t o 4 3 0 cm  1  i n t h e DMSO-d, compound  The l a t t e r  appears t o  ( f i g u r e 3.16) a n d t h e  b  frequency r a t i o  1.046 t e n d s t o c o n f i r m t h i s a s s i g n m e n t  and i n d i c a t e  31 t h a t t h e v i b r a t i o n a l modes a r e a l m o s t p u r e Rh-0 s t r e t c h e s (see chapter 6). O t h e r i r b a n d s f o r [ R h ( d i e n e ) ( P P h ^ ) ! , ] * a r e l i s t e d i n t a b l e 3.6. + 23 The d i s c o v e r y o f a b e t t e r p r e p a r a t i o n o f [Rh(COD)(DMSO)^] i t s DMSO-d^ a n a l o g u e  i n v o l v i n g o n l y s t o i c h i o m e t i c amounts o f s u l f o x i d e  a l l o w e d u s t o c o n f i r m t h e 0-bonded n a t u r e o f t h e DMSO l i g a n d s ; cm \  and  v ( R h - 0 ) = 4 7 3 , 4 6 5 cm \  f i g u r e 3.17.  v(SO)=950  The Rh-0 s t r e t c h e s a g a i n e x h i b i t  -70-  T a b l e 3.5.  Some I n f r a r e d D a t a DMSO a n d DMSO-d, 6  a  -1 (cm ) f o r [ R h ( C 0 D ) ( P P h  ) L ] P F ,L=  3  DMSO  6  DMSO-d. 0  Frequency  Assignment  Frequency  b  v(CH)  2260 m  v(CD)  b  v(CH)  2125 m  v(CD)  1420 m  6(CH)  1042 m  6 (CD)  1327 m  6(CH)  1020 s  6 (CD)  1038 s  P (CH )  ( 8 3 1 s)°  P (CD )  992 s ( 9 8 3 )  P (CH )  b  P (CD )  r  r  3  3  958 s , b r ( 9 4 7 v)( S O ) 450 m  • 950 s , b r ( 9 5 5 )  v(Rh-O)  430 m  v(H v(D  Assignment  r  r  compound) compound)  (1.25)  3  C  3  v(S0) v(Rh-0)  mulls; values i n parentheses f o r CtLjB^ solutions;  1.046  a  Nujol  b  O b s c u r e d ; o t h e r 6 a n d p modes a r e a l s o o b s c u r e d i n t h e 1 4 5 0 - 9 5 0 cm r e g i o n , and thus t h e i s o t o p e r a t i o s h e r e cannot be a s s i g n e d w i t h certainty.  c  From SbF^ c o m p l e x ,  4000-250 cm" .  r  since obscured i nthePFg~ d e r i v a t i v e .  1  1  -71-  Table  NBD:  3.6.  Some L i g a n d V i b r a t i o n s o f [ R h ( d i e n e ) ( P P h ^ L ] ^  1 4 8 0 s , 1331m, 1 3 1 0 s , 1 1 8 1 s , 1155m, 1070w, 1 0 0 0 s , 878m, 800m, 775m, 5 6 0 s .  COD:  1 4 8 0 s , 1340m, 1315m, 1230m, 1189w, 1165m, 1080m, 1000m, 875m, 8 6 5 s , 4 8 8 s ,  PPh : 3  450m.  3060m, 1975w, 1900w, 1820w, 1585w, 1574w, 1 4 8 0 s , 1 4 4 2 s , 1415m, 1268w, 1 1 9 2 s , 1 1 0 0 s , 1029m, 7 5 5 s , 7 4 3 s , 7 0 7 s , 7 0 0 s , 512s, 418s.  530s,  I I  1200 1000 WAVENUMBER ICM")  400  1  F i g u r e 3.16.  The i n f r a r e d  s p e c t r a o f [Rh(COD) ( P P h ^ ) ( L ) ] P F g a s a N u j o l m u l l , ,  (a) L=DMS0, ( b ) L=DMS0-d . T h e r e a r e p o l y s t y r e n e p e a k s a t 1 6 0 1 a n d 905 c m . 6  - 1  calibration  WAVENUMBER (CM") 1  F i g u r e 3.17.  The i n f r a r e d s p e c t r u m o f [ R h ( € O D ) L ] S b F a s a N u j o l m u l l . (a) L=DMSO, (b) L=DMS0-d6. T h e r e a r e p o l y s t y r e n e c a l i b r a t i o n p e a k s a t 1601 a n d 905 c m ~ l . 2  6  -74-  the  expected deuterium s h i f t  o f a b o u t 1.05.  A c o r r e l a t i o n e x i s t s b e t w e e n t h e b a n d s a s s i g n e d a s v(M-O) a n d t h e frequency reduction this  o f v(S0)  on c o o r d i n a t i o n  of sulfoxides  to metals;  i s t h e t o p i c o f c h a p t e r 6. 3.1.3.4. O t h e r S u l f o x i d e The  that,  Complexes  "*"H nmr d a t a o f t h e o t h e r s u l f o x i d e  complexes  ( t a b l e 3.3) show  e x c e p t f o r p-CH^, a l l r e s o n a n c e s a r e s h i f t e d u p f i e l d f r o m t h e f r e e  ligand  positions,  bonded s u l f o x i d e The  i n d i c a t i n g a g a i n a p h e n y l d i a m a g n e t i c s h i e l d i n g o f 0ligands.  i r data  ( t a b l e 3.2) i n t h e 9 0 0 - 1 0 0 0 cm.. r e g i o n  for  systems  modes ( i . e . ,  for the  1  uncomplicated by t h e presence o f a-methyl r o c k i n g DMSO-d,, TMSO, TBPTSO, a n d NPSO s y s t e m s ) show t h a t  t h e SO s t r e t c h  shifts  D  by  70-110 cm  1  on c o o r d i n a t i o n  precludes i t s use i nhelping systems which c o n t a i n in the region  0-bonding. ir  v(S0)  This wide s h i f t  with  complexity  range  i n t h e MBMSO, MPSO, a n d MPTSO modes; t h e s h i f t  o f i n t e r e s t i s i n t h e same 70-110 cm  1  o f b o t h bands  range  i n t h e 9 0 0 - 1 0 0 0 cm  the a-methyl-containing sulfoxides  (table 1  b a n d s i n t h e 4 0 0 - 5 0 0 cm  region  diaryl p-tolyl  upon  i s consistent  1  with  region.  sulfoxides  a p p e a r t o b e 0-bonded t o r h o d i u m  s h i f t s ) i n s o l u t i o n , we h a v e b e e n u n a b l e t o i s o l a t e d i s c r e t e  possibly  3.2).  Assignments o f v(Rh-0) were p r e c l u d e d by t h e m u l t i p l i c i t y o f  Although d i a r y l nmr  assign  the methyl rocking  Nevertheless, the increased coordination  to themetal.  due t o u n f a v o u r a b l e s t e r i c  sulfoxides sulfoxide.  studied  interactions  were d i p h e n y l s u l f o x i d e  i n the solid  (upfield  complexes,  state; the  (DPSO), and S - o - t o l y l  The  c h o i c e o f S-vs O - c o o r d i n a t i o n w i t h a s u l f o x i d e l i g a n d h a s 29  u s u a l l y been r a t i o n a l i z e d considering  i n terms o f s t e r i c  However,  t h a t b o t h t h e DMSO l i g a n d s a r e 0-bonded i n t h e u n h i n d e r e d  [Rh(COD)(DMSO)complex, electronic role  effects.  f a c t o r s must p l a y a s u b s t a n t i a l  i n t h e c a t i o n i c rhodium(I) d i e n e complexes.  Other recent  examples  s h o w i n g 0 - b o n d e d DMSO l i g a n d s a r e t h e R h ( I I I ) c a t i o n , 3_2 ( f i g u r e 1.4) w i t h t h r e e 0-bonded D M S O  32  and [Ru(COD)(DMSO)^]  2 +  with f o u r .  Thus  3 3  s u l f o x i d e s c a n probe t h e " h a r d n e s s " (oxygen bonding) o r " s o f t n e s s " 34 ( s u l f u r b o n d i n g ) o f a s i t e on a m e t a l . The h a r d s i t e s f o u n d h e r e a n d o n o t h e r s o f t - l i g a n d - R h ( I ) - c a t i o n m o i e t i e s , s u c h a s [ R h ( P P h ) 2]"*", 3  have s i g n i f i c a n c e f o r c a t a l y t i c p r o c e s s e s .  F o r example, a s mentioned  i n c h a p t e r I , t h e h a r d - h a r d i n t e r a c t i o n s o f a n enamide w i t h a Rh(I) c a t i o n , i s an i m p o r t a n t f a c t o r selectivity  i nachieving high  enantio-  i n homogeneous a s y m m e t r i c h y d r o g e n a t i o n .  Attempts a t i s o l a t i n g  [ R h ( N B D ) ( D M S O ) J S b F , a s w e l l a s [Rh(COD)(MPSO)„]~ Z  [Rh(COD)(DPSO) ] , +  2  thick oils  group on s u b s t r a t e s ,  [Rh (COD) (MBMSO) 1  +  2  o r brown s o l i d s r e s u l t i n g  The c o m p l e x e s to be f i v e - c o o r d i n a t e  L  D  and [Rh(COD)(DIOS)]  +  yielded  from d e c o m p o s i t i o n .  [ Rh ( d i e n e ) (PPh,,) (DIOS) ] P F , , p r e p a r e d i n s i t u , (e.g. f i g u r e  only  3.18).  PPh,  F i g u r e 3.18. [ R h ( d i e n e ) ( P P h ) ( D I O S ) ] P F 3  6 <  appear  -76-  The  olefinic  diene  and  -50°C f o r NBD  protons  a r e i n e q u i v a l e n t a t 35°C f o r diene=COD  ( f i g u r e s 3.06, 3 . 0 8 ) .  a - m e t h y l s o f DIOS r e s o n a t e  At these  t h r e e peaks c o r r e s p o n d i n g  d e r i v a t i v e may r e p r e s e n t DIOS, c h e l a t e d t o Rh. chemically different at but  carbon.  The m e t h y l s  (R,S)-and  t h i s Rh(I)  t o these methyls  (at sulfur) of  of (S,S)(at sulfur)-DIOS are  (R,R)-DI0S because o f t h e c h i r a l  centers  from t h e f i r s t  two.  Apparently  shift  coordination to  c e n t e r enhances these d i f f e r e n c e s so t h a t t h e t h r e e  are observed.  The i n e q u i v a l e n c e o f t h e a c e t a l m e t h y l s  t h e s t r u c t u r e i n f i g u r e 3.18.  also  peaks  supports  I t a p p e a r s t h a t t h e DIOS c h e l a t i o n  o v e r c o m e s t h e r e l u c t a n c e o f COD t o s u p p o r t ir  i n t h e COD  ( S , R ) - D I 0 S s h o u l d h a v e t h e same c h e m i c a l  they should d i f f e r  both  g r o u p s o f PPh^*  the various diastereomers  from  the  a t 62.5 i n t h e nmr a n d t h e r e f o r e m u s t  be d i a m a g n e t i c a l l y s h i e l d e d b y t h e p h e n y l The  temperatures  5-coordination.  The s o l u t i o n  o f t h e s e DIOS s p e c i e s i s c o m p l e x b u t t h e r e i s a s t r o n g v ( S 0 ) a t 950 cm  (oxygen  1  bonding). 3.1.3.5. The  Other Mixed  versatility  Ligand  Complexes  of the acetone-containing  c a t i o n s as p r e c u r s o r s  f o r mixed l i g a n d complexes i s f u r t h e r d e m o n s t r a t e d by t h e ease o f p r e p a r a t i o n o f t h e new c o m p l e x e s (py)]SbF , 6  [ R h ( d i e n e ) (PPh^) ( C 0 ) ] P F g , 2  and [ R h ( C O D ) ( P P h ) ( A s P h ) ] P F . 3  [Rh ( d i e n e ) ( P P h j ) (PPhMe,,) ]  +  3  6  one  PPhMe  2  i n CDC£  3  The m i x e d p h o s p h i n e  c o u l d n o t be i s o l a t e d .  -20°C o f t h e COD d e r i v a t i v e p r e p a r e d  i n situ  showed o l e f i n i c  from t h e a c e t o n e c a t i o n and  peaks a t 6 3 . 1 5 ( [ R h ( C O D ) ( P P h ) ( P P h M e ^ ] ? ; +  3  62.97 f o r [ R h ( N B D ) ( P P h M e ) ]  4.91  ( [ R h ( C O D ) ( P P h M e ) ] , c f . 65.06 f o r [Rh(NBD) ( P P h M e ) ]  3  +  1  3  ) , 4.52  ([Rh(COD)(PPh ) ] ), +  3  +  2  1  complexes,  The nmr s p e c t r u m a t  cf.  2  [Rh(NBD) ( P P h ^ ) -  2  2  +  1  2  3  ) , 5.38,  2  -77-  5.68([Rh(COD)(PPhMe )(PPh )] ?). +  2  in significant described  3  The  presence of these p r o d u c t s , each  amount, i s i n a c c o r d w i t h  earlier.  the l i g a n d exchange  [ R h ( N B D ) ( P P h ^ ) ( A s P h ^ ) ] P F ^ was  reactions  p r e p a r e d by  Schrock  13 and Osborn  from  [ R h ( N B D ) ( P P h ^ ) p l u s AsPh , 2  d e m o n s t r a t e t h e f l u x i o n a l b e h a v i o u r and protons  ( t a b l e 3.4, The  figure  i n e q u i v a l e n c e of the diene  3.03).  f i v e - c o o r d i n a t e c a r b o n y l complexes  e v e n b e l o w -30°C.  but they d i d not  3  u n d e r CO a r e  Some a v e r a g i n g p r o c e s s w i t h t h e NBD  causes the o l e f i n i c  protons to s h i f t  derivative  f r o m 64.23 a t 35°C t o 4.07  -30°C w h i l e t h e m e t h i n e p e a k r e m a i n s s t a t i o n a r y a t 3.75 U n d e r A r , t h e NBD p r e s u m a b l y due o f t h e NBD complex  derivative  ( 2 0 5 0 , 1983  o f t h e NBD  ligand.  1  species  compared t o t h a t o f t h e  "*") i s c o n s i s t e n t w i t h t h e g r e a t e r  The  3.05).  The h i g h e r v ( C 0 ) r a n g e i n C H C £  ( 2 0 8 0 , 2045 cm' )  cm  at  (figure  d e r i v a t i v e disproportionates to several  t o t h e l o s s o f CO.  fluxional  implied l a b i l i t y  3  COD  ir-acidity  of these weakly held  carbonyl  13 groups  s u g g e s t e d t h e i r p o s s i b l e use as h y d r o f o r m y l a t i o n  (section  3.4).  3.2  The R e a c t i o n s o f t h e M i x e d L i g a n d C o m p l e x e s 3.2.1. The  see  Hydrogen.  Introduction reactivity  of t h e Osborn  c h a p t e r 1.3.1) i s due  labile  with  catalysts  type c a t a l y s t s  (eg  [Rh(diene)(PPh ) ] , +  3  i n p a r t t o t h e r e p l a c e m e n t o f t h e d i e n e by  solvent molecules v i a the hydrogenation r e a c t i o n  [Rh(diene) ( P P h ) ] 3  Accordingly  2  +  + 3H  2  2  the mixed  -»- [ R h ( H ) ( P P h ) ( s o l v e n t ) ] 2  3  2  l i g a n d complexes  (1.18). +  2  synthesized  + norbornane  (1.18)  i n the present  -78-  w o r k w e r e t r e a t e d w i t h R^, e s p e c i a l l y t o s e e i f S — b o n d i n g o f t h e s u l f o x i d e s c o u l d be encouraged. the  first  dihydrido diene  The o b s e r v a t i o n  intermediate,  at low temperature of  [Ir(H)^(diene)(PPh^)>  35 reported  during  the course  of our work, suggested another area t o  explore. 3.2.2. The  Experimental h y d r o g e n u p t a k e b y some o f t h e m i x e d l i g a n d c o m p l e x e s  i n s e c t i o n ( 3 . 1 ) was m e a s u r e d , g e n e r a l l y i n DMA ampoule t e c h n i q u e s hydrogenation  complexes l i s t e d  i n chapter  Some s y s t e m s w e r e p r e p a r e d benzyl  2.  i n t a b l e 3.7 r e a c t w i t h  DMA was d e g a s s e d s i m p l y b y s t i r r i n g  phenyl  solution, using the  and t h e l o w t e m p e r a t u r e , m a g n e t i c a l l y  vessel described  sulfide  i n the s o l i d  (PBS),  ( I A ) l i g a n d s by +  dropping  cation into  T h e b i s - c a r b o n y l c o m p l e x was p r e p a r e d  degassed i n situ  c a t i o n w i t h 1 a t m CO; e x c e s s CO was  pumped o f f a n d t h e g a s u p t a k e was m e a s u r e d i m m e d i a t e l y  after  was  into the flask.  Attempts at preparing perature  The  and p u m p i n g o n i t f o r 5 m i n a t 0°C.  and i t a c o n i c a c i d  reacting the acetone-containing  introduced  state.  i n s i t u u s i n g DIOS, t h i o u r e a ( t u ) , DPSO,  DMA c o n t a i n i n g t h e l i g a n d .  rapidly  stirred  A l l of the i s o l a t e d  an ampoule c o n t a i n i n g t h e [ R h ( d i e n e ) ( P P h ^ ) ( a c e t o n e ) ]  by  prepared  involved bubbling  hydride  olefin  E^ f o r 5 m i n v i a  intermediates  a t l o w tem-  hypodermic tubing  through  a s o l u t i o n o f t h e m i x e d l i g a n d c o m p l e x i n a n nmr t u b e i m m e r s e d i n a d r y ice/acetone  slush bath.  p r o b e s e t a t -60°C.  T h e s a m p l e was t h e n d r o p p e d i n t o t h e X L 100  -79-  3.2.2.1.  The  ( a ) I n (CD )„C0: 1 Z  a n nmr red  spectrum of  [Rh(NBD)(PPh )(DIOS)]PF +2.5H 3  0.045 mmol) w e r e r e a c t e d w i t h  t o deep brown. by  The DIOS p e a k s  exchange:  nmr  i n t h e nmr  (DIOS)  62.3(m,0.5,methine), the  high f i e l d  nmr  ( b ) I n C D C £ : The  1 . 5 - 1 . 0 ( m , 4 , C H ) . nmr No  2  reaction  uptake of  2  0.085 mmol) a n d DIOS  and of  (0.030  3  g, 0.09  T h i s d e e p b r o w n s o l u t i o n was s p e c t r u m was  triplets  complex  i n DMA  under H ,  transferred  that  was  i s attributed  0  by gas  J  „=16 Jr—n  Hz;  t o a n nmr  3.20.  DMA  g,  was  100 m i n  at  tube under The  f o r the  H  2  doublet [Rh(NBD)(PPh ) ] 3  t o [ R h ( H ) „ (PPh„) (DMA) „ ] , J.,, +  0  o Z  Z  figure  (0.056  p e r Rh a f t e r  a l s o measured  Z  23 H z ,  2  recorded i n the hydride region.  o b s e r v e d a t 31.5T  &  mmol) i n 1 m l d e g a s s e d moles H  with  precipitate.  [Rh(NBD)(PPh )(acetone)]PF  t o a c o m p l e t e d u p t a k e o f 2.5  t h e nmr  (norbornene)  i s c o m p l i c a t e d by a r e a c t i o n  I n DMA:  30°C.  3.9-2.9(m,  region.  (c)  followed  were  h y d r i d e s c o u l d be d e t e c t e d i n  s o l v e n t w h i c h l e d t o a brown u n i d e n t i f i e d H  from  (norbornane)  2  the  The  ( f i g u r e 3.19)  3  1.6-1.0(m,l,CH ).  hydrogen  q  changed  1.46(m, 6,C-CH ) . nmr  2  65.2(m,2,C=C-H); 2 . 8 ( m , 2 , m e t h i n e ) ;  solution  (CD^CO in  64.6-4.2(m,2,methine);  7,§.-CH +S-CH ) ; 2. 9-2.4 (m,3,_0-S-CH ) ; 3  The  2  0.045 mmol) and  i n degassed  t u b e a t room t e m p e r a t u r e o v e r n i g h t .  broadened  &  [ R h ( N B D ) ( P P h _ ) ( a c e t o n e ) ] P F , (30 mg, 5 b  o  DIOS (12 mg,  nmr  Norbornane  Z  i n t h e s o l u t i o n was  =  Kn—rl  detected  chromatography.  3.2.3. The  R e s u l t s and results  derivatives,  Discussion  i n table  by c o n s u m i n g  3.7  indicate  that  the PPh , A s P h 3  a p p r o x i m a t e l y 3 moles of H , 2  form  3 >  DIOS, and solvated  tu  2  +  F i g u r e 3.19  100 MHz  1  H  nmr  s p e c t r u m o f [Rh(NBD) ( P P h ) ( a c e t o n e ) ] P F  reacted overnight with H  3  9  i n (CD-) C0. 7  6  + DIOS  -82-  dihydride  species  and n o r b o r n a n e  (cf.,the  o f r e a c t i o n 1.13, s e c t i o n 3 . 2 . 1 . ) . species  reacts with  only  stoichiometry  The b i s c a r b o n y l  2 moles of  t o form e i t h e r a d i h y d r i d e and  norbornene, or a s o l v a t e d , non-hydridic  species  t h a t can hydrogenate  norbornene t o norbornane. The  o t h e r m o n o d e n t a t e S-, N-, a n d 0 - d o n o r s do n o t p r e v e n t a  p r e f e r e n t i a l r e d u c t i o n o f t h e complex t o m e t a l .  The f i n a l  greenish  s o l u t i o n s of t h e monodentate s u l f o x i d e / N B D complexes a r e c h a r a c t e r i s t i c 36 of Rh(II) by  species  and so r e d u c t i o n  disproportionation according  o f t h e d i e n e t o monoene  followed  t o r e a c t i o n (3.4) i s p o s s i b l y  2 R h ( I ) -> R h ( 0 ) + R h ( I I )  The  other  (3.4)  c a s e s must i n v o l v e h y d r i d e  to metal.  occurring.  formation  and t h e n r a p i d  decomposition  The f i n d i n g t h a t t h e DMSO/COD d e r i v a t i v e i s l e s s s u s c e p t i b l e  t o h y d r o g e n a t i o n t h a n t h e NBD o n e s , a g r e e s w i t h genation  of [Rh(NBD)L ]  +  2  t h e noted ease o f hydro-  compared t o [Rh^OD)!^]" ", L = t e r t i a r y p h o s p h i n e 1  1 or  arsxne. I t a c o n i c a c i d appears t o be p r e f e r e n t i a l l y reduced i n s t e a d o f t h e  diene,  at l e a s t i n the c a t a l y t i c hydrogenation of t h i s acid discussed i n  s e c t i o n 3.3, and m e t a l p r o d u c t i o n  occurs  completely  coordination of the ligand i n thei n  situ  hydrogenated.  Initial  only a f t e r t h i s  substrate i s  r e a c t i o n s m u s t b e f a s t s i n c e t h e same r e s u l t s f o r h y d r o g e n a t i o n a r e  obtained  starting with  the preformed  complexes.  These f a s t h y d r o g e n u p t a k e r e a c t i o n s were found t o be d i f f u s i o n controlled using  the v e s s e l w i t h magnetic s t i r r i n g .  A run with  L=PPh  Q  -83-  T a b l e 3.7.  S t o i c h i o m e t r y o f Hydrogen Uptake by [Rh(diene)(PPh )(L)]A Complexes  v  3  Isolated diene  Complexes  T  A  L PPh  3  NBD  PPh  3  NBD  DMSO  NBD  py  NBD  acetone  P F  6  COD  DMSO  P F  6  In  Situ  2  (b) Final  Solution  T o t a l Time for reaction  °C  SbF.  NBD  Moles H /Rh  '  (c)  30  3.0  clear  gold  0  2.7  clear  gold  SbF, 6  30  0.7  green-brown+metal  10 m i n  SbF, 6  30  0.2  yellow+metal  3min  30  0.2  orange+metal  4min  20  0.6 >  y e l l o w - b r o w n + m e t a l 110 m i n  SbF, 6  30  2.9  gold  SbF, 6  30  2.8  gold-brown  80 m i n  0  (e  60 m i n  (c)  20  min  Complexes (c)  NBD  PPh  NBD  AsPh  NBD  DIOS  SbF,  30  2.5 .  d a r k brown  90 m i n  tu  SbF, 6  30  2.0  red  90 m i n  2.8  red-brown  700 m i n  NBD  3  NBD  (co)  NBD  3  0  60 m i n  SbF, 6  30  1.8  red-brown  170 m i n  IA  SbF, 6  30  1.2  orange-brown+metal  8min  NBD  3' DMSO  SbF, 6  30  0.8  green-yellow+metal  17 m i n  NBD  3 DMSO  SbF, 6  30  0.9  green-yellow+metal  15 m i n  NBD  PBS  SbF, 6  30  0.9  orange-brown+metal  10 m i n  NBD  DMA  SbF  30  0.2  orange+metal  4min  (a) (b) (c) (d) (e)  ( d )  2  6  5 m l DMA, 1 atm H , [Rh]^8mM. Measured a t time o f m e t a l f o r m a t i o n i f t h i s On s t a n d i n g f o r a f e w h o u r s t h e s e s o l u t i o n s t o some r e a c t i o n o f t h e h y d r i d e w i t h t h e DMA. T h e f l a s k was s h a k e n c o n t i n u o u s l y , ( more v i g o r o u s a g i t a t i o n i n acetone. 2  ;  than  stirring),  -84-  using instead a well a t 0°C.  s h a k e n r e a c t i o n f l a s k was t o o f a s t  Thus, a l t h o u g h d i s t i n c t breaks were observed  to follow  i n some o f t h e  uptake versus time p r o f i l e s using t h e v e s s e l w i t h s t i r r i n g , have r e s u l t e d  from a d i f f u s i o n c o n t r o l l e d  m e a n i n g f u l k i n e t i c d a t a was j u d g e d The  nmr s p e c t r u m  even  t h e s e may  p r o c e s s , and t h e c o l l e c t i o n o f  impossible using this  vessel.  o f t h e DIOS d e r i v a t i v e r e a c t i o n w i t h 2.5 H^/Rh i n  DMA i n d i c a t e s t h a t a d i s p r o p o r t i o n a t i o n r e a c t i o n  (3.5) o c c u r s s i n c e t h e  o n l y h y d r i d e d e t e c t e d was t h a t a s s i g n a b l e t o [ R h ( H ) ( P P h ) ( D M A ) ] 2  c i s - h y d r i d e s and t r a n s - p h o s p h i n e s  (figure  3  2  with  +  2  3.20).  2 [Rh(NBD) ( P P h ) ( D I O S ) ] P F , + 5H. -> 3  6  2 norbornane  The  +  (3.5)  2  [Rh(H) (PPh ) (DMA) ] 2  3  2  +  2  +  [Rh(DI0S) ] 2  b i s p h o s p h i n e d i h y d r i d e was formed i n d e p e n d e n t l y  [Rh(NBD)(PPh,.)„]SbF  1  i n DMA.  Although  are resonances  on c a r r y i n g o u t t h e H  t h e spectrum  2  different  cation  (see s e c t i o n 3.1.2.7).  to the  reaction i n  i s broadened by exchange, t h e r e  c o r r e s p o n d i n g t o b o t h S- a n d 0-bonded s u l f o x i d e  3.19),  hydrogenating  from  P r o t o n nmr s i g n a l s a t t r i b u t a b l e  b i s - D I O S c a t i o n c a n be o b s e r v e d acetone-d^.  +  to those recorded f o r the i n s i t u Attempts  (figure  [Rh(diene)(PPh^)(DIOS)]  at generating [Rh(DI0S) ] 2  +  by  [ R h ( N B D ) ] P F g a n d DIOS ( r a t i o 1:2) w e r e n o t s u c c e s s f u l  (chapter 4.2).  2  The n o r b o r n a n e  produced  by r e a c t i o n  ( 3 . 5 ) was d e t e c t e d  b y G.C. a n d nmr. No h y d r i d e s w e r e o b s e r v e d  i n t h e nmr a t -60°C o f s o l u t i o n s o f  [Rh(NBD)(PPh„)(DMSO)]PF, i n ( C D ) C 0 o r C D C £ o  3  O  J  o  0  Z  3  which  had been r e a c t e d  +  -85-  with  H2  a t -78°C; no  n o t e d on  reaction  change i n the  with  H^.  orange colour  of  When t h e s e s o l u t i o n s  f o r m e d r a p i d l y , w h i c h may  the  solutions  was  w e r e warmed m e t a l  i n d i c a t e metal h y d r i d e formation at  some  stage.  3.3.  Attempts at The  (3.5)  the Asymmetric Hydrogenation of  brown s o l u t i o n  (5 m l ,  l a c k of  a c i d , but  with  no  e.e.,  asymmetric i n d u c t i o n  u s e d i n p l a c e o f DIOS, t h e  suggesting  that  the  The  complexes  at  active  (IA)  30°C.  rate  s o l u t i o n of  Considering  I f PTSE ( 1 4 ,  the  dihydride figure  "same" s y s t e m d e p o s i t s m e t a l a f t e r 20 formed v i a e q u a t i o n also  chapter  (3.5)  is  1.3) min  sus-  4.2). L=acetone,  6  a l l hydrogenated, i t a c o n i c acid at  i n e i t h e r MeOH o r the  a-methyl  bisphosphine  catalyst.  3  the  reaction  to  [ R h ( d i e n e ) ( P P h ) L ] P F , d i e n e = C 0 D , NBD;  f i g u r e 1.3)  mM  min  Olefins  g e n e r a t e d by  p r o d u c t , the  u n d e r H.^ ( s e e  DMSO, MPTSO ( 1 8 , same i n i t i a l  i n 150  b i s PTSE c a t i o n  c e p t i b l e to reduction  i n Rh)  g itaconic acid  i n the  complex i s almost c e r t a i n l y the  a 1.5  M  c a t a l y t i c a l l y h y d r o g e n a t e d 0.1  succinic  is  0.01  Prochiral  acetone at  20°C.  c a t a l y s t s h y d r o g e n a t e s 0.1  about  Thus 5 ml  g substrate  in  of 100  -4 min  with  an  initial  hydrogen uptake r a t e  1 , 2 - b i s ( d i p h e n y l p h o s p h i n o ) e t h a n e was to displace  any  c o o r d i n a t e d COD;  c h r o m a t o g r a p h y and product from the  COD  was  reaction  this  detected. with  of  (1.0±0.3)xl0  added t o  the  final  s o l u t i o n was The  a-methyl s u c c i n i c  L=R-MPTS0 was  not  optically  itaconic acid  i s p r e f e r e n t i a l l y h y d r o g e n a t e d and  not  influence  rate  i n t e r m e d i a t e s u c h as  or  product of  this reaction  [Rh(H)„(diene)(IA)(PPh„) ]  +  the  and  can  be  Excess  reaction  a n a l y z e d by  The  the  M/sec.  solution gas  acid active.  ligand  L  does  t h u s a common postulated.  The  -86-  very  a c t i v e homogeneous h y d r o g e n a t i o n c a t a l y s t , [Rh(COD) ( P P h ^ ) ( p y ) ]PF^.  probably  involves a similar pyridine-free intermediate  in section  (3.2.3) t h a t the  absence of s u b s t r a t e s COD  i s slower  report  ( s e c t i o n 3 . 2 . 3 ) , and  t h a t m e t a l i s f o r m e d a f t e r a few A  is  or a l k e n e s ) .  2  Hydrogenation of this  the  COD/py c a t a l y s t  1  used. A t r o p i c a c i d , a n o t h e r p r o c h i r a l s u b s t r a t e , was  by  the  coordinated  i s consistent with  h o u r s when t h e  ,  shown  a n a l o g o u s NBD/py s y s t e m g o e s t o m e t a l i n  (alkynes  t h a n NBD  s i n c e i t was  21  t h e s e m i x e d l i g a n d c a t a l y s t s a t 30°C.  the  solutions deposit The  the  less labile  sulfur-bonded hopefully with  w o u l d be m o r e p r o f i t a b l e i n t h e  3.4.  f o r an  Reactions  using  of  sulfoxide ligands  simpler  solution  asymmetric  as  behaviour,  hydrogenation  [Rh(NBD)(PPh )(CO)^]  +  3  complexes RhH(CO)P ,where P i s a t e r t i a r y 3  and  a t c o n d i t i o n s o f 1 atm  p r o d u c t r a t i o s o f 10 w i t h no  and  phosphine,are  37 38 39 catalysts. ' '  selective hydroformylation  c o m p l e x e s t r a d i t i o n a l l y u s e d f o r t h e Oxo achieve,  study  Introduction  The efficient  search  chiral  the  4).  Hydroformylation 3.4.1.  (50°C)  metal.  o p p o s e d t o 0-bonded o n e s , and  (chapter  hydrogenated  temperatures  r e s u l t s of these experiments i n d i c a t e t h a t  complexes w i t h  catalyst  At h i g h e r  not  process  39  90°C, l i n e a r  Unlike  very Co  , the rhodium c a t a l y s t s  to branched  hydrogenated side products  39  aldehyde  , and  indeed, 38  Rh  b a s e d c a t a l y s t s a r e now  Studies  h a v e shown t h a t t h e  most s e l e c t i v e . less  To  r e p l a c i n g Co  ones i n i n d u s t r i a l  trisphosphine  processes.  complex, RhH(CO)(PPh^)^, i s  p r e v e n t p h o s p h i n e l i g a n d d i s s o c i a t i o n and  s e l e c t i v e c a t a l y s t s s u c h as R h H ( C O ) ^ ( P P h ^ ) > 2  the  formation  reactions are c a r r i e d  of  -87-  out w i t h an excess o f phosphine  present. ° J  Few d a t a i f a n y e x i s t o n c a t i o n i c h y d r o f o r m y l a t i o n c a t a l y t i c systems,  a n d s o i t was o f i n t e r e s t  to test  the [Rh(NBD)(PPh )(CO) 1  +  2  3  complex. 3.4.2. The  E x p e r i m e n t a l and R e s u l t s gas uptake  experiments were c a r r i e d out i n a dimpled  flask  w i t h a s i d e arm i n t h e u s u a l f a s h i o n  ( s e c t i o n 2.3).  heptene  down a l u m i n a c o l u m n s t o r e m o v e  s u b s t r a t e s were f i r s t  peroxide impurities, a)  and t h e n h y d r o f o r m y l a t e d as f o l l o w s :  An a m p o u l e c o n t a i n i n g 40 mg  i n t o a deoxygenated  temperature. and  t o 380 t o r r ,  t h e t e m p e r a t u r e was  raised  was i n t r o d u c e d t o a t o t a l o f 1 a t m a t t h e new b a t h A r a p i d u p t a k e o f 1.0 m o l e o f g a s (H^) p e r Rh was m e a s u r e d  The h y d r o f o r m y l a t i o n r e a c t i o n t h e n s t a r t s v e r y s l o w l y b u t b u i l d s  t o g i v e a maximum r a t e o f 1 x 1 0 ^M  s o l u t i o n i s gold-brown was s t o p p e d a f t e r  (H^+CO)/secafter  at this point.  200 m i n .  2 0 h a n d t h e p r o d u c t s w e r e a n a l y z e d b y G.C.:  r e a c t i o n gave a f t e r  The  The 1 - h e x e n e ( 0 . 2 1 m l ) r e a c t i o n  h e x e n e , 60% 1 - h e p t a n a l , and 24% 2 - h e p t a n a l ,  b)  (0.2-0.4 m l ) under  t h i s was a c c o m p a n i e d b y a s o l u t i o n c o l o u r c h a n g e f r o m y e l l o w t o  orange. up  (5 m l ) a n d o l e f i n  dropped  The CO/Rh g a s u p t a k e r a t i o o f 2.0 was v e r i f i e d .  CO p r e s s u r e was t h e n r e d u c e d  t o 50°, and  [Rh(NBD)(PPh„)(acetone)]PF, was  s o l u t i o n o f DMA  a CO a t m o s p h e r e a t 25°C. The  passed  1-Hexene a n d 1-  The 1 - h e p t e n e  1 6 % 1-  (0.43 ml)  40 h : 4 5 % 1 - h e p t e n e , 4 0 % 1 - o c t a n o l , a n d 1 5 % 2 - o c t a n o l .  A s l i g h t l y more a c t i v e c a t a l y s t  compound a s a b o v e a n d t h e n r e p l a c i n g t o t a l u p t a k e o f 2.0 m o l e s o f H  ?  i s prepared by f o r m i n g t h e b i s - c a r b o n y l t h e CO b y a p u r e B.^ a t m o s p h e r e .  p e r Rh t a k e s p l a c e a t 50°C a n d a b r o w n  A  -88-  solution results;  t h e r e was no f u r t h e r c a t a l y t i c r e d u c t i o n o f 1 - h e x e n e .  T h e n t h e s y n t h e s i s g a s (CO/H^) m i x t u r e i s i n t r o d u c e d a n d t h e h y d r o f o r m y l a t i o n r e a c h e s a maximum r a t e o f 3 x 1 0 ~*M/sec a f t e r 40 m i n a t 50°C. The  l i n e a r / b r a n c h e d s e l e c t i v i t y o f t h e p r e v i o u s m e t h o d was r e p r o d u c e d  u s i n g 1 - h e x e n e ; a f t e r 16 h o u r s : 2 5 % 1 - h e x e n e , 5 4 % 1 - h e p t a n a l , 2 1 % 2 - h e p t a n a l . c)  The [ R h ( N B D ) ( P P h ) ( C 0 ) ] P F 3  2  1-hexene i n 2 - m e t h o x y e t h a n o l :  6  complex i s a h y d r o g e n a t i o n c a t a l y s t f o r  a t 1 atm  a n d 50° w i t h c a t a l y s t a n d  —6 o l e f i n c o n c e n t r a t i o n s as above, M/sec.  the i n i t i a l  r a t e o f u p t a k e was 6 x 1 0  T h i s s y s t e m a l s o h y d r o f o r m y l a t e s 1 - h e x e n e a t t h e same r a t e a s  when DMA i s u s e d a s t h e s o l v e n t . 3.4.3. The  Discussion complex  [Rh(NBD) ( P P h ^ ) (CO)is  a precursor to a  l a t i o n c a t a l y s t o f good s e l e c t i v i t y and a c t i v i t y . to branched  hydroformy-  The r a t i o o f l i n e a r  a l d e h y d e p r o d u c t i s 2.5 f o r b o t h 1 - h e x e n e a n d 1 - h e p t e n e ;  n o r m a l l y s u c h good s e l e c t i v i t y  i s o b s e r v e d f o r n e u t r a l Rh c a t a l y s t s o n l y 38 39 when t h e r a t i o o f PPh-j t o Rh i s t h r e e o r g r e a t e r . ' I n a d d i t i o n most o f t h e n e u t r a l Rh s y s t e m s  r e q u i r e h i g h e r t e m p e r a t u r e s and p r e s s u r e s t o  39 effect  this  reaction.  A detailed  s o l u t i o n study would  nature of the active catalyst. possibility  be r e q u i r e d  to elucidate the  A s o l v a t e d c a t i o n i c c o m p l e x i s a good  since the s e l e c t i v i t y  i s higher than that encountered f o r  38 n e u t r a l c a t a l y s t s w i t h PPh^/Rh-l n o r b o r n a d i e n e does o c c u r .  , and s i n c e t h e h y d r o g e n a t i o n o f t h e  -89-  4.  Sulfoxides  4.1.  S u l f u r - B o n d e d t o Rhodium  Synthesis  4.1.1.  and  Spectroscopic  Introduction According  t o t h e p r i n c i p l e s o f H a r d and  ( H . S . A . B . ) b o t h Rh(I) the  Properties  and  Rh(III)  should  Soft Acids  Rh(I)  " s o f t " L e w i s a c i d b e c a u s e i t i s l a r g e i n s i z e and  classification. fluence  their  and  that neutral, " s o f t " ligands (a) c h a r a c t e r  to Rh(I)  T h e r e f o r e i t was C£ Rh.  e x p e c t e d t o be Rh,  ( C O D j P P h ^ ) on  i n terms of  the  anticipated that  compounds  since  by  e f f i c i e n t precursors  s u l f o x i d e i n low  can  "soft"  greatly i n demonstrated impart  coordination  s u l f o x i d e s when a t t a c h e d a n c  *  The genation metal d  was  labile  ligands  concentration.  that  should  In a reducing  be  s u l f u r donors f o r supporting  sulfur d if  A c o n s i d e r a t i o n was  /  5  o  and  [Fe(DMSO)(CN) ]  i n R h ( I ) - s u l f o x i d e c o m p l e x e s , and catalytic  3 '  homogeneous h y d r o -  backbonding, s i m i l a r to that observed  [Ru(DMSO)(NH ) ] 3  readily  t h e hope in  TT |  behaviour.  5  c  , m i g h t be  might favourably  of  environment,  to rhodium complexes.  e m p h a s i z e d i n c h a p t e r 1.  IT  to  to c h l o r o - s u l f o x i d e complexes  i s also a useful precursor p o t e n t i a l of  as  [RhC£(ethylene)^]^ w e r e  2 RhC^^^O  class  sites.  "harder" e l e c t r o n donors such  2  (b),  electrons.  this  the m e t a l can  other  [RhC£(cyclooctene)^\  t h e s e compounds c o n t a i n  displaced  in d  I n c h a p t e r 3 i t was  would encourage s u l f u r bonding of The  rich  However l i g a n d s around t h e s e i o n s  to  i s a class  m o r e p o s i t i v e , b o r d e r s on  e l e c t r o n i c behaviour.  Bases  prefer coordination  " s o f t " s u l f u r atom o f a s u l f o x i d e l i g a n d .  R h ( I I I ) , which i s smaller  and  significant  influence  their  that  -90-  4.1.2.  Experimental Synthetic procedures  and s o l u t i o n measurements i n v o l v i n g R h ( I )  complexes were conducted  under an argon  DMSO a d d u c t s w e r e m u l l e d  i n a g l o v e b a g under d r y A r .  w i t h 0.1% w a t e r phine oxides phosphines the product  atmosphere.  A l l the Rh(I)The i s o p r o p a n o l  was u s e d a s s u p p l i e d b y F i s h e r Chem. Co.. T h e p h o s -  (OPPh2Me,OPPhMe2,0PPhEt2) w e r e p r e p a r e d  i na slight into  recrystallizing  excess  by o x i d i z i n g t h e  o f h o t , d i l u t e H2O2, a n d t h e n  extracting  CECH^, d r y i n g o v e r MgSO^, r e m o v i n g t h e s o l v e n t , a n d from  EtOH.  Infrared data refer  t o N u j o l m u l l s u n l e s s o t h e r w i s e s t a t e d . NMR  s p e c t r a l d a t a g i v e n t o 3 d e c i m a l s w e r e a c q u i r e d o n a U.B.C.-made 270 MHz s p e c t r o m e t e r  c o n s i s t i n g o f an Oxford  magnet i n t e r f a c e d  to a Nicolet  Instruments  superconducting  1080 computer.  P r e p a r a t i o n o f t h e Complexes 4.1.2.01. RhC£ L ;L=DMSO,DMSO-d ,TMSO,MPSO,R-MPTSO 3  3  RhC^^^O i n 3 m l 2-propanol  6  (0.2 g , 0.76 mmol) w a s d i s s o l v e d a n d s t i r r e d a n d 0.6 m l ^ 0 .  When L (2.28 mmol) was a d d e d , t h e  s o l u t i o n t u r n e d from r e d t o y e l l o w w i t h i n one hour. o f t e n formed i n i t i a l l y , pensions and  but with stirring  o f yellow product.  f o r 30 m i n  Brown  suspensions  these were converted t o sus-  S o m e t i m e s s o l u t i o n s f o r t h e L=DMS0,DMS0-d^,  TMSO s y s t e m s r e m a i n e d c l e a r , a n d d e p o s i t e d o r a n g e c r y s t a l s  80-95%) o n s t a n d i n g o v e r n i g h t .  T h e L=MPS0 a n d MPTSO s y s t e m s  f i n e y e l l o w powders on s t i r r i n g  f o r 18 h ( 9 0 % y i e l d ) .  f i l t e r e d , washed w i t h 2-propanol complexes can be r e c r y s t a l l i z e d  and e t h e r , and d r i e d from  CH C£ 9  9  (yield,  yielded  The p r o d u c t s i n vacuo.  were  A l l the  by a d d i t i o n o f ether; t h e  -91R-MPTSO a d d u c t i s o b t a i n e d 0.5 m o l e s CH^Cic^. by h e a t i n g  as f e a t h e r y y e l l o w c r y s t a l s i n c o r p o r a t i n g  The compound R h C J i ^ ( D M S O )  0.2 g o f RhCJ> .3H 0 i n 1.0 m l DMSO a t 70° f o r 4 h , a n d 3  2  t h e n a d d i n g 100% EtOH u n t i l T a b l e 4.1 l i s t s Anal.  c a n a l s o be p r e p a r e d  3  the m i c r o c r y s t a l l i n e solid  precipitates.  s o l u t i o n i r d a t a f o r t h e compounds.  (DMSO a d d u c t ) C a l c d  f o r R h C . H , C £ „ 0 S „ : C, 1 6 . 2 4 ; H, 4.09. o  o  F o u n d : C, 1 6 . 3 9 ; H, 4.03. n m r ( C D C £ ) ,  s„ee t a b l e 4.2, f i g u r e 4 . 0 3 ( b ) .  3  n m r ( C D C £ ) , 63.53(s,5,S^-CH^) , 3 . 4 3 ( s , 3 , i m p u r i t y o f R h C £ ( D M S 0 ) ? ) , 2  2  3  3  3.35 ( s , 5 , S - C H ) , 2 . 8 0 ( s , 5 , 0 - S - C H ) . i r , v ( S O ) 1 1 5 0 s , 1 1 3 5 s , 9 3 5 s ; P ( C H ) 3  1032s,996s,977s; Anal.  3  r  3  v(Rh-C£)335s,340m,297m.  (TMSO a d d u c t ) .  Calcd  f o rR h C ^ H ^ C ^ O ^ : C ,  2 7 . 6 2 ; H, 4.63. F o u n d :  C, 2 7 . 6 1 ; H, 4.82. n m r ( C D C £ ) 64.37 (m, 2.6, S-C-H) , 3 . 9 1 ( m , 2 . 0 , S - C - H ) , 3  3.53(m,6,S-C-H+0-S-C-H), 3.03(m,1.3,JD-S-C-H), 2 . 2 9 ( m , 1 2 , S - C - C H " ) . 2  v(SO)1150s,1133s,907s;v(ring)1095m,1075s,1035m,955m,890s,880s;  ir,  (  v(Rh-C£)  345s,318s. A n a l . (MPSO a d d u c t ) .  Calcd  forRhC^H^C^O^:  C, 4 0 . 0 4 ; H, 3.84. F o u n d :  C, 3 9 . 6 5 ; H, 3.72. n m r ( C D C £ ) . 6 8 . 1 - 7 . 4 ( m , 1 5 , p h e n y l ) ; r e s o n a n c e s o f 3  S^-CH : 4 . 0 3 ( s , 1.2) , 3 . 9 6 ( s , 0 . 8 ) ,3.91 ( s , 0 . 5 ) , 3 . 8 4 ( s , 1.2) , 3 . 7 6 ( s , 1.1) , 3  3.68(s,l.l);  resonances o f 0-S-CH^  2.86(s,0.4),2.80(s,0.3),2.72(s,1.8),  2.52(s,0.2).  i r , v ( S O ) 1 1 5 0 s , 1 1 4 0 s , 9 3 0 s ; p ( C H ) 9 8 7 s , 9 7 2 s , 9 5 7 s ; v(Rh-C£) r  3  352s,317s. Anal.  (R-MPTSO a d d u c t ) C a l c d  H, 4.34.  forRhC^H^C^O^.-0.5CH C£ : 2  2  C,  41.18;  F o u n d : C, 4 0 . 4 3 ; H, 4.28. n m r ( C D C £ ) . 6 8 . 0 - 7 . 2 ( m , 1 2 , p h e n y l ) ; 3  5.2(s,l,CH C£. ); 3.86 (s , 3 , ^ - C H ) , 3. 58 (s ,3 ,S-CH ) , 2.80 (s ,3 ,C>-S-CH ) ; 2.38 2  (s,3,C-CH ). 3  2  3  i r , . v(SO)1156s,933s;  3  p (CH )960s;v(Rh-C£)354s,310m. r  3  3  -92-  4.1.2.02  RhC£ (DMSO) (0=L); (0=L)=dimethylformamide, N - f o r m y l p i p e r i d i n e 3  2  RhC£ (DMSO) 3  ( 0 . 1 5 g , 0.34 mmol) was d i s s o l v e d a n d s t i r r e d  3  a t 50°C i n a s t o p p e r e d 1.5 m l 0=L.  tube c o n t a i n i n g 4 m l 1 , 2 - d i c h l o r o e t h a n e and  A f t e r t h e s o l u t i o n was c o n c e n t r a t e d  e t h e r was s l o w l y a d d e d t o o b t a i n o r a n g e c r y s t a l s Anal.  (DMF a d d u c t ) C a l c d  forR h C ^ g C ^ O ^ N :  t o 2 m l under vacuum, (50% y i e l d ) .  C, 1 9 . 1 6 ; H, 4.36; N, 3.19.  F o u n d : C, 1 9 . 2 7 ; H, 4.47; N, 3.27. n m r ( C D C £ )  6 8 . 2 7 ( s , 1 , 0 - C - H ) , 3.646  3  (s,6,S-CH ), 3.447(s:,6,S-CH ),3.11(s,3,N-CH ),3.08(s,3,N-CH ). 3  3  1635s; v(SO)1148s,1135m; Anal.  (NFP a d d u c t ) .  for4 h  3  3  i r , v(C0)  v(Rh-C£)354s,338m,295m.  Calcd f o rRhC^H^Cic^O^N:  F o u n d : C, 2 5 . 3 5 ; H, 4.84; N, 2.93.  nmr  C, 2 5 . 0 9 ; H, 4.84; N, 2.92.  (CDC«, ), 3. 3 0 ( s , 1,0-C-H); 3  3.647  ( s , 6 , S - C H ) , 3 . 4 3 7 ( s , 6 , S - C H ) . i r , v ( C O ) 1 6 2 0 s ; v ( S O ) 1 1 4 5 s , 1 1 3 2 s ; (Rh-C£) 3  3  355s,333m. 4.1.2.03  RhC£ (DPSO) (HOCH(CH ) ) 3  2  RhC£ ?3H 0 3  2  3  2  ( 0 . 0 5 0 g , 0.19 mmol) was d i s s o l v e d a n d s t i r r e d  2 - p r o p a n o l f o r 30 m i n u t e s .  The brown-orange p r o d u c t p r e c i p i t a t e d a few  m i n u t e s a f t e r t h e a d d i t i o n o f 0.14 g ( 0 . 5 7 mmol) o f DPSO. was s t i r r e d  i n 1 ml  The s u s p e n s i o n  f o r 4 h o u r s , f i l t e r e d , washed w i t h 2 - p r o p a n o l and e t h e r , and  dried  i n vacuo  Anal.  Calcd  (70%).  f o r R h C ^ H ^ g C J ^ O ^ : C, 4 8 . 1 2 ; H, 2.99.  H, 3.26. n m r ( C D C £ )  68.2-7.4(m,20,phenyl);  3  (broad s i n g l e t , 3 , C H ) , 1.22(d,3,CH ). 3  3  ir,  F o u n d : C, 4 7 . 9 9 ;  4.05(m,0.5,methine),2.3-1.9 v(OH)3400w;v(SO)1147m,936s;  v(Rh-C£)350s. 4.1.2.04  [(NPSO) H][RhC£ (NPSO) ] 2  4  2  ( a ) R h C £ ^ - 3 H 0 ( 0 . 1 6 g , 0.72 mmol) was d i s s o l v e d a n d s t i r r e d i n 9  -93-  2 m l d e g a s s e d 2 - p r o p a n o l f o r 30 m i n u t e s .  The s o l u t i o n l i g h t e n e d  r e d - o r a n g e when 0.29 m l NPSO ( 2 . 5 mmol) was  added.  v o l u m e was r e d u c e d t o 1 m l u n d e r vacuum; a d d i t i o n hexane p r e c i p i t a t e d washed w i t h  an orange m i c r o c r y s t a l l i n e  hexane and d r i e d  recrystallization.  i n vacuo.  Y i e l d , 40%.  After  to  1 day t h e  of 3 ml degassed  solid  t h a t was  filtered,  Use o f CHCi^/hexane a l l o w e d  C a l c d f o r R h C ^ H ^ C J c ^ O ^ : C, 3 6 . 8 2 ;  H, 7.28. F o u n d : C, 3 6 . 6 7 ; H, 7.24. n m r ( C D C £ )  6 4 . 3 - 3 . 3 (m,8,:S_-C-H) , 3.1  3  (m,8,0-S-C-H), 1.88(m,16,S-C-C-H), 1.1(m,24,S-C-C-C-H). i r , v ( S O ) 1 1 2 2 s ; v ( S - O - H - O - S ) 1 6 0 0 - 1 1 0 0 mb,880-600 s b ; v(Rh-C£)3.50 m, 3 3 7 s ; s e e f i g u r e 4.07. (b) A s o l u t i o n o f R h C £ ' 3 H 0 ( 0 . 1 g , 0.38 mmol) i n 0.15 m l c o n 3  centrated  HC£ a t 70°C was c o o l e d t o 25°C b e f o r e 0.75 m l (5 mmol) o f NPSO  were added. washed w i t h Yield,  4.1.2.05  The o r a n g e c r y s t a l s t h a t a little  65%.  The  2  formed over 5 hours were  filtered,  2 - p r o p a n o l , a i r - d r i e d , and r e c r y s t a l l i z e d as above.  Spectral  data agree with  t h o s e g i v e n above i n ( a ) .  [H(DMS0) J[RhC£ (DMSO) ] 2  4  2  m e t h o d o f H e n b e s t e t a l . was u s e d t o p r e p a r e t h e compound a s  orange-red c r y s t a l s .  n m r ( D 0 ) . 6 3 . 5 6 ( s , 4 . 2, t r a n s - [ R h C J t ^ ( D M S O ) ( D 0 ) ]~) , 2  2  3.50(s,4.0,trans-[RhC£ (DMSO) ]~), 2 . 7 0 ( s , b r o a d , 1 6 , f r e e DMSO). i r , v ( S 0 ) 4  2  1 1 2 5 ; v ( S - 0 - H - 0 - S ) 1 6 0 0 - 1 1 0 0 mb, 9 0 0 - 6 0 0 s b ;  p^(CH )1020s,972m;v(Rh-C£) 3  3 5 0 s , 3 3 6 s ; s e e f i g u r e 4.08. 4.1.2.06  [NEt ][RhC£ (DMSO) ]  After  4  4  2  R h C £ ( D M S O ) ( 0 . 0 6 7 g , 0.15 mmol) a n d N E t C £ 3  3  4  ( 0 . 0 2 5 g , 0.15  mmol) w e r e warmed a t 40°C f o r 30 m i n u t e s i n C H C £ , s o l v e n t ?  ?  was pumped  -94-  off until  an orange p r e c i p i t a t e  0°C a n d t h e n f i l t e r e d . yielded RhC  1 2  H  The m i x t u r e was c o o l e d t o  Recrystallization  a microcrystalline 3 2  formed.  solid.  from h o t CH C£ /ether 2  Yield,  70%. A n a l . C a l c d . f o r  C £ N 0 S : C, 2 7 . 1 3 ; H, 6.07; N, 2.63. 4  2  2  F o u n d : C, 2 7 . 2 5 ;  2  H, 6.0; N, 2.50. n m r ( D 0 ) 6 3 . 54 ( s , 6, S_-CH ); 2. 67 ( s , 6 , f r e e DMSO); 3.19 2  3  ( q , 8 , N - C H ) , 1. 2 5 ( t , 1 2 , N - C - C H ) . n m r ( C D C £ ) 3 . 4 3 ( s , 12,S-CH,,); 2  N-CH), 1 . 3 1 ( t , 1 2 , N - C - C H ) .  2  i r , v(SO)1140s;  3.26(q,8,  (C^) 1017m, 979m, 935m;  v(Rh-C£)345m, 3 3 5 s . 4.1.2.07 [P.S.H ] [ R h C £ ( D M S 0 ) ] ; P . S . = " P r o t o n S p o n g e " , 4  1,8-bis-  2  (dimethylamino)naphthalene [H(DMS0) ][RhC£ (DMSO) ] 2  4  2  a d d i n g 11 mg P r o t o n Sponge. the  (29 mg) was d i s s o l v e d  H, 5.07; N, 4.54.  2  by  t h a t f o r m e d when  i n v a c u o was f i l t e r e d ,  washed  with  A n a l . C a l c d f o r R h C , H C £ , N 0 S : C, 3 5 . 0 7 ; 18 31 4 2 2 2 0  0 1  o  o  o  F o u n d : C, 3 5 . 1 3 ; H, 4.96; N, 4.52. n m r ( D 0 )  67.9  2  (m,6,aromatic H ) ; 3.14(s,12,N-CH ); 3  3.57(s,6,^-CH^), 2.70(s,6,free  DMSO). n m r ( C D C £ ) 8 . 0 - 7 . 5 ( m , 6 , a r o m a t i c H ) ; 2  2  The o r a n g e p i n k p r e c i p i t a t e  s o l v e n t was g r a d u a l l y r e m o v e d  e t h e r , and a i r d r i e d .  i n 5 ml CH C£  2  3.29(d,J=2Hz,12,N-CH ); 3  3.47(s,12,S-CH ). 3  4.1.2.08  [RhC£(DPS0) J 2  2  To t h e r e d s o l u t i o n ,  o b t a i n e d by s t i r r i n g  RhC£ *3H 0 3  2  ( 0 . 1 g, 0.38  mmol) i n d e g a s s e d 2 - p r o p a n o l ( 1 . 5 m l ) a n d w a t e r ( 0 . 4 m l ) f o r 30 m i n u t e s , was a d d e d DPS0 ( 0 . 2 7 g , 1.3 m m o l ) . crystals  after  The r e s u l t i n g  s t a n d i n g f r o m 8 t o 24 h o u r s .  solution  The p r o d u c t was  u n d e r A r , washed w i t h d e g a s s e d 2 - p r o p a n o l and d r i e d 65%.  deposited red  i n vacuo.  filtered Yield,  An a t t e m p t a t r e c r y s t a l l i z a t i o n f r o m d e g a s s e d CH C£ /ether 0  o  -95-  y i e l d e d brown, p a r t i a l l y crystals of R h ^ g H ^  oxidized product.  Anal. Calcd f o r red  C J t ^ O ^ : C, 5 3 . 0 9 ; H, 3 . 7 1 ; C £ , 6.53.  C, 5 2 . 9 8 ; H, 3.83; C£, 7.32. i r ,  Found:  v(SO)1101s; v(phenyl)1068s;  v(Rh-C£)<250.  4.1.2.09 [RhC£(DPS0) ( c y c l o o c t e n e ) ] ( a ) [RhC£(cyclooctene)^]2  ( 0 . 1 g , 0.14 mmol) was a d d e d  to a  d e g a s s e d s o l u t i o n o f DPSO ( 1 . 2 g , 6 mmol) i n 3 m l CH^CJt^ •  After  8 m l o f d r y E t O H w e r e a d d e d , t h e s o l u t i o n was warmed t o 35°C, a n d was c o n c e n t r a t e d b y e v a c u a t i o n u n t i l a y e l l o w p o w d e r f o r m e d . The a i r sensitive microcrystalline solid -10°C was f i l t e r e d Anal. Calcd  obtained by c o o l i n g t h e m i x t u r e a t  under A r , washed w i t h d r y EtOH, and d r i e d  f o r Rh„C._H. C£ 0„S„: o  o  C, 5 3 . 2 8 ; H, 5.26.  Found:  i n vacuo. C,  52.97;  H, 5.26. n m r ( C D C £ ) . 6 7 . 8 - 7 . 2 ( m , 2 0 , p h e n y l ) ; 3 . 9 ( m , 4 . o l e f i n i c H ) , 2.00 3  (m,8,C=C-CH), 1.40(m,16,C=C-C-CH). i r , v(C H g  1 4  v(SO)1109s; v(phenyl)1062s;  ) 1180m, 1137m, 1128m,960m,922m,etc.jv(Rh-C£)  (b) [ R h C £ ( D P S O ) ] 2  0.5 m l d e g a s s e d C Y L ^ I ^ ( a ) was f o l l o w e d . yielding (c)  2  (  5 7  m  §)  w  a  s  t o 14 y l c i s - c y c l o o c t e n e i n  D e g a s s e d E t O H ( 0 . 8 m l ) was a d d e d a n d p r o c e d u r e  An o r a n g e o i l  first  [RhC£(DPSO)(cyclooctene)] [RhC£(TMSO)(CgH^^)] was  too a i r - s e n s i t i v e  added  <250.  2  formed but soon  crystallized  .  p r e p a r e d v i a p r o c e d u r e ( a ) b u t was  t o o b t a i n a good a n a l y s i s , i r ,  v(S0)1118s," v ( C g H ^ ) 4  1175m,1135m,etc.;v(Rh-C£)<250. ( d ) P r o c e d u r e ( a ) was a t t e m p t e d u s i n g An a i r - s e n s i t i v e  [RhC£ ^ 2 ^ ) 2] 2  a  n  a  DPSO.  compound c o n t a i n i n g b o t h c o o r d i n a t e d C2H^ ( i r 1 2 1 7 s ,  9 9 7 s ) a n d D P S 0 ( v ( S 0 ) 1 1 1 3 s ) was i s o l a t e d but- t h e a n a l y s i s c o r r e s p o n d e d  -96-  to  [RhC£(C H ) 2  4  1  •(DPSO)  4.1.2.10 [ R h C £ ( D M S O ) ] 2  Q  ],  ?  2  ( a ) To a d e g a s s e d s o l u t i o n o f e x c e s s s u l f o x i d e of C H C £ 2  2  was a d d e d 0.25 g [RhC£(cyclooctene) ]  2  (1.5 ml) i n 5 ml  . After  filtration  u n d e r A r , t h e s o l u t i o n was c o n c e n t r a t e d t o 1.5 m l ; 10 m l d r y E t O H was a d d e d f o l l o w e d b y 4 m l d r y e t h e r , a n d t h e r e s u l t i n g s o l u t i o n was c o o l e d t o -10°C.  degassed  The v e r y h y g r o s c o p i c a n d a i r - s e n s i t i v e  orange c r y s t a l s were f i l t e r e d  and washed w i t h d r y e t h e r under A r ;  they appear t o o c c l u d e DMSO(v(SO)1020s). A n a l . C a l c d f o r R h „ C H „ . C £ 0 . S , . C „ H , S 0 : C, 1 7 . 9 8 ; H, 4.49. F o u n d : 2 8 24 2 4 4 2 6 0  C, 1 8 . 0 4 ; H, 4.44.  o  n m r ( C D C £ ) , 6 2 . 8 ( s , b r o a d , DMSO). 3  P (CH )1020s,1007s,972s,937w;v(Rh-C£)<250(see r  3  figure  (b) [ R h C £ ( D M S O - d g ) ] was p r e p a r e d b y p r o c e d u r e 2  extremely a i r Rh C D 2  g  2 4  2  4  4  (a) b u t an orange, Calcd f o r  F o u n d : C, 1 5 . 3 4 ; D, 4.00. i r ,  v ( S O ) 1 1 0 9 s , 1 0 9 9 s , 1 0 8 9 s ; 6 ( C D ) 1 0 2 2 m , 1008m; g  v(S0)1101s;  4.01).  a n d w a t e r - s e n s i t i v e powder was o b t a i n e d .  C £ 0 S ; C, 1 5 . 6 7 ; D, 3.91. 2  ir,  3  (CD )820s,767m; 3  ( s e e f i g u r e 4 . 0 1 ) . When t h e m u l l was e x p o s e d t o a i r  v(Rh-C£)<250  i t turned from  yellow  to black i n 3 minutes. 4.1.2.11 [ R h C £ ( D I O S ) ] 2  2  A d e g a s s e d s o l u t i o n o f D I O S . H 0 ( 0 . 2 5 g , 0.92 mmol) i n 5 m l C H C £ 2  2  2  was  a d d e d t o [ R h C £ ( c y c l o o c t e n e ) ] u n d e r A r . S o l v e n t was r e m o v e d u n d e r v a c u u m 2  to y i e l d  a red-brown o i l .  the r e s u l t i n g  2  A f t e r b e i n g washed w i t h degassed e t h e r  l i g h t brown powder was t a k e n up i n 1 m l C H C £ 2  t a t e d by s l o w l y a d d i n g e t h e r . Yield,  T h e p r o d u c t was f i l t e r e d ,  90%. C a l c d f o r R h C £ S 0 C 4  g  1 8  H  3 6  and r e p r e c i p i -  and d r i e d  . H 0 : C , 3 1 . 6 3 ; R, 5.85. 2  2  (3x10 m l ) ,  i n vacuo.  F o u n d : C, 3 1 . 7 6 ;  -97-  1200  1000  WAVE NUMBER  400  fc*T')  F i g u r e 4.01 ( a ) I n f r a r e d s p e c t r u m u s i n g N u j o l m u l l o f [RhC£(DMSO) ] .DMSO. 2  2  "1256 VWtNWMlER  TOo (CM"')  (b) N u j o l mull of [RhC£(DMSO-d ) ] . 6  2  2  -98-  H, 5.70. n m r ( C D C £ ) 3  64. 6-4.0 ( m , 4 , m e t h i n e ) ; 3.9-3. 2 (m,6,_S-CH +S-CH ); 3  2  3.0(s,broad,6,free S-CH ); 2.65(s,broad,8,free S-CH ); 1.45(s,12, 2  3  0 - C - C H ) . i r , v ( 0 H ) 3 6 0 0 - 3 2 0 0 mb; v ( S 0 ) + p ( C H > 1 1 5 0 - 1 0 0 0 s b ; P ( C H > 3  3  r  3  980-950sb,890m;v(Rh-C£)<250. 4.1.2.12  [RhC£(MPS0)(PPh )] 3  2  A d e g a s s e d s o l u t i o n o f m e t h y l p h e n y l s u l f o x i d e ( 0 . 0 9 g , 0.64 mmol) i n 3 ml CH C£ 2  2  was a d d e d t o [RhC£(cyclooctene)^]  Triphenylphosphine added under A r .  ( 0 . 1 1 g , 0.15 m m o l ) .  2  ( 0 . 0 8 3 g , 0.31 mmol) a n d t h e n e t h e r When t h i s  s o l u t i o n was c o o l e d  (15 m l ) w e r e  overnight  a t 0°C a i r  sensitive red crystals deposited.  These were c o l l e c t e d , washed w i t h  e t h e r , and d r i e d i n vacuo.  20%.  CH C£ .(CH CH ) 0: 2  2  3  (CDC£ )  2  Yield,  C, 5 3 . 2 5 ; H, 4.67.  2  for R h ^ g H ^ P ^ ^ O ^ .  F o u n d : C, 5 4 . 0 7 ; H, 4.82. nmr  67.7-6.9(m,40,phenyl); 5.2(s,2,CH C£ );  3  2  2.7(s,broad,6,S-CH ); 1.17(t,6,0-C-CH ). 3  4.1.3  Calcd  3  2  3.43(q,J=7,4,0-CH ); 2  i r , v(S0)1117S;  p (CH )955s. r  3  R e s u l t s and D i s c u s s i o n T a b l e 4.1 l i s t s  synthesized.  s o l u t i o n i r data  f o r some o f t h e compounds  A l l contain sulfur-bonded  purposes of the d i s c u s s i o n of t h e i r  s u l f o x i d es  i n solution.  For  s y n t h e s i s and s p e c t r o s c o p i c  p r o p e r t i e s , t h e compounds c a n b e c l a s s e d a s : 4 . 1 . 3 . 1 . n e u t r a l R h ( I I I ) c o m p l e x e s ; 4.1.3.2. d i p h e n y l s u l f o x i d e c o m p l e x e s ; 4.1.3.3. a n i o n i c Rh(III) 4.1.3.1.  c o m p l e x e s ; a n d 4.1.3.4. R h ( I ) c o m p l e x e s . N e u t r a l R h ( I I I ) Complexes from I s o p r o p a n o l  Solutions  A c o n v e n i e n t p r e p a r a t i o n o f t h e c o m p l e x e s R h C £ L , L=DMS0, DMSO-d^, 3  TMSO, MPSO, a n d R-MPTSO was d i s c o v e r e d  3  during attempts to generate Rh(I)  -99-  complexes from R h C ^ ^ ^ O  and s u l f o x i d e s by u s i n g  isopropanol as  the  ( s e e s e c t i o n 4.1.3.2).  The R h ( I I I )  s o l v e n t and r e d u c t a n t  complexes a r e obtained after  i n high y i e l d s  (80-95%) s i m p l y by c o l l e c t i n g  1 day t h e y e l l o w p r e c i p i t a t e r e s u l t i n g  from the a d d i t i o n o f 3  e q u i v a l e n t s o f s u l f o x i d e t o one o f RhCSc^'^^O, p r e d i s s o l v e d f o r a t least  15 m i n i n i s o p r o p a n o l  compounds ir  The brown  t h a t o f t e n p r e c i p i t a t e i n i t i a l l y , were found by t h e i r  s p e c t r a t o c o n t a i n w a t e r o r i s o p r o p a n o l , b u t on s t i r r i n g  s e v e r a l hours, these stalline on  c o n t a i n i n g 2 0 % V/V w a t e r .  intermediates  a r e converted  over  t o RhCi^L^.  s a m p l e s f o r L=DMS0, DMSO-d^, a n d TMSO w e r e s o m e t i m e s  Crydeposited  l e a v i n g t h e systems t o stand. The  c o m p l e x e s R h C £ L , L=DMS0, DMSO-dg, TMSO, a n d d i e t h y l s u l f o x i d e 3  have been prepared  3  p r e v i o u s l y f r o m h o t aqueous s o l u t i o n s o f NafRhCX,^].  7  8 9 F o r L=DMS0, c r y s t a l l o g r a p h i c a n d i r a n a l y s i s show t h a t i n t h e s o l i d state  the isomer present  i s m e r - R h C & (DMSO) ^ (DMSCD) ( f i g u r e 4 . 0 2 ) , b u t 3  solution  s p e c t r a were n o t examined.  prepared  f r o m i s o p r o p a n o l , o r w a t e r , o r DMSO, a r e d i s s o l v e d i n C H C £  o r Cl^CJc^s band  When c r y s t a l s o f R h C ^ ( D M S 0 ) , 3  t h e i r s p e c t r a show o n l y o n e b r o a d v ( S 0 )  ( s e e t a b l e 4.1).  T h e nmr s p e c t r u m  3  band and one v ( S 0 )  ( t a b l e 4.2, f i g u r e 4 . 0 3 ( b ) )  d i s p l a y s m o r e t h a n t h e t w o DMSO m e t h y l r e s o n a n c e s e x p e c t e d f o r a RhC5- (DMSO)^(DMSO) s p e c i e s . 3  3  raer-  S e l e c t i v e replacement o f t h e oxygen-bonded  s CI  I £\  Rh S ' | "CI  Figure  4.02.  The l o c a l  \ e n v i r o n m e n t o f Rh i n mer-RhC£ (DMS0) (OL).. 3  2  -100T a b l e 4.1  S o l u t i o n I n f r a r e d D a t a f o r Rhodium S u l f o x i d e i n Degassed CH^Cl^. (a) Rh(III)Complexes v(SO)  RhC£ (DMSO) (DMSO) 3  K  114'2[15],929[17]  J  2  R h C £ (TMSO) (TMSO) 3  (c)  3  RhC£ (MPTSO) (MPTSO) 3  2  RhC£ (DPSO) (CH ) CHOH 3  2  3  Av(SO)  1021s,981s,940m  1139[13],928[9]  2  R h C £ (MPSO) (MPSO)  Complexes  (c)  87,-126 117,-94  1147[15],932[12]  968m,957s  102,-113  1154[12],926[10]  969m,959s  109,-119  1145[20],930[18]  2  100,-109  [ (DMSO) H ] [ R h C £ (DMS_0) ]  1127s  [NEt J[RhC£ (DMS0) ]  1138[15]  1018s,1000m,976m 80  1138[15]  1027s,1017m  2  4  4  £  4  2  [P.S.H.][RhC£ (DMS0) ] 4  2  [(NPS0) H][RhC£ (NPS0) ] 2  4  Rh(I)Complexes [RhC£(DMS0) ] 2  ( d )  1127[10],1018[5],933[10]  2  v ( S 0 ) ; under A i r  1100[15],1055[10]  [RhC£(DMS0-d ) ]  80 110,-84  v ( S O ) ; S o l u t i o n under Ar  2  45  1100[20],1053[10]  1140[20],1053[10]  45  [P.S.H][RhC£ (DMS0) ] (e)  1095[15]  1130[20],1056[10]  40  [RhC£(DPS0) l  1125[10]  1045[10]  72  6  2  2  2  2  2  2  [RhC£(DP5K))(CgH )] l4  [RhC£(TMS_0) ( C H g  1 4  )]  1105[15]  2  60  HlOtlO]  2  1133[20],1022[8]  (a)  Bracketed  (b)  D e f i n e d as v ( S O )  (c)  Known t o b e a m i x t u r e o f i s o m e r s ( s e e t e x t ) .  (d)  Measured  (e)  T h i s compound i s d e s c r i b e d for  f i g u r e s g i v e w i d t h o f peak a t h a l f c  o  o  r  d  i  (b)  n  a  t  e  d  s  i n Nujol since this  comparison purposes.  u  l  f  " ( °)free v  o  x  i  d  complex  e  height.  s  sulfoxide-  i s insoluble i n CH C£ . 2  i n s e c t i o n 4.2 b u t i s i n c l u d e d  2  here  89  -101-  DMSO l i g a n d b y o t h e r stereochemistry  o x y g e n d o n o r s , 0=L, w i t h  i n a l l cases  t h e r e t e n t i o n o f mer  ( f i g u r e 4.02, s e e b e l o w ) , a l l o w s t h e  a s s i g n m e n t o f t h e p r o m i n e n t nmr p e a k s o f RhCJl^ (DMSO)^ i n C D C l ^ . The  <53.620 r e s o n a n c e i s a t t r i b u t e d t o DMSO t r a n s  signal  t o DMSO t r a n s  t o C £ , a n d t h e 2.860 s i g n a l t o DMSO ( t a b l e 4 . 2 ) .  A 5% i m p u r i t y o f m e r - R h C £ (DMSO) ,j c o u l d  explain thesmaller  3  r e s o n a n c e s a t 6 3 . 5 0 3 a n d 3.492 ( i n t e n s i t y the  corresponding  could  2:1) o b s e r v e d i n C D C £ , a n d 3  d e g e n e r a t e s i n g l e p e a k a t 63.43 i n CD C£,.,.  This  2  t h a n 2:1, t h a t i s e x p e c t e d f o r mer-RhC£ (DMSO) (DMSO). 3  proportion of this  a t 62.72.  Attempts a t separating  z a t i o n s from CH C£ /ether, 2  failed.  2  "impurity" i nsolution increases  s e v e r a l d a y s , a l o n g w i t h a new s p e c i e s  2  A n a l y t i c a l data,  The  s l o w l y a t 25° o v e r  c o n t a i n i n g DMSC) t h a t  t h e isomers by repeated  resonates  recrystalli-  o r by t h i n l a y e r chromatography on s i l i c a  gel,  a n d t h e f a c t t h a t a d d e d DMSO h a s no e f f e c t o n  s p e c t r a , argue against  Since  methyl  a l s o a c c o u n t f o r t h e o b s e r v e d DMSO/DMSC) i n t e g r a t i o n r a t i o , o f  greater  the  t o DMS0_, t h e 3.435  thepresence o f chloride-bridged  species.  p l a n e s o f s y m m e t r y o f t h e m o l e c u l e make t h e m e t h y l s o f e a c h DMSO  equivalent, methyl inequivalence"^  c a n n o t a c c o u n t f o r t h e e x t r a DMSO  peaks. A u t o i o n i z a t i o n t o [RhC£ (DMSO) ] [RhC£ (DMSO) ]~, +  2  4  observed f o r the analogous dimethyl consistent with  t h e nmr d a t a .  4  sulfide  Curiously,  103  2  similar  t o that  (DMS) complex"'""'", i s a l s o n o t Rh ( I = % ) c o u p l i n g  t o methyl 12  p r o t o n s i s o b s e r v e d f o r t h e DMS c o m p l e x r e p o r t e d not  f o r thecorresponding T a b l e 4.2 p r e s e n t s  estimates  a s mer-RhC£.j (DMS)  3  , but  DMSO o n e . nmr d a t a  f o r the associated  f o r r e a c t i o n 4.1 i n CDC£.j a n d r o u g h  equilibria  constants,  ^.  A l l equilibria  w e r e shown t o b e e s t a b l i s h e d b y w a r m i n g t h e s o l u t i o n s a t 40°C f o r 30  -102-  minutes.  A d d i t i o n o f 0=L h a s l i t t l e  to t h e p o s s i b l e mer-RhC£ (DMSO) 3  i n f l u e n c e on t h e peaks  impurity  3  (see f i g u r e  assigned  4.03).  4 1 v — - — m e r - R h C £ (DMSO) (0=L)+DMSO ( 4 . 1 ) K  mer-RhC£ (DMS0) (DMSO)+0==L 3  1  2  3  NMR s p e c t r a o f t h e i s o l a t e d OL  i s DMF,  compounds, m e r - R h C £ ( D M S O ) ( 0 = L ) , w h e r e 3  2  N F P ( N - f o r m y l p i p e r i d i n e ) , a n d P y N 0 ( p y r i d i n e N - o x i d e ) , show  o n l y t h e e x p e c t e d two e q u a l l y fold  2  i n t e n s e , DMSO m e t h y l r e s o n a n c e s .  A  thirty  e x c e s s o f e a c h o f t h e w e a k e r d o n o r s , DMA a n d 0 P P h M e , r e f l u x e d 2  RhC£ (DMSO) 3  3  i n l^-CpH^CJ!^  y i e l d s m i x t u r e s o f t h e tris-DMSO  d e s i r e d bis-DMSO c o m p l e x e s .  with  and t h e  No r e a c t i o n w a s o b s e r v e d w i t h l a r g e  excesses  of 0 P P h , 0 SMe , and 0 P ( 0 E t ) 3  2  2  3  I n g e n e r a l , t h e 0=L l i g a n d s c a u s e g r e a t e r s h i f t s resonances  than i nthe trans.  i n t h e cis-DMSO  The d i a m a g n e t i c s h i e l d i n g o f t h e c i s -  DMSO m e t h y l g r o u p b y t h e p h e n y l s o f c o o r d i n a t e d O P P h ^ l e i s g r e a t e n o u g h t o a l l o w t h e unambiguous assignment  o f t h e u p f i e l d m e t h y l peak t o t h e  c i s - D M S O i n t h e m e r - R h C £ (DMSO) (OL) c o m p l e x e s . 3  t h e DMSO m e t h y l s  2  t r a n s t o 0=L m i g h t  The c h e m i c a l s h i f t s o f  be e x p l a i n e d by a t r a n s - d i r e c t e d  s h i e l d i n g o f t h e s e m e t h y l p r o t o n s b y t h e 0=L l i g a n d .  Indeed  shielding  chemical  o f t h e s e m e t h y l p r o t o n s , as judged by t h e i r  c o r r e l a t e s r o u g h l y w i t h t h e oxygen donor  t h e amount o f shift,  13 s t r e n g t h o f 0=L : DMA<DMF<  OPPhMe =0PPhEt =DMSO<OPPh Me=NPSO<OP(nBu) <PyNO ( s e e t a b l e 4 . 2 ) . 2  2  2  3  By  14 a n a l o g y , t h e d o w n - f i e l d DMSO m e t h y l p e a k o f I r C £ ( D M S O ) ( D M S O ) 3  2  63.66 c o r r e s p o n d s t o DMSO t r a n s t o DMSO^, a n d t h e o t h e r a t 3.56, trans t o C L  at t o DMSO  Table 4.2 (a) 4.L H nmr data f o r RhCl (DMSO). + OL 3 DMSO DMSO trans t o OL OL c i s to OL l  RhCH. (DMSO) „ (OD+DMSO  V  DMSO  63.620  DMA  3.67(+0.05)  (4.1)  Peaks o f c o o r d i n a t e d OL  63.435  (b) 4.1  62.860  3.49(+0.055)  3.17,3.08(s,N-CH )  0.01  3  1.68(s,C-CH ) 3  NFP  3.647(+0.027)  3.5(m,N-CH ) ,1.7(in,CH )  3.437(0.0)  2  2  0.2  8.30(s,H-C=0) DMF  3.646(+0.026)  3.11,3.08(s,N-CH )  3.447(+0.012)  0.8  3  8.27(s,H-C=0) OPPhMe  3.63(+0.01)  2  2.11,J _ =14  3.4K-0.025)  p  (d,P-CH )  H  3  0.3  7.5-7.9(m,phenyl) OPPhEt„  3.63(+0.01)  — toi * i  2.2-1.7(m,CH )  3.43(0.0)  2  1.14,J=8(t,CH ),7.5-7.9 3  (m.phenyl) OPPh Me  3.62(0.0)  2  2.54,J _ =14(d,CH )  3.29(-0.145)  p  H  3  0.05  7.5-7.9(m,phenyl) OP(nBu),  3.58(-0.04)  3.37(-0.065)  2.0- 1.5(m,CH )  0.6  2  0.9,J=7(t,CH ) 3  NPSO  3.62(0.0)  3.43(0.0)  3.1- 2.5(m,S-CH ) 2  0.9  2.0-1.8(m,-C-CH -) ,1.07, 2  J=7(t,CH ) 3  PyNO  3.57(-0.05)  3.5K+0.075)  9.0(m,ortho)  100  7.85,7.50(m,meta,para) (a) Measured i n CDC*., using the peaks of RhClj (DMSO) as an I n t e r n a l standard. Frequency s h i f t s from these peaks t o corresponding peaks of ,RhCj> (DMS07 (OL) a r e given i n parentheses. A l l the s p e c t r a contain the "contaminants" of m e r - R h « 3 ( D M S O ) at 63.503 and 3.492 (see f i g u r e 4.03). (b) The value i s c a l c u l a t e d from one spectrum and i s a c c u r a t e to ±50%. 3  2  3  2  o <0I  0  o  (01  031  5 z> Q  Q  1  *  UJW  Q  LLQ  O toi  aico  I  co z <  DC5  Z>  Q  I CO  DC  z < cr  r  I CO  CO  LL  LUO  Q  UjQ  o  LUO LUCO  ecu U-Q  O col Q  I  co o (D  CM  0. 0-  Ol ft  LA w.  y  3.620 3.435 2.860  (a)  (C)  (d)  F i g u r e 4.03. 63.8-2.3 r e g i o n o f 100 MHz H nmr s p e c t r a u s i n g CDC£ o f (a)RhC£~(DMS0)„+3DMF "e Scale ( b ) R h C £ ( D M S O ) ( c ) R h C £ ( D M S O ) +2 0 P P h M e (d)RhC£ (1)MS0) + 4 . 5 O P P h M ~ m a r k s c o r r e s p o n d t o t h e p e a k s o f RhC£.j(DMSO)^ a t 63.620, 3.435, a n d 2. J  J  3  3  3  3  2  3  3  2  i  8  6  0  -105-  In a l l cases t h er a t i o  o f m e t h y l peak i n t e g r a t i o n s  s u l f u r b o n d e d DMSO t o t h e o x y g e n - b o n d e d DMSC) p l u s 2.0.  Strong donors  as w e l l a s g r e a t e r  such as PPh^, p y r i d i n e , t h a n 1:1 e x c e s s e s w i t h  0 P ( n B u ) , PyNO, a n d NPSO, d i s p l a c e 3  f o r the  f r e e DMSO was  p i p e r i d i n e , and NEt^,  r e s p e c t t o Rh o f  some DMSO a s w e l l a s DMSO f r o m  RhC£ (DMSO) . 3  3  Replacement have t h e s o l i d  o f DMSO i n R u C £ ( D M S O ) ( D M S O ) , 2  state  some 0=L l i g a n d s  aids  3  stereochemistry depicted i nexplaining  tetrakis(dimethylsulfoxide)  which  i s known t o  i n f i g u r e 4.04 "', b y 1  t h e c o m p l e x nmr s p e c t r u m o f the.  complex  ( t a b l e 4.3, f i g u r e  4.05).  s CI. I  Cl'j  o Figure  4.04.  The l o c a l environment RuC£„(DMS0)..  The i n s i t u RuC£ (DMS0) (DMF) complex a p p e a r s 2  3  stereochemistry with 63.52 ( t r a n s  t h r e e DMSO r e s o n a n c e s  o f t h e Ru i n  t o have t h e e x p e c t e d  o f equal i n t e n s i t y a t  t o DMF), a n d 3.43 a n d 3.32 ( t w o s e t s  m e t h y l s b o t h c i s t o DMF). disproportionate  Thus R u C £ ( D M S O ) 2  i n t o other isomers with  4  of inequivalent  i n CDC£  3  appears t o  t h e cis-RuC£ ( D M S O ) (DMSC))  i s o m e r a p p e a r i n g a t 6 3 . 4 9 , 3 . 4 3 , a n d 3.32.  2  The l a s t  3  two peaks a r e  s h i f t e d a s e x p e c t e d t o 63.38 a n d 3 . 2 8 , r e s p e c t i v e l y , f o r t h e OPPhMe  -106-  T a b l e 4.3 1  ( ) a  H nmr d a t a  f o r RuC£ (DMSO) +0=L*=RuC£ (DMSO) 2  4  2  (OL)+DMSO  (4,2)  OL  DMSO t r a n s t o OL  DMSO  3.49[4.1]  3. 43 [.4.1],3.32[3.8]  DMF  3.52(+0.03)  3. 4 3 ( 0 . 0 ) , 3 . 3 2 ( 0 . 0 )  1  3.49(0.0)  3. 3 8 ( - 0 . 0 5 ) , 3 . 2 8 ( - 0 . 04) 3. 49  0.2  3.49(0.0)  3. 2 7 ( - 0 . 1 6 ) , 3 . 2 1 ( - 0 . 11) 3. 49  0.05  0PPhMe  2  0PPh Me 2  DMSO c i s t o 0L  DMSO o f o t h e r i s o m e r s K, „ 4.2 3. 5 2 [ 3 . 1 ] , 3 . 4 3 [ 3 . 3 ]  (a) M e a s u r e d i n CDCJ.3 u s i n g t h e p e a k s o f RuC£ (DMSO)4 internal standards. Frequency s h i f t s from t h e s e peaks t o t h e c o r r e s p o n d i n g peaks o f RuC£ (DMSO)3(0L) a r e g i v e n i n round b r a c k e t s . Square b r a c k e t s g i v e t h e number o f p r o t o n s c a l c u l a t e d f r o m p e a k i n t e g r a t i o n s , (see f i g u r e 4.05). a  2  2  /  s  F i g u r e 4.05.  63.8-2.5 r e g i o n o f 100 MHz  H nmr s p e c t r a  ( u s i n g CDC£ ) o f 3  (a) RuCj> (DMSO)4 + Q>) RuC&2(DMSO)4 ( c ) RuC£2(DMSO)4 + 4 0PPhMe2 (d) RuCJl-CDMSO^ + 4 OPPl^Me. S c a l e m a r k i n g s r e f e r t o t h e peak p o s i t i o n s of ( b ) . 6 D M F  2  -108-  adduct, and to 63.27 and 3.21 for OPPh^Me although these weak donors seem to give another species with peaks at 63.49 and possibly 3.43. Again, for a l l the spectra examined, the ratios of DMSO to (DMS0+ free DMSO) were approximately 3:1. We have confirmed by nmr studies the e a r l i e r observation that the S-bonded ligands of RhC£ (DMSO) 3  3  exchange at different rates'^, and  can now state that i t i s the DMSO trans to DMSO as well as the DMSO of the supposed mer-RhC£ (DMSO) 3  DMSO trans to C£.  3  "impurity" that exchange faster than  In fact the 0-bonded DMSO and the DMSO situated  trans to i t i n mer-RhC£ (DMSO) (DMSO) appear to exchange at approximately 3  the same rate.  2  For example, a f t e r a solution of RhC£ (DMS0) 3  and DMSO-d (0.4M) i n CHC£ 6  3  3  (4x10 M)  i s reacted at 35° for 80 minutes, the yellow  powder that i s precipitated on addition of a large excess of ether  contains  75% DMS0-d trans to DMSO, <5% DMSO-dg trans to C£, and 85% DMS0-d 6  (figure 4.06).  &  The "opposite" product containing DMSO-d, trans to C£, o  and DMSO trans to DMSO, could be obtained using RhC£,(DMSO-d ),/DMSO t  O' CI  Figure 4.06.  CI  The main product from the s e l e c t i v e exchange reaction of RhC£ (DMSO) with DMSO-dg i n CHC£ 3  mixtures.  3  Such " l a b e l l e d " compounds could be useful i n nmr studies of  substitution reactions.  -109-  The  other RhC£ L 3  3  complexes  (L=TMS0,MPS0, a n d R-MPTSO) g i v e i r  and nmr d a t a c o n s i s t e n t w i t h 2 S- a n d 1 0-bonded l i g a n d s .  The s i m i l a r  s p e c t r a o f t h e R-MPTSO c o m p l e x t o t h a t o f R h C X - ( D M S 0 ) s u p p o r t t h e 3  same s t r u c t u r a l two  £>-CH  assignment:  ~*"H nmr r e s o n a n c e s  3  observed.  3  mer-RhC£ (S-MPTSO) (R-MPTSO)^; 3  2  only the  e x p e c t e d f o r t h e S-bonded l i g a n d s a r e  U s e o f r a c e m i c MPSO r e s u l t s  i n a mixture of "multistereo-  i s o m e r s " , R h C ^ ( R - M P S O ) ( R - M P S O ) ( R - M P S O ) , RhC£ (S-MPSO)(R-MPSO)(R-MPSO) 3  etc.,  which  observed.  3  i n t u r n produces  t h e complex s e t o f m e t h y l peaks t h a t i s  F o r t h e TMSO a d d u c t , a r e m a r k a b l e  downfield s h i f t  on c o m p l e x a t i o n i s n o t e d f o r t h e a - m e t h y l e n e p r o t o n w h i c h w i t h r e s p e c t t o a n S-bonded TMSO r i n g  o f 1.6 ppm  i s p r o b a b l y endo  and hence i n c l o s e p r o x i m i t y t o  the metal. Stereochemical assignments based C y, 3  f o r R h C i ^ L ^ , L=TMS0,MPS0,  o n v(Rh-C£) a r e r i s k y b u t w o u l d  favour the f a c isomer  2 i r bands) over t h e m e r ( a p p r o x i m a t e l y  data, at least Attempts  C^y* 3 b a n d s ) .  a n d R-MPTSO, (approximately H o w e v e r nmr  f o r L=R-MPTS0, a r e more c o n s i s t e n t w i t h t h e mer f o r m u l a t i o n .  a t i s o l a t i n g c o m p l e x e s f o r R-TBPTSO a n d S-0TPTS0 w e r e n o t  successful.  4.1.3.2.  D i p h e n y l s u l f o x i d e Complexes  When 3 DPSO a r e a d d e d t o R h C £ ' 3 H 0 p r e d i s s o l v e d 3  fairly  air-stable,  red crystals  are deposited after  best f o r m u l a t e d as [RhC£(DPSO) ] 2  ={=  2  T 2>  h  e  i n wet i s o p r o p a n o l ,  8-24 h , a n d t h e s e a r e  a i r s e n s i t i v i t y of solutions of  R-MPTSO b e c o m e s S-MPTSO when s u l f u r - b o n d e d t o a m e t a l .  -110-  t h i s complex imply v(S_0) a t 1116 cm  1  that Rh(I) i n CH C£ 2  has indeed been produced; a  u n d e r A r i s r e p l a c e d b y o n e a t 1045 cm  2  ( f r e e DPSO) o n e x p o s u r e t o a i r . out  o f t h e CR^Ci^  sumably a s i m p l e  A brown o x i d a t i o n p r o d u c t  1  precipitates  s o l u t i o n a n d shows no v ( C - H ) , a n d t h e r e f o r e i s p r e c h l o r o o x i d e o f Rh.  c r y s t a l s was c o n f i r m e d  t o be Rh(I)  amount o f c i s - c y c l o o c t e n e An  single  The o x i d a t i o n s t a t e o f t h e r e d  when t r e a t m e n t  with a stoichiometric  i n CH^Ci!^ y i e l d e d [RhC£ ( c y c l o o c t e n e ) (DPSO) ] • 2  independent p r e p a r a t i o n o f t h e l a t t e r  complex i s d e s c r i b e d i n s e c t i o n  4.1.3.4. The The  reduction of Rh(III) probably  dimer,  [RhCS.(cyclooctene),,] > 2  occurs  b y r e a c t i o n 4.3, L=DPS0.  has p r e v i o u s l y been prepared  according  t o r e a c t i o n 4.3, L = c i s - c y c l o o c t e n e .  RhCX, *3H 0 + 2 L + ( C H ^ C H O H -> % [ R h C J l L ] 3  2  2  2  + 3 H 0 . + 2HC& + 2  ( C H ^ C O (4.3)  I f d r y i s o p r o p a n o l i s u s e d , t h e r e a c t i o n y i e l d s a b r o w n powder analyzing correctly f o rRhC& (DPSO) (isopropanol). 3  2  s u g g e s t t h a t t h i s powder i s a m i x t u r e DPSC). by  Exchange p r o c e s s e s  a broadening  of isomers  Infrared spectra  c o n t a i n i n g DPSO a n d  involving the coordinated  alcohol are signalled  o f t h e i s o p r o p y l m e t h y l p e a k s i n t h e nmr ( C D C A ^ ) .  compound c o n s t i t u t e s a n i n t e r e s t i n g o f i s o p r o p a n o l by R h C £ . 3 H 0 / D P S O 3  2  intermediate mixtures  i n the  This  dehydrogenation  ( r e a c t i o n 4.3),  b e c a u s e when  t h e p o w d e r i s s u s p e n d e d i n t h e a l c o h o l c o n t a i n i n g 2 0 % V/V w a t e r u n d e r A r , red c r y s t a l s  o f [RhC£(DPSO) ] s l o w l y form. 2  2  The w a t e r a d d e d i n t h i s  r e a c t i o n may e n h a n c e HC& e l i m i n a t i o n a n d c o n s e q u e n t r e d u c t i o n o f t h e Rh(III).  Traces  o f a s i m i l a r a l c o h o l adduct c o n t a i n i n g only  s u l f o x i d e were recovered  u s i n g t h e S-OTPTSO  0-bonded  l i g a n d , but the corresponding  -111-  Rh(I)  adduct could  4.1.3.3. A n i o n i c The  n o t be i s o l a t e d .  R h o d i u m ( I I I ) Complexes  a l k y l c h a i n s o f NPSO may s o l u b i l i z e a n y R h s p e c i e s  formed  i n t h e RhCl^'3H 0/isopropanol  r e a c t i o n b e c a u s e no p r e c i p i t a t e f o r m e d  a f t e r s e v e r a l days.  o f hexane t o a d a y - o l d s o l u t i o n under  2  Ar  precipitated  Addition  [ (NPSO) H] [RhCJ> (NPSO) ] i n l o w y i e l d 2  4  (40%).  2  Equation  4.4 r e p r e s e n t s a p o s s i b l e r e a c t i o n scheme a l t h o u g h no R h ( I ) were detected.  The t e t r a c h l o r o r h o d a t e ( I I I )  RhC£ '3H-0 + 3 NPSO + i ( C H  species  compound c a n b e p r e p a r e d i n  )„CH0H  •|[ ( N P S O ) H ] [ R h C J l ( N P S O ) ] + y " [RhC£ ( N P S O ) ] " + - j ( C H ) C O + 3 H 0 2  better for  yield  4  £  3  f r o m R h C £ ' 3 H 0 i n c o n c e n t r a t e d HC£, a s i n i t i a l l y 3  thepreparation  2  o f t h e DMSO a n a l o g u e ,  2  2  described  [H(DMS0) ][RhC£ (DMSO)^], b y 2  4  Henbest e t a l . ^ , a l t h o u g h these workers d i d n o t r e p o r t  any s p e c t r a l  properties. B o t h t h e NPSO a n d DMSO t e t r a c h l o r o r h o d a t e ( I I I ) surprisingly intense  and broad a b s o r p t i o n  1600-1100 a n d 900-600 cm" by  1  complexes have  bands i n t h e s o l i d  state at  ( s e e f i g u r e s 4.07,4.08) t h a t a r e n o t c a u s e d  t h e anion as evidenced by t h e spectrum o f t h e corresponding  salt.  Salts containing  hydrogen-bonded bases as c a t i o n s  and so a s t r u c t u r e  c a t i o n s was t h o u g h t t o b e [ R S 0 - H - 0 S R ] .  An X-ray c r y s t a l  +  determination now v e r i f i e d is  2  + 4  a r e known t o  cause such broad bands i n t h e s e r e g i o n s " ^ , 2  NEt  of the  structure  o f [H(DMSO)^][RhC£ (DMSO) ] , c u r r e n t l y i n p r o g r e s s , h a s 4  this proposal.  shown i n f i g u r e 4.09.  18  The s t r u c t u r e , r e f i n e d t o R=2.9%, R =3.3%/ w ^  J . . U .1 l-IJ. I  1200 WAVENUMBER ( C M  F i g u r e 4.07.  I n f r a r e d s p e c t r u m o f a N u j o l m u l l o f [H(NPSO) ] [RhCS, (NPSO) ] The o n l y a b s o r p t i o n i n t h e 4 0 0 0 - 1 8 0 0 r e g i o n i s v ( C H ) . 4  1  I  I Mil  6.0  7.0  I I  8.0  I  [ I I I I II  1400  1 II  9.0  I I I I II [ I I  I  1200  I M II I I II  10  I  1 II 1 I I II I  1000  WAVENUMBER (CM ')  12  I  II I M I I II  I  I ! I 1 I I I I!  800  14  16  I  I I I I I I I i I  I  18  20  I II I I I I H  I  600  25  I II I M I II  -  F i g u r e 4.08.  I n f r a r e d S p e c t r u m o f N u j o l m u l l o f [H(DMSO) ] [ R h C l , ( D M S O ) ]  I  400  #  30  35 40  I II M I I I i  I !  -114-  F i g u r e 4.09.  The c o n t e n t s o f a u n i t c e l l i n c r y s t a l l i n e [H(DMS0) ][RhC£ (DMSO) ] i n c l u d i n g s e l e c t e d bond d i s t a n c e s , c o r r e c t e d f o r t h e r m a l l i b r a t i o n s . One c a t i o n i s n o t shown. 2  4  2  1.482(3) 1.783(5)-  /  -1.535(3)  j-1.561(4)  O  -H 2.420(5)^  o  1.765(5)  O  -115-  The  hydrogen b i s ( d i m e t h y l s u l f o x i d e ) c a t i o n  o The  very  of thermal  s h o r t 0—0 d i s t a n c e  (2.42—2.47A d e p e n d i n g on t h e method  motion c o r r e c t i o n ) i s consistent with the presence of a  strong hydrogen b o n d .  D i s t i n g u i s h i n g between a symmetrical  1 7  minimum p o t e n t i a l o r a c l o s e l y the proton  single  s p a c e d d o u b l e minimum p o t e n t i a l f o r  i s n o t p o s s i b l e by t h i s d i f f r a c t i o n study.  19  T h e mean  o  S-0 b o n d l e n g t h , 1 . 5 4 7 ( 1 5 ) A , i s l o n g e r  than that of  c r y s t a l l i n e DMSO(1.531 a t -5°C o r 1.471 a t -60°C) c o n s i s t e n t w i t h p r o t o n a t i o n a t oxygen  20  (see chapter  The  d e c r e a s e i n t h e mean CSO a n g l e  has  a l s o been observed b u t n o t d i s c u s s e d  , and t h i s i s 21 22 1, f i g u r e 1 . 8 ) . '  (104.1±1.6) f r o m f r e e DMSO(107°)  20  i n 0 - b o n d i n g o f DMSO t o t r a n s i t i o n  15 23 metal complexes. or coordinated The and  T h e CSC a n g l e s  a n d C-S l e n g t h s  a r et y p i c a l of free  DMSO (100°,1.78(1) r e s p e c t i v e l y ) . s t a t e i r b a n d s a s s o c i a t e d w i t h t h e c a t i o n s o f t h e DMSO 2  f o r other  is very 1000  compounds w i t h s t r o n g a n d s y m m e t r i c a l  intense, very broad  cm . 1  1  7  2  h y d r o g e n b o n d s , v (OHO)  ( 1 6 0 0 - 6 0 0 cm "*"), a n d c e n t e r e d  a t approximately  A unique feature o f thes u l f o x i d e cations i sthe l o s s o f  v ( S 0 ) , e x p e c t e d a s a b r o a d p e a k a t - 9 5 0 cm  1  t o be c o n s i s t e n t w i t h t h e  r e d u c t i o n i n S-0 b o n d o r d e r t r a n s i t i o n m e t a l c o m p l e x e s w i t h a n S-0 ° 15 23 d i s t a n c e o f 1.54A a b s o r b a t t h i s f r e q u e n c y . ' T h i s may b e e x p l a i n e d by t h e p r e s e n c e o f t h e o t h e r a n o m a l i e s : t h e w i d e " t r a n s m i s s i o n w i n d o w " in  14  NPSO c o m p l e x e s , a s w e l l a s w i t h t h e c a t i o n s o f [ H ( D M S O ) ] [ I r C i ^ ( D M S O ) ] 24 p r o b a b l y H [ IrC£,].4DMS0 , a r e v e r y s i m i l a r (see f i g u r e s 4.07,4.08). o  and As  solid  '  t h e v (OHO) a b s o r p t i o n  e n v e l o p e a t 1100-900, a l o n g w i t h t h e enhanced  3.  i n t e n s i t y o f t h e 9 0 0 - 6 0 0 cm i n t e n s i t y may w e l l r e s u l t  1  r e g i o n : the apparent borrowing of v(S0)  from a Fermi resonance e f f e c t  suggested  1 7  -116-  previously"""' as a p o s s i b l e o r i g i n o f t r a n s m i s s i o n windows a l s o , f o r e x a m p l e , i n [ (DMF) H ] [ P d ^ J l g ]  2 5  2  Direct CHC£ ir  3  spectroscopic observation  or the [H(DMSO) ] 2  +  observed  , and [H(OAsPh ) ] [ H g B r ] .  2  3  2  2  of the [H(NPSO) ] 2  cation i n D 0 i s notpossible. 2  2  +  6  6  cation i n The s o l u t i o n  o f t h e f o r m e r s u g g e s t s t h a t HC£ i s e l i m i n a t e d when t h e t e t r a c h l o r o -  rhodate s a l t  i s dissolved, since  ( t a b l e 4.1). solid  2  T h e DMSO a s s o c i a t e d w i t h t h e c a t i o n o f t h e l a t t e r  s t a t e , a p p e a r s i n t h e nmr a t t h e c h e m i c a l  i n D 0. 2  been  [RhCJt.^(NPSO) (NPSO) ] a p p e a r s t o f o r m  shift  i n the  f o r f r e e DMSO  S o l u t i o n i r e v i d e n c e f o r a 2:1 a d d u c t o f DMSO w i t h HNCS h a s  r e p o r t e Jd .  2  7  Protonated  s u l f o x i d e s have been p o s t u l a t e d a s i n t e r m e d i a t e s i n  the a c i d - c a t a l y z e d decomposition work o n l y  indirect  of sulfoxides  28  ; prior  t o the present  evidence from s t u d i e s i n magic a c i d e x i s t e d f o r  p r o t o n a t i o n a t oxygen.  29  Trans-Tetrachloro-bis(dimethylsulfoxide)rhodate(III) A c r y s t a l s t r u c t u r e o f t h e sodium s a l t has  been communicated by S o k o l  o  of this octahedral  30 et a l . , but the only figures  anion  provided  o  o  w e r e : R=10.3%, R h - S = 2 . 2 2 0 A , R h - S = 2 . 3 6 0 A , a n d Rh-C£=2.320-2.340A. 1  r e a s o n was g i v e n  2  f o r t h e u n e q u a l Rh-S d i s t a n c e s .  In contrast, the  t r a n s DMSO l i g a n d s i n f i g u r e 4.09 a r e r e l a t e d b y a C giving  equivalent  for the other  Rh-S b o n d l e n g t h s  i nthe unit c e l l .  the Russian the  2  a x i s o f symmetry,  o f 2.322(2) f o r one a n i o n  slightly  longer  o f DMSO ( e x c e p t  from  than those  workers. C o n s i s t e n t w i t h t h e i d e a t h a t S-bonding  S-0 b o n d o r d e r  and 2.329(2)  T h e Rh-C£ d i s t a n c e s , r a n g i n g  t o 2 . 3 7 1 ( 7 ) , w i t h a mean o f 2.354, a r e  No  f o r t h e case o f s i g n i f i c a n t  2.331(8)  found by  increases metal  -117-  + s u l f u r d ^ b a c k b o n d i n g ) , t h e S-0 b o n d l e n g t h s , 1 . 4 8 2 ( 3 ) a n d 1 . 4 7 9 ( 3 ) o  are  s h o r t e r t h a n t h a t f o u n d i n f r e e DMSO, 1.531A. In our c r y s t a l ,  octahedra,  although  t h e anions  of the unit c e l l  one i s d i s o r d e r e d .  I texists  are undistorted i n two p o s s i b l e  o r i e n t a t i o n s o f a s q u a r e p l a n a r arrangement o f c h l o r i d e s , one r e l a t e d t o the other  b y a 16° r o t a t i o n a b o u t t h e S-Rh-S a x i s .  bond c h a r a c t e r  i n t h e Rh-S b o n d s d u e t o Rhd  -> Sd -  TT  I f t h e r e were double b a c k b o n d i n g , one TT  m i g h t e x p e c t t h e r e t o b e o n l y o n e o r i e n t a t i o n o f t h e DMSO l i g a n d s with respect  t o t h e c h l o r i d e s where optimum o v e r l a p  could occur;  t h e e x i s t e n c e o f two d i f f e r e n t  arrays with respect against  o f such  orbitals  orientations of thechloride  t o t h e DMSO l i g a n d s o b s e r v e d i n t h i s c r y s t a l  argues  backbonding. o  I n a d d i t i o n , t h e Rh-S d i s t a n c e s o f 2.332 a n d 2.329A a r e much l o n g e r t h a n t h o s e o f some o t h e r Rh-DMSO c o m p l e x e s : e . g . t h e Rh-S t r a n s t o py  ° 31 i n R h C £ ( p y ) ( D M S 0 ) i s 2.283A, a n d t h e Rh-S d i s t a n c e s 3  g  o  and  t r a n s t o DMSO  2  C£ i n R h C £ ( D M S O ) a r e 2.231 a n d 2.254A, r e s p e c t i v e l y . 3  lengthening  3  of mutually  PdC£ (DMS0) 2  32 2  compared  A similar  t r a n s S-bonded DMSO was n o t e d f o r t r a n s to cis-Pd(N0 ) (DMSO) 3  2  2  3 3  Therefore  S-bonded  DMSO a p p e a r s t o e x e r t a s u b s t a n t i a l t r a n s i n f l u e n c e b y w a y o f i t s o 34 bonding  orbitals.  In general  the RhC£ L 3  3  c o m p l e x e s , L=DMSO,TMSO,MPSO, r e a d i l y  react  9 w i t h NaC£ i n H 0 , 2  o r [NEt^]C£ i n C H C £ 2  2  o r water, t o form the anions,  trans-[RhC£ L ] . Other s a l t s o f t h e s e a n i o n s c a n be p r e p a r e d f r o m their [H(R SO) ] d e r i v a t i v e s by adding strong bases, as reported 4  2  2  2  p r e v i o u s l y f o r [H(DMSO) ][IrC£ (DMSO)^ . 2  the noncoordinating  4  1 4  F o r example, a d d i t i o n o f  base l,8-bis(dimethylamino)  naphthalene,  trivially  -118-  called and  Proton  Sponge ( P . S . ) , t o t h e NPSO a n d DMSO Rh a n i o n s , d i s s o l v e d  suspended r e s p e c t i v e l y  i n CH C£ , f o l l o w e d by a d d i t i o n o f e t h e r , 2  2  p r e c i p i t a t e s t h e c o m p l e x , [P.S.H] [ R h C J l ^ ( R ^ O ) ] , w h e r e [P.S.H ] protonated  Proton  i s  Sponge.  S-bonding o f the presumably t r a n s s u l f o x i d e s i s observed all  +  o f these s a l t s  i nthes o l i d  for  s t a t e and i n CR^CJ^ s o l u t i o n .  For  0.05M [RhC£ (DMSO) ]~in D 0 , o n e s u l f o x i d e i s s u b s t i t u t e d b y D 0 i n 4  2  2  2  l e s s t h a n 3 0 s e c o n d s a t 35°C a c c o r d i n g t o e q u i l i b r i u m 4.5. both 1  H  [ R h C £ ( D M S 0 ) ] ~ a n d [RhCl^(DMSO)(D 0)]~ 4  2  nmr s p e c t r u m  2  of the [H(DMS0) ]  '4-' c  cf  are recognized i n t h e  s a l t , by the methyl  +  2  F o r example,  c  p e a k s a t 63.50  S +  D«0  2^  I >CI  D M S O  ^  Rh  +  Cf  I  N  (4.5)  CI  s and  3.56 r e s p e c t i v e l y ; a v a l u e o f  adding  ,.=0.5±0.2M a t 35°C was e s t i m a t e d b y  known a m o u n t s o f DMSO a n d m e a s u r i n g t h e i n t e n s i t i e s a t t h e t w o  chemical s h i f t s .  Thus r e a c t i o n  (4.5)  illustrates  the high k i n e t i c  trans  35 e f f e c t o f S-bonded s u l f o x i d e s . weeks i n aqueous s o l u t i o n . at  The c o r r e s p o n d i n g  a slower r a t e (see chapter  4.1.3.4. The title  The mono-aquated s p e c i e s i s s t a b l e f o r  Rh(I) dimers  routes t o [RhC£L ] 2  of labile  i nCH C£ 2  2  2  aquation  5).  Rhodium(I) Complexes from displacement  I r anions undergo  [RhC£(olef i n ) ] , . , 2  c i s - c y c l o o c t e n e o r ethylene from t h e  by donor l i g a n d s , L, p r o v i d e s  and RhCJlI^complexes  convenient  when L i s a p h o s p h i n e ,  arsine,  -119-  etc..  36  However, even w i t h  r h o d i u m atom, o n l y  a ten fold  [RhC£(olefin)L]^ c o m p l e x e s  w h e r e L i s t h e S-bonded l i g a n d olefin-chiral asymmetric  sulfoxide  induction  by d i f f r a c t i o n  e x c e s s o f DPSO a n d TMSO p e r  (reaction  could  4.6).  Pt complexes, u s e f u l  be  Similar  mixed  i n the study of  (see c h a p t e r 1.3.4), have been  studies.  isolated,  characterized  37  (4.6)  Other s u l f u r - b o n d e d mixed (PPh^)^*  ligand  excess of s u l f o x i d e  a n  ^  i t s DMSO-d^ a n a l o g u e a r e p r e p a r e d by u s i n g  ligand.  The  and a i r - s e n s i t i v e i n t h e s o l i d i s rapidly replaced  was  state;  b y o n e a t 1140  1  consists  CH C£ 2  2  solution  w h i c h must p e r t a i n  i r spectrum of  containing  Rh(II).  [RhC£(DMSO) ] 2  (CH^SO^ disproportionate 38  (table  4.1)  o f p e a k s f o r S - b o n d e d a n d f r e e DMSO, b u t n o t 0 - b o n d e d DMSO. The  i n t e r m e d i a t e between  that  o f f r e e and  a chemical s h i f t  S-bonded l i g a n d , a n d  d i s s o c i a t i o n o f DMSO i s o c c u r r i n g ,  and  this confirms  i t i s f a s t on t h e nmr  time 30  scale. would  Such l a b i l e b e h a v i o u r , n o t o b s e r v e d f o r i n part  trans-PdC^tDMSO^.  account f o r the r e a c t i v i t y of the Rh(I)  cm  to a higher  rapidly  s p e c t r u m i n CDC£.j i s a s i n g l e b r o a d p e a k a t 6 2 . 8 0 ,  that  t h e v ( S 0 ) a t 1100  Formation of sulfone,  likely  an  are extremely hygroscopic  on e x p o s u r e t o 0^,  cm  state, Rh(II) or Rh(III).  t o Rh m e t a l a n d a g r e e n f i l t r a t e  nmr  complexes  not d e t e c t e d . I n degassed w a t e r , the complexes  The  [RhC£(MPSO)-  c a n a l s o be p r e p a r e d .  [RhCMDMSO^^  oxidation  Rh c o m p l e x e s , s u c h a s  complex.  1  -120-  A complex via  f o r m u l a t e d a s [RhC£(DIOS)^]^• ^I^O  the rhodium(I) o l e f i n precursor.  c a n a l s o be prepared  T h i s compound g i v e s no t e r m i n a l -1 40  v ( R h - C d ) a n d n o v ( S O ) w h i c h w o u l d b e e x p e c t e d i n t h e i r a t >250 cm and  - 9 3 0 cm \  r e s p e c t i v e l y , a l t h o u g h v(S_0) a n d v ( S 0 ) o f f r e e  sulfoxide  a r e p r e s e n t ; a s t r u c t u r e c a n be envisaged w i t h " d a n g l i n g " , monodentate DIOS l i g a n d s , a n a l o g o u s  t o t h a t o f m e t a l complexes  w i t h d a n g l i n g DIOP  41 ligands. due  A d e f i n i t i v e i n t e r p r e t a t i o n o f t h e nmr d a t a c a n n o t b e made  t o exchange  p r o c e s s e s t h a t must be o c c u r r i n g , b u t s u l f u r - b o n d e d  species are observed. ligand are very All  Thus R h ( I ) complexes  with this  S-bonded  chelating  labile.  o f t h e R h ( I ) compounds d i s c u s s e d h e r e h a v e b e e n f o r m u l a t e d a s  d i m e r s s o l e l y on t h e b a s i s o f t h e agreement o f such s t r u c t u r e s w i t h t h e a n a l y t i c a l data ( 3 - c o o r d i n a t e Rh(I) i s r a r e ) , and t h e i r s p e c t r a  which  do n o t show t e r m i n a l v(Rh-C£) s t r e t c h e s , n o r m a l l y e x p e c t e d a t >250 cm 4.1.3.5.  The N a t u r e o f R h o d i u m - S u l f u r B o n d i n g  i nSulfoxide  Complexes  S e v e r a l t r e n d s a r e a p p a r e n t f r o m some s p e c t r o s c o p i c a n d s t r u c t u r a l d a t a g i v e n i n t a b l e 4.4 f o r t h e DMSO c o m p l e x e s and  f o r some o t h e r DMSO c o m p l e x e s  order i n c r e a s e s from about the f i r s t complex;  described  i nthis  of the platinum metals.  work  T h e S-0 b o n d  2 (that o f f r e e s u l f o x i d e ) i n t h e F e ( I I ) and  R u ( I I ) compound, t o p r o b a b l y a l m o s t 3 f o r t h e A u C £ ( D M S 0 ) 3  these extremes  s y s t e m s , m e t a l d ^ •>  c a n be r a t i o n a l i z e d  s u l f u r d^ backbonding  I ) a n d c o m p e t e s s u c c e s s f u l l y w i t h o x y g e n P^  s i n c e i n t h e F e a n d Ru i s o p t i m i z e d ( f i g u r e 4.10, s u l f u r d^ m u l t i p l e  w h e r e a s f o r t h e Au s y s t e m , t y p e I I I b o n d i n g i s l i k e l y the greater e l e c t r o n e g a t i v i t y o f A u ( I I I ) .  approached  bonding, due t o  -121-  ©  I  I F i g u r e 4.10.  The o t h e r  The r a n g e o f b o n d i n g modes f o r S-bonded s u l f o x i d e s .  complexes l i s t e d ,  intermediate  type  i n c l u d i n g those  I I bonding w i t h  o f Rh, a r e l i k e l y  l i t t l e metal to sulfur  of  back-  b o n d i n g : g e n e r a l l y i t i s e x p e c t e d t h a t t h e l a r g e r t h e Av(SO) v a l u e , the  stronger w i l l  course,  b e t h e M-S  the stronger  bond  ( a s h o r t e r M-S  t h e S-0 b o n d .  bond) and, o f  T h u s t h e S-M b o n d s t r e n g t h s ,  based  g on A v ( S O ) , f o r t h e n e u t r a l d order  Au(III)>Pt(II)  "hard"  1  : : :  c o m p l e x e s i n t a b l e 4.4 d e c r e a s e i n t h e  Pd(II)>Rh(I)  which i s i n keeping  s u l f u r donor o f s u l f o x i d e s .  with a  The r e l a t i v e l y w e a k  adduct, i n terms of Av(SO), i s probably  relatively  DMSO-Rh(II)  a r e s u l t of the high  trans  i n f l u e n c e o f the metal-metal bond."^ The Rh c o m p l e x e s s y n t h e s i z e d  i n the present  w o r k show t h e e f f e c t  of t h e f o r m a l o x i d a t i o n s t a t e o f t h e m e t a l on v ( S 0 ) .  Neutral  Rh(III)  c o m p l e x e s o f DPSO,TMSO, a n d DMSO ( c f . t a b l e 4.1) a b s o r b i n t h e i r a t 30 t o 40 cm Rh(I)  1  h i g h e r , and p r o b a b l y  adducts.  f o r m s t r o n g e r M-S  The A v ( S O ) s e r i e s :  f o r R h C j i ^ L ^ , a n d 65-85 cm  1  95,108 c m "  f o r [RhCJl^L^]  on v ( S O ) o f c h a r g e on t h e c o m p l e x e s .  1  bonds, than  similar  f o r [ R h C £ L ] , 80,95 2 +  5  , r e v e a l s the expected  cm"  1  influence  -122T a b l e 4.4 Physical  D a t a f o r S u l f u r - B o n d e d DMSO A d d u c t s  Complex  Av(SO)  f r e e DMSO  r(S-0)  ( a )  0  [Fe(CN) (DMS0)]  3 _  r(M-S)^  1.531  2 +  Reference 20  15  5  [Ru(NH ) (DMS0)]  ( b )  5  0  1.53  2.19  4  fac-[RuC£ (DMS0) ]~  45  1.49  2.26  42  cis-RuC£  35,65  1.48  2.27  15  3  5  3  3  (DMSO) (DMSO)  2  3  [RhC£(DMS0) J 2  2  RhC£(C0)(DMSO)  2  [Rh(0Ac) (DMS0)] 2  46  this  52,62  43  31  2  work  44  t r a n s - [ R h C £ (DMSO) ] "  65-85  1.47  2.29  8 , t h i s work  m e r - R h C £ (DMSO) (DMSO)  80,95  1.43  2.24  7 , t h i s work  [RhC£(DMSO) ]  95,108  4  3  2  2 +  5  trans-PdC£ (DMSO) 2  cis-Pd(NO -) (DMS0) 3  2  2  cis-[Pd(DMSO) (DMSO) ]  2  +  45  61  1.47  2.29  32  81,102  1.46  2.24  33  85,95  39,46  45,85  14,chapter 5  t r a n s - [ IrC£ (DMSO) ] ~  70  14,chapter 5  mer-IrC£ (DMSO)  85  14  95  14  2  cis-[IrC£ (DMSO) ]~ 4  2  4  2  (DMSO)  3  IrC£ (DMS^0) 3  3  15 13 2 ( ±>°) cis-PtC£ (DM_SO) I  r ( C  H  0 ) C £  DM  2  2  2  cis-[Pt(DMSO) (DMSO) ] 2  AuC£ (DMS0) 3  +  72  1,45  2.235  47,chapter 5  80,105  1.46  2.235  48  88,99  46  143  49  (a)  A v ( S O ) = v ( S 0 ) - 1 0 5 5 ( f r e e DMSO) i n cm .  (b)  T h e a v e r a g e d S-0 b o n d d i s t a n c e f o r DMSO i n t h e m o l e c u l e ( A ) .  (c)  T h e a v e r a g e m e t a l - s u l f u r d i s t a n c e i n A.  (d)  C  1  1 5  H  1 3  0 i s benzylacetophenone chelated  Data r e f e r  to Nujol  mulls.  t o I r by oxygen and b e n z y l . carb  -123-  4.2  Reactions of Rhodium-Sulfoxide t o Form M e t a l - H y d r i d e  4.2.1.  Complexes w i t h Hydrogen;  Complexes.  Introduction  Metal-hydride formation i s a c r u c i a l homogeneous h y d r o g e n a t i o n .  T h u s i f a Rh  to undergo such a r e a c t i o n ,  i t has  t h e modes o f H  heterolytic  2  (2) o x i d a t i v e  X=H,C£,etc.  The  catalyst. complexes  (1) b a s e - p r o m o t e d  c f . e q u a t i o n s 1.05,1.08 i n  addition  > [Rh(III)-H]~ + H  2  ( r e a c t i o n 4.8,  R h ( I ) + H X ->•  4.2.2  as a p o t e n t i a l  f r o m R h ( I I I ) and R h ( I )  ( e q u a t i o n 4.7,  2  Rh(III) + H  o f HX,  s u l f o x i d e complex i s observed  a d d i t i o n d i s c u s s e d i n c h a p t e r 1.3:  cleavage of H  f i g u r e 1.5);  step i n metal-catalyzed  promise  H y d r i d e c o m p l e x e s can be g e n e r a t e d by  Attempts  c f . equations  (4.7)  +  1.12,1.15).  Rh ( I I I ) (X) (H)  (4.8)  Experimental  Heterolytic  4.2.2.1 DMA,  Cleavage  of Hydrogen  R e a c t i o n s o f RhC&^L^: H y d r o g e n u p t a k e s  by  solutions with dry  o r 1 , 2 - 0 2 ^ 0 ^ 2 d r i e d w i t h P 0,-,as s o l v e n t s , w e r e m e a s u r e d a c c o r d i n g 2  to the procedure  d e s c r i b e d i n c h a p t e r 2.  (dimethylamino)naphthalene 4.2.2.2 2  uptake  0.21  mmol) and  sublimed before  use.  [P.S.H] [RhCJt.,, (DMSO) Q] :  P r e p a r a t i o n of  the H  was  P r o t o n Sponge ( P . S . ) , 1 , 8 - b i s -  o f a 1,2-C H CJt2  4  2  solution  (5 m l )  P r o t o n Sponge ( 0 . 0 4 6 g , 0.21  D u r i n g t h e measurement of of RhC£ (DMSO) 3  mmol) a t 30°  a i r - s e n s i t i v e y e l l o w p r e c i p i t a t e formed a f t e r  50 m i n u t e s .  and  3  (0.095  1 atm,  The  g,  a very  same compound  -124-  c a n a l s o be p r e p a r e d b y f i r s t s u s p e n s i o n o f 0.19 and t h e n s t i r r i n g occasionally p e n s i o n was  a d d i n g 0.10  g RhC£ (DMSO) 3  3  g P.S.  i n 3 ml CH C& 2  the s o l u t i o n v i g o r o u s l y  t o a degassed 2  then f i l t e r e d  A f t e r l h the sus-  under A r .  The  washed w i t h 1 m l c o l d , d e g a s s e d C H C £ , and d r i e d 2  20%.  A n a l . C a l c d f o r RhC  Found:  C, 3 9 . 2 1 ; H,  g  5.73;  H  compound  i n vacuo.  2  C £ N 0 S : C, 3 9 . 6 3 ; H, 2  N,  2  4.83.  2  atm,  f o r 40 m i n u t e s , a l t h o u g h  t h e compound d o e s n o t p r e c i p i t a t e . c o o l e d , and  a t 30° a n d 1  Yield,  5.73; N,  2  nmr(CDCJ^/(CD > C0) 3  was  5.13.  68.0-7.5  2  ( m , 6 , a r o m a t i c H ) ; 3 . 3 2 ( s , b r o a d , 1 8 , D M S O and N - C H ) ; 2 . 6 0 ( s , 6 , f r e e DMSO); 3  p e a k s due  t o i m p u r i t i e s o f C H C £ , and some Rh-DMSO c o m p l e x 2  were p r e s e n t i n m i n o r amounts, b r o w n w h i l e t h e s p e c t r u m was  2  i r (the N u j o l m u l l turned from y e l l o w to  recorded) ,  1230m, 8 4 5 s  S p o n g e , [ P . S . H ] ) ; v(S_0)1138; v (Rh-C£) 352. t a b l e 4.1.  The h y d r o g e n u p t a k e f o r s u c h a r e a c t i o n  U p t a k e s u s i n g a P.S./Rh r a t i o 4.2.2.3  of 1 or 2 both r e s u l t  Reaction of RhC& (DMS0) 3  When P . S . ( 0 . 1 7 g, 0.80 RhCJL (DMSO) 3  resulted.  3  3  mmol) was  added  11 h o u r s o f r e a c t i o n ,  (0.05 g ) . 2  2  A n a l . Found:  2  of  a t 38°C, a r e d  solution  filtered.  A  s p e c t r u m was r e c o r d e d  a d d e d , and t h e v o l u m e  s l o w l y r e d u c e d by e v a c u a t i o n u n t i l  CH C£ /Et0H. 2  E t O H (8 m l ) was  T h i s p r o d u c t was  i n a H /Rh r a t i o  t h e s o l u t i o n was  s a m p l e was w i t h d r a w n u n d e r A r , a n d i t s nmr Degassed  i n figure  t o a degassed suspension of 2  ( f i g u r e 4.12).  i s plotted  listed  w i t h P r o t o n Sponge u n d e r A r :  ( 0 . 4 4 g , 1.0 mmol) i n 8 m l C H C ^  After  s o l v e n t was  (protonated Proton  Solution i r data are  +  in  ( a t 63.50,2.63)  of  a n o r a n g e powder  formed  c o l l e c t e d , and r e c r y s t a l l i z e d t w i c e f r o m C, 3 5 . 3 5 ; H,  4.83;  N, 4.61.  i r (Nujol) ,  v ( S 0 ) 1 1 2 8 s ; v ( c o o r d i n a t e d P . S . ) 1 6 3 5 w , 1605m, 1590m, 1 0 2 2 s ,  825s;  v ( [ P . S . H ] ) 840m n m r ( C D C J l ) ,  T h i s compound  +  2  2  s e e t a b l e 4.5,  f i g u r e 4.13.  4  0.39  -125-  F i g u r e 4.11  ( a ) The h y d r o g e n u p t a k e o f RhCJt.3(DMSO)3+2 P r o t o n S p o n g e i n 1,2-C2H4CJL a t 30°C. ( b ) A n o t h e r e q u i v a l e n t o f RhC£3(DMSO) was a d d e d at t h i s p o i n t . The f i n a l t o t a l Rh c o n c e n t r a t i o n was 6 . 4 x l O M ( 5 m l s o l v e n t ) . 2  3  - 2  0.81  1  1  1  i  *IME  1  1  (SEC)  1  r  -126Table A.5 nmr data f o r the r e a c t i o n  of Proton Sponge with  RhCi^DMSO)^  in C D C £ . 2  Peak Type (a)  Species  2  Peak PosJ.tj.on(5) and 0.8 P. S. l^+RhCl.^ ( D Reaction a f t e r l l h i n CH C& a t 38 c  2  Rh(I)-DMSO+free DMSO  2  I n t e g r a t i o n ( n o . of "''H) M S O ) 0 . 8 P.S. + Orange Crystals'-^  s,br  2.60(7)  Rh-(DMSO)  s  3.49(4)  3.50(3)  Rh-(DMSO)  s  3.45(6)  3.54(11)  /  m,C=C-H  Coordinated P r o t o n Sponge Derivative  1  7.7-7.5(2.1)  7.7-7.5(5)  7.7-7.5(5)  dof d,J =2,J =7Hz  7.0  7.0 (1)  7.0 (1)  s,br,N-CH ? 3  5.15  s,br,N-CH  3  1  ^  RhCfl., (DMSO-d,)„ Crystals l"-  s,N-CH  2  3  ( e )  (0.4)  (e)  (0.75)  5.15(1.5)  5.15(1.3)  3.79(2.5)  3.75(6)  3.75(6)  3.44(1.5)  3.47(3)  3.47(2.6)  Protonated  s,br,N-H  18.3(0.5)  Proton  m,C=C-H  8.0-7.7(2.5)  8.0-7.5(1.2) 8.0-7.5(1.3)  Sponge  d,J=2Hz,N-CH,  3.29(5)  3.29(6)  ( e )  (f)  (a)  s = s i n g l e t , d-doublet, m=multiplet, br=broad.  (b)  The s t o i c h i o m e t r y of the r e a c t i o n was determined by nmr.  (c)  Recrystallized several  (d)  R e c r y s t a l l i z e d from DMSO-d^/acetone  (e)  Observed u s i n g CD CJ,,,.  (f)  S o l u t i o n was too d i l u t e to observe t h i s peak.  (f)  3.29(3.4)  P.S. added  i n excess of 0.8 moles per mole Rh remains unreacted. times from C^CJi^/EtOH (see f i g u r e 4.13). (see f i g u r e 4.14).  2  F i g u r e 4.13.  100 MHz H nmr s p e c t r u m ( u s i n g CD C £ > o f o r a n g e c r y s t a l s f r o m t h e r e a c t i o n i n CH.CJl^ o f 0.8 P.S. + RhCjU ( D M S O ) . I m p u r i t i e s i n the C D C £ a r e t h e p e a k s a t 65.35 a n d 1.67 2  2  2  [P.S.H]  PS. DERIVATIVE OQ  c  tD  Ul • UJ Cu O Ln n >* Ln rt H* 3 n • O N O rO Ul ho ra • Ml  3  ro o o S  a  3  1  n o 3 3 • i-t o 03 CO  13 ^ '•TJ ro w •  LO •  PS  DERIVATIVE  n rt  I-t  +s 3  Ul  3* /-> n c ^ CO  &  LO  H-  3 a oo s c/i o o a 1 r-o •o  •  Ul rt  '—s  M rt ON O - ho WLo w *—- • O v  /  • >! t— 1  ^>PS. DERIVATIVE  l-h  w  ^—s rt i-t  3  rt  3ro-  .—[PS.HJ  Cu CU o O fD ro i-t rt O Cu O CO HQ  3  C 3 CO 3 ro ro ro o 1—' cu i-t • U l co cn Ul rt cu cu  ?r ^ it  h-  1  ro co  pu  s-  o>  I-I  Ul  rt  ON  •  Ui  Hi i-t  o  3  rt  " 3*  ro  c -631-  +  -130-  is  sparingly  w i t h H 0.  s o l u b l e i n CH C& , 2  l s  v  e  r  2  y  s o l u b l e i n DMSO, a n d  A f u r t h e r p r e c i p i t a t e o b t a i n e d from the mother  2  a complex m i x t u r e . be r e c r y s t a l l i z e d  The  initial  reacts liquor i s  p r e c i p i t a t e d e s c r i b e d above  by d i s s o l u t i o n  also  i n a minimum amount o f DMSO f o l l o w e d  by a d d i t i o n o f a c e t o n e . n m r ( C D C £ ) , 2  can  s  2  above.  Attempts at chromatography  alumina  failed.  e  e  t a b l e 4.5,  f i g u r e 4.14, i r  as  of the p o l a r products using  Oxidative Addition Reactions IL, u p t a k e m e a s u r e m e n t s w e r e c o n d u c t e d o n some o f t h e R h ( I ) compounds s y n t h e s i z e d , and o n some t h a t w e r e g e n e r a t e d i n s i t u . involved  first  [Rh(NBD) ]PF , 2  dissolved  6  The  latter  d r o p p i n g a b u c k e t c o n t a i n i n g a R h ( I ) precursor([RhC£(C rL, , ) „ ] „ o 1 4 Z 1 0  [RhC£(C0) ] ) i n t o a degassed s o l u t i o n o f t h e 2  2  i n a solvent of high vapour pressure  (DMA,  sulfoxide  2-methoxyethanol  all  u n d e r v a c u u m a t 20-50°C. A f t e r t h e r h o d i u m c o m p l e x d i s s o l v e d ,  was  i n t r o d u c e d , t h e f l a s k was  are l i s t e d  type  i n t a b l e 4.6.  s h a k e n and t h e u p t a k e r e c o r d e d .  Some r e a c t i o n s w i t h HC£,  t h e c r y s t a l l i n e HC£"DMA a d d u c t ^ , w e r e c a r r i e d 1  added  hydrogen  The  results  i n the form of  o u t by r a p i d l y w e i g h i n g  t h i s h y g r o s c o p i c compound and a d d i n g i t t o a S c h l e n k t u b e c o n t a i n i n g R h ( I ) complex  i n degassed  4.2.2.4 P r e p a r a t i o n o f ethane:  [Rh(NBD) ]PF 2  &  t h e s o l u t i o n was  [Rh(MSE) ]PF ; 2  (30 mg,  6  MSE=meso-l,2-bis(methylsulfinyl)  0.070 mmol) was  vigorously  stirred  i n vacuo, i s not a i r s e n s i t i v e  added  t o MSE  (40 mg,  A f t e r a few m i n u t e s ,  m i c r o c r y s t a l l i n e p r e c i p i t a t e , w h i c h was dried  a  solution.  i n 4 ml of degassed 2-methoxyethanol. and  (ME)),  f o r 30 m i n a t 30°C.  was  0.2  introduced  The p a l e  f i l t e r e d , washed w i t h e t h e r ,  i n the s o l i d  state.  mmol)  yellow, and  A t 190-195°C i n  -131-  air  t h e compound t u r n s b r o w n .  C, 1 7 . 2 7 ; H, 3.62.  Yield,  90%.  Anal:  F o u n d : C, 1 7 . 1 6 ; H, 3.56.  Calcd  nmr(DMSO-dg), 6 3 . 4 0 ( s ,  broad,8,CH -S); 3.07(s,broad,12,CH -S). i r ( N u j o l ) , 2  3  v ( o t h e r MSE  modes)1406s,  f o r RhCgH^S^O^PF^.:  v (SO)1110s, 1085s;  1 3 2 2 s , 1254m, 1 1 3 0 s , 1015m, 9 7 5 s , 960m; v ( P F ) 6  840s, 560s.  4.2.3  R e s u l t s and  4.2.3.1  Discussion  The H e t e r o l y t i c C l e a v a g e o f  by RhC&  (sulfoxide)^  3  The RhC^^L^ c o m p l e x e s , L = s u l f o x i d e , a r e i n e r t H„ i n 1,2-C„H,C£„ o r CH„C£„ a t 30-50°C. 2 2 4 2 2 2 added, t h e RhC£ (DMSO) 3  of H  2  complex  3  Complexes.  t o r e a c t i o n w i t h 1 atm  H o w e v e r i f 2 m o l e s NEt„ a r e 3  ( t h e o n l y one t e s t e d )  t a k e s up one  w i t h a c o n c o m i t a n t s o l u t i o n c o l o u r change from y e l l o w  mole  t o deep  brown.  I t a c o n i c a c i d and p r o b a b l y s u l f o x i d e ( s u l f i d e s w e r e s m e l l e d ) a r e s l o w l y hydrogenated c a t a l y t i c a l l y by t h i s A n u p t a k e o f one m o l e o f H DMA.  These d a t a ,  listed  promoted h e t e r o l y t i c  cleavage of H , 2  3  3  results  3  RhC£ (DMSO) +%H 3  3  3  2  solvent  the base-  r e a c t i o n 4.7, b u t s i n c e R h ( l I I ) - H and i r s t u d i e s , r a p i d e l i m i n -  i s indicated:  "H-Rh(HI)-C£"  2  Consistent with t h i s , of 1 mole N E t  are consistent with  b y s o l u t i o n nmr  to form Rh(I) species  RhC£ (DMSO) +H  Although NEt  by R h C i ^ L ^ a l s o o c c u r s i n t h e b a s i c  2  i n t a b l e 4.6,  s p e c i e s were n o t d e t e c t e d a t i o n o f HC£  s o l u t i o n u n d e r t h e same c o n d i t i o n s .  Rh(I)  the r e d u c t i o n of RhC£ (DMSO) 3  i n a r a t i o of H /Rh of o n l y 2  3  i n the presence  0.5:  —%RhC£ (DMSO) +"55Rh(I)"  coordinates  3  3  to RhC£ (DMSO)  be a v a i l a b l e f o r r e a c t i o n w i t h  3  HC£.  3  ( s e c t i o n 4.1.3.1), i t must  still  -132Table 4.6  Complex  Maximum Rate of Temp. Uptake  Concentration Solvent 10 M  RhCS. (DMSO)  6  Rh« (DMSO) +2.0 P.S.  32  3  3  °C 1,2-C H C4 2  4  2  30  Total moles H /Rh< ) a  2  10 M/sec 5  0  0  1,2-C H CJ>  30  6.0  0.39  [RhC£,(DMSO) (acetone) lPF,>2P.S. I X 'y 6 RhC^ (DMSO) +2NEt  27  1,2-C H CS.  30  4.3  22  1,2-C H C£  2  30  6.3  [RhCJ> (DMSO) ]NEt +2P.S.  15  1,2-C H C£  2  30  0  0.9,metal at 4000s 1.1 0  RhCi (DMSO)  6  DMA  30  2.0  1.0  6  DMA  40  2.5  1.2  11  DMA  40  2.5  1.5,metal at 1000s  3  3  (  J  3  3  3  4  2  3  +  4  3  RhCJl (MPSO) 3  3  [RhC£(DPSO) ] 2  2  [Rh(NBD) ]PF +1.3MET+2.6P.S, (c) 2  (b) (c) (d) (e) (f) (g)  2  2  2  4  2  4  4  5  ME  20  (d)  6.5  ME  20  (d)  +2.4DIOS  7.4  ME  50  0.8  +1.2PTSE  5  ME  20  (d)  0.5,metal at , ^ 400s (d) metal at 100s  8  DMA  53  0.9  1.2  [RhCJl (CgH ) ]  (a)  2  4  +2MSE  &  14  2  2  2  +2. 4DI0S  ( f}  2  (e)  (8)  No mention of metal formation means that the system was stable with respect to H2 reduction for at least 30 min. Prepared by adding AgPFg to RhC* (DMSO) i n acetone, f i l t e r i n g the AgCJi, removing the acetone i n vacuo, and adding 1.2-C2H4C&2Without adding Proton Sponge, the ligand does not dissolve. These reactions were monitored by using an ordinary Hg manometer. Only the MSE system gave a measurable uptake. [Rh(MSE)2]PF6 precipitated at this point. DIOS was the only chelating ligand that solubilized this compound i n DMA or ME. The hydrogenation of cyclooctene, rapid i n i t i a l l y , had almost stopped at the point (1000s). 3  3  -133-  Final  confirmation of the reduction process  a R h ( I ) compound f o r m u l a t e d  i s the i s o l a t i o n of  as [P.S.H.][RhC& (DMSO)^]. L i k e 2  [RhC£(DMS0) ] , t h e RhC£ (DMSO) ~ a n i o n  goes t o m e t a l and p r e s u m a b l y  R h ( I I ) when d i s s o l v e d i n d e g a s s e d H 0 .  T h e H„ r e d u c t i o n o f R h C £ „ ( D M S 0 )  2  2  2  o  i n t h e p r e s e n c e o f P.S. i s c o m p l i c a t e d  by s i d e r e a c t i o n s i n c l u d i n g t h e  c o o r d i n a t i o n o f t h e b a s e t o Rh ( s e e b e l o w ) , 0.4 m o l e s H is  2  obtained.  while  and s o an u p t a k e o f o n l y  p e r R h i s m e a s u r e d , a n d a p o o r y i e l d o f t h e R h ( I ) compound T h e u p t a k e p l o t s show a n i n d u c t i o n p e r i o d  f u r t h e r a d d i t i o n o f R h C £ (DMSO)  results  3  to the f i n a l  3  i n no i n d u c t i o n p e r i o d b e f o r e  suggests that t h e Rh(I) product  subsequent H  CO r e d u c t i o n o f R h ( I I I ) t o R h ( I ) c o m p l e x e s 53 Ru(IV) t o R u ( I I I ) complexes.  reaction solution uptake.  2  52  and t h e H  to H  2  3  2  to give  ( t a b l e 4.6).  reduction of  [RhC£ (DMS0) ]~, 4  2  2  3  support  reduction of  comes f r o m t h e m e a s u r e d H : R h u p t a k e r a t i o  when R h C £ ( D M S O ) i s t r e a t e d w i t h 1 e q u i v a l e n t base-promoted H r e a c t i o n (using P.S.).  2  Some i n d i r e c t  f o r t h e involvement o f such a s i d e r e a c t i o n i n the H  3  This  i sw e l l established f o r the  i n t o RhCil^(DMSO)  t h i s was f o u n d t o b e i n e r t  3  4.11),  I n s e c t i o n 4.1.3.3. i t was d e m o n s t r a t e d  t h a t C£~ s u b s t i t u t e s r e a d i l y  RhC£.j(DMSO)  (figure  may b e i n v o l v e d i n a n a u t o c a t a l y t i c  step o f t h e o v e r a l l r e a c t i o n ; such behaviour  and  o  o f a b o u t 1.0  o f AgPF^ p r i o r  tothe  2  Although  the hydride  Ir(H)C£ (DMSO) 2  3  readily  forms from  IrC£ (DMSO) 3  3  14 i n i s o p r o p a n o l a t room t e m p e r a t u r e  , no h y d r i d e s were i s o l a t e d o r d e t e c t e d  i n t h e i s o p r o p a n o l r e a c t i o n s w i t h t h e R h ( I I I ) complexes d i s c u s s e d i n s e c t i o n s 4 . 1 . 3 . 1 . , 4 . 1 . 3 . 2 . , a n d 4.1.3.3. hydride  F o r example, an  undetected  i n t e r m e d i a t e m u s t b e i n v o l v e d i n r e a c t i o n 4.3, L=DPS0.  i s o p r o p a n o l s o l u t i o n o f R h C £ . 3 H 0 a n d 3 DMSO d e p o s i t e d 3  2  metal,  A t 60° a n indicative  -134-  o f some r e d u c t i o n  process.  I t was h o p e d t h a t a n a l o g u e s t o M c Q u i l l i n ' s a c t i v e  hydrogenation  54 c a t a l y s t , RhCl (BH^) 2  L=sulfoxide,  (py) DMF 2  , c o u l d b e i s o l a t e d u s i n g RhCJc^L.^,  r a t h e r t h a n RhCJ^py^ as p r e c u r s o r .  However, a d d i t i o n  o f NaBH^ t o a DMF s o l u t i o n o f a n y o f t h e R h C ^ ^ c o m p l e x e s r e s u l t s i n r e d u c t i o n t o m e t a l and f o r m a t i o n  of sulfides.  b a s e d o n 6:1 BH^ /RhCH^(DMSO)probably BH^  Hydrogenation c a t a l y s t s  i n v o l v e s u l f i d e and p o s s i b l y  ligands.  4.2.3.2.  Oxidative Addition Reactions  of Rh(I)-Sulfoxide  Complexes  w i t h H„ a n d HC£  r The 4.6.,  hydrogen r e a c t i o n s w i t h the Rh(I)  failed  hydride metal,  to yield  intermediates  systems, l i s t e d  i s o l a b l e d i h y d r i d e s v i a r e a c t i o n 4.8(a)  The  although  must be i n v o l v e d i n t h e r e d u c t i o n o f R h ( I )  and i n any r e d u c t i o n o f c o o r d i n a t e d Rh(I)  i n table  + H  Rh(III)(H)  2  to  olefin. 4.8(a)  2  i n s i t u r e a c t i o n o f [Rh(NBD)„]PF. w i t h m e t h i o n i n e a n d b a s e I  may g e n e r a t e a d i n u c l e a r c o m p l e x s i m i l a r  D  t o one o f P t ( I I ) r e c e n t l y  56 characterized  , but the Rh(I)  system i s i n any case reduced t o m e t a l  i n t h e p r e s e n c e o f added o l e f i n i c  s u b s t r a t e and H  ( s e c t i o n 4.3).  2  A d d i t i o n o f 2 m o l e s o f m e s o - 1 , 2 - b i s ( m e t h y l s u l f i n y l ) e t h a n e , MSE, to  [Rh(NBD) ]PF^ under H 2  diene  2  r e s u l t s i n the p a r t i a l hydrogenation  and p r e c i p i t a t i o n o f [Rh(MSE)_]PF,. l b  s u g g e s t a n a l l S-bonded R h ( I ) is  The v ( S 0 ) —  complex i n t h e s o l i d  of the  a t 1 1 1 0 a n d 1085 cm'  state.  This  o n l y s o l u b l e i n s t r o n g d o n o r s o l v e n t s s u c h a s DMA o r DMSO.  compound Exchange  -135-  processes  must be i n v o k e d  methylene protons  equivalence  and a l l the m e t h y l protons  i n DMSO-d, a t 35°C. 6 resonances  t o e x p l a i n the  Nevertheless,  of a l l the  i n t h e H nmr, m e a s u r e d 1  the chemical  shifts  of these  (63.40 and 63,07, r e s p e c t i v e l y ) a r e c o n s i s t e n t w i t h a l l  S-bonding t o R h ( I ) .  A n a l o g o u s a l l S-bonded c o m p l e x e s ,  [M(meso-MSE)2] > +  46 M=Pd(II),Pt(II), for  have been prepared.  Unfortunately  this  facile  the p r e p a r a t i o n o f the Rh(I)-MSE c h e l a t e s i s n o t a p p l i c a b l e f o r t h e  DIOS l i g a n d ( t a b l e  4.6).  S u l f o x i d e s s u c h a s DPSO,MPSO, a n d P T S E , s u b s t i t u t e d w i t h g r o u p s , do n o t s t a b i l i z e  Rh(I)  m e t a l even though these backbonding 2  2  1.4).  [RhC£(DPSO) ] 2  2  2  o f HC£ ( e q u a t i o n 4 . 8 ( b ) ) ,  no h y d r i d e s  2  page 2 1 3 ) ,  2  to  2  for  Rh(I)  134).  does n o t r e a c t w i t h s t o i c h i o m e t r i c amounts  added i n the form o f t h e c r y s t a l l i n e  HCJl *DMA  i n DMSO d o e s s l o w l y r e a c t w i t h HC£-DMA a t 20°C  2  c o u l d be d e t e c t e d  through the decomposition Rh(I)  b y nmr;  s u l f i d e s were produced, p o s s i b l y  of Rh(III)-H species. + HC£  Dihydrides  R h ( I I I ) (H) (C£)  a r s i n e s a r e known t o r e d u c e DMSO a t ^40°C complexes are r e p o r t e d  and f o r i n s i t u  ( r e f e r e n c e 58, page  2  i n CH C£  [RhC£(DMSO) J  r e d u c t i o n by H  T h i s o b s e r v a t i o n was a l s o n o t e d  ( r e f e r e n c e 57,  3  complexes c o n t a i n i n g S P h  adduct.  or Rh(III) against  aromatic  l i g a n d s a p p e a r t h e m o s t l i k e l y t o p r o m o t e Rh->-S  (see chapter  [RuC£ (MPTSO) 1  but  route  59  ofCo(III)— 4.8(b)  , and P t ( I I ) — s u l f o x i d e  t o decompose t o s u l f i d e s i n t h e p r e s e n c e o f 60  a c i d , a t room t e m p e r a t u r e ,  RhC£ (DMS0) 3  3  catalytically  r e d u c e s DMSO  61 a t 80°C, 1 a t m H  2  b u t u n t i l the present  study,  no r e d u c t i o n i n v o l v i n g  -136-  Rh u n d e r  such m i l d  present a problem  c o n d i t i o n s had been o b s e r v e d , and c l e a r l y i n c a t a l y t i c h y d r o g e n a t i o n systems  t h i s may  involving  sulfoxides.  4.2.3.3.  T h e R e a c t i o n o f P r o t o n Sponge w i t h RhC£^(DMSO)^  The  p r e v i o u s l y mentioned  in  Cl^CJi^ under  to  promote  it  i s unlikely  r e a c t i o n o f P r o t o n Sponge w i t h  A r i s i n t e r e s t i n g because  activation i ncatalytic  t h i s base has been  RhC& (DMSO) 3  used  studies w i t h theassumption  t o coordinate a t a metal center.  3  that  The s t o i c h i o m e t r y o f  t h i s r e a c t i o n , a s j u d g e d b y nmr s t u d i e s , i n v o l v e s 0.8 m o l e s P.S. r e a c t i n g w i t h 1.0 m o l e s RhCJc.^ (DMSO) ^ t o g i v e e q u a l a m o u n t s o f u n c o o r d i n a t e d p r o t o n a t e d p r o t o n s p o n g e , [ P . S . H ] , a n d a Rh c o m p l e x w i t h a m o i e t y +  from p r o t o n sponge, a l o n g w i t h p r o b a b l y another Rh(III)-DMSO and  a little  is  signalled  at  1 5 8 0 cm  appearance P.S.; of  1100,  1  Rh(I)-DMS0 ( t a b l e 4.5).  i n t h e i r b y t h e d i s a p p e a r a n c e o f t h e i n t e n s e P.S. b a n d a n d t h e DMSO b a n d a t 930 cm  o v e r 40 m i n u t e s , a n d t h e 1 6 0 5 cm \  coordinated  Rh(I)-DMS0 s i n c e t h i s peak r a p i d l y d i s a p p e a r s on exposure  b r o a d peak a t 1140 o f Rh(III)-DMSO,  are  reduced  slightly  f r e e DMSO; a n d 8 3 0 ,  [P.S.H ] . +  a n d t h e P.S. p e a k a t 8 2 0 c m "  1  i n intensity.  r e a c t i o n i n CT^CJc^  c  a  n b e m o n i t o r e d b y nmr.  shown i n f i g u r e 4.12 a n d p e a k a s s i g n m e n t s  Resonances d e r i v e d the  1  o f new p e a k s , a s s i g n e d a s f o l l o w s :  The  is  complex  The r e a c t i o n i n Cr^CJc^ a t 30°C  t h e s o l u t i o n t o a i r ( c f . t a b l e 4.1); 1055,  The  derived  The f i n a l  a r el i s t e d  spectrum  i n t a b l e 4.5.  f r o m t h e P.S. m e t h y l g r o u p s , i n i t i a l l y  a t 62.78 i n  f r e e b a s e , a r e c o n v e n i e n t l y a s s i g n e d b y u s i n g RhC£^(DMSO-d^)^. T h e  [ P . S . H ]"*" m e t h y l p e a k a t 63.29 i s i n i t i a l l y  broadened  by exchange o f t h e  -137-  p r o t o n w i t h f r e e P.S., b u t a f t e r 1 h r i n t o t h e r e a c t i o n , s h a r p e n s t o a d o u b l e t w i t h a c o u p l i n g c o n s t a n t o f 2 Hz d u e t o t h e p r o t o n a t e d Unexpected  m e t h y l p e a k s o f w h a t i s a s s u m e d t o b e a c o o r d i n a t e d P.S.  d e r i v a t i v e a r e n o t e d a t 65.15,  3 . 7 9 , a n d 3.44,  a r o m a t i c p e a k s a t 6.95 a n d 7 . 5 - 7 . 7 1  on t h e n i t r o g e n o f [ P . S . H ] RhC£„(DMSO-d,)„  as w e l l as associated  not observed  i n [P.S.H ] B F ^ o r o t h e r  S i n c e t h e b r o a d peak a t 618.3, due t o t h e p r o t o n  [P.S.H-]" " c o m p l e x e s .  groups  nitrogen.  +  ,still  appears  i n the reaction of  + P.S. i n C T K C £ , i t m u s t b e t h e P.S. a n d n o t t h e DMSO 0  that are being  deprotonated.  S m a l l a m o u n t s o f c r y s t a l l i n e m a t e r i a l c o n t a i n i n g a c o o r d i n a t e d P.S. m o i e t y b u t d i s p l a y i n g p e a k s t h a t do n o t c o r r e s p o n d t o t h o s e o f t h e r e action solution,  can be i s o l a t e d  (see t a b l e 4.5).  gave m e a n i n g f u l X-ray d i f f r a c t i o n d a t a . salt  V a r y i n g amounts o f a  [P.S.H.]  +  a r e apparently c o - c r y s t a l l i z e d w i t h the product since the i n t e g r a t i o n  of t h emethyl resonances depending The crystals Indeed, day  None o f t h e c r y s t a l s  o f [P.S.H.]  i n t h e nmr g i v e s v a r i a b l e  +  results  o n t h e mode o f r e c r y s t a l l i z a t i o n . p r o t o n s p o n g e c o m p l e x may c o n t a i n R h ( I ) i n Cl^CJc^  t u r n d a r k e r orange  a slow oxygen uptake  on a 1,2-C H C£ 2  4  2  since solutions of the  over a p e r i o d o f days i n a i r .  o f 0.4 m o l e s 0 / R h was m e a s u r e d a f t e r 1 2  s o l u t i o n o f RhC& (DMSO) /P.S. r e a c t e d b e f o r e h a n d 3  f o r 4 h o u r s a t 38°C u n d e r N . 2  brown and a brown s o l i d  3  The s o l u t i o n changed f r o m r e d t o opaque  precipitated with spectral properties  similar  t o t h o s e o f t h e P.S. c o m p l e x . F o r m u l a t i o n o f a s t r u c t u r e t h a t g i v e s t h e c o r r e c t amounts o f i n e q u i v a l e n t P.S. m e t h y l g r o u p s  and y e t p r o v i d e s a f a i r l y u n i f o r m  deshielding  -138-  of a l l t h e aromatic  protons  has n o t y e t been achieved.  Deprotonation  o f a m e t h y l o f t h e P.S. b y a n o t h e r P.S. a n d t h e n c h e l a t i o n o f Rh b y t h e r e s u l t i n g CH~ group and an a r o m a t i c  ring  i sa possibility,  such a case o f a c t i v a t i o n of a nitrogen-attached i s unknown. S t u d i e s w i t h m o l e c u l a r  although  c a r b o n - h y d r o g e n bond  m o d e l s s u g g e s t t h a t Rh c o o r d i n a t i o n  w i t h a n i t r o g e n l o n e p a i r , f o l l o w e d by o r t h o m e t a l l a t i o n t o g i v e a four-membered m e t a l l o c y c l e , i s n o t f e a s i b l e because o f s t e r i c a c t i o n s between t h e N-methyl g r o u p s , and t h e s t r a i n c r e a t e d such a r i n g . chemistry  inter-  i n forming  The o n l y l i t e r a t u r e r e p o r t i n v o l v i n g t h e o r g a n o m e t a l l i c  o f P.S. i s t h e i s o l a t i o n o f a R u ( 0 ) c o m p l e x f o r m e d b y t h e  electrophilic  s u b s t i t u t i o n of a coordinated  a r e n e r i n g i n t o a P.S.  62 ring P.S.  , but i f such a r e a c t i o n occurred  w i t h RhCfc^(DMSO)^, a  d e r i v a t i v e w o u l d r e s u l t w h i c h w o u l d h a v e t o o many i n e q u i v a l e n t  N - m e t h y l g r o u p s t o b e c o n s i s t e n t w i t h t h e nmr 4.3  Attempts a t C a t a l y t i c Asymmetric  4.3.1.  data.  Hydrogenation  Introduction  The as  dimerized  merits  [RhL(solvent)  discussed  of using ]  +  i n chapter  chelating ligands  o r RhCJc-L(solvent) 1.  (L) on Rh(I)  , f o r asymmetric s y n t h e s i s were  A few c h e l a t i n g s u l f o x i d e complexes w i t h  s t r u c t u r e s have been s y n t h e s i z e d  as d e s c r i b e d  and  from  others  c a n be formed i n s i t u  (methylene-succinic  such  i n s e c t i o n s 4.1 a n d 4.2,  [Rh(NBD)„]PF, o r [RhC£(C H_.).]„ 0  Z  precursors. Itaconic acid  c e n t e r s , e.g.  t>  o 14  Z Z  acid) i s a useful p r o c h i r a l  s u b s t r a t e as a t e s t f o r c a t a l y t i c a c t i v i t y because the o l e f i n i c  acid  i s r e a d i l y a v a i l a b l e , i s e a s i l y reduced s i n c e i t i s a c t i v a t e d toward  -139-  H  a t t a c k , and  has  acid  shown i n f i g u r e 1.1,  functionalities  c h a p t e r 1.  like  t h e a-amino a c i d  Since the a c i d i c  precursors  c a r b o x y l a t e s can  63 e i t h e r decompose rhodium e q u a t i o n 1.19,  hydrides  c h a p t e r 1.3)  and  catalyst f o r hydrogenation,  or promote t h e i r  thus i n f l u e n c e the a c t i v i t y  i t i s also useful  of a  to t r y non-acid  s t r a t e s s u c h as s t y r e n e d e r i v a t i v e s o r u n s a t u r a t e d 4.3.2.  formation (cf. Rh  sub-  esters.  Experimental 64  a - E t h y l s t y r e n e was  prepared according to a reported  This i s not a very convenient  s u b s t r a t e to use because of the  s p e c i f i c r o t a t i o n of the hydrogenated  p r o d u c t , and  t o measure the o p t i c a l r o t a t i o n s of neat a-methyl covered  from  the r e a c t i o n mixture  the polarimeter m i c r o c e l l ) . (U. o f B r i t i s h  Columbia).  mixtures i s outlined  E t h y l a t r o p a t e was The  4.3.3.  p r o p y l benzene r e quantity to  p r e p a r e d b y K.  fill W.  Wang  p r e p a r a t i o n of the v a r i o u s r e a c t i o n  shaken f l a s k s u s i n g the procedure  4h f o l l o w e d b y  low  thus i t i s necessary  ( i n a t l e a s t 1 ml  i n t a b l e 4.7.  b e c l e a n e d o f Rh m e t a l b y  procedure.  Gas  uptakes were measured i n  d e s c r i b e d i n c h a p t e r 2.  immersion  soaking i n a l c o h o l i c  Flasks could  i n c o n c e n t r a t e d H„SO, a t 150° 2  KOH.  for  4  R e s u l t s and D i s c u s s i o n  The stabilize  chelating sulfoxides the Rh(I)  (DIOS,MSE,PTSE, s e e t a b l e 4.7)  do  s y s t e m s a g a i n s t r e d u c t i o n t o m e t a l u n d e r homogeneous  c a t a l y t i c h y d r o g e n a t i o n c o n d i t i o n s (50-90°, 1 atm  H^^  The  i s n o r m a l l y an  Rh m e t a l p r o d u c e d  heterogeneous  i n these experiments, which  0.2M  h y d r o g e n a t i o n c a t a l y s t , m u s t be p o i s o n e d b y  s i n c e t h e r e was  not  g e n e r a l l y no  substrate).  sulfur  excellent donors  e f f e c t i v e r e d u c t i o n of the o l e f i n i c s u b s t r a t e s .  -140-  For c a t i o n i c complexes d e r i v e d sulfoxides  DIOS, P T S E , and. MSE,  achieved.  The  reaction  14,  fortunately olefin.  from  no  [ R h ( N B D ) ^ J P F ^ and  c a t a l y t i c hydrogenation  c a t i o n i c s y s t e m w i t h m e t h i o n i n e and b a s e  t a b l e 4.7,  does a c t i v e l y hydrogenate  t h e system does not hydrogenate  reactions  complex i s s t i l l t a b l e 4.7,  and  (P.S.),  s t y r e n e but  a prochiral  s i n c e , w i t h o u t t h i s added l i g a n d ,  the  [RMNBD^JPF^  (see r e a c t i o n  complexes of the c h e l a t i n g  after several  ethyl styrene;  reduction  sulfoxides  h o u r s a t 50°C, 1 a t m H^.  are  unfortunately  a side reaction,  The  one  c a s e where enough h y d r o g e n a t e d  was  r e c o v e r e d t o measure o p t i c a l r o t a t i o n s , r e a c t i o n  reduced  enantiomeric excess  product  (e.e.).  expected, monodentate s u l f o x i d e  H^  reduction  to metal  (reactions  An i n s i t u c a t a l y s t system  was  reduced  verified  (CH^S  catalytically  by n o t i n g  a t 62.1,  quite  rapidly.  (a-methyl s u c c i n i c  formed  As  not  to  r e f e r e n c e 66).  and  ligand, reaction  instead  t h e s u l f i d e i n t h e ^H nmr  r e f e r e n c e 5 7 , p a g e 3 2 ) , and  gave  might  by warming R h C ^ ' S ^ O i n  the s u l f o x i d e  acid)  2, t a b l e 4.7,  Carbonyl complexes a r e  20 and  m e t h y l - b u t y l m e t h y l s u l f o x i d e as s o l v e n t tively  sulfoxide  complexes a r e more s u s c e p t i b l e  19,  the  itaconic  possibly  t o metal but are i n a c t i v e hydrogenation c a t a l y s t s .  be  reduced  However o n l y  or m e t a l f o r m a t i o n , decomposes t h e a c t i v e s p e c i e s  no m e a s u r a b l e  16,  r e f e r e n c e 65).  DIOS c o m p l e x e s a r e a c t i v e c a t a l y s t s f o r t h e h y d r o g e n a t i o n o f a c i d and  un-  coordinates i n these  an a c t i v e h y d r o g e n a t i o n c a t a l y s t  Chlororhodium to metal only  was  ethyl atropate,  I t i s n o t c l e a r h o w e v e r w h e t h e r MET  catalytic  t h e added  (+)-2-  21,  selec-  of i t a c o n i c a c i d .  of the r e a c t i o n  t h e c o p i o u s amounts o f  This  solution condensed  -141-  water i n t h e uptake  R^SO  apparatus:  + H  >  2  Rh  R R S + H 0 X  2  S m a l l amounts o f m e t h y l s u c c i n i c a c i d were a l s o The  sulfoxides  criteria  listed  studied  apparently  generation  cally  a c t i v e . This  that  and  (see  with better  concentration  2  (criterion  con-  reduction  sulfoxides. (e.g.  o f Rh(I)  In general,  complexes  sulfoxides  DIOS c o m p a r e d t o P T S E ) s h o u l d backbonding.  S - d o n o r t h a n MPSO a n d , i n d e e d ,  t o an a c t i v e Rh(I)  RhC£ (Et S) 3  i n a c t i v e and u n s t a b l e  under  similar  ( r e a c t i o n 20) .  complication  of sulfoxide reduction,  again encountered i n t h e c a t a l y t i c MBMSO, a n d p o s s i b l y  2  c a t a l y s t for thehydrogenation of maleic  a c i d ^ w h e r e a s RhC£.j (MPSO)^ i s f a i r l y  The  strongly  h y d r i d e s i s s u p p o r t e d by t h e i r  t o Rh i n t h e a b s e n c e o f m e t a l - > s u l f u r  i s expected t o be a s t r o n g  conditions  t o be c a t a l y t i -  The  e l e c t r o n d o n a t i n g groups  a precursor  t o promote  ( c r i t e r i o n 4).  i n terms o f t h e s e l f  of coordinated  b i n d more s t r o n g l y Et S  catalytic  s e c t i o n 4.1) t o s t a b i l i z e Rh-H s p e c i e s  o f any R h - s u l f o x i d e  thereduction  support  i s p r o b a b l y b e c a u s e s u l f o x i d e s do n o t b i n d  siderable reactivity  is  t o meet c e r t a i n o f t h e  o r t o encourage o x i d a t i v e a d d i t i o n r e a c t i o n s  instability  detected.  thesulfoxides f a i l  of hydrides i n s u f f i c i e n t  enough t o Rh(I) 1)  fail  i n c h a p t e r 1.3.1. f o r l i g a n d s  h y d r o g e n a t i o n . The work i n d i c a t e s t h a t the  2  catalyst  reduction  i n thedeactivation  n o t e d i n s e c t i o n 4.2, i s i n v o l v i n g RhC£ "3H 0 and 3  o f t h e DIOS s y s t e m s .  2  T a b l e 4.7 Attempts  Catalyst  Cone.  ( a )  Olefin  mM 1.  [Rh(NBD) ]PF 2  6  ( b )  Conc.  Solvent  M  (c)  T  °C  Max.  Solution  Rate  Colour  ( d )  Comments  ( e )  10 M/ sec 5  13  I.A.  0.25  DMA  43  0  B  - m e t a l a t 100s  8  I.A.  0.38  DMA  63  4.0  B  - m e t a l between 2 and 16h  +1.2 DIOS 2.  [RhC£(CgH ) ] 1 4  2  2  +2.4 DIOs( ) f  -catalyst -20%  3. [ R h C £ ( C g H ) ] 1 4  2  6  2  M.S.  0.34  DMA  58  1.0  RB  +4 D l O S ^ g ) 4. [ R h C £ ( C H ) ] g  1 4  2  E.S.  0.60  BuOH  65  6.4  R  +4 DIOs(g) 5. [RhC£(DI0S) ] z n o  S.A. w i t h n o e . e . a f t e r 1 6 h  -catalyst  -catalyst  [RhC£(CgH ) ] 1 4  2  2  slowly  deactivated  rapidly  deactivated  -metal a t 3h, 20% conv.(h) 8  I.A.  0.36  ME  63  0.5  Y  - m e t a l between 2 and 16h  8  I.A.  0.36  BuOH  63  0.3  Y  - m e t a l between 2 and 16h -catalyst  6.  deactivated  - s t o p p e d a t 3 0 % conv. a f t e r 5h 11  2  slowly  rapidly  deactivated  1.5  I.A.  0.32  BuOH  63  0  Y  - m e t a l b e f o r e 16h  2.3  I.A.  0.15  DMA  50  0  Y  -no m e t a l  2.3  I.A.  0.15  DMA  80  0  Y  -metal a t 100s  11  I.A.  0.15  ME  50  0  0  - m e t a l a t 4000s  13  I.A.  0.15  ME  50  0  Y  -CO e v o l u t i o n , n o m e t a l  6  S  0.19  ME  50  0  0  -metal a t 100s  +2 BDIOS^ ) g  7. [ R h ( M S E ) ] P F 2  6  8. [ R h C £ ( C H ) ] g  1 4  2  2  +2 MSE 9. [ R h C £ ( C O ) ] 2  2  +2 MSE 10.[Rh(NBD) ]PF 2  +DTH  6  T a b l e 4.7 ( c o n t . ) Max.  [Rh(NBD) ]PF 2  Cone. mM 5  6  Olefin ^Conc. M E.A. 0.19  (c)  (  Solvent ME  T °C 60  v w  Solution  Rate Colour 105M/sec  (d)  Comments  (e)  - m e t a l a t 300s  +PTSE [RhC£(C H ) ] g  l 4  2  2  I.A.  0.15  DMA  53  0  - m e t a l b e f o r e 24h  I.A.  0.15  ME  50  0  -metal a t l h  0.19  ME  50  VL0  0.23  ME  63  1.1  0.19  ME  50  M.0  I.A.  0.15  ME  50  0  - m e t a l a t 4000s  I.A.  0.15  ME  50  0  -CO  +3PTSE [Rh(NBD) ]PF 2  6  +MET [Rh(NBD) ]PF 2  6  YG  - m e t a l o n l y a t 100% conv  +MET+2P.S. [Rh(NBD) ]PF 2  E.A.  6  - m e t a l a t 500s  +MET+2P.S. [Rh(NBD) ]PF 2  6  - m e t a l o n l y a t 100% conv  +2P.S. [RhC£(C H ) ] g  l 4  2  2  2.0  +2MET [RhCJl(CO) ] 2  13  2  +2MET  evolution  -no m e t a l  [RhC£(CgH ) ] l4  2  2  10  I.A.  0.15  DMA  60  0  6  I.A.  0.12  DMA  70  0.4  B  - m e t a l a t 2000s  15  I.A.  1.5  MBMSO  86  0.5  0  -only  - m e t a l a t 200s  +4MPTS0 RhC£ (MPSO) 3  (f 3  RhC«- -3H 0( ) i  3  2  ^  sulfoxide  - r a t e decreases -50%  reduced slowly  c o n v . a t lOOh  T a b l e 4.7  (cont.)  R e a c t i o n s o l u t i o n s w e r e p r e p a r e d , u n l e s s o t h e r w i s e n o t e d , by f i r s t d i s s o l v i n g t h e Rh c o m p l e x , t h e l i g a n d , and t h e s u b s t r a t e i n 5 m l s o l v e n t i n v a c u o a t 20°C, and t h e n i n t r o d u c i n g 1 atm C g H j ^ c i s - c y c l o o c t e n e ; BDIOS=DIOS w i t h b e n z y l g r o u p s i n s t e a d of methyls a to the s u l f o x i d e group; DTH=2,5-dithiahexane; MET=(S)-methionine. I.A.=itaconic atropate.  a c i d ; M. S . = a - m e t h y l s t y r e n e ; E . S . = a - e t h y l s t y r e n e ;  S=styrene;  E.A.=ethyl  DMA=dimethylacetamide; BuOH=n-butanol; ME=2-methoxyethanol; MBMSO=(+)-2-methyl-butyl methyl sulfoxide. B=brown; R B = r e d - b r o w n ; R = r e d ; Y = y e l l o w ; O=orange; G = g r e e n . S.A.=  methyl s u c c i n i c a c i d ; conv.=conversion of  substrate.  The o l e f i n was a d d e d u n d e r a p o s i t i v e p r e s s u r e o f H2 a c c o r d i n g t o t h e c o n d i t i o n s l i s t e d i n t a b l e 4.6.  after  t h e s o l u t i o n was  pretreated  The l i g a n d and R h - p r e c u r s o r w e r e p r e m i x e d i n d e g a s s e d CH^CJ^The s o l v e n t was t h e n r e m o v e d by e v a c u a t i o n and t h e r e s u l t i n g o i l was t a k e n up i n a s o l u t i o n o f t h e s u b s t r a t e d i s s o l v e d i n the r e a c t i o n s o l v e n t . The  solution, distilled  from the r e a c t i o n m i x t u r e ,  The c h i r a l compound MBMSO (1 m l ) , and t h e n H2 was introduced.  g a v e no  optical  rotation.  R h C ^ . S H ^ O w e r e h e a t e d f o r l h a t 60°C i n v a c u o ,  and  -145-  5.  Hydridoirldlum  5.1.  Preparation  5.1.1.  Sulfoxide  Complexes  and S p e c t r o s c o p i c  Properties  Introduction  Another approach t o t h e use of c h i r a l asymmetric synthesis  sulfoxides i n catalytic  i s the synthesis of c h i r a l  analogues of  I r C £ H ( D M S 0 ) ^ , a known c a t a l y s t f o r some h y d r o g e n a t i o n and o x i d a t i o n 2  reactions  (see chapter  low  ( 2 0 % ) i n two s t e p s  yield  1.3).  step  involved the synthesis  acid  complexes,  identified  the  starting  from  2  [IrC£^]  of e i t h e r the yellow  [H(DMS0) ][IrC£ (DMS0) ]. 4  2  initial  c i s - or pink  The y e l l o w  A tentative rationalization  o f t h e m e t h y l p r o t o n s was a l s o p r o p o s e d .  1  trans-  i s o m e r was  i n v o l v i n g nmr  stability chemical  I n t h e second step of  s y n t h e s i s , a n I r a c i d c o m p l e x was r e a c t e d w i t h  a hydride  The  as t h e c i s a c i d s o l e l y on t h e b a s i s o f i t s g r e a t e r  in polar solvents. shifts  The DMSO c o m p l e x h a s b e e n p r e p a r e d i n  isopropanol  to yield  c o m p l e x a n d a c e t o n e ; t h e t r a n s a c i d was t h o u g h t t o y i e l d  trans-dichloro-mer-tris(DMSO)-hydridoiridium(III). Two r o u t e s were b r i e f l y  to I r hydride  complexes c o n t a i n i n g  chiral  sulfoxides  i n v e s t i g a t e d h e r e . T h e s y n t h e s i s o f I r C i l ^ L ^ was a t t e m p t e d ,  s i n c e t h e s e compounds s h o u l d at l e a s t i n s i t u .  Also  react with  isopropanol  to yield  s i n c e t h e i r i d i u m ( I ) complex,  hydrides,  [IrC£(cyclooctene) ] , 2  can  be e f f i c i e n t l y p r e p a r e d from c o m m e r c i a l l y  and  s i n c e i t m i g h t b e e x p e c t e d t o o x i d a t i v e l y a d d HC£ i n t h e p r e s e n c e o f  s u l f o x i d e , preliminary experiments of t h i s 5.1.2.  available I r starting  k i n d were a l s o  2  materials,  tried.  Experimental  Chalcone  ( b e n z y l i d e n e a c e t o p h e n o n e ) was p r e p a r e d b y c o n d e n s i n g  acetophenone  -146-  and  benzaldehyde.  z  T h e c o m p l e x e s c i s - a n d trans-[H(DMSO)^][IrC£^(DMSO) ]  have been prepared  from H ^ I r C ^ ] ,  they were prepared  f r o m IrC£^ o r I r C £ . 3 H 0 a s f o l l o w s .  5.1.2.1.  and c h a r a c t e r i z e d ; f o r t h i s 3  2  Trans-[H(DMSO) ][IrC£ (DMSO) ] 2  After  4  2  IrC£ (0.45 g , 1.3 mmol) h a d r e a c t e d w i t h c o n c e n t r a t e d 4  (0.3 m l , 4 mmol) i n 5 m l i s o p r o p a n o l green-red  s o l u t i o n was c o o l e d  35 mmol) was a d d e d . were f i l t e r e d vacuo.  work  1  f o r 4 h o u r s a t 55°C, t h e r e s u l t i n g  t o room t e m p e r a t u r e , a n d DMSO ( 2 . 5 m l ,  The orange n e e d l e s t h a t c r y s t a l l i z e d  i n a i r , washed w i t h  Yield,  out overnight  i s o p r o p a n o l and e t h e r , and d r i e d i n  0.45 g , 52%.' m-.p. 152-154°.  nmr(D 0)  63.50(s,12,DMS0),  2  2 . 7 1 ( s , 1 2 , f r e e DMSO); 4.72(HOD). i r , v ( S 0 ) 1 1 2 7 s ; P ( C H ) 1 0 2 7 s , r  v(OHO) 1 7 0 0 - l l O O m , 9 0 0 - 6 0 0 s ; 5.1.2.2.  HC£  3  980s;  (Ir-C£) 335m, 3 2 6 s .  Cis-[H(DMSO)J[IrC£(DMSO) ]  DMSO ( 0 . 5 3 m l , 7.5 mmol) was a d d e d t o t h e r e d s o l u t i o n f o r m e d b y heating  IrC£ .3H 0 3  2  ( 0 . 3 g , 0.87 mmol) a n d a q u e o u s HC£ ( 1 . 1 m l , 2.4M) a t  85° f o r 30 m i n u t e s . glass-stoppered  Heating  was c o n t i n u e d  Schlenk tube.  f o r 38h i n a i r i n a c l o s e d  When t h e t u b e was o p e n e d , a s t r o n g  o f d i m e t h y l s u l f i d e emanated f r o m t h e orange s o l u t i o n .  smell  The s o l u t i o n was  r e d u c e d t o a n o i l b y p u m p i n g , a n d t h e r e s i d u e was d i s s o l v e d i n 1 m l water and e x t r a c t e d w i t h CH C£ (3xlO m l ) .  Propan-2-ol  (0.5 m l ) w e r e added t o t h e s y r u p ,  obtained  by evaporating  layer,  0.21 g , 4 0 % .  2  with  to yield  those  the acid.  published.  1  2  Yield,  nmr(D 0) 2  ( 5 m l ) a n d DMSO t h e aqueous  S p e c t r a l data  63.52(s,12,DMS0),  agree  62.71(s,12,free  DMSO). The  CH C£ 2  2  e x t r a c t s y i e l d e d 0.02 g o f I r C £ ( D M S O ) ( D M S O ) . 3  2  1  -147-  5.1.2.3. (a)  T r a n s - d i c h l o r o - m e r - t r i s (DMSO) h y d r i d o i r i d i u m ( I I I )  [IrCX,(cyclooctene)^]2  on d i s s o l v i n g under Ar.  (0.1  i n d r y DMSO (0.4  g , 0.11 mmol) f o r m e d a y e l l o w  ml,  solution  5.6 mmol) a n d C H ^ C ^ ( 3 m l ) a t 10°C  A f e w l a r g e c r y s t a l s o f HC£.DMA ( 0 . 0 2 7 g , 0.22 mmol) w e r e  r a p i d l y weighed and added.  T h e s o l u t i o n , now c o l o u r l e s s ,  was r e d u c e d  i n v o l u m e t o 0.5 m l i n v a c u u m , a n d d r y e t h e r w a s s l o w l y a d d e d u n t i l t h e s o l u t i o n went t u r b i d . deposit white was  induced  little and  c r y s t a l s a t room t e m p e r a t u r e .  a t 0°C, t h e p r o d u c t  e t h e r , and d r i e d  clear  and then l e f t t o  A f t e r more  crystallization  was f i l t e r e d under A r , washed w i t h a  i n vacuo; the w h i t e  c r y s t a l s are very  t u r n t o a y e l l o w o i l i n m o i s t a i r . Y i e l d , 70%. A n a l .  mono-DMSO s o l v a t e ,  C,  T h i s was warmed u n t i l  o  amount o f c y c l o o c t e n e ( f i g u r e 5.1).  o  s a m p l e was l i k e l y  nmr(CDC£ ) 3  r  The h y d r i d e  and  i n good y i e l d  3  as evidenced  as f o l l o w s .  b y t h e i r nmr  6 3 . 7 3 ( s , 6 , D M S O ) , 3 . 5 7 ( s , 1 2 , D M S 0 ) , 2.62 i r , v(Ir-H)  2180s;  be obtained without  solvating  i n 10 m i n .  o f [IrC£(cyclooctene)^\ ^ (0.25  a t room t e m p e r a t u r e .  The w h i t e  washed w i t h e t h e r , and r e c r y s t a l l i z e d by d i s s o l u t i o n addition  of isopropanol/ether  IrC£ S 0 C H 2  3  3  6  i g  DMSO  When HC&.DMA (68 mg, 0.56 mmol) i s a d d e d g , 0.28 mmol) i n  5 m l 2 - p r o p a n o l a n d 1.0 m l DMSO, t h e s u s p e n d e d compound t u r n s to white  v(S0)  o f s o l v a t e 1 0 2 7 s ; v(Ir-C£) 302w.  complex c a n a l s o  to a degassed suspension  contaminated w i t h a small  T28.86(S,1,hydride).  1134s,1110s; P ( C H ) + v(S0)  for the  Found:  n  b u t o t h e r s were not,  (s,6,DMSO o f s o l v a t i o n ) ;  (b)  Calcd  I r C £ S 0 „ C , H , . S 0 C „ H . : C, 1 6 . 6 6 ; H, 4.37. 2 3 3 6 19 2 6  1 8 . 1 3 ; H, 4 . 1 3 . T h i s  data  hygroscopic  (V/V=l/2).  : C, 1 4 . 4 6 ; H, 3.81.  product  from  orange  was f i l t e r e d ,  i n 1 m l DMSO a n d  Y i e l d , 60%. A n a l .  Calcd  for  F o u n d : C, 1 5 . 5 2 ; H, 4.17. T h e s p e c t r a l  • i 5 F i g u r e 5.1.  i  I . . . . •  ppm  . . I 1  3  100 MHz H nmr s p e c t r u m o f IrCJ£ H(DMS0)--DMS0 i n CDCl 1  2  -149-  d a t a were s i m i l a r  t o those  f r e e DMSO p e a k ; a l i t t l e  o f the product  ( a ) e x c e p t t h a t t h e r e was no  free cyclooctene  ( 6 5 . 5 , 2 . 0 , 1.4) was a l s o  detected. (c)  Three attempts s t a r t i n g w i t h e i t h e r  complexes f a i l e d Instead was  t o reproduce the published  as a mixture  of hydrides  ( C D C £ ) 6 3 . 5 1 ( m a i n DMSO p e a k ) ;  3.73,  3  ir,  T29.45 (main h y d r i d e ) ;  v(Ir-H)  (d)  acid  p r e p a r a t i o n o f IrCJc^HtDMSO) .  o n l y a f e w m i l l i g r a m s o f a y e l l o w compound p r e c i p i t a t e d , a n d t h i s  identified  peaks);  thec i s or trans  2150-2180; v(S0)  a n d o t h e r n e u t r a l c o m p l e x e s , nmr  3.63,  3 . 5 7 , 3.21,  2.91 ( s m a l l DMSO  28.85 ( s m a l l amount o f h y d r i d e  from ( a ) ) ,  1130-llOOs.  Reaction w i t h chalcone:  The h y d r i d e  from  (a) a n d c h a l c o n e  were 3  reacted  i nisopropanol according  pale yellow was  isomer o f the reported  obtained  judging  (each  protons  3.50,  chelate ring). 1580;  v(C0)  were t o o weak t o o b s e r v e .  24h i n C D C £  and  at least  equal  3  under A r ,  two f u r t h e r  unreac'ted  intensity  Ir(C^rL^O)Cl^(DMSO) > 2  ^»  J  MX  The i r d a t a 1540;  v(S0)  3  = 2 2  H  z  ' ' 1  differ 1127;  i n e c  l  u l v a l e n t :  slightly  from  P ( C H ) 1022; r  3  1 5 8 0 cm  those  v(Rh-C£)  \  2  t h es o l u t i o n turned  from c o l o u r l e s s  concentrations  similar  to yellow to the  a p p e a r e d t o f o r m : IrC£ (DMSO) (DMSO^) 3  p e a k s a t 6 3 . 6 3 , 3.52, 1:2);  68.4-7.2  3  When I r H C £ (DMSO) . DMSO was h e a t e d a t 40°C  I r species with  hydride  63.56 a n d 3.46 ( r a t i o  = A X  (CDC£ ):  s , 3 , S - C H ) ; 5.71, 4 . 6 9 ,  Reference 3 g i v e s v(C0)  R e a c t i o n w i t h CDCJc^:  for  complex,  2.04 ( e a c h  A M  of alkyl  remaining  3.38,  q o f AMX s y s t e m , J = 1 0 , J '  reported: v(phenyl)  (e)  alkyl  f r o m t h e a g r e e m e n t o f t h e nmr d a t a  ( m , 1 0 , a r o m a t i c ) ; 3.92, 3.65  t o the method o f Henbest e t a l . . The  CHDC£  0  2.88; I r C £ ( D M S O )  a t 65.2.  3  2  1  1  with  w i t h peaks a t  -150-  5.1.2.4. (a)  Chloro-cis-dihydrido-mer-tris(DMSO)iridium(III)  [IrC£(cyclooctene) ]2 ( 0 . 1 g ) w a s d i s s o l v e d i n 0.4 m l DMSO a n d 2  3 m l CH^Ci^ under A r . turned  Upon i n t r o d u c t i o n o f 1 a t m E^, t h e s o l u t i o n  colourless; after  5 m i n . i t was c o n c e n t r a t e d  vacuum and 1 m l i s o p r o p a n o l a white,  and t h e n enough  air-stable precipitate.  hours and t h e n f i l t e r e d . i n vacuo.  Yield,  This  The p r o d u c t  70%. A n a l .  t o 0.5 m l u n d e r  e t h e r were added t o g i v e  suspension  was c o o l e d  was w a s h e d w i t h e t h e r  f o r a few and d r i e d  C a l c d , f o r I r C i > S ^ C ^ Q : C, 1 5 . 5 3 ; H, 4.34.  F o u n d : C, 1 5 . 5 7 ; H, 4.42. n m r ( C D C £ )  63.57(s,6,DMSO),  3.39(s,6,DMSO); x26.3(d,J=6 H z , I r - H ) ,  29.5(d,J=6Hz,Ir-H) . i r , v ( I r - H )  3  3.53(s,6,DMS0),  2 1 7 7 s , 2 0 8 7 s ; v ( S 0 ) 1 1 2 8 s , 1 1 2 0 s h , 1090m; P ( C H ) 1 0 3 5 s , 978w; v(IrC£) r  3  t o o weak. (b)  Reaction  s m a l l amounts  o f t h ed i h y d r i d e w i t h CDC£ : 3  of at least  two d e c o m p o s i t i o n  were o b s e r v e d : t h eo n l y m o n o h y d r i d o i r i d i u m described  3  (c)  3  products  a p e a k a t 63.45 may b e  t h e r e q u i r e d s e c o n d p e a k a t 3.56 was  3  CHDC£2 was o b s e r v e d a t 65.2 i n s i g n i f i c a n t  Reaction  rapidly with  w i t h HC£.DMA:  3  t o g i v e t h e f o l l o w i n g nmr s p e c t r u m  t o I r H C £ ( D M S O ) ( D M S O ) w i t h c i s - c h l o r i d e s a n d DMSO 2  trans t o the hydride: x30.60(s,l,Ir-H).  amounts.  A s t o i c h i o m e t r i c amount o f HC£.DMA r e a c t s  the d i h y d r i d e i nCDC£  which i s assigned  of the dihydride  s p e c i e s d e t e c t a b l e was t h a t  i n s e c t i o n 5.1.2.3(63.72,3.57,x28.86);  due t o m e r - I r C £ ( D M S 0 ) , a l t h o u g h hidden;  A f t e r 2 0 h a t 22°C i n C D C £ ,  2  63.56(s,6,DMSO),  3.-51(s,6,DMSO),  2.68(s,6,DMS0);  O t h e r p e a k s o b s e r v e d a r e : 6 2 . 6 3 ( s , l , f r e e DMSO);  3.01(s,broad,6,N-CH ), 3  2.16(s,3,C-CH ). 3  o f t h e N-CH_ g r o u p s o f DMA m u s t r e s u l t  S e e f i g u r e 5.2. T h e e q u i v a l e n c e from proton  exchange w i t h  some  -152-  H C £ . D M A ; t h e s p e c t r u m o f H C £ . D M A i n CDCSL^ a l s o shows o n e  unreacted  peak due t o e q u i v a l e n t N - C H ^ 5.1.2.5.  groups.  The A t t e m p t e d P r e p a r a t i o n o f [ I r C & ( D M S O ) ^ ]  The  2  p r o c e d u r e u s e d f o r t h e p r e p a r a t i o n o f [RhC£(DMSO)^]  followed  ( s e c t i o n 4.1.2.).  A white  iridium hydride,  w  a  s  2  p o s s i b l y formed  from t r a c e s o f water by o x i d a t i v e a d d i t i o n , p r e c i p i t a t e d on a d d i t i o n of ether, P (CH ) r  3  i r ,v(Ir-OH) 3440s, sharp;  2200 v ( I r - H ) ; v ( S 0 )  1143s,  1103s;  1030s.  5.1.2.6.  T h e A t t e m p t e d P r e p a r a t i o n o f I r C J l ^ L ^ ; L=MPS0, DPSO, MBMSO,  TBPTSO, OTPTSO When I r C £ . 3 H 0 3  i n MeOH ( 6 m l ) from red  (0.07  a n d H^O  t o amber.  from these 5.1.3.  2  g ) a n d L ( I r : L = l : 4 ) w e r e h e a t e d a t 63°C  (0.6 m l ) f o r 1 6 h u n d e r A r ,  thesolutions  turned  No compound c o u l d b e p r e c i p i t a t e d o r c h r o m a t o g r a p h e d  solutions.  Use o f i s o p r o p a n o l  lead to metal  formation.  Discussion R o u t e s t o t h e DMSO compounds w e r e f i r s t  [H(DMS0) ][IrC£ (DMS0) ] were r e a d i l y 2  4  2  studied.  synthesized  The a c i d  complexes,  from t h e a v a i l a b l e  starting materials,  I r C J t . ^ ,  of Henbest e t al.?*  I t i s n o t c l e a r whether these workers recognized t h e  nature  of the [H(DMS0) ] 2  symmetrically these  acids  rhodium  +  o r I r C & . 3 H 0 , by s l i g h t l y m o d i f y i n g 3  2  c a t i o n , but indeed,  t h e i r bands due t o a  hydrogen-bonded system are present  (see chapter  complexes).  t h e method  i nthespectra of  4.1.3.3 f o r a d i s c u s s i o n o f t h e a n a l o g o u s  -153-  An  orange c r y s t a l l i n e m o d i f i c a t i o n o f t h e t r a n s isomer  t h e p r e p a r a t i o n i n v o l v i n g IrC£^. 65° is  was f o r m e d  from  I f t h e t r a n s c o m p l e x i s warmed a t  f o r 15 m i n i n T> 0, t h e a q u a t e d s p e c i e s t r a n s - [ I r C f t ^ ( D M S O ) (D^O) ] ~ 2  formed and i d e n t i f i e d  a t 63.58. acid  by the methyl  This reaction p a r a l l e l s  p e a k s t h a t grow  that of the corresponding  ( c h a p t e r 4.1.3.3) a n d s u p p o r t s  Only  from t h ec i s a c i d a r e  2  a f t e r h e a t i n g f o r 15 m i n .  t r a n s Rh  the stereochemical assignment.  m i n o r amounts o f t h e D 0 - s u b s t i t u t e d p r o d u c t s observed  i n t h e """H nmr  T h e l a r g e amount o f d i m e t h y l s u l f i d e  f o r m e d i n t h e p r e p a r a t i o n o f t h e c i s a c i d may r e s u l t  from t h e a c i d -  catalyzed decomposition  The f o r m a t i o n  and  decomposition  o f DMSO o r c o o r d i n a t e d DMSO.  of hydridoiridium species  is  n  o  t  a  likely  source  o f s u l f i d e s i n c e n o r e d u c i n g a g e n t was p r e s e n t . The as  o x i d a t i v e a d d i t i o n o f a s t o i c h i o m e t r i c amount o f HCJ".  t h e DMA a d d u c t ) t o [ I r C J c . ( c y c l o o c t e n e ) ] 2  2  i n DMSO/CH C£ 2  a l l o w s t h e i s o l a t i o n o f I r C £ H ( D M S O ) ^ , 3_7 ( e q u a t i o n 5.1, 2  The  use o f excess  necessary  DMSO i n t h e r e a c t i o n s o l u t i o n  figure  t o a v o i d t h e f o r m a t i o n o f a. c y c l o o c t e n e / D M S O m i x e d  c o o r d i n a t e d o l e f i n come i n t h e nmr s p e c t r u m a l o n g w i t h a DMSO p e a k a t 6 3 . 4 6 .  [H(DMSO) ] [IrCJ~, (DMS0) ] 2  The  solutions  4  2  complex  peaks o f t h e  (CDCA.^) a t 6 4 . 7 ,  I f excess  2.5, and  HC£ g a s i s u s e d ,  then  i s produced.  o n l y s t e r e o c h e m i s t r y f o r the h y d r i d e complex t h a t i s c o n s i s t e n t  w i t h t h e two m e t h y l  resonances o f i n t e g r a t i o n r a t i o  1:2 i n t h e nmr  s p e c t r u m i s o n e w i t h t r a n s c h l o r i d e s a n d m e r i d i a l DMSO l i g a n d s 5.3,  5.3).  (DMSO:Ir=10:1) a p p e a r s  o b t a i n e d when a 3 : l = D M S 0 : I r r a t i o was e m p l o y e d ; b r o a d  1.5  2  (added  37); other  isomers  (figure  s h o u l d g i v e t h r e e peaks b e c a u s e t h e two m e t h y l  -154-  F i g u r e 5.3.  The Formation and Some Reactions of Ir-Sulfoxide Hydride Complexes  -r-  DMSO HCI  (5.1)  56 CI | H S S  37  CDCI, - C H D C U  (5.2)  S  °  N  L C I  6  C  si  l  a  CI I X I  s  DMSO  + H2.  (5.3)  CI r K k ^ C D C I  3  ^-CHDCl,  38  || i s cis-cyclooctene. S  represents S-bonded DMSO.  0  represents DMSO.  <5  5)  N' CI |  C I  H  X  S  + CI | C I N  s  -155-  g r o u p s i n some o f t h e DMSO t h e n become m a g n e t i c a l l y is  confusing  therefore that a preliminary c r y s t a l  yellow hydride (37);  this  complex prepared  hydride  v(Ir-C£) a t 3 3 4 s a n d 300w ( v e r s u s different  high f i e l d  nmr p e a k a t T35.29 ( v e r s u s  trace of a hydride  according  Small  of a  shows t h i s  1  a t 2 1 8 0 cm  302w, t h e v a l u e  m e t h y l peak p o s i t i o n s were n o t r e p o r t e d . s p e c i e s , prepared  structure  by Henbest e t a l .  h a s t h e same v ( I r - H )  inequivalent. I t  geometry  but different  1  found h e r e ) , and a  28.86).  Unfortunately  amounts o f h y d r i d e  t o t h e m e t h o d o f H e n b e s t e t a l . , showed no  a t x35.29 a l t h o u g h  p e a k s a t x 2 9 . 4 5 a n d 28.86 w e r e  present. The the  white  hydride  prepared  h e r e does r e a c t w i t h c h a l c o n e  t o form  c h e l a t e d a l k y l c o m p l e x , _56 ( s e e r e a c t i o n 1.20, f i g u r e 5.3 o r c h a p t e r  1.3).  The u p f i e l d  shifts  i n e q u i v a l e n t DMSO m e t h y l s ,  ( o f u p t o 1.5 ppm!) f o r t h e r e s o n a n c e s o f t h e observed  i n t h e nmr o f t h i s  product,  are the  3 same a s t h o s e proximal  reported  , and a r e caused by t h e r i n g  currents of the  phenyls of the a l k y l s .  A c i s d i h y d r i d e , _3_8, f i g u r e 5.3, was a l s o p r e p a r e d by  t h e o x i d a t i v e a d d i t i o n o f H^ t o t h e c y c l o o c t e n e  stereochemistry data;  the  t r a n s DMSO c o n t a i n m a g n e t i c a l l y  I t appears that t h e white  d i m e r i n DMSO. T h e  inequivalent methyl  dihydride originally  prepared  1  i s  i s o m e r o f _38_ c o n t a i n i n g a n 0-bonded DMSO t r a n s t o t h e h y d r i d e .  would account f o r t h ed i f f e r e n t  s p e c t r a l data  2250 cm , 6 2 . 7 8 ( s , 3 , D M S ( ) ) ; o t h e r w i s e , 1  to  yield  shown i s u n a m b i g u o u s l y d e t e r m i n e d b y t h e nmr s p e c t r a l  the mutually  groups.  i n good  those  found i n t h e present  study.  reported;  the reported  1  This  v ( l r - H ) a t 2170,  spectra are identical  -156-  Th e h y d r i d e s _3J7 and _38_ d e c o m p o s e i n t h e p r e s e n c e o f CDCH^ o r HC&.DMA. 5.3;  nmr  The  major products,  d a t a n o t e d i n t h i s and  assignment of t h e i r  previous  stereochemistries.  w i t h HC&.DMA ( 5 . 4 ) hydride  as d e t e r m i n e d by  results  The  as  CHDC£  in this  2  rearrangement of other  w i t h CDC£^ p r o c e e d a s  the hydride  allow a f a i r l y  r e a c t i o n of the  t h a t i s not  t h a t r e a c t i o n s between i r i d i u m h y d r i d e s  hydrides  1  appear i n f i g u r e  i n the q u a n t i t a t i v e formation  species of stereochemistry  proceed without  work  nmr,  o f a new  : an  situ not  Reactions  hydrocarbon,  Mixtures  of the cyclooctene  r e a c t w i t h HCJl.DMA.  No  d i m e r and  5.2.  sulfoxides  f r o m r e a c t i o n s o f MPSO, DPSO,  2  On  using  5.2.1.  metal.  and  S u l f o x i d e Complexes  Introduction I r i d i u m - s u l f o x i d e c o m p l e x e s a r e known t o c a t a l y z e t h e  2  isopropanol  s u b s t i t u t e d s u l f o x i d e s , t h i s p r o c e d u r e gave I r  Iridium - Chiral  in  s u l f o x i d e were  Attempts at the Asymmetric H y d r o g e n a t i o n of P r o c h i r a l Ketones  Olefins using  H  yielding  e x c e s s DPSO i n  excess of a c h i r a l  compounds w e r e i s o l a t e d 3  the phenyl  the  O x i d a t i v e a d d i t i o n r e a c t i o n s on  MBMSO, TBPTSO, o r OTPTSO w i t h I r C £ - 3 H 0 i n MeOH. and  of  HC£  case.  i r i d i u m ( I ) systems c o n t a i n i n g an attempted.  rule  i r i d i u m c h l o r i d e i s formed  i s t r a n s f e r r e d to the halogenated  succeed.  CH^C/^ d i d n o t  mono-  ( p h o s p h i n e c o m p l e x e s ) and  B r i e f attempts to i s o l a t e pure complexes w i t h other d i d not  dihydride  c o n s i s t e n t w i t h the  l i g a n d s . ~*  expected  confident  f r o m a l c o h o l s and  t o a,3-unsaturated Therefore  the use  other H  2  donors to ketones to g i v e a l c o h o l s ,  ketones to give saturated ketones of c h i r a l  t r a n s f e r of  (see chapter  s u l f o x i d e l i g a n d systems w i t h  and 1.3.2).  prochiral  -157-  substrates  seemed a p o t e n t i a l m e t h o d t o a c h i e v e c a t a l y t i c  asymmetric  hydrogenation. The  asymmetric  hydrogenation of p r o c h i r a l ketones to a l c o h o l s  of h i g h o p t i c a l p u r i t y Co a n d Rh c a t a l y s t s  (70-80%) has been a c c o m p l i s h e d u s i n g  and h y d r o g e n .  various  Normally a-diketones give the best  7 results,  e.g. b e n z i l  hydroxybutyric acid e.e.  (79%) 8  (80%)  has been produced  , the l a c t o n e of , and  2,3-butanedione  and  transfer  9  ; 2-octanol with  chiral catalyst  effective.  system  RuCi^CPPhg)^  1 1  Hydrogenation of a,^-unsaturated ketones, p r o c h i r a l catalyst  (IrCJi^I^DMSO) ^ formed  at the o l e f i n ,  i n s i t u ) has  been r e p o r t e d , a l t h o u g h such s u b s t r a t e s have been reduced u s i n g as the hydrogen and  transfer  itaconic acid  5.2.2.  catalyst.  12  The  not  RuCJt^CPPh.^  o l e f i n i c bond i n a t r o p i c  c o u l d n o t be r e d u c e d w i t h I r - s u l f o x i d e  acid  catalysts.  13  Experimental Samples o f 3-methyl-3-penten-2-one,  2-octanone (U.  synthesis  f o r hydrogenation  from s o l v e n t , a l t h o u g h a system w i t h  a c h i r a l a l c o h o l s o l v e n t has p r o v e n  u s i n g the Henbest  13%  f r o m 2 - o c t a n o n e . H o w e v e r no a s y m m e t r i c  has been r e p o r t e d u s i n g a w e l l - d e f i n e d involving  2-oxo-3,3-dimethyl-4-  ( A l d r i c h Chem. Co.)  of B r i t i s h Columbia).  b e n z i l and  2,3-butanedione  m e t h y l p r o p e n - l - o n e was (Eastman)  were k i n d l y  4-methyl-3-penten-2-one, d o n a t e d by P r o f . D.  and  Dolphin  P r o f . R.  P i n c o c k (U.B.C.) d o n a t e d  (Eastman  Organic Chemicals). l,3-Diphenyl-2-  p r e p a r e d by f i r s t  reacting  w i t h p h e n y l magnesium b r o m i d e , and  a-methyl  then o x i d i z i n g  of  cinnamaldehyde the  tfr^. ^  by column  g e l i n 30-60° p e t r o l e u m e t h e r a n d  chromatography  using s i l i c a  p r o d u c t was  resulting  a,£-unsaturated a l c o h o l w i t h a c t i v a t e d  1  The  samples  purified  benzene ( 1 : 1 ) , and t h e n by e l u t i n g w i t h t h i s s o l v e n t m i x t u r e ; t h e u n s a t u r a t e d k e t o n e was  i d e n t i f i e d b y i t s mass s p e c t r u m  (M+ a t 2 2 2 ,  a,Bm/e),  -158-  and  i t s nmr (CDCJc^): 6 2 . 2 3 ( s , 3 , C H ) , 7 . 0 - 7 . 7 ( m , l l . p h e n y l + C=C-H). 3  A more d i r e c t p r e p a r a t i o n i n v o l v e s t h e c o n d e n s a t i o n and  1-phenylpropan-l-one. The  of benzaldehyde  2  H2 t r a n s f e r r e a c t i o n s w e r e c a r r i e d o u t i n a 1 0 m l r o u n d  bottom f l a s k f i t t e d w i t h a septum, a thermometer, and a condenser. The N  2  in and  system c o u l d be d e g a s s e d v i a c o n n e c t i o n s source  from t h e top of t h e condenser.  an o i l bath K.  and s t i r r e d  t o a v a c u u m pump a n d a  S o l u t i o n s were thermostat ted  using a magnetic f l e a .  Brzezinska k i n d l y provided  P r o f . W.  Cullen  t h e r e a c t i o n f l a s k and o t h e r  facilities. Standard c o n d i t i o n s were maintained  f o r the  experiments:  t e m p e r a t u r e o f 8 3 ° , 4 m l i s o p r o p a n o l , 0.1 m l w a t e r , 15 mg t r a n s [H(DMS0) ]tIrC£ (DMS0) ] 2  4  2  ( 5 . 7 x l O ~ M ) , and s u b s t r a t e 3  a l c o h o l , w a t e r , and c a t a l y s t were f i r s t 2h  t o form i n s i t u hydride  used, IrC£ .3H 0 3  for  2  species.  stirred  (0.24M).  under N  When t h e c h i r a l  The  a t 83° f o r  2  s u l f o x i d e s were  ( 1 5 mg) a n d 3 e q u i v a l e n t s o f s u l f o x i d e w e r e h e a t e d  l h i n the isopropanol/water  solution.  Then s u b s t r a t e  (^0.1 m l )  was i n j e c t e d a n d t h e r e a c t i o n was m o n i t o r e d b y g a s c h r o m a t o g r a p h y ( s e e chapter 2.1). Where p o s s i b l e , t h e r e a c t i o n s w e r e a l s o m o n i t o r e d b y nmr. A l l the  s u b s t r a t e s had peaks w i t h chemical  greater  s h i f t s b e t w e e n 61.8 a n d 3.0, o r  than 65.5, so t h a t t h e c o n v e r s i o n  followed despite the large isopropanol  o f t h e s u b s t r a t e c o u l d be  and w a t e r peaks.  Thus a serum-  c a p p e d nmr t u b e w i t h d e g a s s e d r e a c t i n g s o l u t i o n ( u n d e r N ) was a l s o 2  in  t h e thermostatted o i l bath, The  presence o f induced  and s p e c t r a were r e c o r d e d c h i r a l i t y i n the 2-octanol  place  occasionally. product  was t e s t  -159-  for using a chiral  l a n t h a n i d e nmr  s h i f t reagent,  tris[3-(heptafluorobu-  t y r y l ) - d - c a m p h o r a t o ] e u r o p i u m ( I I I ) s u p p l i e d by A l p h a C h e m i c a l s . t h e i s o p r o p a n o l and w a t e r w e r e e v a p o r a t e d vacuo, was  and  t h e n t h e r e s i d u e was  decanted  f r o m any  s o l i d s and  t a k e n up  the r a t i o  of reagent  from the r e a c t i o n s o l u t i o n i n i n 0.2  transferred  ml of a s t a n d a r d s o l u t i o n of s h i f t  reagent  to hydrogenated  Typically  ml  CCH^;  t o an nmr  i n CCl^  p r o d u c t was  was  this  solution  tube.  Then  added so  a b o u t one.  0.2  that  The  d i a s t e r e o t o p i c a l l y r e s o l v e d methyl groups a to the h y d r o x y l of 2-octanol a p p e a r as d o u b l e t s a t  5.2.3.  6^15.^  R e s u l t s and D i s c u s s i o n The  attempts a t the asymmetric  a r e s u m m a r i z e d i n t a b l e 5.1; 5.2.  The  may  be due  those i n v o l v i n g o l e f i n s are given i n table  lack of e f f e c t i v e c h i r a l  successfully  hydrogenated  i n d u c t i o n i n the products  to a concurrent r e d u c t i o n of the c h i r a l  r e a c t i o n mixtures..  An  r e a g e n t method.  one  and  The  i r band, p r e c i p t a t e d  Another  possibility  an  the  i s that  iridium metal,  the source of the n o n e n a n t i o s p e c i f i c  b u l k y s u b s t r a t e s such as  b e n z i l were not  from  since  have been too s m a l l t o d e t e c t u s i n g t h e  f o r m e d d u r i n g t h e r e a c t i o n , was catalysis.  sulfoxide,  TBPTSO  enantiomeric excess i n the 2-octanol product  f r o m t h e MPTSO s y s t e m may shift  from  substrates using catalysts containing  o r a n g e compound, c o n t a i n i n g no v ( S 0 )  chiral  hydrogenation of s a t u r a t e d ketones  hydrogenated.  1,3-diphenyl-2-methylpropen-l-  -160-  T a b l e 5.1  The r e d u c t i o n o f k e t o n e s c a t a l y z e d b y I r ( I I I ) - s u l f o x i d e •• Complexes ( ) a  Substrate  Time u n t i l 100% c o n v e r s i o n  Ligand  e. e.  2,3-butanedione  DMSO  18h  (b)  2,3-butanedione  (R.R)-PTSE  72h  (b)  benzil  DMSO  no  2-octanone  R-MPTSO  48h  2-octanone  R-TBPTSO  25% c o n v e r s i o n i n 14h(e)  (a)  reduction <4%  ( c )  <4%  (d) (d)  T h e s t a n d a r d c o n d i t i o n s w e r e : T=83°, 4 m l 2 - p r o p a n o l , 0.1 m l H 0 , 0.24M s u b s t r a t e , [IrCJc.4(DMSO) JI" o r ["IrC£ (sulfoxide) "]= 6xlO M. 2  2  3  3  _ 3  9  (b) (c)  A c e t o i n and p r o d u c t s from r e d u c t i v e d i m e r i z a t i o n b y G.C. b u t t h e y c o u l d n o t b e i s o l a t e d . Some I r m e t a l f o r m e d .  were observed  (d)  T h e e.e. o f t h e 2 - o c t a n o l p r o d u c t was d e t e r m i n e d u s i n g t h e c h i r a l s h i f t r e a g e n t . An e.e. o f l e s s t h a n ^ 4 % would n o t be d e t e c t e d j u d g i n g f r o m t h e s i g n a l t o n o i s e r a t i o o f t h e nmr spectra.  (e)  An o r a n g e p r e c i p i t a t e ,  presumably an I r - s u l f i d e complex,  formed.  -161-  T a b l e 5.2  The r e d u c t i o n o f o l e f i n s c a t a l y z e d b y I r ( I l l ) - s u l f o x i d e  3-methyl-3-penten-2-one  (a)  Maximum R a t e of Hydrogenation  Ligand  Substrate  complexes  (7.5±2.0)xlO~ M m i n  DMSO  4  - 1  100%  c o n v e r s i o n i n 400 m i n ^ (c) 85% c o n v e r s i o n i n 68h -4 -1 <lxl0 M min  R-TBPTSO 4-methyl-3-penten-2-one  DMSO  1,3-diphenyl-2-methyl-  DMSO  propen-l-one R-TBPTSO (d)  (R,R)-PTSE itaconic  acid  DMSO  ethyl atropate N-acetamidocinnamic  (a)  DMSO acid  DMSO  The s t a n d a r d c o n d i t i o n s w e r e : T=83°, 4 m l 2 - p r o p a n o l , 0.1 m l H 0 , 0.24 M s u b s t r a t e , [ I r C ^ C D M S O ^ ] o r ["IrC£ ( s u l f o x i d e ) " ] = 6x10" M. -  2  3  3  3  (b)  T h e p r o d u c t w a s shown b y G.C. a n d nmr t o b e t h e s a t u r a t e d k e t o n e i n >90% y i e l d . A w h i t e DMSO-hydridoiridium complex ( v ( I r - H ) = 2250 cm-'-) p r e c i p i t a t e d a t t h e e n d o f t h e r e a c t i o n . -  (c)  C o n d i t i o n s u s e d h e r e w e r e : T = 8 3 ° , 6 m l 2 - p r o p a n o l , 0.2 m l H 0 , 0.25 m l s u b s t r a t e , t I r ] = 1 . 3 x l O " M , [ s u l f o x i d e ] = 4 x 1 0 " M . A c o n c e n t r a t e d f r a c t i o n o f s a t u r a t e d k e t o n e i n 2 - p r o p a n o l was d i s t i l l e d f r o m t h e r e a c t i o n m i x t u r e b u t i t h a d no o p t i c a l rotation. An orange I r - s u l f i d e complex p r e c i p i t a t e d d u r i n g the reaction. 2  2  (d)  An u n i d e n t i f i e d y e l l o w I r complex  precipitated.  2  -162-  5.3.  Solvent Transfer Hydrogenation  of a,g-Unsaturated  Aldehydes t o  the Unsaturated A l c o h o l s C a t a l y z e d by H y d r i d o i r i d i u m S u l f o x i d e 5.3.1.  Complexes.  Introduction A wide v a r i e t y  o f t r a n s i t i o n m e t a l complexes a r e a v a i l a b l e f o r  the c a t a l y t i c h y d r o g e n a t i o n o f t h e o l e f i n i c bond i n a , g - u n s a t u r a t e d c a r b o n y l compounds, a l t h o u g h a p r o b l e m  encountered  f o r aldehyde sub16  s t r a t e s c a n b e d e a c t i v a t i o n o f t h e c a t a l y s t b y CO a b s t r a c t i o n .  To  accomplish the s e l e c t i v e hydrogenation of the carbonyl function r e a c t i o n 5.6), and  e s p e c i a l l y f o r unhindered  substrates,  i s more  (e.g.,  difficult,  t o o u r k n o w l e d g e o n l y o n e e f f i c i e n t homogeneous c a t a l y s t h a s b e e n  d i s c o v e r e d ^ a n d t h i s i n v o l v e s t h e u s e o f [RhC£(CO) ] i - t h e p r e s e n c e of t e r t i a r y amines (and a c o r r e s p o n d i n g polymer-supported system) under 2 h y d r o f o r m y l a t i o n c o n d i t i o n s ( e . g . 80 kg/cm , C 0 / H = 1 , 9 0 ° C ) . 1  n  2  2  2  H RCH=CHCH0  The 5.2)  ^  (5.6)  2  p r e s e n t w o r k shows t h a t H e n b e s t ' s  a t 80°C u n d e r a N  2  atmosphere,  to the unsaturated a l c o h o l  5.3.2.  RCH=CHCH 0H  catalyst  system  converts a,g-unsaturated  (see  section  aldehydes  (see t a b l e 5.3).  Experimental Crotonaldehyde,  cinnamaldehyde,  o b t a i n e d from Eastman O r g a n i c C h e m i c a l s . c o n d i t i o n s noted  and a-methyl  cinnamaldehyde  were  The t e c h n i q u e s and s t a n d a r d  i n s e c t i o n 5.2.2 w e r e u s e d .  The c i n n a m y l  alcohol  products can be r e c o v e r e d by e v a p o r a t i o n o f t h e r e a c t i o n s o l v e n t f o l l o w e d by c h r o m a t o g r a p h y 5.3.3.  o f t h e r e s i d u e on a l u m i n a .  R e s u l t s and D i s c u s s i o n With cinnamaldehyde  a t 9 0 % c o n v e r s i o n , t h e r e i s e s s e n t i a l l y no  -163-  r e d u c t i o n o f t h e o l e f i n i c bond; c i n n a m y l a l c o h o l i s formed y i e l d s b u t , depending  i n high  o n t h e w a t e r c o n t e n t , up t o 1 2 % b y - p r o d u c t s  18 (including ethers  ) were d e t e c t e d .  a-Methyl cinnamaldehyde the  a t t h e same 9 0 % c o n v e r s i o n g i v e s  u n s a t u r a t e d a l c o h o l w i t h 100% s e l e c t i v i t y .  hindered a t t h e o l e f i n i c bond, s t i l l w i t h >90% s e l e c t i v i t y  Crotonaldehyde,  less  gives the trans-2-buten-l-ol  a t 90% c o n v e r s i o n .  The maximum  selectivities  a c h i e v e d f o r t h e s e t h r e e s u b s t a n c e s u s i n g t h e Rh s y s t e m s w e r e 9 0 , 87, and 50%, r e s p e c t i v e l y . " ' " Use  7  of IrCJl H(DMSO) , 2  3  3_7, i n s t e a d o f t h e i n s i t u  catalyst  from trans-[H(DMSO) ] [IrCJl (DMSO) ] , shortened r e a c t i o n times con2  siderably  2  this  2  (table 5.3). At higher water concentrations  2-propanol-H 0), and  4  the H  2  (<10:1 V/V  t r a n s f e r r e a c t i o n s were s t r o n g l y  inhibited,  i s l i k e l y d u e t o t h e d e c o m p o s i t i o n o f t h e h y d r i d e , _3_7_, w h i c h  turns yellow i n the presence of moisture. 13 G u l l o t t i et a l , , using i n s i t u sulfoxide catalysts  formed  from IrC£ -3H 0,had u s e d l o n g r e a c t i o n t i m e s (72h) and had n o t e d 3  2  r e d u c t i o n o f t h e o l e f i n i c bond as w e l l a s t h e c a r b o n y l group unsaturated aldehyde substrates.  With t h e system d e s c r i b e d  with here  f u r t h e r r e d u c t i o n o f c i n n a m y l a l c o h o l and t h e 2 - b u t e n - l - o l t o t h e s a t u r a t e d a l c o h o l s was r e l a t i v e l y  slow; a-methyl  cinnamic alcohol  showed n o r e d u c t i o n e v e n a f t e r 2 0 h . The r e a s o n s f o r t h e p r e f e r e n t i a l r e d u c t i o n o f t h e c a r b o n y l moiety a r e not too c l e a r ,  s i n c e t h e same c a t a l y s t  system e f f e c t s t h e 3  h y d r o g e n a t i o n o f t h e o l e f i n i c bond i n a , g - u n s a t u r a t e d k e t o n e s  and  a l s o , b u t more s l o w l y , t h e r e d u c t i o n o f s a t u r a t e d c y c l o h e x a n o n e s t o  -164Table  Hydrogenation  5.3  of a ,ig-Unsaturated  Aldehydes At  Time f o r 90% Conv.,min.  Substrate  cinnamaldehyde a-methyl  80  cinnamaldehyde  crotonaldehyde  (a)  0.25 V/V)  (or  15  ( b )  90%  % Unsat. Alcohol  )  78  Conversion % Sat. Aldehyde  (c)  trace  0  250  90  0  0  50  85  5  trace  M substrate, i n situ a t 80°C u n d e r N .  10 M Z  I r , i n isopropanol-water  (30:1  2  (b)  U s i n g 10~ M H I r C £ ( D M S O ) , 10~ M isopropanol-water.  (c)  A b o u t 1 2 % b y - p r o d u c t s ; a t 300:1 V/V i s o p r o p a n o l - w a t e r , t h e % c i n n a m y l a l c o h o l = 8 5 % w i t h 5% b y - p r o d u c t s ; a t 10:1 V/V, t h e h y d r o g e n a t i o n was c o m p l e t e l y i n h i b i t e d .  2  2  2  % Sat. Alcohol  3  a q u e o u s HC£,  30:1  V/V  -165-  the a l c o h o l s . group v e r s u s type  18  Steric  f a c t o r s could favour  reduction of the aldehyde  a ketone group b u t , s i n c e t h e c a t a l y s t s w i t h  l i g a n d s i n v a r i a b l y reduce the o l e f i n i c  bond i n  phosphine-  a,3-unsaturated 15 17 19  aldehydes whether using  gas o r a hydrogen donor s o l v e n t  e l e c t r o n i c arguments a r e favoured. IrCJc^HCDMSO)  i n d i c a t e more a c i d i c  i n the case of corresponding  Some e x c h a n g e d a t a character  i n the hydrogen  at the carbonyl H  Reduction  -> RCH-0 — Ir-H  *RCH(OH) Ir  t o be enhanced w i t h  v i a a d d i t i o n of the metal hydride  than  could  +  -> RCH„OH  (5.7)  catalysts i s  increasing hydridic character  i n the reverse d i r e c t i o n to that  shown i n ( 5 . 7 ) , b u t b o t h modes o f a d d i t i o n seem f e a s i b l e 165-167, 182, 1 8 8 ) .  ,  e.g.  of aldehyde groups v i a t r a n s i t i o n - m e t a l hydride  usually considered  '  with  p h o s p h i n e c o m p l e x e s , and t h i s  enhance a d d i t i o n o f t h e m e t a l h y d r i d e  RCH=0 IrH  1  '  ( r e f . 16, pp.  -166-  6.  V i b r a t i o n a l A n a l y s i s o f Oxygen-Bonded S u l f o x i d e  6.1.  Complexes  Introduction Despite  the' c o m p l e x i t y  of i n f r a r e d spectra of coordinated  oxygen  d o n o r s o f t h e t y p e 0=L, f o r e x a m p l e , s u l f o x i d e s , p h o s p h i n e o x i d e s , a n d pyridine oxides,  a number o f r e c e n t  s y n t h e t i c papers report  thelocation  o f v(M-K)) a n d v ( L O ) modes f o r a w i d e r a n g e o f m e t a l s a n d l i g a n d s . c u l a r l y r e l i a b l e a r edata  f o r DMSO ( d i m e t h y l s u l f o x i d e ) a n d TMSO  methylene s u l f o x i d e ) complexes based on t h e d e t a i l e d v i b r a t i o n a l o f Adams a n d T r u m b l e Mf-0  character  1  a n d B e r n e y a n d Weber  2 3 ' .  (ii)  they a r enormally  (iii)  they a r e s h i f t e d  o f medium i n t e n s i t y a n d a r e m e t a l - s e n s i t i v e , t o l o w e r f r e q u e n c y when t h e d e u t e r a t e d  i s used, u s u a l l y suggesting  ligand  t h a t 0=L moves a s a w h o l e d u r i n g M-K)  ,  they y i e l d  ligand  studies  t o c e r t a i n bands i s comprised o f t h e f o l l o w i n g :  t h e bands cannot be a t t r i b u t e d t o f r e e l i g a n d v i b r a t i o n s ,  (iv)  (tetra-  The e v i d e n c e f o r a s s i g n i n g  (i)  stretching  Parti-  a constant  ratio  complexes o f a g i v e n m e t a l ,  o f v(M-K)) v a l u e s  f o r two d i f f e r e n t  f o r e x a m p l e , 0.93 f o r TMSO  versus  DMSO , 3  (v)  they sometimes agree w i t h c r y s t a l  field  stabilization  energy  2 3 7 ordering criterion  o f a s e r i e s o f t r a n s i t i o n m e t a l -MD=L c o m p l e x e s indicates that metal-ligand  such trends, constants The  c a n be estimated  ' ' .  bond s t r e n g t h s , w h i c h  from these data,  The l a s t  reflect  especially i f force  c o u l d be c a l c u l a t e d . success of such c a l c u l a t i o n s i n d e s c r i b i n g t h e i n f r a r e d s p e c t r a 3 o f h e x a c o o r d i n a t e TMSO c o m p l e x e s encouraged us t o analyze o u r c o m p i l a t i o n  -167-  o f v(SO)  a n d v(MO)  data  l i t e r a t u r e and i n t h i s  6.2.  f o r s u l f o x i d e complexes d e s c r i b e d  i n the  thesis.  Calculations A r o u g h c o r r e l a t i o n was i n i t i a l l y  assigned  a s v(M-O) a n d t h e f r e q u e n c y  nation of s u l f o x i d e to metal.  noted between the  r e d u c t i o n o f v(SO)  Data are given  on c o o r d i -  i n t a b l e 6.1 f o r 0-  b o n d e d DMSO a n d TMSO i n some t r a n s i t i o n m e t a l c o m p l e x e s . sometimes a m b i g u i t y  bands  There i s  i n t h e a s s i g n m e n t o f t h e 0-bonded S O - s t r e t c h  c e r t a i n o f t h e DMSO c o m p l e x e s b e c a u s e o f t h e m e t h y l r o c k i n g modes (two  Av(SO) v a l u e s  a r e thus g i v e n ) , but nevertheless  g e n e r a l l y w i t h i n c r e a s i n g Av(S-O).  v(M-0)  within 15 16 '  increases  Such a r e l a t i o n s h i p has been  19 suggested data  , b u t n o t p r e v i o u s l y documented.  p l o t t e d f o r systems where t h e r e  Except f o r t h e [CrL,]  3+  D  complexes  Figure  6.1 shows t h e  i s t h o u g h t t o b e no  ambiguity.  (L=DMS0, TMSO), t h e d a t a  fall  within  a r e m a r k a b l y w e l l - d e f i n e d b a n d f o r a l l t h e mono-, b i - , a n d t r i v a l e n t species.  Figure  6.1 u n f o r t u n a t e l y d o e s n o t a i d i n e s t a b l i s h i n g t h e 2+  c o r r e c t a s s i g n m e n t s f o r v ( S O ) . a n d p^(CE^)  i n t h e [M(DMSO)^]  species  (M=Mn(II),Fe(II),Co(II),Ni(II)). We t h o u g h t t h a t a m o r e m e a n i n g f u l c o r r e l a t i o n s h o u l d using  the corresponding  from t h i s  force constants  which should  be obtained  c o r r e c t the  deviations  l i n e a r r e l a t i o n s h i p o f some i o n s s u c h a s C r ( I I I ) a n d A £ ( I I I ) .  -168-  T a b l e 6.1 I n f r a r e d id a t a — f o r 0-bonded DMSO a n d TMSO c o m p l e x e s  Complex—  1. 2.  [Cr(DMS0),]  3 +  cis-[Pt(DMSO)  (DMSO) ]  2+  2  3.  cis-[Pd(DMSO) (DMSO) ]  4.  mer-RhCl (DMSO)(DMSO)  5.  cis-RuCl (DMSO)(DMS0)  6.  [Fe(DMSO),]  7.  [Rh(COD)(DMSO)  8.  [Rh(COD)(PPh  2  +  2  3  2  3  3 +  ]  )(DMSO)]  +  [Mn(DMSO),] 2+ [Fe(DMSO)J [Co(DMSO),] [Ni(DMSO),] [Cu(DMSO) ]  2+ 2+ 2+  4  trans-CuCl (DMSO) 2  9. 10.  [Cr(TMSO),]  3 +  c i s - [ P t (TMSO) (TMSO) ]  2+  2  11.  cis-[Pd(TMSO) (TMSO) ]  12.  [Fe(TMSO),]  13.  [Rh(COD)(PPh  14.  [Ni(TMSO) ]  15.  [Co(TMSO),] 2+ [Fe(TMSO),] 2+ [Mn(TMSO) ] — 6  16. 17.  2  3 +  )(TMSO)]  6  2 +  2  +  Av(SO)-  v(MO)  127  529  2,8  176,158  517  9  135,150  493  9  120  491  10,chapter 4  140  480  11,12  115  475  8,13  105  473,465  chapter 3  97  450  chapter 3  100 o r 55  418  2,8,14  105 o r 70  438,415  2,8,14  105 o r 61  436  2,8,15,16  105 o r 55  444  2,8,14  115 o r 67  467  8,15,17  132 o r 75  496,481  1,8,18  90  484  3,13  143,127  480,469  9  121,102  473,458  9  102  440  3,13  87  432  chapter 3  52  413  3,13  54  406  3,13  55  397  3,13  48  388  3,13  a.  Mulls;  _b  DMSO a n d DMSC) d e s i g n a t e S- a n d 0 - b o n d e d , r e s p e c t i v e l y  c:  Frequency s h i f t  Reference  i n cm  on 0-coordination.  ( a n d f o r TMSO)  200 o2  S  u  ^2  150-1  10  85  o  JO  t—\  J2  ^100  <1  Jl  4  >8  .13  50H  .17  ,16  J 5  400 Figure  ON  I  J4  450 6.1.  \) (MO),  c m "  500 1  P l o t o f f r e q u e n c y s h i f t o f v ( S 0 ) on c o o r d i n a t i o n o f 0-bonded s u l f o x i d e v s . v ( M 0 ) ; O , d i m e t h y l s u l f oxide complexes; • , t e t r a m e t h y l e n e s u l f o x i d e complexes. Numbers r e f e r t o c o m p l e x e s l i s t e d i n t a b l e 6.1.  -170-  F i g u r e 6.2 3 T h e b e n t MOL m o d e l ( f i g u r e 6.2) o u t l i n e d b y B e r n e y a n d Weber yield  t h e most u s e f u l r e s u l t s  f o r the molecules o f v a r i e d  discussed  here.  located.  A c c o r d i n g l y , only t h e crude treatment  F matrix  I n the usual  experiment o n l y v ( S 0 ) and v(M0) a r e involving a diagonal  i sjustified  X -X (AF 3  2  1 1  +BF  The F m a t r i x angle  2 2  +CF  3 3  )+A(DF  has diagonal  1 1  F  2 2  +EF  elements  bending constant.  reference  F  2 2  y  M  + y  +GF  3 3  =  F  3 3  F  ' 22 F  M  The c o n s t a n t s  0  )-HF  1 1  =  F  0L'  a  1 1  n  F  d  2 2  F  F  3 3  =0  0  B  =  L  y  +  0  y  C  2~  =  +  M 2~ 0M  = F  A,B,C,D,E,G,H, d e r i v e d  L V M L ~T~2 0L 0M 0L P  +  r  r  r  ysinVuy+uy+yy 2  ML  L0  oM  2, ML- 0L A r  R  E =  y  0  (  OL  r  2 0 ( ^  2 2 0M 0L  + OM  y  •  2  "  0M 2 2 0M 0L  r  r  )  +  r  2  G =  V L  S I  S i n  r  2  ~ ~ ~ "OM  A  •  y  )  M L y  OL  Y  L 0 ML 0M) y  r  (R  • 0 M  +r  y  2 2 0M 0L  L 0 y  U  0L  Y  _2 "OM  r  y  0 M ML 2 2 r r OM OL  y  y  ( r  (6.1)  33 MOL'  20, a r e :  r  D=  F  ii  y  =  geometry  s o t h a t t h e problem can be s o l v e d e a s i l y by u s i n g 20 expanded s e c u l a r e q u a t i o n (6.1) f o r a bent t r i a t o m i c .  the  A  will  + r  0L  )  t  h  from  e  -171-  _4 r  (y  L V+ +  L  y  2 0M  r  (  M  y  +  V  + V M L 2 2 OM OL  2 0L  r  V V  (  + M L P  P  r  r  0 ML 2 2 OM OL t J  ( r  + r  + r  OL  y , y , and y  a r e t h e m a s s e s , i n a.m.u., o f t h e m e t a l ,  and  t h e s u l f o x i d e ( s u b t r a c t i n g t h e mass o f t h e o x y g e n ) , unknowns o f t h e t h r e e s i m u l t a n e o u s  <S (MOL)=A,j, w h i c h i s n o r m a l l y  )  r  The  The  OM  equations  t o o low i nfrequency  t h e oxygen,  respectively.  are^Q'^OL'  A N  ^  t o be l o c a t e d i n  o  infrared  analyses.  The v a l u e ^ j O L ^ ' " ^ =  elaborate calculations  vities  to F  a  n  3  m  ^yne A  determined  b y more  w a s u s e d , o r , i f v a r i e d , h a d t h e same 3  d F ^ previously described  .  s o l v e d f o r F ^ o r T?^ u s i n g e q u a t i o n s ( 6 . 2 )  Equation  sensiti-  (6.1) c a n be  and (6.3).  Therefore  with o  A^ c o r r e s p o n d i n g  t o v(MO) a n d a n i n i t i a l  guess f o r  can be o b t a i n e d and used w i t h A2 c o r r e s p o n d i n g 1?22"  Thus i t e r a t i v e l y  theequations  F 2 2  =  mdyne/A,  6 . 0  t o v(OL) t o s o l v e f o r  r a p i d l y converge t o a unique  solution.  F =[A -A (BF22+CF )+A EF22F33]/[A A-A (DF22+GF )+HF2 F ] 3  2  3 3  F 2=[A2-A2(AF 2  The  1 1  +CF  1  3 3  1  )+A EF 1  3 3  F  1 1  ]/[A2B-A (DF 2  3 3  1 1  -rEF  3 3  2  )+HF  1 1  F  3 3  3 3  ]  approximate s t r u c t u r a l parameters used i n c a l c u l a t i n g  m a t r i c e s a r e a l l w i t h i n 5% o f known c r y s t a l l o g r a p h i c a l l y values  (6.2)  2  1 1  ( f o r example s e e r e f e r e n c e s 11,21,22,23). o  F ^  (6.3)  the G  determined  T h e s e w e r e a n MOL a n g l e o  o f 1 2 4 ° , a n LO=SO l e n g t h o f 1.54A, a n MO l e n g t h o f 1.36A p l u s t h e i o n i c 23 radius of the metal 16.0  f o r oxygen  ion  , a n d a n L mass e q u a l t o t h e l i g a n d mass m i n u s  ( e . g . , 88 amu f o r TMSO).  -172-  As m e n t i o n e d a b o v e , a c o m p l i c a t i o n i n t h e a n a l y s i s o f t h e s p e c t r a o f 0-bonded DMSO c o m p l e x e s i s t h e p r e s e n c e v i b r a t i o n s p^CCH^) w h i c h a r e s i m i l a r stretch  8 15 16 25 ' ' ' , and  w h i c h may  2+ I n d e e d , Co(DMSO), h a s  latter.  b  2+ w h e r e a s Co (DMSO-d^.) ^  has  two  o n l y one  a t 970  cm  -1  rocking  S-0 coupled  i n t e n s e b a n d s a t 994  cm  s h o u l d a l s o s h i f t , and  c o u p l i n g b e t w e e n modes.  i n energy to the  b o r r o w i n t e n s i t y o r be  b a n d s a r e s h i f t e d w e l l b e l o w 900 t h a t v(S0)  of methyl  infrared  and  . Although  to  950  cm  u s i n g the f r e q u e n c i e s of a l l bands thought This y i e l d e d the average values F  Q L  and  F^  which,  of  were c a l c u l a t e d  t o have v(S0)  F^  ,  obvious  t h i s argues perhaps i n favour and  -1  t h e p^CCH^)  on d e u t e r a t i o n i t i s not  In t h i s study, F  the  character.  i n f a c t , were  t o o b e y t h e same r e l a t i o n s h i p c a l c u l a t e d f o r t h e DMSO-d, and  found  TMSO  —o  c o m p l e x e s , w h e r e no the use  ambiguity  value exists.  Certainly,  o f t h e s u l f o x i d e s w i t h no p^CCH^) v i b r a t i o n s p r o v i d e s t h e more  r e l i a b l e data, although of v(S0)  i n t h e v(SO)  f o r some DMSO c o m p l e x e s t h e g r e a t e r  or i t s s i m i l a r p o s i t i o n found  i n corresponding  intensity  TMSO o r DMSO-d,  —6 compounds o f t e n a l l o w s i t s u n i q u e a s s i g n m e n t  ( c h a p t e r 3, r e f e r e n c e s  27).  i n the cases where  Average F  v a l u e s were a l s o estimated  s p l i t t i n g s were 6.3.  6.2  Discussion  lists  the f o r c e constants  w i t h t h e most r e l i a b l e v(S0) TMSO c o m p l e x . i s  v(M0)  observed.  R e s u l t s and Table  6,26,  and  v(M0)  c a l c u l a t e d f o r the  values  compounds  ( e i t h e r t h e DMSO-dg a n d / o r  c h a r a c t e r i z e d , a s w e l l a s t h e DMSO o n e ) .  In a l l cases  o  the bending  c o n s t a n t - F„_,. MOL  was  h e l d a t 0.35  mdyne A i n a c c o r d w i t h  previous  ^ COMPLEX  cm  2+  [FeL ]  2+  [CoL ]  2+  ±  l  ^  t  i  ^  DMSO v(SO)  [MnLg]  ±  v(MO) F _ OL -1 o cm md/A  -1  955 1000  418  950 985  6  [ N i L ] 2+ g  436  950 1000  A£Me L 3  AiEt^L  444  AfcEt-CllL 3+ [A<IL ] [FeL ]  3 +  6  -[Rh(COD)L ]  +  2  MO  v(SO) v(MO) F o  6766 6768  -tRh(COD)(PPh )L]  +  3  1763 970 409  1.63  971 465  985  473  6797  1.50  982 452  991  505  6.86  1.75  984 485  960  539  "6731  2700  965  964 940 950  526 480 473  [CrL,]  3 +  -mer-RhCfl,L„L 3^2% d ^is-tPdL^] " 2 4  :is-[PtL*L J  2 +  2  MOL-°-  3 5  ndyne A  450  928  529  935  491  905 920  493  879 897  517  b -  B  a  r  OL  MO  F  515  970 522,506 6.06 2.05 1723 950 443 435 6.36 2.01 950 5.67 2.58 928 5.86 2.49 935  6717  1731 4790  6.81  1.40  1770  6.91  958  o  x  i  d  e  c  o  f  f  l  p  l  e  x  e  s  TMSO  T753  490  4 6 5  f  v ( S 0  >  V  ( °) F M  m  md/A  J+  6  l  DMSO-d F  992 1001  u  6.79 1.45  438 '6762 415  950 994  g  s  2.55  904 916  3.23  I n d i c a t e s an average a  g  e  6.76  1.58  6.97  1.35  6.92  1.60  6.58  6.38  1.85  MO  v(MOL)  Ref.  974  388 7.22  1.22  122  2,3,8,13,14  967  397 7.09  1.30  123  2,3,8,13,14  968  406 7.07  1.39  123  2,3,8,13,15,16  970  413 7.09  1.45  124  2,3,8,13,14 26 26 26  953  499 6.68  1.75  159  3,6  921  443 6.25  1.71  128  3,8,13  1.90  Chapter 3  6.41  1.80  935  432 6.44  1.85  107  5.87 6.05  2.33 2.21  932  484 6.27  2.09  132  5.68  2.24  2724  1U  480 1745 469  2.58  102  ', ~ ^"0D-l,5-cyclooctadlene  2,3,8,13 Chapter 4  901 473 1792 920 458 879 895  Chapter 3  9,27  dd - L * = s u l f u r •bonded s u l f o x i d e  -174-  calculations  3  .  This approximation  w i l l be d i s c u s s e d below.  T h e F,„ MO o  and  F  values  c a l c u l a t e d f o r TMSO+M a r e c o n s i s t e n t l y 0.07 mdyne/A 3  higher not  and lower,  r e s p e c t i v e l y , than  a serious discrepancy.  those  o b t a i n e d b y B e r n e y a n d Weber ,  I t must b e e m p h a s i z e d t h a t t h e s e  constants  are crude approximations frequencies  t o t h e t r u e v a l u e s , s i n c e they a r e based on 2 17 t h a t may n o t b e p u r e M-0 o r 0-S s t r e t c h e s ' . F o r e x a m p l e ,  s i g n i f i c a n t d e r e a l i z a t i o n o f v i b r a t i o n a l energy i s expected f o r complexes w i t h l i g h t  i o n s l i k e Al(III).The  calculated using v(S0) values, a r eprobably constants; predicted values systems a r e l i k e l y  F UJ-i  higher  and observed  values, which a r e than  thetrue F  up o f v(MOL) g i v e n i n t a b l e 6.2 f o r TMSO-^M  low, e s p e c i a l l y  i f they a r e t o correspond  t o 6(ML)  1 3 values. ' 1  Nevertheless,  theF  and F ^ numbers g i v e t h e t r u e s t i d e a  o f M-0 a n d 0-S b o n d s t r e n g t h s g i v e n t h e l i m i t e d d a t a , w h i c h a r e c o m p r i s e d o f f a i r l y w e l l known s t r u c t u r a l p a r a m e t e r s b u t o n l y two s t r e t c h i n g f r e quencies.  Essentially F  a r e v(M0) v a l u e s  s i z e o f t h e i o n s and l i g a n d s .  c o r r e c t e d f o r t h e mass a n d  3  -175-  T a b l e 6.3.  V i b r a t i o n a l data f o r other sulfoxide  Complex  v(SO) -1 cm  v(M0) -1 cm  1019  372  973  F  complexes^  F  Ref.  8.00  1.00  13  399  7.16  1.36  3  992,943  410  6.59  1.71  28  952,935  424  6.19  1.88  28  986^  454,436  6.80  1.89  29  Mo(Et NCS) (N )(NO)(DMSO)  955^  450  6.32  1.95  30  [Cu(DMSO) ]  940,988  467  6.44  1.96  8,15,17  923,980  496,481  6.18  2.21  1,8,18  915  480  5.62  2.36  11,12  La(NO_) (DMSO), J 3 4 Nd(NO„)„(DMSO) 3 J 4  1000  402-  7.11  1.58  31,32  /  1000  405-  7.10  1.61  31,32  Yb(N0 ) (DMSO)  3  1000  420 3  7.05  1.79  31,32  Lu(N0 ) (DMSO)  3  1000  422-  7.04  1.82  31,32  [Ca(TMSO) J b  2  [Zn(TMSO) J 6  2  HgC£ (DMSO) 2  +  +  2  Hg(SCN) (DMSO) 2  Mo0 C£ (DMSO) 2  2  2  2  2  2  3  2 +  4  trans-CuC£ (DMSO) 2  cis-RuC£ (DMSO) 2  0  3  3  3  3  2  (DMSO)  OL mdyne/A 0  — The d a t a f o r t h e l a n t h a n i d es w e r e n o t u s e d i n t h e o f t h e d i f f i c u l t y i n a s s i g n i n g v(MO). — T h e b a n d r e p o r t e d a t 1030 o r  1024 cm  1 . xs  o MO mdyne/A  c o r r e l a t i o n s because  m o r e l i k e l y t o be p  r  (CH  3>  Figure  6.3.  C o r r e l a t i o n of force 0.35 mdyne/A.  c o n s t a n t d a t a f o r TMSO c o m p l e x e s ; F  taken M  0  L  -177-  When F  i s plotted against  Q L  (figure  c o m p l e x e s ( t a b l e s 6.2,6.3), a good l i n e a r 95%  confidence  data,  a linear  least  correlation results.  squares f i t ,  To  which neglects the Ca(II)  gives  F  = -(1.30±0.22)F  Q L  with a correlation coefficient weakening w i t h by  6.3) f o r a l l t h e TMSO  (8.85±0.38)  r=0.97.  The o v e r a l l  explained  ( p ^ ) - ^ s u l f u r ( d ^ ) d o u b l e bond c h a r a c t e r a s  draws e l e c t r o n d e n s i t y from t h e oxygen f o r s t r o n g e r  Perhaps s u r p r i s i n g  i s the higher  strength of " s o f t " metal  l i n k a g e s w i t h R h ( I ) , P d ( I I ) and P t ( I I ) , at least  t r e n d o f S-0 b o n d  i n c r e a s i n g M-0 b o n d s t r e n g t h i s q u a l i t a t i v e l y  t h e r e d u c t i o n o f oxygen  the metal  +  MO  although  f o r P d ( I I ) and P t ( I I ) , w i t h o x a l a t e s  bonding  - "hard"  there i s s i m i l a r and v a r i o u s  33  oxygen behaviour,  cationic  27 complexes  .  I t i s our f e e l i n g  t h a t t h e c h a r g e on t h e m e t a l ,  and t h e  t r a n s l i g a n d ( n o r m a l l y a s o f t e r one s u c h a s S-bonded s u l f o x i d e ) c r e a t e a "hard"  s i t e , a n d t h e s t r e n g t h o f M-*-0 b a n d i s t h e n d e t e r m i n e d b y t h e  e l e c t r o n e g a t i v i t y x o f t h e i o n . T h i s w o u l d a l s o e x p l a i n why t h e s t e r i c a l l y unhindered  complex  [Rh(COD)(DMSO) ] 2  0- i n s t e a d o f S - c o o r d i n a t i o n  strength order  generally f i t s  (X i n b r a c k e t s ) : C a <Ni (1.91)<Fe I I  <Vt^(2.28).Although is  I I I  i : t  (see chapter  I I I  I X  3).  Rh(I) centre displays  I n d e e d , t h e M-MD  (1.55)^e^l.83)<Zn  bond 35 36  I X  ( 1 . 65)<Co  ' i : C  ( l . 90)  (>1.61)<Rh (2.2)<Cr (>1.66)<Pd (2.20) I  Zn(II) i s ordered  i n i t s usual position  of the soft  i n w e l l with the order of x values  (1.00) < M n  (1.96)<A£  +  I I  I I  incorrectly according  t o x, i t  i n terms of t h e I r v i n g - W i l l i a m s order (see  a l s o r e f e r e n c e 3 on t h i s p o i n t ) .  I n t e r a c t i o n s o f v(M0) w i t h  other  v i b r a t i o n a l modes p r o b a b l y  account f o r the higher  than  expected  F ^ values  f o r A£(III) a n d C a ( I I ) ;  off-diagonal constants  i n the F matrix  -178-  tend has  t o lower  t h e F.,,. v a l u e o f -Ail ( I I I ) MO  3  , -though a d i f f e r e n t  o  y i e l d e d a n F.,_ f o r k l ( I I I ) o f 1.80 mdyne/A. MO C r ( I I I ) complexes were an e x c e p t i o n  c o r r e l a t i o n proposed above.  analysis  r  t o t h e Av(SO) v e r s u s v(M0)  Considering  therelatively  strong  TMSO->-Cr(III) bond,v (MO) =484 c m " , t h e f o r m e r r e l a t i o n s h i p p r e d i c t s 1  t h a t v ( S 0 ) o f TMSO s h o u l d i n s t e a d o f t h e 9 3 2 cm  1  be lowered on complexation  o b s e r v e d . However, F  w r t  t o a b o u t 900 cm  and F. take OL  into  T  MO  1  a c c o u n t t h e l i g h t e r mass o f C r ( I I I ) asid i m p r o v e t h e t r e n d ( f i g u r e 6 . 3 ) . The  e x c e l l e n t agreement  ( f i g u r e 6.4) o f t h e d a t a  c o m p l e x e s , a n d l e s s w e l l - d e f i n e d DMSO d a t a  from  f o r t h e DMSO-d, —6  t a b l e s 6.2 a n d 6.3, w i t h  t h e c o r r e l a t i o n o f f i g u r e 6.3 i s s u r p r i s i n g c o n s i d e r i n g t h e v a r i e t y o f complexes i n c l u d e d . f i g u r e 6.4 i s F i s r=0.95.  The l e a s t  squares l i n e  t o 95% confidence f o r  =-(1.24± 12)F +(8.78+.12). The c o r r e l a t i o n i  MO  Compounds w i t h v e r y w e a k a n d s t r o n g MO b o n d s  ( i . e . , F ^ < 1 . 2 and  >2.6 mdyne/A) a r e r a r e , a n d h e n c e t h e number o f d a t a p o i n t s as  these  coefficient Q  decreases  extremes a r e approached.  Our  f i n d i n g s c a s t doubt on recent  v(MO) a s s i g n m e n t s f o r some 31  lanthanide  c o m p l e x e s M ( N 0 ) ( D M S 0 ) , w h e r e M=La,Nd,Yb,Lu, a n d n=3 o r 4. 3  This paper assigned ( t a b l e 6.3, r e f e r e n c e v(MO), F  We f i n d  values  formerly  assigned  complicate 400 on  cm  1  b a n d s n e a r 4 0 0 cm \  previously assigned  t o v(M0)  3 2 ) , a s 6(CSO) b a n d s , a n d p e a k s n e a r 2 0 0 c m  f a r from t h e l i n e a r  values  lanthanide  to  v a l u e s n e a r 0.0, w i t h  r e g i o n o f f i g u r e 6.4; t h e  , and i t i s p o s s i b l e t h a t t h e s e  bands  systems by o v e r l a p p i n g w i t h v(M0) i n t h e  r e g i o n . T h e s u p p o s e d v ( M 0 ) a t 200 cm  t h e grounds that they  - 1  do f i t t h e . c o r r e l a t i o n . T h e 6 ( S O ) v i b r a t i o n s  to locate ' '  these  n  t h a t t h e l a t t e r number g i v e s F  that f a l l  are d i f f i c u l t  3  do n o t s h i f t  1  must a l s o be  questioned  o n u s i n g DMSO-d^, w h i l e t h e 4 0 0 cm  -1  -180-  bands do. In p r i n c i p l e , F _ values ML)  should  DMSO a n d DMSO-d^ c o m p l e x e s , w h i l e F^Q  values  f o r the deuterated  be e s s e n t i a l l y  the data  t h e same f o r  i n t a b l e 6.2 show t h a t  complexes a r e c o n s i s t e n t l y lower by  o 0.05 are  t o 0.30 mdyne/A, p r o b a b l y somewhat i l l - d e f i n e d  because v(S0)  f o r t h e DMSO c o m p l e x e s  and because the v i b r a t i o n s a r e n o t pure  modes. S u l f o x i d e c o m p l e x e s o f some g r o u p I V A a n d VA e l e m e n t s do n o t f o l l o w t h e c o r r e l a t i o n o f f i g u r e 6.4 ( s e e t a b l e 6.4, f i g u r e 6 . 5 ) . equation  F  Either high  OL  o f t h e l i n e d r a w n i n f i g u r e 6.5 i s  =  -( 1  0 2  ±°-  3 4  the r e l a t i v e l y  i o n masses r e s u l t  different metal  The  )  F M O  + (7.95±0.60), w i t h r = 0.83.  l o w v(M0)  o f m o s t o f t h e compounds t o g e t h e r  i n a lowestimation of F  or, equally  with  likely,  b o n d i n g i n t e r a c t i o n s w e a k e n S-0 more t h a n f o r t h e t r a n s i t i o n  systems. The  ordering of theions considered  by v a r i a t i o n o f t h e b e n d i n g f o r c e c o n s t a n t  here i s u n l i k e l y F M  Q  L  .  t o be a f f e c t e d  By v a r y i n g F ^  from  o 0.10  t o 0.60 mdyne A f o r a l l t h e c o m p o u n d s , F  i n c r e a s e d b y 1% w h i l e  Ui-i  3 F^Q is the  decreased by approximately  30%,  expected t o change i n a c o n t i n u o u s trends  observed here w i l l  i n agreement w i t h r e f e r e n c e  .  F M  0  f a s h i o n as F ^ i n c r e a s e s , so that  be preserved.  L  -181-  T a b l e 6.4.  V i b r a t i o n a l d a t a f o r g r o u p I V A a n d VA C o m p l e x e s  COMPLEX  v(SO)  SbC£ (DMSO) 3  BiC£ (DMSO) 3  3  979,897  405  6.21  1.57  37  980,908  411  6.25  1.74  37  977,908  408  6.24  1.71  37  984,930  403,394  6.47  1.61  37  979,929  404,394  6.42  1.61  37  900  430  5.56  1.95  5  895  415  5.64  1.79  5  940  405  6.20  1.66  5  960  370  6.70  1.31  5  2  941  413,406  6.21  1.59  38  2  942  414  6.23  1.64  38  942  430,419  6.20  1.75  38  950  410  6.36  1.60  23  947  420  6.29  1.70  38,39  954  435  6.34  1.86  40  928  459,451  5.89  2.09  38  911  471  5.59  2.30  38  923,907  482,477  5.60  2.41  38  2  3  [BiPh (DMSO) ] 3  2 +  2  [BiPh (DMSO-d ) ] 3  6  [BiPh (DMSO)0]  2 +  2  2 +  3  [BiPh.(DMSO-d,)0] J —D Z SnEt C£ (DMSO) 2  2  SnMe C£ (DMSO) 2  2  SnMe Br (DMSO) 2  2  2+  2  [SnPh (N0 )(DMSO) ] 2  3  3  SnPh C£ (DMSO) 2  2  2  SnMe (N0 ) (DMSO) 2  3  2  cis-SnI (DMSO) 4  2  cis-SnBr (DMSO) 4  cis-SnC£ (DMSO) 4  Ref  37  3  BiBr (DMSO)  MO  1.66  2  3  F  6.21  3  BiBr (DMSO)  OL  424,405  SbBr (DMSO) 3  F  982,926,913  2  BiC£ (DMSO)  v(M0)  2  2  1  +  -183-  7.  Conclusions  and  The  goals  primary  chemistry  Recommendations of t h i s r e s e a r c h were to study  o f s u l f o x i d e s t o Rh  and  I r centers  and  the  to use  coordination  this  knowledge  t o d e s i g n homogeneous, p l a t i n u m m e t a l c a t a l y s t s f o r a s y m m e t r i c using  chiral  gained  while pursuing  discussed  7.1.  s u l f o x i d e s as these  A summary o f t h e new  o b j e c t i v e s , and  information  some i m p l i c a t i o n s , a r e  below.  Coordination  7.1.1.  ligands.  synthesis  Chemistry  P r e p a r a t i o n o f S u l f o x i d e C o m p l e x e s o f R h o d i u m and  Displacement of the (acetone)]A  (diene=l,5  l a b i l e acetone l i g a n d from  Iridium  [Rh(diene)(PPh^)-  c y c l o o c t a d i e n e , n o r b o r n a d i e n e ; A=PF^ >SbFg )  a l l o w s f a c i l e c o o r d i n a t i o n of s u l f o x i d e s through the oxygen l o n e and  [Rh(diene)(PPh^)(sulfoxide)]  +  complexes have been c h a r a c t e r i z e d  u s i n g DMSO, TMSO, NPSO, MBMSO, MPSO, R-MPTSO, and Diaryl  s u l f o x i d e s (DPSO, S-OTPTSO) and  were not  isolated.  c o m p l e x was  The  general  reactivity  (L=AsPh ,py,(CO) ) were s y n t h e s i z e d . (sulfoxide)2l , +  although  Of  2  Aqueous i s o p r o p a n o l many s u l f o x i d e s p r o v i d e (L=DMSO,TMSO,MPSO, a n d one  a r o u n d t h e Rh  solids  of the p r e c u r s o r  [Rh(diene)(PPh )L]  acetone +  3  the  cationic  species  complexes [Rh(diene)-  o n l y t h e COD/DMSO s u b s t i t u t e d d e r i v a t i v e c o u l d b e  i n s i t u preparation of others  b o n d e d and  R-TBPTSO l i g a n d s .  DIOS c o o r d i n a t e , b u t  a l s o d e m o n s t r a t e d when o t h e r  3  pairs,  i s possible.  s o l u t i o n s o f RhCA^.SH^O on an e a s y and  R-MPTSO).  isolated  efficient  Normally  two  route  treatment  with  t o RhCA^L^ c o m p l e x e s  sulfoxides are  sulfur-  i s oxygen-bonded; the c h l o r i d e s are arranged m e r i d i a l l y i n most c a s e s .  No  complexes showing s u l f u r bonding  of  -184-  t h e m o l e c u l e s R-TBPTSO o r S-OTPTSO bulky  groups around  sulfur hinder  o b s e r v a t i o n was r e p o r t e d  1  The  and t h i s  utility  The oxygen-bonded  allows  a n d i n some c a s e s t h e i s o l a t i o n ,  RhC&g(DMSO)2(0=L) u s i n g  presumably t h e  c o o r d i n a t i o n t o Rh; a s i m i l a r  f o rPt(II) centers.  s u l f o x i d e i n RhCA^L^ i s l a b i l e , in situ,  c o u l d be i s o l a t e d ;  the generation  o f t h e complexes mer-  amides, amine o x i d e s , and phosphine  oxides.  o f RuCJ^(DMSO)^ a s a s t a r t i n g m a t e r i a l f o r o t h e r  Ru(II)  2 compounds h a s b e e n d e m o n s t r a t e d  ; there  i s e q u a l l y p r o m i s e f o r RhC&^L^  c o m p l e x e s now t h a t a c o n v e n i e n t  p r e p a r a t i o n has been d i s c o v e r e d .  Some  3 R h ( I I I ) c o m p l e x e s o f N - d o n o r s h a v e b e e n made p r e v i o u s l y f r o m RhCJl^ ( D M S O ) , 4 i n c l u d i n g R h C i l ^ ( p y ) (DMSO) , a n a n t i - t u m o r 2  Diphenylsulfoxide solutions  t o give Rh(I)  (DPSO) r e a c t s w i t h directly  agent. t h erhodium  as t h ec h l o r i d e - b r i d g e d  [ R h C J K D P S O ^ ^ . v i a RhC£^(DPSO)^(isopropanol)  species  intermediates:  RhC£ .3H 0  + 2 L + ( C H ^ C H O H -> ^ [ R h C ^ ^  Di-n-propyl  s u l f o x i d e (NPSO) r e a c t s t o g i v e a c o r r e s p o n d i n g R h ( I )  3  dimer  trichloride  2  (indirect  e v i d e n c e ) and a R h ( I I I ) p r o d u c t ,  [RhC£^(NPSO)2!"containing a s y m m e t r i c a l l y [ ^S=0-H-0=S^ ] . +  [IrC£,]7 0 A crystal  The c o m p l e x e s  + ( C H ^ C O + 2HC£  isolated  hydrogen-bridged  a s [ (NPSO) H ] 2  cation  [H(DMSO) ] [ I r C J i ^ D M S O ^ ] , ( [ H ( D M S O ) ] ) +  2  2  a n d trans-[H(DMSO)„][RhC£.(DMSO)„] m u s t a l s o c o n t a i n t h i s z 4 z structure of the last  (7.1)  complex r e v e a l s t h e s h o r t  2  cation.  oxygen-oxygen  o  distance  (^2.45A) b e t w e e n t h e DMSO o f t h e c a t i o n t h a t i s e x p e c t e d f o r  a s t r o n g H-bond.  I n addition, very  l o n g Rh-S d i s t a n c e s a r e o b s e r v e d  because o f t h estrong t r a n s i n f l u e n c e of the mutually  t r a n s DMSO l i g a n d s .  -185-  The  ease o f a q u a t i o n o f t h i s anion t o trans-[RhCi^(DMSO)(r^O)]  reflects The  t h e w e a k e n i n g o f t h e Rh-S b o n d s . much m i l d e r c o n d i t i o n s r e q u i r e d f o r t h e p r e p a r a t i o n o f  RhC£.jL.j u s i n g i s o p r o p a n o l r a t h e r t h a n water"* may r e s u l t presence o f t r a c e s of R h ( I ) , generated catalyze the formation  from t h e  b y r e a c t i o n 7.1, t h a t  o f RhCJc-^L^ i n a r e a c t i o n s i m i l a r  could  t o one  employed f o r t h e s y n t h e s i s o f R h ( I I I ) - p y r i d i n e complexes.^ The  RhCJl^L^  complexes r e a c t s t o i c h i o m e t r i c a l l y w i t h  H (l:l) 2  i n base promoted r e a c t i o n s :  Rh(III) + H  Using by  Proton  -H 2  +  > [HRh(III)]  Sponge (P.S.) as a b a s e ,  such a route although  -  >Rh(I) + H  2  prepared  t h e r e were c o m p l i c a t i o n s due t o s i d e r e a c t i o n s ,  o r t h e N - m e t h y l g r o u p s . The r h o d i u m ( I I I )  The  (7.2)  [P.S.H][RhC£ (DMSO)^] was  including a possible m e t a l l a t i o n of the proton  reaction  +  (7.2) have n o t been observed rhodium(I) cyclooctene  sponge a t t h e r i n g and/  hydride  intermediates of  or isolated.  precursor,  [RhC£(C H ,) ]„, has been 0  1  0  o 14  2. 2  u s e d t o i s o l a t e a r a n g e o f c o m p l e x e s i n c l u d i n g [RhC£(C rL .)L]„,L=DPSO, 0  o  14  z  TMSO, [ R h C £ ( D M S 0 ) ] , [ R h C £ ( D I O S ) ] , a n d [RhC£(MPSO)(PPh^)] . 2  2  2  seem t o f o r m t h e r m o d y n a m i c a l l y stabilizing  2  -  Sulfoxides  weak a d d u c t s w i t h R h ( I ) w i t h no a p p r e c i a b l e  i n t e r a c t i o n s s u c h a s Rh(dir)-+S (d-rr) b a c k b o n d i n g .  Accordingly  s u l f o x i d e l i g a n d s a p p e a r u n a b l e t o c l e a v e Rh-C£-Rh b r i d g e s , a n d o n l y partially  displace coordinated  the s u l f o x i d e i s added i n g r e a t The  Rh(I)  c y c l o o c t e n e , or ethylene, except excess.  c o m p l e x e s do n o t y i e l d  the o x i d a t i v e a d d i t i o n o f  when  hydrogen.  i s o l a b l e d i h y d r i d e s p e c i e s through I n s t e a d , complexes o f monodentate  -186-  sulfoxides,  I n c l u d i n g the mixed s u l f o x i d e - t r i p h e n y l p h o s p h i n e c a t i o n s ,  are reduced t o rhodium metal presumably v i a t r a n s i t o r y hydride Some R h ( I ) inert  c o m p l e x e s o f t h e c h e l a t i n g s u l f o x i d e s , DIOS a n d MSE, a r e  t o hydrogen under c e r t a i n c o n d i t i o n s .  appears t o be formed a l o n g w i t h  2  [Rh(MSE) ]PF, p r e c i p i t a t e s from mixtures 0  1:2)  3  2  2  6  2  2  were a l s o n o t observed  o f HC£ t o R h ( I )  complexes.  results HC£  r e a c t i o n o f e x c e s s HC£ g a s w i t h  meridinal the  reported and  decomposition.  [IrC£(cyclooctene) ] 2  (1:1)  S-bonded DMSO c a n b e i s o l a t e d .  i n DMSO  H o w e v e r , when  t r a n s c h l o r i d e s and  A h y d r i d o i r i d i u m complex w i t h  s p e c t r o s c o p i c p r o p e r t i e s was  We w e r e u n a b l e t o r e p r o d u c e h i s  preparation,  cannot e x p l a i n the d i f f e r e n c e s i nthe s p e c t r a l data. A c i s d i h y d r i d e compound w i t h mer S-bonded s u l f o x i d e s ,  as  2  a s t h e c r y s t a l l i n e DMA  2  b y H e n b e s t e t al.7  bidentate  involving a Rh(III)-H  complex, IrHC£ (DMSO)^, w i t h  same s t r u c t u r e b u t w i t h d i f f e r e n t  generated  [RhC£(DMSO)^] , d i m e t h y l  o f [H(DMSO)"J [ I r C J l ^ D M S O ) ^ .  i s a d d e d i n a s t o i c h i o m e t r i c amount  adduct, the h y d r i d e  complexes  r e d u c t i o n t o Rh m e t a l .  In thereaction with  o r v i a a n a c i d - c a t a l y z e d DMSO  i ntheformation  2  (ratio  i ntheattempted o x i d a t i v e a d d i t i o n  s u l f i d e was p r o d u c e d e i t h e r by d e c o m p o s i t i o n intermediate  Also  D  the potentially  l i g a n d s DIOS, MSE, P T S E , a n d MET, u n d e r w e n t H Hydrides  i n a dispropor-  o f [Rh(NBD)„]PF, a n d MSE  with  +  2  2  Other i n s i t u  or [RhC£(CgH^) ]  [Rh(DIOS) ]  i n DMA u n d e r H .  +  Z  [Rh(NBD) ]PF  The  +  2  D  i n 2 - m e t h o x y e t h a n o l u n d e r H,,.  using  F o r example,  [Rh(H) (PPh ) (DMA) ]  t i o n a t i o n r e a c t i o n of [Rh(NBD)(PPh^)(DIOS)]  Z  compounds.  IrC(DMSO)  i n DMSO.  3  i s obtained  Henbest prepared  with apparently  by the r e a c t i o n o f H  by another r o u t e  7  2  with  formulated  [IrCUCgH^)^  a different dihydride  a n 0 - b o n d e d DMSO t r a n s t o a h y d r i d e .  T h e mono- a n d  isomer  -187-  dihydride or  complexes prepared i n t h e present s t u d i e s  CHCJl^  s t o i c h i o m e t r i c a m o u n t s o f HC£ t o y i e l d new i r i d i u m c o m p l e x e s  t a i n i n g one l e s s c o o r d i n a t e d  hydride  HIrC£  H IrC£ + CHC£  + HIrC£  HIrC£  + CHC£  2  r e a c t i o n o f HC£.DMA w i t h  +  2  •+ I r C £  3  3  H  2  + CH C L  ?  + CH C£ 2  the dihydride  > 'Ir=Ir(DMSO)  2  complex, f o r example, y i e l d s  i n s i t u , what a p p e a r s t o b e IrC£ (H)(DMSO) (DMSO) w i t h 2  c h l o r i d e s , a n d DMSC) t r a n s formation  chiral  2  to the hydride.  This  c i s DMSO, c i s  reaction requires the  o f m o l e c u l a r H , b u t t h i s was n o t t e s t e d 2  Preliminary  con-  ligand:  H I r C £ + HC£ 2  The  react with  for.  attempts t o i s o l a t e complexes from t h e r e a c t i o n of t h e  s u l f o x i d e s R-MPTSO, R-TBPTSO, S-OTPSO, a n d P T S E w i t h  IrC£  2  methanol o r 2-propanol were n o t s u c c e s s f u l .  It i s likely  preparations  complexes t h a t a r e d i f f i c u l t  to separate.  produce s e v e r a l s t a b l e isomeric A cleaner  addition reactions  route  to hydrido 0  of the preparative  i n p r i n c i p l e to other  would be t h e s y n t h e s i s  oxidative  1  1 4  routes  2  2  described  S-donors.  of d i a l k y l  t o d a t e none have been i s o l a t e d .  i n this section are appli-  An i n t e r e s t i n g a r e a t o p u r s u e  s u l f i d e complexes o f Rh(I)  and I r ( I ) ;  C a t a l y t i c reactions of i n s i t u Rh(I) 8  complexes o f s u l f i d e s have been s t u d i e d could  complexes might i n v o l v e  l i g a n d may b e n e c e s s a r y t o d i s p l a c e t h e o l e f i n .  All cable  such  t o [IrC£(C H .)„]„ , a l t h o u g h t h e p r e s e n c e o f e x c e s s o  chiral  that  .3H 0  a n d s o t h e i s o l a t i o n o f compounds  f u r t h e r the understanding of such c a t a l y s t s .  -188-  7.1.2.  Spectroscopic Properties of the Sulfoxide  B o t h i r a n d nmr  s p e c t r o s c o p y y i e l d v a l u a b l e i n f o r m a t i o n on  s t r u c t u r e and b e h a v i o u r o f t h e s e c o m p l e x e s specifically, The  on t h e n a t u r e of t h e s u l f o x i d e - m e t a l  i r f r e q u e n c y o f t h e S-0  t h i s peak always f a l l s  860 cm  the  i n s o l u t i o n , a n d more bonds.  s t r e t c h i n g mode u n a m b i g u o u s l y  i n d i c a t e s t h e mode o f s u l f o x i d e - m e t a l b o n d i n g .  -1  Complexes  F o r DMSO c o m p l e x e s  i n t h e r a n g e o f 1 2 0 0 - 1 0 5 5 cm  1  f o r S - b o n d i n g , and  f  f o r 0 bonding, whether  t h e sample  i s i n s o l u t i o n or the  solid  state. The a c t u a l a s s i g n m e n t o f v ( S 0 ) c a n be e q u i v o c a l f o r t h e c a s e o f 0-bonding  i f t h i s frequency l i e s  n e a r t o an i n t e n s e m e t h y l  mode o f t h e s u l f o x i d e w h i c h i s s i t u a t e d n e a r 980±20 cm  rocking the  of complexes w i t h o u t bands t h a t c o m p l i c a t e the v(S0) r e g i o n [ R h ( d i e n e ) ( P P h . ) L ] , L=DMS0-d,  and TMSO, a n d  +  J  o  a l l o w e d t h e l o c a t i o n o f v ( S 0 ) a t 950 cm t h e a s s i g n m e n t o f v (RhO)  a t -450  cm  synthesis  e.g.  [ Rh (COD) (DMSO-d,) J o  +  Z  f o r t h e DMSO a n a l o g u e s  ,  and  Crude a p p r o x i m a t i o n s f o r the  c a l c u l a t i o n s o f f o r c e c o n s t a n t s f o r M-<-0=L s y s t e m s i n t h e c a s e o f  sul-  f o x i d e complexes  between  h a v e b e e n shown t o l e a d and F ^ Q J and  the f o r c e constants F may  be u s e d t o v e r i f y  complexes limited  had  v ( S 0 ) and v(M0)  t o be c o n s i d e r e d  s t u d i e s had  the observed d i r e c t assignments.  proportionality  A wide range of  to expose the p r o p o r t i o n a l i t y ;  found l i t t l e 9  coordination to metal centers.  to a useful c o r r e l a t i o n  s i g n i f i c a n c e i n changes  I t m i g h t be p r o f i t a b l e  some m o r e  i n v(S0)  on  to analyze  c o r r e s p o n d i n g d a t a f o r s e r i e s o f compounds w i t h p h o s p h i n e - , a r s i n e - , pyridine-oxide  ligands.  and  1000-  -189-  The  TMSO a n d DMSO-d^ l i g a n d s h a v e p r o v e d u s e f u l f o r p r o b i n g  t h e s t r e n g t h o f M-0 i n t e r a c t i o n s . unhindered  [Rh(COD)]  " h a r d " i n t h e HSAB  +  moiety  The 0-bonding o f s u l f o x i d e s t o t h e  suggests that t h i s Rh(I) center i s  classification  scheme.  A study o f i r d a t a f o r a range i n d i c a t e s t h a t s i n c e v(SO) s h i f t s  o f s u l f u r - b o n d e d DMSO a d d u c t s  t o h i g h e r frequency on c o o r d i n a t i o n  i n t h e a b s e n c e o f m e t a l diT->SdiT b a c k b o n d i n g , t h e  to "harder" metals  sulfur of a sulfoxide i s a r e l a t i v e l y  " h a r d " d o n o r atom.  Crystal  s t r u c t u r e a n d i r d a t a p r o v i d e no e v i d e n c e f o r b a c k b o n d i n g of rhodium  complexes,  a b s o r b s a t 30-40 c m  - 1  and t h e r e f o r e t h e f i n d i n g h i g h e r f o r Rh(III)-DMS0  t h a t t h e S-0 b o n d  than Rh(I)-DMS0 i s  c o n s i s t e n t w i t h former having a s t r o n g e r hard-hard i n c r e a s e i n t h e f o r m a l p o s i t i v e charge was  a l s o shown t o i n c r e a s e t h e e n e r g y The  -  +  c a t i o n have  broad,  a n d 9 0 0 - 6 0 0 cm  that  t o b e d u e t o t h e v (0-H-0) mode o f s y m m e t r i c a l l y b r i d g i n g a  bonds.  D i f f e r e n c e s between t h e s e s p e c t r a l f e a t u r e s and those  o f o t h e r H-bond b r i d g e d s y s t e m s resonance  complexes  o f v ( S 0 ) , as expected.  i n t e n s e a b s o r p t i o n bands i n t h e i r a t 1 6 0 0 i l O O  hydrogen  i n t e r a c t i o n . An  on Rh(III)-DMS0  complexes c o n t a i n i n g t h e [R2S0-H-0SR2]  are thought  i n t h e case  effects;  have been e x p l a i n e d i n terms  t h e nature o f these e f f e c t s has  of Fermi  been d i s c u s s e d by  others. The  nmr c h e m i c a l s h i f t s  i n f o r m a t i o n about  o f p r o t o n s a t o t h e SO g r o u p  t h e mode o f b o n d i n g  DMSO i n t h e c o m p l e x e s IrC£„(DMSO)_(DMSO)  7  of thesulfoxide.  give  Oxygen—bonded  [Rh(COD) (DMSO) ] , RhC£^ (DMSO) ^ (DMSJ3) , a n d +  2  r e s o n a t e a t 52.80, 2.86, and 2.92, r e s p e c t i v e l y ,  -190-  whereas t h e S bonded l i g a n d s o f R h ( I I I ) , 63.7-3.4.  Ir(III)  fall  The l a b i l e Rh(I)-DMS0 l i g a n d s r e s o n a t e  i n t h e range  a t 62.8, a  weighted  mean p o s i t i o n o f t h e f r e e a n d c o o r d i n a t e d l i g a n d , a n d a l o w t e m p e r a t u r e nmr s t u d y upfield  i s r e q u i r e d t o l o c a t e t h e v a l u e f o r c o o r d i n a t e d DMSO. T h e  shifts  o f t h e s u l f o x i d e resonances f o r t h e complexes  (PPh^)(sulfoxide)] adjacent  phenyl  +  where 0-bonding o c c u r s , r e f l e c t  groups o f PPh^.  Similar  shielding  [Rh(diene)-  s h i e l d i n g by t h e e f f e c t s by t h e  p h o s p h i n e o x i d e s O P P l ^ M e a n d OPPhMe^ w e r e e x p l o i t e d t o a s s i g n t h e mer c o n f i g u r a t i o n t o t h e RhCJ"^(DMSO)^(0=L) c o m p l e x e s . T h i s t e c h n i q u e i s g e n e r a l l y a p p l i c a b l e t o s y s t e m s o f unknown s t e r e o c h e m i s t r y t h a t c o n t a i n a l a b i l e 0 - d o n o r l i g a n d , f o r e x a m p l e RuCJl,,(DMSO)^(DMSO). inequivalence o f the methyl aids  i nstereochemical The  g r o u p s o f t h e DMSO i n c e r t a i n c o m p l e x e s a l s o  determinations.  i n e q u i v a l e n c e i n t h e nmr s p e c t r a o f t h e o l e f i n i c  1 2 + [Rh(diene)L L ] l i g a n d s , proved these complexes.  complexes, where L extremely Evidence  1 2 and L a r e d i f f e r e n t  3- a n d 5 - c o o r d i n a t e  nmr b e h a v i o u r  protons i n monodentate  u s e f u l i n studying t h es o l u t i o n behaviour of f o rtheexistence of the disproportionation  r e a c t i o n 7.3, a s w e l l a s f o r 3 - c o o r d i n a t e and  The m a g n e t i c  T - s h a p e d COD i n t e r m e d i a t e s  NBD i n t e r m e d i a t e s , was p r o v i d e d b y s t u d y i n g t h e  of thediene  protons.  (7.3)  -191-  7.2.  Attempts a t t h e C a t a l y t i c Asymmetric  Hydrogenation of P r o c h i r a l  O l e f i n s and Ketones Only a few o f t h erhodium c a t a l y t i c a l l y hydrogenated  complexes  prepared i n t h i s  prochiral olefins - usually  thesis  itaconic  acid-  and  i n no c a s e was t h e r e d e t e c t a b l e i n d u c e d asymmetry i n t h e p r o d u c t s .  The  complexes  [ R h ( d i e n e ) ( P P h ) ( L ) ] , L=acetone, +  3  COD, NBD, h y d r o g e n a t e  DMSO, R-MPTSO, d i e n e =  i t a c o n i c a c i d r a p i d l y a t 30°C i n a c e t o n e or'MeOH,  b u t t h e d i h y d r i d o - o l e f i n i n t e r m e d i a t e i n t h e p r o c e s s i s thought t o be [ R h ( d i e n e ) ( P P h ^ ) ( I A ) (H) 2]"*" w h e r e a c h i r a l and  thus cannot l i k e l y  hydrogenated  product.  cause any e n a n t i o m e r i c excess Again itaconic acid  [Rh(NBD)(PPh )(acetone)] 3  The  active catalyst  sulfoxide i s not coordinated  +  i s hydrogenated  a n d DIOS i n a m o l a r r a t i o  i sl i k e l y  2  3  2  using  o f 1:1 i n DMA.  t o be [ R h ( H ) ( P P h ) ( D M A ) ^  c a s e a s n o e . e . was d e t e c t e d i n t h e a - m e t h y l In these cases, t h el a b i l i t y  (e.e.) i n t h e  i n this  succinic acid product.  of thesulfoxides coordinated to a Rh(I)  center allows unfavourable ligand r e d i s t r i b u t i o n reactions t o occur. Of t h e c h l o r o - s u l f o x i d e Rh c o m p l e x e s , [RhC£ (C H.. .) „] a n d DIOS i n a m o l a r r a t i o o 14 2 2 Q  a l c o h o l s o r DMA  only those prepared  o f 1:2 o r g r e a t e r ,  from  using  as t h e solvent,hydrogenated i t a c o n i c a c i d a t a rea-  s o n a b l e r a t e b u t even t h e s e r a p i d l y d e a c t i v a t e d b e f o r e 20% c o n v e r s i o n ; the reason f o r t h er a p i d decrease i na c t i v i t y of t h e s u l f o x i d e t o s u l f i d e . i n MBMSO s e l e c t i v e l y  i s thought t o be a r e d u c t i o n  F o r example an i n s i t u  complex o f RhCJ^.S^O  reduced t h e s u l f o x i d e instead o f i t a c o n i c a c i d  that  was a l s o p r e s e n t . T h u s r e d o x p r o c e s s e s a t t h e c o o r d i n a t e d s u l f o x i d e present problems  i n d e s i g n i n g an asymmetric  c a t a l y t u s i n g such  ligands.  -192-  Reduction hydrogenation  of the s u l f o x i d e a l s o appears to occur  transfer  f r o m i s o p r o p a n o l t o 3 - m e t h y l - 3 - p e n t e n - 2 - o n e , and  o c t a n o n e , c a t a l y z e d by and  i n the  TBPTSO t o g e t h e r  i n s i t u c a t a l y s t s generated  i n a molar r a t i o  o f 1:3.  to  by h e a t i n g  In these  2-  IrCJ^-^I^O  c a s e s , an  iridium  complex w i t h presumably c o o r d i n a t e d s u l f i d e l i g a n d s p r e c i p i t a t e s , t h i s d e s t r u c t i o n of the c h i r a l the products  R h ( I ) , and  and  Ir(III)-  respectively.  o f c o o r d i n a t e d s u l f o x i d e s t o be  hydrides  asymmetric hydrogenation  2-octanol,  in  t h a t i t i s t h e weak b o n d i n g o f s u l f o x i d e s t o  the s u s c e p t i b i l i t y  R h ( I I I ) - and  l i g a n d w o u l d e x p l a i n t h e l a c k o f e.e.  w h i c h w e r e 3 - m e t h y l p e n t a n - 2 - o n e and  These s t u d i e s suggest  and  that l i m i t  catalysts.  reduced  t h e i r u s e f u l n e s s as The  first  by  hydrogenation  l i m i t a t i o n could  be  r e m e d i e d p e r h a p s by u s i n g c h e l a t i n g s u l f o x i d e s w i t h s t r o n g l y e l e c t r o n donating 7.3.  groups.  The  Other C a t a l y t i c The  complex  and  1 atm  converted  i s a more s e r i o u s  Reactions  J  Z  that operates  (CO+I^).  Both  t o a 72/28 m i x t u r e  g r e a t e r e f f i c i e n c y and  i n DMA  1 - h e x e n e and  under m i l d c o n d i t i o n s 1-heptene s u b s t r a t e s  of l i n e a r / b r a n c h e d aldehyde  selectivity  o f c a t i o n i c a c t i v e s p e c i e s , and  of t h i s  catalyst  f u r t h e r study  to the unsaturated mild  s e l e c t i v e hydrogenation a l c o h o l s has  are  products.  from the  of the unexplored  The to  presence area  of  profitable.  of a, (3-unsaturated  been accomplished  at  s y s t e m compared  result  c a t i o n i c r h o d i u m h y d r o f o r m y l a t i o n c a t a l y s t s c o u l d be unusual  hydro-  D  a n a l o g o u s n e u t r a l r h o d i u m c a r b o n y l compounds may  The  one.  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