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Rhodium(I) polysiloxyphosphine complexes as hydrogenation catalysts Brzezińska, Zofia Carolina 1978

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RHODIUM(I) POLYSILOXYPHOSPHINE COMPLEXES AS HYDROGENATION CATALYSTS by ZOFIA CAROLINA BRZEZINSKA M.Sc, Warsaw Technical University, 1970 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES (Department of Chemistry) We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September 1978 c) Z o f i a Carolina Brzezinska, 1978 In presenting th is thes is in p a r t i a l fu l f i lment of the requirements for an advanced degree at the Un ivers i ty of B r i t i s h Columbia, I agree that the L ibrary shal l make it f ree ly ava i l ab le for reference and study. I fur ther agree that permission for extensive copying of th is thes is for scho la r ly purposes may be granted by the Head of my Department or by h is representat ives . It is understood that copying or pub l ica t ion o f th is thes is fo r f i n a n c i a l gain s h a l l not be allowed without my wri t ten permission. Chemistry Department of . The Univers i ty of B r i t i s h Columbia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 11th October 1978. i i Abstract A new synthetic route to insoluble c a t a l y t i c c h l o r o ( p o l y s i l o x y -phosphine)rhodium complexes has been developed. This was achieved by synthesizing the characterizable monomeric complexes, [C£ 3Si-(CH 2) 2-P(C 6H 5) 2] 2Rh(CO)C£, [C£ 3Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£, [C£ 3Si-(CH 2)g-P(C 6H 5) 2] 3RhC£, and [ C 2 , 3 S i - (CH 2) 2~P ( C ^ ) ] 4Rh 2CJt 2, which were subsequently homopolymerized and copolymerized with CJ^Si-CH or an excess of a ligand by hydrolysis i n water/dioxane mixture. The i d e a l i z e d formulae of the products obtained are the following: { [ 0 3 / 2Si-(CH 2) 2-P(C 6H 5) 2] 2Rh(CO)C£} x, { [ 0 3 / 2 S i - ( C H 2 ) n - P ( C 6 H 5 ) 2 ] 3 R h C £ . ( 0 3 / 2 S i - C H 3 ) m } x n = 2,8 and m = 2-200, { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 > 7 R h C U x and U 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 4 R h 2 C £ 2 . ( 0 3 / 2 S i - C H 3 ) m } x m = 0,200 x = very large but undetermined for a l l the polymers. The nature of the metal centres i n the polymers was probed by studying reactions of the polymers with hydrogen and carbon monoxide. A l l the polymers, with the exception of the carbonyl complex, are active c a t a l y s t s for the hydrogenation of o l e f i n s . Their c a t a l y t i c a c t i v i t y towards styrene and cyclohexene decreases upon r e c y c l i n g . i i i Copolymerization of the trisphosphine species with Ci^Si-CH^ allows higher a c t i v i t y to be maintained over a larger number of cycles. Copolymeri-zation with an excess of a phosphine (P/Rh>3) results i n i n i t i a l l y lower a c t i v i t y but prevents i t s further decrease. An increase of the length of the spacer "arm" between the matrix and the metal centre causes an increase of the o v e r a l l l i f e - t i m e of the trisphosphine c a t a l y t i c complexes. Deactivation of the trisphosphine complexes i s postulated to be partly due to dimerization of the starting complexes to di-y-chloro-tetraphosphine species and the phenomena described above are thought to be the result of improved metallic s i t e i s o l a t i o n which i n turn prevents the dimerization. Soluble siloxyphosphinerhod iura(I) complexes were also synthesized to serve as study models for the polymeric analogues. They are also effective hydrogenation catalysts but their a c t i v i t y i s considerably higher than that of the polymers. i v TABLE OF CONTENTS Page Chapter 1. Introduction 1 1-1. Supported C a t a l y t i c Systems. 1 1-2. Syntheses of Organosiloxanes. 8 1- 3. This Work. 12 Chapter 2. Experimental 13 2- 1. Abbreviations and Symbols. 13 2-2. Techniques and Instrumentation. 14 2-3. Reagents. 16 2-4. Gas Uptake Apparatus. 17 2-5. Syntheses of Ligands and Soluble Complexes. 24 2-6. Syntheses of Polymeric Complexes. 32 2-7. Reactions of Soluble Complexes, with 41 H 2, CO and HCJl(g).. 2-8. Reactions of Polymeric Complexes with 47 H 2, CO and HC2,(g). 2-9. Hydrogenation of Olefins with Soluble Complexes. 51 2-10. Hydrogenation of Olefins with Polymeric Complexes. 53 2- 11. Electron Microscope Studies. 83 Chapter 3. Discussion 90 3- 1. Syntheses and I d e n t i f i c a t i o n of the Ligands and 90 th e i r Soluble Complexes. 3- 2. Syntheses of the Polymeric Complexes. 105 Chapter 4. Reactions of the Complexes with H 2, CO, and HC£(g). 118 4- 1. Reactions with H 2. 120 4-2. Reactions with CO. 125 4- 3. Reactions with HCJl(g). 128 Chapter 5. C a t a l y t i c Hydrogenation of Ole f i n s . 131 5- 1. Hydrogenation of Styrene with the Soluble 136 Siloxyphosphine Complexes. 5-2. Hydrogenation of Olefins with the Polymeric Complex 136 R2-75-5-3. Hydrogenation of Styrene with the Polymeric Complexes. 139 5-4. Hydrogenation of Styrene and Cyclohexene with 150 the Polymeric Complex R2-0 i - n Solutions of D i f f e r e n t Volumes. 5-5. E l e c t r o n Microscope Studies. 151 Conclusions. 155 Bibliography. 158 V TO MY MOTHER v i Acknowledgement In w r i t i n g t h i s t h e s i s , I was a s s i s t e d by a number of people, e s p e c i a l l y those mentioned here, who have acted as both friends and advisors to me. F i r s t , I wish to express my gratitude to Professor W. R. Cullen, my main advisor, for h i s help and guidance during the course of t h i s work. To Professor B. R. James and Doctors G. Strukul and D. J. Patmore, I am indebted for many stimulating discussions and suggestions, and to Professor J . Leja i n the Mineral Engineering Department and h i s a s s i s t a n t Mrs. S. Finora for t h e i r help with the electron microscopy. For con-s t r u c t i n g and maintaining most of the apparatus used i n t h i s work, I am g r a t e f u l to the s t a f f of the Mechanical Workshop at the Chemistry Department, i n p a r t i c u l a r Mr. B. Snapkauskas, whose s k i l l and experi-ence were extremely h e l p f u l ; to Mr. P. Borda of the M i c r o a n a l y t i c a l Laboratory at the Chemistry Department for p e r s i s t i n g with some d i f f i c u l t analyses. My thanks and appreciation go also to Mr. R. Thayer for drawing a l l the i l l u s t r a t i o n s i n t h i s t h e s i s ; to Dr. N. P. C. Westwood for reading t h i s text and o f f e r i n g many h e l p f u l suggestions, and to Mrs. A. Wong for typing the manuscript. I also want to thank Dr. K.-E. J . H a l l i n f or h i s help and f o r t i t u d e during the course of my studies and Dr. R. T. Oakley for his advice and simply for being a good p a l . To my mother, I express my greatest thanks for her encouragement and unflagging f a i t h i n me and my work. To b e a u t i f u l Vancouver and the mountains - what more can I say? -1-CHAPTER 1  INTRODUCTION 1-1. Supported C a t a l y t i c Systems. The b a s i c p r i n c i p l e behind the idea of "heterogenizing homogeneous c a t a l y s t s " i s to combine the v e r s a t i l i t y and s e l e c t i v i t y of s o l u b l e c a t a l y t i c compounds w i t h the t e c h n o l o g i c a l advantages of heterogeneous systems. Conventional heterogeneous c a t a l y s t s though widely used indus-t r i a l l y , e x h i b i t c e r t a i n disadvantages. L i m i t e d knowledge about the nature of the c a t a l y t i c a l l y a c t i v e s i t e s allows f o r improvements of mainly e m p i r i c a l nature. The molecular composition of the homogeneous c a t a l y t i c precursors i s u s u a l l y w e l l defined and t h e r e f o r e by v a r y i n g the s t e r i c as w e l l as e l e c t r o n i c environment of the metal centre i t i s p o s s i b l e to r e g u l a t e the course of the ca t a l y z e d r e a c t i o n as d e s i r e d . The s o l u b l e c a t a l y s t s , however, create problems of t h e i r own which i n c l u d e : (1) separation from the r e a c t i o n mixture and recovery of these u s u a l l y expensive compounds; (2) p l a t i n g of the r e a c t o r w a l l s ; and (3) c o r r o s i o n of the r e a c t i o n v e s s e l s . A s o l u b l e complex attached to an i n s o l u b l e matrix takes on p r o p e r t i e s of a heterogeneous species at a bulk l e v e l , but the i n t e r a c t i o n s t a k i n g place around the metal centre are probably very s i m i l a r to those f o r the s o l u b l e homogeneous compound; the extent of the l a t t e r e f f e c t i s governed by the length of a "spacer arm" between the polymeric matrix and the metal centre. A s o l u b l e c a t a l y s t immobilized t h i s way w i l l combined the p r o p e r t i e s of both homo- and heterogeneous systems. H o p e f u l l y , i t should be p o s s i b l e to enhance the d e s i r e d features and minimize the negative ones. The u l t i m a t e such c a t a l y s t would c o n s i s t of a w e l l defined complex uniformly d i s t r i b u t e d over a s o l i d phase of known p h y s i c a l p r o p e r t i e s , and one which -2-would e x h i b i t optimal a c t i v i t y , s e l e c t i v i t y and e f f i c i e n c y . Various approaches to ob t a i n i n g such a product have been enunciated by a 1-4 number of workers. Both the s o l i d support and the s o l u b l e c a t a l y s t p o r t i o n of aheterogenized complex must be t a i l o r e d to s u i t the needs of the r e a c t i o n which i s to be ca t a l y z e d . The i n s o l u b l e matrix must e x h i b i t mechanical and heat s t a b i l i t y and chemical i n e r t n e s s to r e -agents . So f a r l e s s a t t e n t i o n has been paid to ino r g a n i c than organic supports such as polystyrene''" p o l y v i n y l p y r i d i n e s ^ , polycarboxyla-4,15,16 , „ ... 16 . . , . 11,17 tes , poly-8-diketonates , and p o l y a l c o h o l s . Among the ... 1,2,4,12,14,18 . ... 11 , . . 19 inorg a n i c supports s i l i c a , p o l y s i l i c o n e s , and alumina have been i n v e s t i g a t e d most. There are b a s i c a l l y four ways of at t a c h i n g f u n c t i o n a l groups to 1 2 20 polymers. They are presented s c h e m a t i c a l l y ' ' i n F i g . 1. F i g . l . Various methods of at t a c h i n g a complex to a polymeric support. (b) % * <*M. > m ( ^ . ) + M L ' n — > ( ^ - > ) m M L n _ m (C) m < ~ L + M L ' n — , ( ^ - » m M L ' n _ m (d) m L m o n o m e r + ML' n y^monomerL » J M L ' n / monomen \ / . \ ( L L M L 'n - m — (tHmMLn m -m -3-Method (a) r e f e r s to polymers which already contain c o o r d i n a t i n g groups capable of r e a c t i n g d i r e c t l y w i t h a metal complex. A good example i s i r o n pentacarbonyl which re a c t s w i t h conjugated double bonds 21 of polybutadiene to give macromolecular complexes v i a double-bond i s o m e r i z a t i o n : - ( C H 2 ) ^ CH ^ \ CH - (CH 2 ) n -Fe(CO)3 J m 1 22 23 Chromium hexacarbonyl r e a c t s w i t h polystyrene ' to give a macrocomplex c o n t a i n i n g Cr(CO) 3 f u n c t i o n s coordinated to the polymer v i a the phenyl r i n g s . Polymeric siloxyphosphines have been complexed w i t h metals by li g a n d exchange Method (b) in v o l v e s attachment of the l i g a n d to the support f i r s t ^ which i s then complexed w i t h a s o l u b l e metal compound. F u n c t i o n a l i z a t i o n of an organic polymer such as polystyrene i s exemplified"'" i n F i g . 2. Inorganic supports such as s i l i c a are e a s i l y f u n c t i o n a l i z e d v i a s i l a n e 26—28 condensation w i t h the -OH groups on the surface of s i l i c a >-0H 'A •OH + X,Si-(CH,) -P(C,H.) 0 + 3 I n o 5 I •OH 1-0 \ • 0 - S i - ( C H 2 ) n - P ( C 6 H 5 ) 2 •0 (1) where X=-C£, -0CH 3 > -OC 2H 5 > and -OCOCHg. A l t e r n a t i v e l y , l i g a n d s can be attached to s i l i c a i n a r e a c t i o n between 18 chloromethylphenylated s i l i c a and l i t h i u m d e r i v a t i v e of a phosphine Once l i g a n d s are attached to the polymer they can react w i t h metal complexes F u n c t i o n a l i z a t i o n of polystyrene w i t h l i g a n d s . F^PX Lewis acid PR. -5-to form complexes of t h e i r own v i a ligand exchange 1,2,29,30 For example 31 (2) ^ - 0 - S i - (CH 2) 2-P (C 6H 5) 2Rh(acac) (CO) Phosphine complexes, which have been studied most, have l a b i l e ligands. This c a l l s f o r multiple linkage to the polymer i n order that the complex i s not l o s t from the support. If the polymer i s f l e x i b l e enough i t may allow more than one anchored ligand to i n t e r a c t with a p a r t i c u l a r metal centre, e f f e c t i v e l y creating chelated complexes. Heterogenization can also be achieved by employing method (c) which involves the reaction of a polymer with a preformed ligand-metal complex. The ligands contain functional groups which are capable of being u t i l i z e d subsequently i n binding to a s o l i d support. This technique has been employed only with inorganic s u p p o r t s ^ ' . For example: It i s a good method for increasing the l i k e l i h o o d of multiple attachment of the metal to the support. In the f i r s t three methods the manner of the attachment of a complex to a polymeric matrix i s not well defined. It i s possible to determine only an o v e r a l l anchored ligand to metal rates. However, the actual degree of coordination at any p a r t i c u l a r metal centre i s not w e l l defined. Following method (d) gives a much better chance of synthesizing a macro-molecular species with m e t a l l i c centres i n an e s s e n t i a l l y unchanged (3) X=C£, 0C 2H 5. -6-environment of c o o r d i n a t i n g l i g a n d . Here a w e l l c h a r a c t e r i z e d monomeric does not appreciably change the environment of the metal centre i t i s p o s s i b l e to produce a w e l l defined polymeric complex. Method (d) has been explored r e l a t i v e l y l i t t l e . However, a few i n t e r e s t i n g organometallic macromolecular complexes have been synthesized v i a the p o l y m e r i z a t i o n and copolymerization of the v i n y l i c f u n c t i o n of 33 the l i g a n d . II-(diene a c r y l a t e ) t r i c a r b o n y l i r o n _2, v i n y l c y c l o p e n t a d i e n y l -34 34 manganese t r i c a r b o n y l 3_, H-(benzyl acrylate)chromium t r i c a r b o n y l 4_, 34 35 II-styrene chromium t r i c a r b o n y l 5_, and v i n y l f e r r o c e n e 6_ were s u c c e s s f u l l y polymerized and copolymerized w i t h each other, w i t h styrene,or w i t h methyl a c r y l a t e . metal complex i s polymerized. Assuming that the process of p o l y m e r i z a t i o n 0 Fe(CO)3 Mn(CO)3 2 3 0 Fe -7-The application of the .physicochemical a n a l y t i c a l techniques i s limited with regard to insoluble macromolecular substances. Therefore the polymeric products obtained may be hard to characterize. Some information about their nature can be obtained i n d i r e c t l y from their chemical r e a c t i v i t y as compared with that of the monomeric analogues. The porosity of the support, i t s swelling properties, polymer cross-linking, f l e x i b i l i t y of the network, and r e l a t i v e p o l a r i t i e s of the polymer and substrates are the major properties of the polymer which influence the ov e r a l l properties of the macrocomplex. The effect of the i s o l a t i o n of metallic centres by f i x i n g them to a r i g i d matrix 3 6 was observed for atitanocene complex. Titanocene species which form inactive dimers i n solution proved to be 60 times more active when supported on 20% divinylbenzene-styrene copolymer. However, the heterogen-3 6~'3 9 ized catalysts synthesized to date are, with a few exceptions . ' , cataly-t i c a l l y less active than their homogeneous analogues. The decreased a c t i v i t y i s most l i k e l y due to the d i f f u s i o n barriers caused by the aforementioned properties of the polymeric backbone. The influence of the polymer has been very c l e a r l y demonstrated i n experiments done by 38 39 40 J. K. S t i l l e et a l ' and H. B. Kagan et a l . An insoluble c h i r a l rhodium complex analogous to the soluble Rh(I)-DI0P complex, supported on a copolymer of styrene and divinylbenzene, catalyzes asymmetric hydro-generation of various o l e f i n i c bonds with much lower o p t i c a l yields and 40-reaction rates ' " than the soluble analogue. I t was suggested that contraction of the resin i n the polar solvent system (benzene/ethanol) used for hydrogenation of polar a-acetamid'ocinnamic acid was responsible for the i n a c t i v i t y of the catalyst. On the other hand, when the complex was -8-supported on a more polar support the o p t i c a l y i e l d s of the catalyzed 38 reactions were the same as for the soluble analogue . Moreover, hydrogenations with the same ca t a l y s t supported on a polymer which contained asymmetric centres of i t s own gave o p t i c a l y i e l d s widely 39 d i f f e r e n t depending on the configuration of the asymmetric centre of the polymeric backbone. It can be seen c l e a r l y from the e x i s t i n g evidence that both the supported metal complex and the matrix i t s e l f play important r o l e s . The r e l a t i o n s between the substrates, solvents and both components of the macromolecular ca t a l y s t have to be considered when designing a heterogenized c a t a l y t i c system for a p a r t i c u l a r reaction. 1-2. Syntheses of Organopolysiloxanes . Organopolysiloxanes are r e a d i l y prepared by hydrolysis of chloro-s i l a n e s , alkoxysilanes, acetoxysilanes, or silazanes, followed by con-densation of r e s u l t i n g s i l a n o l s . 2ESiC£ 2HC£ 2 E S 1 0 R 2E SiOH + 2 H 0 R H V > " , S i O S i E + H ? 0 (4) 2ESiOAc 2H0Ac 2HSiN= 2HN= Extensive monographs have been published about polycondensation reactions 41-44 45-49 i n general and polysiloxanes i n p a r t i c u l a r . K i n e t i c s of these reactions follow a general pattern of i n t e r f a c i a l polycondensation 41 reactions. Here, the factors of main influence are: r e l a t i v e r e a c t i v i t i e s -9-of the functional groups i n the monomers, monomer concentrations, reaction temperature, reaction time, nature of the solvent, nature of the catalyst, and mechanical factors. High concentrations of monomers promote formation of high molecular weight polymers. However, i t i s very important that the monomer solution i s not too viscous since this would prevent good mixing of the reagents. At low monomer concentrations oligomerization to small rings predominates, which i s disadvantageous i f the desired product i s a polymer of high molecular weight. D i l u t i o n on the other hand allows better heat dis s i p a t i o n which i s an important consideration since most of the polycondensation reactions are exothermic. Use of a solvent also renders the reaction less violent. The hydrolysis of chlorosilanes i s an extremely fast reaction and the r e l a t i v e rates depend on the nature and number of substituent groups. It has been found that the rates of hydrolytic polycondensation of members of a series of compounds R SiC&, are i n the following order: x 4-x SiC£.>RSiC£0>>R0SiC£0>R0SiC£ 4 5 1 2 5 The hydrolysis of tet r a - and' organotrichlorosilanes yields hydrochloric acid whereas the products of hydrolysis of organodichlorosilanes are mainly soluble, 44 51 either linear or c y c l i c ' , and of r e l a t i v e l y low molecular weight. For a given degree of substitution the rate of hydrolysis i s determined by the inductive effect of the substituent groups. I t i s important i n copolymeri-zation to choose the starting monomers so that their r e a c t i v i t i e s are very sim i l a r . Since silane hydrolysis proceeds v i a an ionic mechanism the -10-p o l a r i t y of the monomers and t h e i r ion-pair structure become the factors of overriding importance"^ ,but very big differences i n the s t r u c t u r e 4 ^ of the s t a r t i n g monomers would r e s u l t i n low y i e l d of the mixed product. 52 53 The s t e r i c and electron donating character of substituent groups ' as well as the number of chlorosilane groups i n each type of the monomeric molecules have to be considered when preparing a polymer with high content of mixed product. Allowance of differ e n c e i n monomer r e a c t i v i t y can be made by adjusting reactant r a t i o s . In h y d r o l y t i c .polycondensation of chlorosilanes water i s one of the s t a r t i n g reagents as well as the elimination product. The o v e r a l l equilibrium highly favours formation of siloxane =Si-0-Si= bonds but may be upset by proper choice of conditions.A large excess of water which promotes hydrolysis w i l l also r e s u l t i n suppression of the condensation process y i e l d i n g polymers of lower molecular weights. Removal of water 54 as the product may be effected by either Dean-Stark d i s t i l l a t i o n or by heating the product to higher temperatures. The r e l a t i o n s h i p between the molecular weight of the polymer and the reaction temperature i s complex. In general the rate of polycondensation increases with the increased temperature. However, the reverse and side 55 56 reactions also proceed f a s t e r . It has been reported ' that upon heating to higher temperatures methylpolysiloxanes undergo thermal rearrangement from higher to lower molecular weight structures. It has also been noted"^ that evolution of hydrocarbons predominates over the process of conden-sation of -OH groups i n polysiloxanes containing organic substituents with a negative inductive e f f e c t . Since the s t a r t i n g monomers are highly r e a c t i v e the o v e r a l l rates of -11-i n t e r f a c i a l polycondensation reactions are determined by the rate of phase intermixing. Rapid mixing promotes formation of high-molecular weight polymers. The nature of the solvent i n which the organochlorosilane monomer i s dissolved p r i o r to mixing with^the water phase i s very important 41 There i s a number of theories , some c o n f l i c t i n g , as to the s e l e c t i o n of a solvent which would ensure maximum molecular weight of the polymer product. In most cases the solvent i s selected by t r i a l and error. Usually the rates of h e t e r o l y t i c reactions which involve i n at l e a s t one stage a proton cleavage are accelerated by the presence of solvents with high d i e l e c t r i c constants. Solvents with higher d i e l e c t r i c constants promote formation of high-molecular weight polymer as w e l l as side products. In hydrolytic.condensation of chlorosilanes hydrogen chloride i s evolved. 53 58 Hence the basic solvents capable of acting as HC£ acceptors ' enhance formation of the high-molecular weight products. Addition of other electron donating reagents such as p y r i d i n e " ^ ' ^ has a s i m i l a r e f f e c t . Hydrolysis of chlo r o s i l a n e s , as an i o n i c reaction, can be either a c i d - or base-catalyzed. Hydrolysis i n strongly i d i c medium favours48,61,62 48 production of c y c l i c or low-molecular weight polymers whereas the base-catalyzed polymerization gives products of high-molecular weight Rearrangement of i n i t i a l l y formed small c y c l i c molecules to higher polymers 63 often takes place. The mechanisms proposed for both acid-and base-catalyzed processes involve n u c l e o p h i l i c attack at s i l i c o n with a sub-sequent cleavage of aSi-0 bond. Lewis acids also cleave Si^O bonds. Tin 63 6 A t e t r a c h l o r i d e , d i b u t y l t i n , bis(diorganophenoxyphosphinoxy)dibutoxy-titanium*^, and other t i t a n i u m ^ and platinum*^ compounds of such character -12-catalyze chlorosilane polycondensation reactions. A l l the factors mentioned above have to be considered i n synthesi-zing organopolysiloxanes. The i d e a l conditions for producing a highly cross-linked insoluble polymer of high molecular weight w i l l be found by t r i a l and error. 1-3. This Work . The aim of t h i s work was to produce insoluble polysiloxane-phosphine rhodium(I) complexes which could be used as ca t a l y s t s for the hydrogenation of o l e f i n s . ' Method (d) discussed previously i n t h i s chapter was chosen as one which would produce a we l l defined polymeric complex. Because rhodium(I) phosphine complexes are known to be good hydrogenation c a t a l y s t s rhodium(I) complexes with C£^Si-(CH2)n~P(CgH^)^ ligands would be synthesized as soluble monomers. The very re a c t i v e SiCJ^ f u n c t i o n a l groups of the ligands would allow, by means of h y d r o l y t i c polycondensation, production of highly cross-linked insoluble polymers. . Carbonylchlorbbis(phosphine)rhodium would be employed as a polymerization " p i l o t " compound since the in f r a r e d carbonyl stretching frequency would serve as an ind i c a t o r of the influence of the polymerization process on the metal centre. The c a t a l y t i c a c t i v i t y of the polymeric complexes would be compared with those of model soluble s i l o x y -phosphine complexes s p e c i a l l y prepared for t h i s purpose. -13-CHAPTER 2  EXPERIMENTAL 2.1. Abbreviations and Symbols. EM e l e c t r o n microscope IR i n f r a r e d U V u l t r a v i o l e t EPR e l e c t r o n paramagnetic resonance NMR nuclear magnetic resonance ppm part per m i l i o n s s i n g l e t d doublet dd double doublet t t r i p l e t dt double t r i p l e t q quartet m m u l t i p l e t Cp cyclopentadiene acac acetylacetonate NBD norbornadiene DMF dimethylformamide DMA dimethylacetamide DMSO dimethylsulphoxide DVB divinylbenzene COE cyclooctene DIOP 2,3-0-isopropylidene-2,3-dihydroxy-l,4-bis(diphenyl-phosphino)butane A (CH 3 ) 3 S i-(CH 2)2-P(C 6H5)2 B [(CH3) 3Si-0-]2(CH3)Si-(CH2)2-P(C 6H 5) 2 C C£2(CH3)Si-(CH2)2-P(C6H5)2 D C£ 3Si-(CH 2)2-P(C 6H 5) 2 E C£ 3Si-(CH 2) 8-P(C 6H 5) 2 F {[(CH 3) 3Si-0-] 2(CH 3)Si-(CH 2) 2-P(C 6H 5) 2}Rh(NBD)C£ G {[(CH3)3Si-0-]2(CH3)Si-(CH2)2-P(C6H5)2}2Rh(CO)C£ H {[(CH 3 ) 3 S i-0-]2(CH 3)Si-(CH2)2-P(C 6H5) 2}3RhCJl J {[(CH 3) 3Si-0-] 2(CH 3)Si-(CH 2)2-P(C6H5)2>4Rli2CS.2 K [C £ 3 S i -(CH 2) 2-P(C 6H 5) 2]2 R h( c°) C ! i L [C£ 3Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£ M [C2. 3Si-(CH 2)8-P(C6H5)2]3RhCK. N [C£ 3Si-(CH 2) 2-P(C 6H 5) 2]4Rh 2C£ 2 P { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 2 R h ( c o ) C £ J x Rn-m {[0 3/ 2Si-(CH 2) n-P(C 6H5)2]3 RhC£. ( 0 3 / 2 S i - C H 3 ) m } x S { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 . 7 R h C J l } x T2-m {[0 3/2Si-(CH2)2-P(C6H 5)2]4 Rh2W2- (°3/2Si-CH 3) m} x -14-2-2. Techniques and Instrumentation. In a l l the syntheses of oxygen and/or moisture s e n s i t i v e compounds Schlenk tubes and f i l t e r s were used. Except for handling of non-chlorovinyl-siloxanes a l l operations were done either i n a dry-box under helium or i n the Schlenk apparatus under nitrogen. Infrared spectra were recorded on Perkin-Elmer models 457 and 225 spectrophotometers. The solutions were held i n KBr c e l l s with the path length 0.25 mm. Neat samples and Nujol mulls were held between Csl plates with the path length 0.1 mm. The polystyrene spectrum band at 1601 cm ^ was used for c a l i b r a t i o n s . Infrared samples of a l l the polymers were prepared i n the form of Nujol mulls by combining 25 mg of the polymer itfith 2 drops (always the same size) of Nujol. Handling of a l l the samples was done i n a. helium atmosphere i n a dry-box. Proton and phosphorus magnetic resonance spectra were measured at 30°C i n deuterobenzene C^D^, unless otherwise indicated. The spectra 31 were recorded on a Varian model XL-100 spectrometer. A l l P NMR spectra were decoupled from the protons. The proton resonance peak positions were given i n ppm downfield from an external tetramethylsilane (6 s c a l e ) . The m u l t i p l i c i t y , coupling constants, integrated peak areas, and proton assign-ments are indicated i n parentheses or follow the reported peak p o s i t i o n s . A multiplet centered at e.g. 6=5.35 i s noted as 5.35(m). Negative notation i n the phosphorus spectra indicates chemical s h i f t downfield from external 85% H^PO^. The peak m u l t i p l i c i t y and coupling constants are indicated i n parentheses, the integrated areas proportions follow the reported peak pos i t i o n s . Low r e s o l u t i o n mass spectra were determined on Varian/MAT CH4B and -15-A.E.I. MS902 mass spectrometers. Electron microscope micrographs were recorded on an ETEC Autoscan microscope with ORTEC Multichannel X-Ray analyzer model 6200. Column chromatography was done on F l o r o s i l (100-200 mesh) purchased from Fisher S c i e n t i f i c Co. The solvents and F l o r o s i l were deoxygenated p r i o r to use. Column preparation and product e l u t i o n and c o l l e c t i o n were done under nitrogen. Thin layer chromatography was done on Eastman Chromatogram sheets of 13181 s i l i c a gel with fluorescent i n d i c a t o r (No. 6060). Gas l i q u i d chromatography was done using an Aerograph model A-90-P gas chromatograph from Wilkens Instrument and Research Inc. equipped with a 2 m long column ( i n t e r n a l diameter 4.5 mm). Helium was the c a r r i e r gas. . The column packing used for separation of v i n y l siloxanes was 10% FFAP on Chromosorb W-AW 60/80 mesh. The gas flow rate was 15 mL/min, and the column temperature 150°C. For the separation of saturated and unsaturated hydrocarbons the column packing used was 10% carbowax 1500 on Chromosorb W-AW 60/80 mesh. The conditions f or separation of hydrogenation products from each other and from the s t a r t i n g d e f i n e s were as follows: styrene 140° , the flow 50 mL/min. cyclohexene 60° , the flow 50 mL/min. 1-octene 50° the flow 25 mL/min. 1-heptene 50° the flow 25 mL/min. U l t r a v i o l e t i r r a d i a t i o n reactions were done with a 200 Watt mercury lamp (Hanovia S-654 A36) i n a heavy glass wall Carius tube which was cooled by a stream of a i r . -16-Th e constant temperature baths were thermostatically c o n t r o l l e d with thermoregulator Jumbo-MS (from Hopler, West Germany) and s o l i d state relays constructed i n the Mechanical Shop of the Department of Chemistry, University of B r i t i s h Columbia. The f i n e regulation of gas admission i n the gas uptake apparatus shown i n F i g . 3 was achieved with an Edward's vacuum needle valve (#OSID). A l l the stopcocks used i n the Carius tubes and i n the modified version of the apparatus i n F i g . 3 (used for HC£(g) uptake measurements) were purchased from Kontes ( t e f l o n vacuum valves K-826600 and K-826610). The connecting points Q and R of the same apparatus (Fig. 3) were 0-ring connectors Kontes K-671'750. Microanalysis (C,H,C£) were performed by Mr. P. Borda of the M i c r o a n a l y t i c a l Laboratory, Chemistry Department, University of B r i t i s h Columbia, and by A l f r e d Bernhardt Mikroanalytisches Laboratorium, Elbach-iiber-Engelskirchen, West Germany (Rh,P,Si). 2-3. Reagents. 7 - 0 c t e n y l t r i c h l o r o s i l a n e was purchased from S i l a r Laboratories; a l l other ch l o r o s i l a n e s , from Peninsular Chem Research; diphenylphosphine, from Strem Chemicals Inc.,Rhodium t r i c h l o r i d e trihydrate,from Johnson Matthey and Mallory Ltd.; styrene, from Matheson Colman and B e l l ; c y c l o -hexene, from Mallinckrodt Chemical Works; 1-heptene and 1-octene, from A l d r i c h Chemical Co.; carbon monoxide and hydrogen chloride gases, from Matheson of Canada Ltd.; nitrogen, helium, and hydrogen gases, from Canadian Liquid A i r Ltd. A l l l i q u i d o l e f i n s were passed through an Adsorption Alumina -17-(purchased from Fisher S c i e n t i f i c Co.) column p r i o r to use i n reactions. 67 Di-y-chlorotetracarbonyldirhodium(I) , norbornadienechlororhodium(I) and d i - y - c h l o r o t e t r a e t h y l e n e d i r h o d i u m ( I ) w e r e prepared by published method The petroleum ether used was the 30-60°C bp f r a c t i o n . A l l solvents used i n column and t h i n layer chromatography were deoxygenated by passing nitrogen through them. Benzene, toluene, and dioxane were dried by prolonged r e f l u x i n g with LiA£H^ i n nitrogen atmosphere. Dichloromethane and deuterated solvents were deoxygenated by the freeze- and-thaw method. Deuterated benzene was dried with ^2^5" 2-4. Gas Uptake Apparatus. 2-4-1. Apparatus for Hydrogen Uptake Measurements. A constant pressure gas uptake apparatus shown i n F i g . 3 was constructed. A Pyrex round-bottom / 25 mL f l a s k with a side arm was connected v i a a glass s p i r a l with a tap F to the o i l manometer ^ through the tap (J. The o i l manometer was made of thick wall c a p i l l a r y tubing f i l l e d with n-butyl phthalate, a l i q u i d with n e g l i g i b l e vapour pressure. S^  was connected to the mercury manometer J_ which consisted of a c a l i b r a t e d burette i n the l e f t side and a mercury r e s e r v o i r i n the r i g h t . The rig h t arm of the mercury manometer was i n turn connected v i a an Edward's high-vacuum needle valve and a shut o f f metal tap to the gas handling part of the apparatus. This part consisted of the mercury manometer U, the gas i n l e t tap 0, the connecting tap M, and tap N connecting the system to a pump. The reaction f l a s k was thermostatted i n a glycerine bath W. The J/igure 3. Apparatus f o r constant gas-uptake measurements -19-bath consisted of a c y l i n d r i c a l glass container surrounded by polystyrene i n s u l a t i o n and enclosed i n a wooden box on four supports. A magnetic s t i r r e r _P was placed under the box. A shaker Y_ was used f o r an a l t e r -native means of mixing the reaction s o l u t i o n . Both the manometers and T_ were immersed i n a water bath X i n a transparent P l e x i g l a s s container. Both the baths were independently regulated by thermoregulators with relay control c i r c u i t s . The heat was provided by 25 W elongated e l e c t r i c l i g h t bulbs. These with the aid of mechanical s t i r r e r s ensured temperature co n t r o l within ±0.1°C. A cathetometer was used to follow the l e v e l changes i n the mercury gas burette. 2-4-2. Apparatus for Hydrogen Chloride Uptake Measurements,. A modified version of the apparatus shown i n F i g . 3 was used. Here the ground-glass stopcocks and the metal valves were replaced by greaseless t e f l o n stopcocks. The connections at points Q and R were made with 0-ring connectors. 2-4-3. Procedure for a T y p i c a l Gas Uptake Experiment Using the Apparatus  shown i n F i g . 3. Experiments involving c a t a l y s t s not s e n s i t i v e to a i r . The required amount of the complex was weighed out into the f l a s k A. The side arm C^  was stoppered and the f l a s k was connected through the s p i r a l and the tap _F to the gas-handling part of the apparatus at Q. The system was evacuated and r e f i l l e d with nitrogen. The gas was admitted through the tap CL The required amount of a solvent (and substrate i f required) -20-was introduced through the side arm C_. C was closed. The contents of the f l a s k were degassed by the freeze-and-thaw method. During t h i s operation the valve was closed. The gaseous reactant was introduced through tap CJ, at a pressure somewhat lower than that required for the experiment and then taps F_ and M were closed. The f l a s k and the s p i r a l were disconnected from (} and reconnected to R; the f l a s k being placed i n the thermostated bath W. The contents of the f l a s k were s t i r r e d with the magnetic s t i r r e r and allowed to come to thermal equilibrium. In the meantime the taps (3, H, J_, K, Z_, L_, and were opened and t h i s whole part of the apparatus evacuated. The tap N_ was closed and the gaseous reactant was admitted through the tap O at a pressure s l i g h t l y lower than that required for the experiment. Tap Cj was closed. Then tap F was opened and the pressure i n the whole apparatus was adjusted to the desired l e v e l . Taps Cj, hf Z_, J_, and H were closed and a reading of the mercury l e v e l i n the l e f t arm of the manometer _T was taken. The e l e c t r i c timer was started. Any gas uptake resulted i n a r a i s i n g of the o i l l e v e l i n the l e f t arm of the manometer ^. In order that the o i l l e v e l i n both the arms remained the same gas was admitted through the taps L and Z. This resulted i n a corresponding r i s e of the mercury l e v e l i n the l e f t arm of the manometer T_. The change of height of the mercury was recorded as a function of time. Since the l e f t arm of the manometer T_ was made of a c a l i b r a t e d pipette the volume of the gas which reacted was known. Experiments Involving Catalysts A i r Sensitive i n t h e i r S o l i d State. Flask A used i n these experiments had a bottom with indentations which were supposed to break the l i q u i d surface thereby helping i n mixing of the -21-shaken reaction s o l u t i o n . The required amount of the ca t a l y s t was weighed out i n a glove-box into a bucket. The bucket was suspended on the hook J3 i n the side arm C^ , and the f l a s k was stoppered at 15. The required amount of solvent (and substrate i f needed) was introduced through the neck B under a stream of nitrogen. The s p i r a l was connected to the apparatus at Q so that a continuous stream of nitrogen flowed through i t . The f l a s k A was quickly connected to the s p i r a l by the j o i n t 15. The contents of the f l a s k were degassed by the freeze-and-thaw method. From t h i s point the procedure was the same as for the non-air-sensitive samples, with one exception. Af t e r the pressure i n the whole system was brought to a desired l e v e l the bucket containing the ca t a l y s t was dropped into the so l u t i o n by turning the hook JJ i n the side arm CL The timer was started simultaneously. The gas uptake measurements were done i n the same way for a l l the experiments. 2-4-4. Atmospheric Pressure Hydrogenation Apparatus. When the polymeric c a t a l y s t s were used a double manifold apparatus was employed for the hydrogenation reactions c a r r i e d out at atmospheric pressure. Usually a few reactions were ca r r i e d out simultaneously. Each reaction vessel consisted of a 25 mL round bottom f l a s k K with a side arm (Fig.4). The side arm was stoppered with a teflon-rubber septum plug. The f l a s k was connected by the j o i n t M to the water-cooled condenser N which i n turn was attached v i a a two way tap A to the double manifold. The f l a s k could be evacuated by opening the taps A and E_ to the pump. Opened taps 15 and allowed continuous flow of hydrogen through the gas l i n e Y. Figure 4. Apparatus f o r hydrogenation i n the presence of polymeric c a t a l y s t s . -23-During the reaction constant atmospheric pressure was maintained by opening the taps A to the continuous very slow stream of hydrogen i n the l i n e Y. The f l a s k s K were immersed i n the glycerine bath Ii i n a transparent P l e x i g l a s s container enclosed i n a three-sided wooden frame on four supports. A magnetic s t i r r e r was placed under each f l a s k . The hight of the bath could be regulated with a lab-jack. The bath was thermostated by a thermoregulator with a relay control c i r c u i t . The heat was provided by a 25W elongated e l e c t r i c l i g h t bulb. This with the aid of a mechanical s t i r r e r ensured the temperature co n t r o l within ±0.1°C. 2-4-5. Procedure for a Ty p i c a l Hydrogenation Reaction Using Polymeric  Catalysts. The required amount of the c a t a l y s t was weighed out i n a glove-box into a f l a s k K. The side arm L_ was stoppered with a teflon-rubber septum and the other neck with a glass stopper. A small (caution!) continuous stream of hydrogen was allowed to flow out through the tap A and the condenser N. Taps Ji and C^  were opened permanently. The f l a s k K was connected quickly to the condenser by the neck M. The contents of the f l a s k were immediately evacuated by turning the tap A to the vacuum l i n e Z_, tap E being open. Hydrogen was readmitted by turning the tap A to the gas l i n e Y. The teflon-rubber septum was removed from the side arm L_ and a small (caution!) continuous stream of hydrogen was allowed to flow out. The required amount of a solvent and an o l e f i n were introduced through the side arm JL. The septum was replaced. The contents of the f l a s k were degassed by the freeze-and-thaw method and hydrogen was admitted. The f l a s k was then immersed i n the glycerine bath thermostated at 35°C. The reaction mixture was s t i r r e d with a magnetic s t i r r e r (3. The -24-pressure was maintained constant at 760 mm Hg by having the tap A opened to the gas l i n e Y_. A very slow constant stream of hydrogen was f l o w i n g through Y throughout the experiment. U s u a l l y three r e a c t i o n s were c a r r i e d out simultaneously; then the r e a c t i o n f l a s k s were set up i n a s e r i e s . The progress of the r e a c t i o n was monitored by GLC, samples being withdrawn p e r i o d i c a l l y through the septum. 2-5. Syntheses of Ligands and Soluble Complexes. 2-5-1. P r e p a r a t i o n of V i n y l Siloxanes, C h l o r o t r i m e t h y l s i l a n e (108 g, 1 mol) and m e t h y l v i n y l d i c h l o r o s i l a n e (72 g, 0.5 mol) d i s s o l v e d i n 200 mL of d i e t h y l ether were added slowly to 400 mL of water at such a r a t e as to maintain the r e a c t i o n temperature at 6-10°C. The r e a c t i o n v e s s e l was cooled i n an i c e - s a l t - w a t e r bath. The mixture was next s t i r r e d f o r an a d d i t i o n a l l h w h i l e the temperature was allowed to increase to ambient. The ether l a y e r was separated, washed w i t h water and the solvent was flash-evaporated l e a v i n g 84.3 g of a c o l o u r l e s s o i l . The presence of at l e a s t three major components i n the product mixture was detected by GLC. Three f r a c t i o n s , a l l c o l o u r l e s s l i q u i d s , were separated by repeated d i s t i l l a t i o n at a reduced pressure as f o l l o w s : a) F i r s t f r a c t i o n i d e n t i f i e d as (CH^Si-O-SKCH^^,:bp 35-.37°C (74 mm)-, [lit71l00.1°C (757 mm)], 3.7 g. ' A n a l - C a l c d f o r C 6 H 1 8 ° S ± 2 : C, 44.4; H, 11.1. Found: C, 44.0; H, 10.9. Mass spectrum: m/e 162(M +). 1H NMR: 0 . 0 7 ( s , S i ( C H 3 ) 3 ) . b) Second f r a c t i o n i d e n t i f i e d as [(OLj) 3 S i - 0 - ] ^ SiCOLj) (CH=CH2) : bp 72 100°C(77 mm), l i t 164-6(760 mm), 34 g(27.5% y i e l d ) . Anal. Calcd f o r -25-C o H o / 0 o S i _ : C, 43.6; H, 9.8. Found: C, 43.6; H, 9.7. Mass spectrum: y ZH Z J m/e 248(M +). "*"H NMR: 0.10 (s,18H,Si(CH 3) 3) ; 0.12(s,3H,Si-(CH 3)) ; 5.9(m,3H,Si-(CH=CH2)). c) Third f r a c t i o n i d e n t i f i e d as (CH 3) 3Si-[OSi'(CH 3) (CH=CH2) ] -O-Si-(CH 3) 3: b.p. 122-4°C(77 mm). 5.5 g. Anal. Calcd for C ^ H ^ O ^ i g : C , 42.9; H, 8.6. Found: C, 42.9; H, 8.8. Mass spectrum: m/e 420(M +). 1H NMR: 0.10 (s,18H,Si(CH 3) 3); 0.13(s,9H,Si-(CH ) ) ; 5.9(m,9H,Si-(CH=CH2)). _ 3 Higher siloxypolymers •'• b.p. >140°(1x10 mm), 40.2 g remained i n the s t i l l pot. 2-5-2. Preparation of Phosphine Ligands. A l l phosphine ligands were prepared by u l t r a v i o l e t i r r a d i a t i o n of a mixture of diphenylphosphine (1 mol) and the appropriate v i n y l s i l a n e (1.2 mol). In a t y p i c a l reaction 12 g (64.5 mmol) of diphenylphosphine and 19.2 g (77.5 mmol) of [ ( C H ^ S i - 0 - ] 2 S i ( C H 3 ) (CH=CH) were introduced into a Carius tube which had previously been evacuated and then f i l l e d with nitrogen. The mixture was then cooled i n l i q u i d nitrogen, degassed on the vacuum l i n e , and subsequently r e f i l l e d with nitrogen. The tube was closed and i r r a d i a t e d with a mercury lamp for 48h, while continuously shaken and cooled with a stream of a i r . When the reaction was completed the products were transferred into a nitrogen f i l l e d d i s t i l l a t i o n apparatus. D i s t i l l a t i o n yielded the a i r s e n s i t i v e , colourless l i q u i d i d e n t i f i e d as [ ( C H 3 ) 3 S i - 0 - ] 2 ( C H 3 ) S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 : b.p. 142°(10~ 3mm), 71.4% y i e l d . Anal. Calcd for c 2 i H 3 5 ° 2 P S i 3 : C ' 5 8- 1> H> 8 - 1 - Found: C, 57.9; H, 8.2. Mass spectrum: m/e 434(M +). 1H NMR: 0.11(s,18H,Si(CH 3> 3); 0.08(s,3H,Si-(CH 3)); 0.60(m,2H,Si-CH2-); 2.09(m,2H,P-CH2-); 7.38(m,10H,P(C 6H 5) 2). 3 1 P NMR:+9.14(s). -26-The following were prepared i n the same way: (CH 0) QSi-(CH 0) 0-P(C,H c)„: b.p. 128°C(lxlO~ 3mm), 79.6% y i e l d . Anal. _} J Z Z o _> Z Calcd for C ^ H ^ P S i : C, 71.4; H, 8.4. Found: C, 71.6; H, 8.4. Mass spectrum: m/e 286(M +). 1H NMR: 0.14(s,9H,Si(CH 3) 3); 0.68(m,2H,Si-CH2-); 2.48(m,2H,P-CH„-); 7.40(m,10H,P(C,H C)„). 3 1 P NMR:+10.32(s). Z D J Z C £ 2 ( C H 3 ) S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 : b.p. 142°C(lxl0~ 3mm), 86.2% y i e l d . Anal. Calcd f o r C ^ H ^ C ^ P S i : C, 55.2; H, 5.2; C£, 21.5. Found: C, 55.4; H, 5.4; CI, 21.2. Mass spectrum: m/e 326(M +). 1H NMR: 0.83(s,3H,Si-CH 3); I. 29(m,2H,Si-CH2-); 2.33(m,2H,P-CH2~); 7.45(m,10H,P(C 6H 5) 2). 3 1 P NMR:+10.38(s) , — "\ 28 77 C£ 0Si-(CH 0)„-P(C £H c) 0: b.p. 142°C(lxlO mm), [ l i t . ' 142-144°C o z z b 5 z ( l x l 0 _ 1 mm)], 85.6% y i e l d . Anal. Calcd for C ^ H ^ C ^ P S i : C, 48.4; H, 4.0; CI, 30.6. Found: C, 48.6; H, 4.0; CI, 30.4. Mass spectrum: m/e 347(M +). 1H NMR: 1.63(m,2H,Si-CH2-); 2.35(m, 2H.,P-CH2") ; 7 .45(m, 10H,P(C 6H 5) 2). 3 1 P NMR:+10.35(s) . — 1 98 77 C £ 0 S i - ( C H 0 ) 0 - P ( C £ H c ) 0 : b.p. 210-215°C(6.5x10 mm), [ l i t . ' 218-221°C j 2. o O -> Z (5xl0 _ 1mm)] , 30.6% y i e l d . Anal. Calcd f o r C ^ H ^ C ^ P S i : C, 55.6; H, 6.0; C£, 24.7. Found: C, 56.1; H, 6.3; CI, 24.6. Mass spectrum: m/e 431(M +). 1H NMR: 1.42(m,14H,Si-(CH„)-,-); 2.30(m,2H,P-CH -) ; 7.36(m,10H,P(C,H_) .) . 3 1 P NMR: l I Z O J z +16.08(s). 2-5-3. Preparation of (NBD) { [ (CH3> Si-0-] 2 (CH 3)Si- (CH 2) 2~P ( C ^ ) 2>RhC£, F. [Bicyclo-(2,2,l)-hepta-2,5-diene]di-y-chlorodirhodium, [(NBD)RhC£] , (0.461 g, 1.0 mmol) was introduced into a Schlenk tube. The tube was sub-sequently evacuated and f i l l e d with nitrogen. The compound was suspended i n 8 mL of dichloromethane. A solu t i o n of [ (CH^Si-O-] 2 (CH 3) S i - (CH,,) 2 ~ P(CgH,-)2 (0.868 g, 2.0 mmol) i n 8 mL of dichloromethane was gradually i n t r o -duced with a syringe into the suspension. The reaction v e s s e l was closed -27-and the contents were s t i r r e d with a magnetic bar, at room temperature f o r l h . The reaction product was p u r i f i e d by column chromatography and was eluted as a yellow band with acetone i n petroleum ether solvent mixture (15% v/v). After evaporation of the solvents the product was redissolved i n petroleum ether and cooled to -75°C thereby giving l g (75.0% y i e l d ) of yellow s o l i d . Anal. Calcd. for C 2 8 H 4 3 C £ 0 2 P R h S i 2 : C, 50.6; H, 6.5; CZ, 5.4. Found: C, 50.8; H, 6.6; CZ, 5.3. Mass spectrum: m/e 664(M +), 1H NMR: 0.08 (s,3H,Si-CH 3); 0.12(s,18H,Si(CH 3) 3),: 1.40(m,2H,Si-CH2-); 2.30(m,2H,P-CH2") ; 7.23(m,10H,P(C 6H 5) 2) ; 1.40(m,2H, ^ CH 2(NBD)); 3.03(m,2H, ^ CH(NBD) trans to CZ); 3.72(m,2H, ^ CH(NBD)); 5.23(m,2H,^ CH(NBD) trans to P). 3 1 P NMR: -31.45(d,J(Rh-P)=171.6 Hz). 2-5-4. Preparation of {[(CH 3) 3Si-0-] 2(CH 3)Si-(CH 2) 2-P(CgH^) 2} 2Rh(CO)C£, G. To a degassed s o l u t i o n of 0.389 g (1.0 mmol) of [Rh(CO) 2C£] 2 i n 8 mL of benzene a s o l u t i o n of 1.736 g (4.0 mmol) of { [ ( C H 3 ) 3 S i - 0 - ) 2 ( C H 3 ) S i -(CH 2) 2~P-(CgH^) 2} i n 8 mL of benzene was added. The mixture was refluxed for 4h under nitrogen. The reaction was monitored by IR spectroscopy: samples were taken p e r i o d i c a l l y and the v(C=0) region was observed. The r e a c t i o n was terminated with the disappearance of the carbonyl peaks of the s t a r t i n g material. The s o l u t i o n was cooled to room temperature. The yellow product p r e c i p i t a t e d out upon the addition of ethyl alcohol. TLC using acetone/ petroleum ether mixture (1:9 v/v) as eluent indicated the presence of only one component (1.25 g, 60.0% y i e l d ) , mp 39-44°C. Anal. Calcd for C 4 3 H y o C £ 0 5 P 2 R h S i 6 : C, 49.9; H, 6.8; CZ, 3.4. Found: C, 50.3; H, 6.8; CZ, 3.2. Mass spectrum: m/e 450 (M +), probe not heated; m/e 1034 (M +), probe temp. 300°C. -28-IR: v(CEO) 1968 cm"1. 1H NMR: 0.14(s,6H,Si-CH3>, 0.18(s,36H,Si(CH ) 3 ) ; 0.70-1.50 (m) and 2.96 (m), ( t o t a l 8H, r e l a t i v e i n t e n s i t i e s 2:1, -CH 2-CH 2~); 7.16 (m) and 7.97 (m)(total 20H, r e l a t i v e i n t e n s i t i e s 2:1, P ( C 6 H 5 ) 2 ) . 3 1 P NMR: -29.44 (s); -29.65(d,J(Rh-P)=124.6 Hz), r e l a t i v e i n t e n s i t i e s vary from 1:5 to 2:7 for d i f f e r e n t preparation batches. 2-5-5. Preparation of {[(CU )3Si-0-]2(CH3>Si-(CH2>2~P(CgH ) 2> 3RhC£, H. The compound was prepared by the reaction of 4.557 g (105 mmol) of [ ( C H 3 ) 3 S i - 0 - ] 2 ( C H 3 ) S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 and 0.681 g (17.5 mmol) of (C 2H 4) 4Rh 2C& 2 i n 120 mL of benzene. The volume of the s o l u t i o n was reduced to czi. 20 mL by evaporation of the solvent at a reduced pressure. The reaction mixture was s t i r r e d f o r 45 min at room temperature a f t e r which time i t was f i l t e r e d and evaporated to dryness i n vacuo. Evacuation for two days was necessary i n order that a l l the solvent could be removed. The product obtained was a viscous, dark red o i l (4.75 g, 94.0% y i e l d ) . Anal. Calcd for C , 0 H 1 „ C C £ 0,P oRhSi n: C, 52.5; H, 7.3; C£, 2.5; Rh, 63 105 6 3 9 7.2; P, 6.5. Found: C, 52.2; H; 7.3; C£, 2.6; Rh, 6.9; P, 6.3. "hi NMR: 0.07 (s,21H,Si-(CH ) and S i ( C H 3 ) 3 ) ; 0.72 (m, 2H, Si-CH 2-.); 1.48 (m,2H,P-CH 2~); 7.88 (m,10H,P(C^) 2) ; and 0.18 (s,42H,Si-(CH 3) and S i ( C H 3 ) 3 ) ; 1.12 (m,4H,Si-CH2-); 2.72 (m,4H,P-CH - ) ; 7.06 (m, 20H,P ( C ^ ) 2) . 3 1 P NMR: -29.75 (dd, J(P-P)=39.0 Hz, J(Rh-P)=140.0 Hz); -44.97 (dt, J(P-P)=39.0 Hz, J(Rh-P)=188.0 Hz); -29.92 (s); r e l a t i v e i n t e n s i t i e s 20:10:1. IR (neat): v(Rh-C£) 260 (w) cm"1. 2-5-6. Preparation of { [ (CH 3) 3Si-0-] 2 (CH 3)Si- (CH 2) 2 ~ P ( C ^ ) 2 > 4 R h 2 C £ 2 , J . The compound was prepared by reaction of ( C 9 H A ) A R h 9 C £ 9 (0.487 g, 1.25 -29-mmol) and [ (CH 3) 3 S i - 0 - ] 2 ( C H 3 ) S i - (CH 2) 2~P ( C ^ ) 2 (2.172 g, 5.00 mmol) i n 50 mL of r e f l u x i n g benzene. Af t e r 3h the reaction mixture was cooled to room temperature and i t s volume was reduced to oa. 20 mL by evaporation of the solvent under reduced pressure. The so l u t i o n was then f i l t e r e d and evaporated to dryness i n vacuo. Evacuation for two days was necessary i n order that a l l the solvent could be removed. The product was obtained as a very viscous dark red o i l (2.34 g, 93.0% y i e l d ) . Anal Calcd for C 8 4 H l 4 0 C £ 2 0 g P 4 R h 2 S i 1 2 : C, 50.1; H, 7.0; C£, 3.5; Rh, 10.2; P, 6.2. Found: C, 50.5; H, 7.2; C£, 3.8; Rh, 10.1; P, 6.4. 1H NMR: 0.12 (s,84H,Si-CH 3 and SiCCH^) ); 1.00 (m,8H,Si-CH2-); 2.14 (m, 8H, P-CH 2~); 7.22 (m) and 7.90 (m), ( t o t a l 40H r e l a t i v e i n t e n s i t i e s 2:1, P ( C 6 H 5 ) 2 ) . 3 1 P NMR: -47.02 (d, J(Rh-P)=196.5 Hz). IR(neat): v(Rh-C£) 255(m-w) cm"1. 2-5-7. Preparation of [C£„Si-(CH„)_-P(C,H C)J oRh(C0)C£, K. 5 Z Z o j Z Z  The complex was prepared i n the reac t i o n between stoichiometric amounts of (C0) 4Rh 2C£ 2 and C^Si-(CH 2) 2~P ( C ^ ) 2 . The phosphine (1.400 g, 4.0 mmol) was dissolved i n 8 mL of benzene and added to the s o l u t i o n of ( C 2 H 4 ) 4 R h 2 C £ 2 (0.389 g, 1.0 mmol) i n 8 mL of benzene. The mixture was refluxed and the extent of the reaction was monitored by IR spectroscopy (v(C=0) region). The reaction was completed a f t e r 4h. The reaction mixture was cooled to room temperature and f i l t e r e d . The product p r e c i p i t a t e d out of the so l u t i o n upon the addition of petroleum ether. The complex, an oxygen and moisture s e n s i t i v e yellow s o l i d , was p u r i f i e d by r e p r e c i p i t a t i o n with petroleum ether out of a benzene s o l u t i o n (1.65 g, 96.0% y i e l d ) , mp 52-75°C. Anal. Calcd f or C 2 g H 2 g C £ 7 0 P 2 R h S i 2 : C, 40.0; H, 3.3; C£, 28.9; Rh, -30-12.0; P, 7.2. Found: C, 40.4; H, 3.3; CZ, 28.6; Rh, 12.1; P, 7.1. IR(C,D,); v(CHO) 1970(s) cm"1. 33"P NMR: -30,00 (d, J (Rh-P)=127.5 Hz), b o "4 NMR: 1.92 (m,4H,Si-CH2-); 2.98 (m,4H,P-CH2"); 7.-10 (m) and 7.74 (m), ( t o t a l 20H, r e l a t i v e i n t e n s i t i e s 3:2, P(C,H C)„). O 5 Z 2-5-8. Preparation of [CJ^Si-(CH 2) 2~P (CgH^ 2 ] 3RhC£, L, and [C£ 3Si-(CH 2)g-P(C 6H 5) 2] 3RhC£, M. The c h l o r o t r i s ( t r i c h l o r o s i l y l p h o s p h i n e ) r h o d i u m complexes were prepared i n the reaction between stoichiometric amounts of ( C 2 H 4 ) 4 R h 2 C £ 2 and the appropriate phosphine. In a t y p i c a l reaction 0.934 g (2.4 mmol) of C J ^ S i - ( C H 2 ) 2 ~ P ( C ^ ) 2 dissolved i n 4 mL of benzene was added to 0.156 g (0.4 mmol) of (C 2H 4) 4Rh 2C& 2 i n 8 mL benzene. The i n i t i a l l y orange s o l u t i o n immediately turned dark red. I t was s t i r r e d at room temperature of l h and then f i l t e r e d . The orange product was obtained by evaporating the s o l u t i o n to dryness under the vacuum (0.900 g, 95.3% y i e l d ) , mp 170-210°C (decomp). Anal. Calcd f o r C 4 2 H 4 2 C 1 Q P 3 R h S i 3 : C, 42.7; H, 3.6; CZ, 30.1; P, 7.9; Rh, 8.7. Found: C, 42.4; H, 3.7; CZ; 29.8; P, 7.7; Rh, 8.9. 3 1 P NMR: -28.53 (dd, J(P-P)=39.9 Hz, J(Rh-P)=136.2 Hz); -42.97 (dt, J(Rh-P)=187.1 Hz, J(P-P)=40.0 Hz); -25.88 (dd, J(Rh-P)=97.6 Hz, J(P-P)=26.4 Hz); -39.49 (dt, J(Rh-P)=142.3 Hz, J(P-P)=25.4 Hz); -49.34(s); -48.77(B); -44.37(s); -43.89(S). 1H NMR: 1.38(m), 1.96(m), 2.71(m), and 4.12(m)(total 12H. , (-CH2-CH2-); 7.06 (m), 7.74 (m), and 8.36(m) ( t o t a l 30H, P ( C 6 H 5 ) 2 ) ; r e l a t i v e i n t e n s i t i e s 1:3:1:1:10:4:1; -13.96(m,Rh-H). IR(C 6D 6): v(Rh-H) 2095 (w) cm"1; (Nujol): v(Rh-H) 2095(w); v(Rh-C£) 260(w), 280(w) cm"1. In a s i m i l a r reaction [C£ 3Si-(CH 2)g-P (C^-H^),,] 3RhC£ was obtained i n -31-93.2% y i e l d , mp 147-172°C. Anal. Calcd for C 6 0 H 7 g C £ 1 0 P 3 R h S i 3 : C, 50.2; H, 5.4; CI, 24.8; Rh, 7.2; P, 6.5. Found: C, 50.5; H, 5.7; CI, 24.4; Rh, 7.3; P, 6.5. 3 1 P NMR: -26.25 (dd, J(Rh-P)=139.2 Hz, J(P-P)=39.9 Hz); -40.94 (dt, J(Rh-P)=188.0 Hz, J(P-P)=40.1 Hz); -34.55(m); -30.06(m); -25.35(m); -22.86(m); -22.30(m); r e l a t i v e i n t e n s i t i e s of dd plus dt to the rest of the peaks 4:1. 1H NMR: 1.05(m), 1.93(m), 2.45(m), and 3.93(m) (-(CH 2) g-) ; 7.05(m), 7.87(m), and 8.35(m)(P(C,H C)„); r e l a t i v e i n t e n s i t i e s 72:10:5:1: o 5 z 20:9:1; -14.32(m), Rh-H) IR(C,D,); v(Rh-H) 2090(m); 2170(sh) cm"1; (Nujol); — D O v(Rh-H) 2090(m); 2170(sh); v(Rh-C£) 260(w), 280(w) cm"1. The preparation of [C£„Si-(CH„)_-P(C,H C)A „RhC£ was repeated i n 5 Z z D 5 z 5 glassware pretreated with trimethylchlorosilane. The spectra showed the following pattern: 3 1 P NMR: -42.67 (dt, J(Rh-P)=186.8 Hz, J(P-P)=39.8 Hz); -28.27 (dd, J(Rh-P)=140.4 Hz, J(P-P)=39.3 Hz); -40(m); -37(m); -27(m); -24(m); r e l a t i v e i n t e n s i t i e s of the (dt and dd) to a l l the m u l t i p l e t s 5:2. •""H NMR: 1.46(m), 1.90(m), 2.72(m) and 4.16(m) ( t o t a l 12H, -CH2-CH2-) ; 7.04(m), 7.72(m), and 8.36(m)(total 30H, P ( C 6 H 5 ) 2 ) ; r e l a t i v e i n t e n s i t i e s 2:2:2:1:13:5:trace; -14.00 (m, Rh-H). {"^P}1!! NMR: no change i n the downfield region; -14.00 (d, J(Rh-H) = 10 Hz). IR(C 6D 6): v(Rh-H) 2095(w) cm"1. 2-5-9. Preparation of [C£ 3Si-(CH 2) 2-P(C 6H 5) 2] 4Rh 2C£ 2, N. The complex was obtained i n the reaction of 0.695 g (2.0 mmol) of C £ 3 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 with 0.195 g (0.5 mmol) of ( C ^ ) 4 R h 2 C £ 2 i n 15 mL of -32-benzene. The so l u t i o n was refluxed for 3h, cooled, and f i l t e r e d . An orange product was obtained by evaporating the so l u t i o n of dryness i n vacuo (0.76 g, 91.0% y i e l d ) , decomp 210-230°C. Anal. Calcd for C^H^C 1 4 P 4 R h 2 S i 4 : C, 40.3; H, 3.4; C£, 29.8; Rh, 12.4; P, 7.4. Found: C, 40.4; H, 3.5; CI, 29.5; Rh, 12.4; P, 7.2. 3 1 P NMR: -72.22(m), -68.77(m), -46.91(m), -43.95(m), -26.67(m), -24.20(m); a l l of approximately the same i n t e n s i t i e s . "4l NMR: 1.4(m), 2.2(m), 3.3(m), and 3.8(m)(total 16H, -CH 2-CH 2-); 7.1(m), 7.6(m), 7.9(m), and 8.3(m) ( t o t a l 40H, P(CgH 5) 2); r e l a t i v e i n t e n s i t i e s 6:6:3:1:30:6:2:2; -15.72 (dt, J(Rh-H)=14 Hz, J(P-H)=18 Hz), -13.95(m), ( r e l a t i v e i n t e n s i t i e s 4:1, Rh-H). IR(C &D 6): v(Rh-H) 2090(m); (Nujol): v(Rh-H) 2090(m); v(Rh-C£) 290 (w,br), 265 (w,br) cm"1. 2-6. Syntheses of Polymeric Complexes. 2-6-1. D i f f e r e n t Methods of Polymerization of [ C J ^ S i - ( C H 2 ) 2 ~ P ( C g H ^ 2 ] 2 ~ Rh(C0)C£. A. A benzene so l u t i o n (ca. 3.5 ml) of 5.931 g (6.89 mmol) of [C£ 3Si-(CH 2) 2-P(CgH^) 2] 2Rh(C0)C£ prepared i n s i t u was introduced dropwise into 5 mL of avigorously s t i r r e d mixture of dioxane and water (4:1 v/v). The suspension of the resultant pale yellow p r e c i p i t a t e was s t i r r e d f o r 2h. A solu t i o n of 4 g of NaHCO^ i n c_a. 50 mL of water was added to the suspension. The product was f i l t e r e d o f f , washed with water, 10% aqueous of NaHCO^, water, dioxane, and benzene, and dried i n vacuo f or 24h. -33-The s o l i d product was transferred to a Soxhlet extractor and extracted with r e f l u x i n g dichloromethane for 24h. The ins o l u b l e polymer was dried i n vacuo for 24h (3.92 g, 81.7% y i e l d ) , decomp. 255-265°C. Anal. Calcd f or C ^ H ^ C i O ^ R h S i ^ C, 50.0; H,4.3; C£, 5.1; Rh, 14.8; P, 8.9. Found: C, 50.0; H, 3.8; C£, 12.3; Rh, 14.8; P, 9.1. IR (Nujol): v(C^O) 1965(s) cm"1. B. A benzene s o l u t i o n (ca. 1.5 ml) of [CJ^Si-(CH 2) 2~P(CgH,.) 2J 2~ Rh(C0)C£ (0.086 g, 0.1 mmol) prepared i n s i t u was added dropwise into 1 mL of an aqueous s o l u t i o n of 0.1 g KOH. A pale yellow p r e c i p i t a t e formed immediately. I t was f i l t e r e d o f f , washed with water, benzene, and then dried i n vacuo for 24h. IR ( n u j o l ) : v ( C E 0 ) 1965(s) cm"1. C. Triethylamine (0.1 g, 1.0 mmol) was added to [C J ^ S i - ( C H 2 ) 2 ~ P(C 6H 5) 2J 2Rh(CO)C£ (0.086 g, 0.1 mmol) which had been prepared i n s i t u i n 1.5 mL of benzene. The mixture was added dropwise to ca. 2 mL of water. A pale yellow p r e c i p i t a t e formed immediately. It was f i l t e r e d o f f , washed with water, benzene, and then drie d i n vacuo for 24h. IR(Nujol):v(CE0) 1965(s) cm"1. 2-6-2. Dif f e r e n t Methods of Polymerization of [Ci^Si-(CH 2) 2~P(C gH 5) 2] 3RhC£. A. Homopolymerization of [C£„Si-(CH„) 0-P(C,H c)J„RhC£ i n the 3 Z Z o D Z 3  presence of N(C 2H^) 3. Triethylamine (0.5 g, 1 mmol) was added to [CJ^Si-(CH 2) 2~P(C^) 2] 3RhC£ -34-(0.316 g, 0.3 mmol) prepared i n s i t u i n 1.5 mL of benzene. The s o l u t i o n was then added to 2 mL of water. Vigorous s t i r r i n g with a magnetic bar was maintained throughout the reaction. An orange product p r e c i p i t a t e d immediately. It was f i l t e r e d o f f , washed with water and benzene, and dried i n vacuo for 24h. Copolymerization of [ C ^ S i - ( C H ^ 2 ~ P ( C ^ ) 2 ] 3 R h C £ with C£ 3£i-CH 3 i n the presence of N(C 2H^) 3 > A number of copolymers were produced which d i f f e r e d i n the s t a r t i n g proportions of C£ 3Si-CH 3and [ C ^ S i - (CH 2) 2~P (CgH^ 2 ] 3RhC£. The preparation procedures were analogous f o r a l l of them. The procedure followed f or the copolymer with the proportion of C£ 3Si-CH 3 to [CJ^Si- (CH 2) 2 ~ P ( C ^ ) ^\ 3RhC£ 100:1 was t y p i c a l . C£ 3Si-CH 3 (4.069 g, 27.2 mmol) and triethylamine (10 g, 0.1 mol) were added to 1.5 mL of a benzene s o l u t i o n of [C£„Si-(CH„)„-P(C,H C)„]„RhC£ 5 L I D J Z j (0.321 g, 0.27 mmol) prepared i n s i t u . The solu t i o n was introduced dropwise into 2 mL of vigorously s t i r r e d water. A pale yellow p r e c i p i t a t e formed immediately. It was f i l t e r e d o f f , washed with water, benzene, and dried i n vacuo for 24h. See Table I for the properties of the products. B. Copymerization of [CJ^Si-(CH 2) 2~P(C^) 2] 3RhC£ with C£ 3Si-CH 3 . i n the presence of KOH(aq). The procedure followed for the polymer i n which the s t a r t i n g pro-portion of C£ 3Si-CH 3and [C£ 3Si-(CH 2) 2~P(C 6H 5) 2] 3RhC£ was 100:1 was t y p i c a l and was repeated for the reactions using d i f f e r e n t component proportions. M e t h y l t r i c h l o r o s i l a n e (3.73 g, 24.9 mmol) was added to ca. 1.5 mL of -35-a benzene s o l u t i o n of [C£_Si- (CH„) „-P(C,H,) „] 0RhC£ (0.295 g, 0.25 mmol) j Z Z o _> z _> prepared i n s i t u . The solu t i o n was added dropwise to a vigorously s t i r r e d s o l u t i o n of 4.5 g KOH i n 6 mL of water. A pale orange p r e c i p i t a t e formed immediately. It was f i l t e r e d o f f , washed with water, benzene, and then dried i n vacuo for 24h. See Table II for the properties of the products. C. Homopolymerization of [C£ 3Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£ i n a DMF/ Water Mixture. A benzene s o l u t i o n (1.5 mL) of [C£ 0Si-(CH„)„-P(C,H C)„]„RhC£ (0.373 g, _> Z Z D J Z j 0.32 mmol) prepared i n s i t u was introduced slowly into 5 mL of a vigorously s t i r r e d mixture of DMF and water (4:1 v/v). A pale yellow product p r e c i p i t -ated immediately. It was f i l t e r e d o f f , washed with water, DMF, and benzene and then dried i n vacuo for 24h. During t h i s procedure the colour changed to orange. Copolymerization of [C£ 3Si-(CH 2) 2-P ( C 6H 5) 2] 3RhC£ with C £ 3 S i - C H 3 i n DMF/Water Mixture. A mixture of 3.370 g (22.5 mmol) of C^Si-CLL^and 1.5 mL of a benzene so l u t i o n of 0.267 g (0.23 mmol) of [ C i ^ S i - ( C H 2 ) 2~P ( C ^ ) 2] 3RhC£ prepared i n s i t u , was introduced slowly dropwise into 10 mL of a vigorously s t i r r e d mixture of DMF and water (4:1 v/v). The r e s u l t i n g yellow p r e c i p i t a t e was f i l t e r e d o f f , washed with water, DMF, and benzene. On drying i n vacuo f o r 24h the product became orange. For r e s u l t s see Table I I I . D. Homopolymerization of [C£ 3Si-(CH 2) 2~P(C &H 5) 2] 3RhC£ i n Dioxane/ Water Mixture. A benzene s o l u t i o n (1.5 mL) of 0.402 g (34.1 mmol) of [ C J ^ S i - ( C l i p 2 ~ P(CtH,-) 9 ] ,RhC£ prepared i n s i t u was introduced dropwise into 4 mL of a - 3 6 -vigorously s t i r r e d mixture of dioxane and water (3:1 v/v). The suspension of the r e s u l t i n g pale yellow p r e c i p i t a t e was s t i r r e d f o r an a d d i t i o n a l 2h. The p r e c i p i t a t e changed colour to orange upon addition of ca ;8 mL of an aqueous s o l u t i o n of 0.5 g of NaHCO^. The product was f i l t e r e d o f f , washed with water, 10% aqueous NaHCO^, water, dioxane, and benzene, and then dried i n vacuo f o r 24h. Copolymerization of [CJ^Si-(CH 2) 2~P(CgH^ 2]^RhCZ with C£ 3Si-CH 3  i n Dioxane/Water Mixture. Methyltrichloros'ilane (4.030 g, 27.0 mmol) was added to 1.5 mL of a benzene s o l u t i o n of [C£„Si-(CH_)„-P(C,H,)_]„RhC£ (0.318 g, 0.27 mmol) 3 z Z o -> / 3 prepared i n s i t u . The s o l u t i o n was added dropwise into 11.5 mL of a mixture of dioxane and water (4:1 v/v). The suspension of the r e s u l t i n g pale yellow p r e c i p i t a t e was s t i r r e d for an a d d i t i o n a l 2h. Its colour changed to orange a f t e r addition of ca_.100 mL of an aqueous s o l u t i o n of 8 g of NaHC03 into the suspension. The product was f i l t e r e d o f f , washed with water, 10% aqueous NaHC03, water, dioxane, and benzene, and then dried i n vacuo f o r 24h. For r e s u l t s see Table I I I . E. Homopolymerization of [CJ^Si-(CH 2) 2~P(C^) 2] 3RhC£ i n Dioxane/ Water Mixture;Followed by Extra c t i o n . A benzene s o l u t i o n (3.5 mL) of 5.427 g (4.59 mmol) of [C£„Si-(CH 0) 0-P(C,H c)„] 0RhC£ prepared i n s i t u was introduced dropwise 3 z z o _> z J •-—• into 5 mL of a vigorously s t i r r e d dioxane and water mixture (4:1 v/v). The suspension of the r e s u l t i n g pale yellow p r e c i p i t a t e was s t i r r e d f o r 2h. Addition of NaHC03, 4 g i n 50 mL of water, changed the colour of the p r e c i p i t a t e to orange. The product was f i l t e r e d o f f , washed with water, 10% -37-NaHCO^ (aq), water, dioxane, and benzene, and dried i n vacuo for 24h. The s o l i d product was transferred to a Soxhlet extractor and extracted with r e f l u x i n g dichloromethane for 24h. The insolu b l e polymer was dried i n vacuo for 24h. Copolymerization of [C£ 0Si-(CH.)„-P(C,H C)_]_RhC£ and C£ nSi-CH„ J Z Z 0 3 / 3 3 3 i n Dioxane/Water Mixture; Followed by Extraction. M e t h y l t r i c h l o r o s i l a n e (10.914 g, 73.0 mmol) was added to 1.5 mL of a benzene sol u t i o n of [CJ^Si-(CH 2) - P ( C ^ ) 2 ] ^hsZl (0.862 g, 0.73 mmol) prepared i n s i t u . The so l u t i o n was introduced dropwise i n t o 25 mL of a vigorously s t i r r e d mixture of dioxane and water (4:1 v/v). A pale yellow p r e c i p i t a t e formed immediately; i t s suspension was s t i r r e d f o r an a d d i t i o n a l 2h. The product became orange a f t e r addition of 20 g of NaHCO^ dissolved i n 250 mL of water to the suspension. The polymer was f i l t e r e d o f f , washed with water, 10% NaHCO^aq), water, dioxane, and benzene, and then dried i n vacuo f o r 24h. The product was subsequently transferred into a Soxhlet extractor and extracted with dichloromethane over a period of 24h. The insolu b l e polymer was then dried i n vacuo f o r 24h. For r e s u l t s see Table IV. F. R e a c t i v i t y of the Polymeric Complexes with Hydrogen Gas -a S t a b i l i t y Test. The apparatus shown i n F i g . 3 was used for measurements of hydrogen -2 uptake. The polymeric complex (4.5 x 10 mmol based on Rh atoms) produced by any of the methods described above was suspended i n 3 mL of toluene at 60°C. Hydrogen at 690 mm Hg was allowed to react with the polymer i n suspension for 24h. Any colour changes of the polymer were noted. -38-Table I. Hydrogen uptake by polymers prepared i n the presence of N ( C 2 H 5 ) 3 . C£ 3 S i - CH 3 / [ C5,3 S i - CGH2 ) 2-i n i t i a l molar r a t i o -P(C,H c) 0] 0RhC£ H„uptake per O J Z J Z Rh atom Polymer colour - change a f t e r reaction 0 1.82 darkens 20 1.37 darkens 80 - no s o l i d polymer produced 100 0.99 no colour change 1.28 , darkens s l i g h t l y Table I I . Hydrogen uptake by polymers prepared i n the presence of KOH(aq). C£„Si-CH 0/[C£ 0Si-(CH 0) 0-P(C,HjJ 0RhC£ H uptake Polymer colour i n i t i a l molar r a t i o per Rh atom reac t i o n 50 1.39 darkens 60 2.05 darkens 70 0.60 darkens 100 1.31 remains yellow 130 0.45 darkens 200 1.53 darkens -39-Table I I I . Hydrogen uptake by polymers prepared i n dioxane/water mixture by procedure D. C£-SiCH_/[C£_Si-(CH 0) 0-P(C,H c)_]_RhC£ organic H. uptake J j J z z o j / j i i . , , ^. solvent/ per Rh i n i t i a l molar r a t i o water r a t i o atom Polymer colour a f t e r reaction(b) DMF/water hydrolysis 0 100 0 200 200 130 100 50 100 dioxane/water hydrolysis 0.06 0.16 ^a u n f i l t r a b l e gel produced 4C 4 4 orange 0.27 yellow 1.00 yellow 0.75 yellow 0.50-0.97 (a) hydrolysis i n large excess of water/dioxane. (b) i n i t i a l l y orange. Table IV. Hydrogen uptake by polymers prepared i n dioxane/water mixture by procedure E. C£,Si-CH,/ [C£,Si-(CH„) _-P(C,H,-) 0 ] „RhC£ dioxane/ H 2 uptake Polymer . 4 . , J i ~> . z z D J Z J i n i t i a l molar r a t i o water per Rh colour r a t i o atom a f t e r reaction(a) 0 4 0.12 l i g h t orange 100 4 0.56 l i g h t orange (a) i n i t i a l l y orange. -40-2-6-3. Homopolymerization of Dif f e r e n t Rh(I) Phosphine Complexes and th e i r Copolymerization with C^Si-CH-}' A l l the polymeric complexes used for any further reactions were prepared according to the procedure B described above. A l l the homo-polymers proved to be pyrophoric upon exposure to a i r . {[0 3^ 2Si-(CH 2) 2-P(C 6H 5) 2l 3RhC£} x:85.3% y i e l d , decomp. 220-230°C. Anal. Calcd f o r : C 4 2 H 4 2 C £ 0 g / 2 P 3 R h S i 3 : C, 54.0 H, 4.5; C£, 3.8; P, 10.0; Rh, 11.0; S i , 9.0. Found: C, 50.8; H, 4.5; CI, 6.2; P, 9.5; Rh, 10.5; S i , 8.9. IR(Nujol):v(Rh-C£) 285fw); 255(sh) cm"1. {[0Si(CH o)-(CH o)„-P(C,H c)„]_RhC£} : not analyzed; the product was completely 3 z z , o 5 z 3 . X ^ soluble i n CH 2 C £ 2 . {[0„ ,„Si-(CH„) 0-P(C,Hj J„RhC£} : 84.1% y i e l d , decomp. 185-195°C. Anal. 3 / z z o o _ 5 z 3 x Calcd for C 6 0 H 7 g C £ 0 g / 2 P 3 R h S i 3 : C, 60.8; H, 6.6; C£, 3.0; P, 7.7; Rh, 8.7; S i , 7.1. Found: C, 59.2; H, 6.3; C£, 4.6; P, 7.6; Rh, 8.4; S i , 6.9. IR(Nujol): v(RhC£) 285(w) 255(sh) cm"1. { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 4 R h 2 C £ 2 } x ; 70.2% y i e l d , decomp. 220-230°C. Anal. Calcd for C 5 6 H 5 6 C £ 2 0 6 P 4 R h 2 S i 4 : C, 50.3; H, 4.2; C£, 5.3; P, 9.3; Rh, 15.4; S i , 8.4. Found: C, 50.6; H, 4.5; C£, 6.6; P, 9.0; Rh, 15.1; S i , 8.3. IR(Nujol):v(Rh-C£) 290(w); 265(sh) cm"1. {[0 3 / 2Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£. [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 0 f 7 } x ; 78.9% y i e l d , decomp. 260-265°C.Anal. Calcd for C C 1 0 H c. „ C£ 0 C C [. P. n Rh S i . n\ 5 1 . o 5 1 . o J.JD 5 . 1 5 . 1 C, 55.6; H, 4.6; C£, 3.2; P, 10.3; Rh, 9.2; S i , 9.3. Found: C, 50.3; H, 4.8; C£, 6.6; P, 10.2; Rh, 9.1; S i , 9.1. ((0 3^ 2Si-CH 3) 7 5.{[0 3^ 2Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£}) x: 73.5% y i e l d , decomp. 255-265°C. Anal. Calcd f o r C 1 1 7 H 2 6 9 C £ 0 1 1 7 P 3 R h S i 7 g ; C, 23.6; H, 4.5; C£, 0.6; P, 1.6; Rh, 1.7. Found: C, 23.6; H, 5.3; C£, 1.4; P, 1.5; Rh, 1.7. -41-((0. 3 / 2Si-CH 3) 1 5 ( ).{[0 3 / 2Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£}) x: 78.2% y i e l d , decomp. 255-265°C. Anal. Calcd for C i n o H / n o C £ 0 o o „ r P 0 R h S i l c o : C, 21.0; H, 4.5; 192 492 229.5 3 153 Found: C, 20.2; H, 4.5 ( ( 0 3 / 2 S i - C H 3 ) 2 0 0 . { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 R h C £ } ) x : 71.2% y i e l d , decomp. 255-265°C. Anal. Calcd for C„,„H,.„C£ 0 o n. c P 0 R h S i o n o : C, 20.3; H, 4.5. 242 642 304.5 3 203 Found: C, 20.2; H, 4.3. ( ( 0 3 / 2 S i - C H 3 ) 1 0 ( ) . { [ 0 3 / 2 S i - ( C H 2 ) 8 - P ( C 6 H 5 ) 2 ] 3 R h C £ } ) x : 86.8% y i e l d , decomp. 250-260°C. Anal. Calcd for C,-„H„-,0C£ 0 1 C / rP 0Rh S i , : C, 24.4; H, 4.8. 160 3/8 154.5 J 103 Found: C, 24.4; H, 4.8. ( ( 0 3 / 2 S i - C H 3 ) 2 0 ( ) . { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 4 R h 2 C £ 2 } ) x : 70.2% y i e l d , decomp. 270-280°C. Anal. Calcd for C 0 1. tH £ 1.,C£ 0 0 o_,P.Rh„Si„„. : C, 20.9; H, 4.5; 256 656 2 306 4 2 204 CI, 0.5; P, 0.8; Rh, 1.4; S i , 38.8. Found: C, 21.0; H, 4.4; CI, 0.2; P, 0.8; Rh, 1.5; S i , 38.6. 2-6-4. Polymerization of C£ 0Si-(CH 0)_-P(C,H C)„. 3 z Z b D Z A benzene s o l u t i o n (3 mL) of 1.740 g (5.0 mmol) of C J ^ S i - ( C H 2 ) 2 ~ P ( C ^ ) 2 was introduced dropwise into a vigorously s t i r r e d mixture (2.5 mL) of dioxane and water (4:1 v/v). The suspension of the white p r e c i p i t a t e which was formed was s t i r r e d for an a d d i t i o n a l 2h. A so l u t i o n of 1.5 g of NaHC03 i n 20 mL of water was added to i t . The product was then f i l t e r e d o f f , washed with water, 10% NaHC0 3(aq), water, dioxane, and benzene, and then dried i n vacuo for 24h. Anal. Calcd for {0 o ,_Si-(CH 0) 0-P(C,H c) 0} : CI, 0.0; and for 3/2 2 2 v 6 5 2 n {0(C£)Si-(CH o)„-P(C,H c)„ : C£, 12.1. Found: Cfc, 9.2. z z b J z n 2-7. Reactions of the Soluble Complexes with H ?, CO, and HC£(g). The rates of the reactions were not followed by the gas uptake -42-measurements due to extremely high s o l u b i l i t y of the complexes even i n solvent vapours. The complexes started reacting, as recognized by the colour changes, with the gaseous reagents before being introduced into the l i q u i d solvent. This did not allow observations of the beginning stages or even most of the reaction progress. 2-7-1. Reaction of { [ (CH 3) 3Si-0-] 2 (CH3)Si-(CH2> 2"P ( C ^ ) 2 > 3RhC£ with H 2 . The complex was dissolved i n deuterated benzene i n an NMR tube, under nitrogen. The NMR tube was connected to the gas uptake apparatus shown i n F i g . 3. The so l u t i o n was degassed by the freeze-and-thaw method and hydrogen was introduced. The colour change from dark red to yellow indicated the reaction progress. As the gas diffused through the s o l u t i o n and reacted with the complex the colour change progressed from the top meniscus to the bottom of the tube. After 8h the s o l u t i o n became yellow throughout. It was then shaken. No further colour changes were observed over a period of 2h. The NMR and IR spectra of the s o l u t i o n were recorded. 4 NMR: -8.5(m); -10.1(m); -17.9(m); ( r e l a t i v e i n t e n s i t i e s 1:1:2, Rh-H). { 3 1P} XE NMR: -9.3(m, p a r t l y decoupled); -17.9(d, J(Rh-H)-23 Hz); ( r e l a t i v e i n t e n s i t i e s 1:1, Rh-H). 3 1P NMR: -41.03(dd, J(P-P)=20 Hz, J(Rh-P)=110 Hz); -20.17(dt, J(P-P)=20 Hz,J(Rh-P)=90 Hz); -29.9'2(s); r e l a t i v e i n t e n s i t i e s 16:8:1. IR(C 6D 6): v(Rh-H) 2075(s), 2160(sh) cm"1. The solvent was then evaporated i n vacuo. The complex was redissolved i n deuterated benzene i n the same NMR tube and remained i n N 2 atmosphere f o r l h . The NMR and IR spectra of the s o l u t i o n showed signals due to the o r i g i n a l Rh(I) complex only. The same NMR tube was again attached to the gas-uptake apparatus and rehydrogenation of the complex was c a r r i e d out i n the same manner. The - 4 3 -NMR and IR spectra of the r e s u l t i n g s o l u t i o n were the same as those of the o r i g i n a l l y hydrogenated compound. 2-7-2. Reaction of { [ (CH 3). 3Si-0-0]. 2(CH 3)Si-(CH 2) -P(C 6H 5) 2} 4Rh with H . The reaction procedure was i d e n t i c a l with that for {[(CH 3)3 S 1-O-] 2(CH 3)Si-(CH 2) 2~P(C 6H 5) 2 > 3RhC£. Aft e r the f i r s t hydrogenation the NMR and IR spectra showed the following pattern (Fig. 39a and b),: "4 NMR: -16.1(m); -17.8(m); -19.8(t, J(P-H)=24 Hz), -20.1(dt, J(Rh-H)=24 Hz, J(P-H)=16 Hz); ( a l l Rh-H). { 3 1P} 4 NMR: -16.1(d, J (Rh-H) =15 Hz); -17.8(d, j(Rh-H)=15 Hz); -19.8(s); -20.1(d, J(Rh-H)=24 Hz). 3 1 P NMR: -48.76(s); -43.95(B ) ; -41.85(B ) ; -38.88(B ) ; -49.38(B ) ; -44.56(B ) ; -42.22(B ) ; -39.50(B ) ; -29.62(s); -21.26(m); -19.04(m); r e l a t i v e i n t e n s i t i e s 83:74:100:70:24:27: 25:25:20:27:25. IR(CgD 6):v(Rh-H) 2102(a), 2165(sh) cm - 1. After removal of hydrogen by pumping,NMR and IR spectra of the sol u t i o n were recorded. Only signals due to the o r i g i n a l Rh (I) complex were present. On rehydrogenation the same spectra showed the same pattern as the o r i g i n a l l y hydrogenated complex. 2-7-3. Reaction of { [ (CHg)3Si-0-.] g ( C H 3 ) S i - ( C H g ) 2 ~ P ( C ^ ) ^ R h ^ with CO. An NMR tube with a s o l u t i o n of the complex i n deuterobenzene was connected to the gas uptake apparatus shown i n F i g . 3. The s o l u t i o n was degassed by the freeze-and-thaw method and carbon monoxide was admitted. As the reaction progressed the colour of the s o l u t i o n changed as i n the hydrogenation reactions described above. -44-After 24h the reaction appeared to be complete and s p e c t r a l analysis was performed. The spectra showed patterns c h a r a c t e r i s t i c of {[(CH 3) Si-0-] 2(CH 3)Si-(CH 2) 2-P(C 6» 5) 2} 2Rh(CO)CA. 3 1 P NMR: -29.81(d, J(Rh-P)=124.7 Hz); -30.00(s); r e l a t i v e i n t e n s i t i e s 30:1. 1H NMR: 0.19(s,42H,Si-CH Q and S i ( C H ^ ) Q ) ; 1.15(m,4H,Si-CH9-); 2.98(m,4H,P-CH2-); 7.16(m) and 8.00(m), ( t o t a l 20H, r e l a t i v e i n t e n s i t i e s 3:2, P ( C 6 H 5 ) 2 ) ; IR(C,D,):v(C=0) 1965(vs) cm"1. D O 2-7-4. Reaction of { [ (CH 3) 3 S i - 0 - ] 2 (CHg) S i - (CH 2) 2~P ( C J ^ ) ^ R h C A with CO. The reaction procedure was the same as for the di-y-chlorobisphosphine-dirhodium.The NMR and IR spectra showed the following pattern: 3 1 P NMR ( C J ) , , 35°C): -30 to -3(m); -29.94(s). D D 3 1 P NMR [(CD 3) 2CO, -60°C]: -47 to -13(m). 1H NMR (CgDg): 0.18(s,63H, Si(CH 3) and S i ( C H 3 ) 3 ) ; 1.05(m,6H,Si-CH,-); 2.71(m,6H,P-CH2~); 7.13(m) and 7.85(m)(total 30H, r e l a t i v e i n t e n s i t i e s 3:2, P(C gH 5) 2).IR(C 6D f i):v(C=0) 1965 (vs) cm 1 . 2-7-5. Reaction of' {[(CH 3) 3Si-0-] 2(CH 3)Si-(CH 2) 2-P(C 6H 5) 2} 2Rh(CO)CJl with { [ (CH 3) 3Si-0-] 2 (CH 3)Si-(CH 2) 2-P ( C J ^ ) 2 > . -2 -2 The free phosphine (3.8 x 10 g, 8.8 x 10 mmol) and the complex - 2 - 2 (9.1 x 10 g, 8.8 x 10 mmol) were dissolved i n benzene-d^ i n an NMR tube. The spectrum of the s o l u t i o n was recorded. 3 1 P NMR: -20 to -3(m); -29.41(s); r e l a t i v e i n t e n s i t i e s 4:1. 2-7-6. Reaction of { [ ( CH^Si-O-] 2 (CH 3) S i - (CH2> 2~P ( C ^ ) 2> 3RhC£ with HC£(g). An NMR tube with the s o l u t i o n of the complex i n benzene was connected to the modified gas uptake apparatus equipped with Teflon stopcocks, as shown -45-i n F i g . 3. The s o l u t i o n was degassed by the freeze-and-thaw method and HC£(g) was introduced. The reaction resulted i n the immediate p r e c i p i t a t i o n of a yellow, insoluble s o l i d . The p r e c i p i t a t e was f i l t e r e d , washed with benzene, dried i n a stream of nitrogen for 8h, and f i n a l l y dried i n vacuo for l h . The product was a no n - c r y s t a l l i n e pale yellow s o l i d , insoluble i n benzene, toluene, acetone, dichloromethane, 1,2-dichloroethane, petroleum ether, dimethylsulphoxide, dimethylacetamide, and carbon disulphide. IR(Nujol) :v(Rh-H) 2110(m) :v (Rh-C£) 253(m), 273(w) cm""1. Anal. Calcd f or { [ (CH 3) 3Si-0-] 2(CHg)Si-(CH 2) 2~P(C^) 2> 3RhC£.HC£ i . e . C 6 3 H 1 0 6 C £ 2 ° 6 P 3 R h S i 3 : C ' 5 1 ' 2 ; H ' 7 ' 2 ' C l> 4 ' 8 , C a l c d f o r { [ 0 (CH 3) S i - (CH 2) 2-P (C 6H 5) 2 ] 2 [ 0 1 / 2 (CA) (CH 3) S i - (CH^) 2~P ( C ^ ) 2]RhC£ .HC£ }^  i . e . C 4 5 H 5 2 C £ 3 0 5 ^ 2 P 3 R h S i 3 : C, 53.0; H, 5.1; C£, 10.5. Found: C, 53.7; H, 7.3; CZ, 9.5. The compound was held i n vacuo for 24h i n order that the hydrogen chloride could be removed. The product was an orange s o l i d insoluble i n any of the solvents mentioned i n the f i r s t part of t h i s experiment. IR(Nujol): a l l three peaks v(Rh-H) 2110, (Rh-C£) 253, and 273 had diminished i n t e n s i t y . Anal. Calcd for { [ 0 ( C R ^ S i - C H 2 ) 2 ~ P ( C g H 5 ) 2 ] 2 [ 0 1 / 2 ( C £ ) ( C H 3 ) S i -(CH 2) 2-P(C 6H 5) 2]RhC£> x _i^_e. C 4 5 H 5 1 C J i 2 0 3 / 2 P 3 R h S i 3 : C ' 5 5 - 9 ' H ' 5 * 2 ' C 1 , 7.2. Found: C, 53.6; H, 5.3; C£, 9.4. -46-2-7-7. Reaction of { [ (CH ) 3Si-0-] 2(CH ) S i - ( C H 2 ) ^ ( C J ^ ) ^ R l ^ C ^ with HC£(g). The reaction procedure was the same as for the analogous c h l o r o t r i s -phosphinerhodium described above. The product was also a yellow s o l i d i nsoluble i n any of the common solvents. IR(Nujol):v(Rh-H) 2100(m);v(Rh-C£) 255(m), 275(w) cm"1. Anal. Calcd for { [ ( C H ^ S i - O - ] (CH-j)Si-(CH 2) 2 ~ P(CJ^) 2 ) 4 R h 2 C £ 2 . 2HC£ i . e . C-.H, . - C J l . O o P . R h - S i ^ : C, 48.3; H, 6.8; Cfc, 6.8. Calcd f o r 84 142 4 8 4 2 12 { [ 0 ( C H 3 ) S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 [ 0 1 / 2 ( C £ ) (CH^) S i - ( C H 2 ) 2 ~ P ( C ^ ) £ ] R h 2 C £ 2 . 2HC£> x i . e . C-~H-mC&c0-, ,„P.Rh 0Si. : C, 49.1; H, 4.8, CI, 12.1. Found: C, 47.8; D U /U j 112. 4 / 4 H, 5.0; C%, 10.8. The compound was held i n vacuo for 24h i n order that the hydrogen chloride could be removed. The product was an orange s o l i d i n s o l u b l e i n common solvents. IR(Nujol); the peaks v(Rh-H) 2100, and v(Rh-C£) 255, 275 cm"1 had diminished i n t e n s i t y . Anal. Calcd for { [0(CH 3)Si- (CH^ 2 ~ P ( C g H j ) 2 ] 3 ^ / 2 (C£) (CH3> Si-(CH 2) 2 ~ P ( C 6 H 5 ) 2 ] R h 2 C £ 2 i . e . C & J i g g C ^ O ^ - ^ R h ^ S i ^ : C, 51.7; H, 4.9; CI, 7.6. Found: C, 48.2; H, 6.3; CI, 9.8. 2-7-8. Reaction of [ ( C H ^ S i - O - j 2Si(CH 3)CH=CH 2 with HC£(g) . A f l a s k with 2 mL of ca. 50% (w/w) s o l u t i o n of the siloxane i n benzene was exposed to HC£(g) i n the manner described above. After 30 min the formation of an insoluble colourless gel was observed. -47-2-8. Reactions of the Polymeric Complexes with H^, CO and HC£(g). 2-8-1. Reactions of Polymeric Complexes with CO i n Toluene Suspension. The reactions were ca r r i e d out i n the apparatus shown i n F i g . 3. The amount of the homopolymeric complexes used was 1.33 x 10 1 mmol and -2 of the copolymeric complex 5.4 x 10 mmol. Each compound was suspended i n 3 mL of toluene i n the f l a s k A at 60°C. The carbon monoxide pressure was 760 mm Hg. The t o t a l gas uptake was measured for each complex a f t e r 3 days. The degree of conversion was calculated by comparison of the observed gas consumption and the expected carbon monoxide uptake value for one molecule of CO for each atom of Rh. Each complex was f i l t e r e d , washed with benzene, and dried i n vacuo. The IR spectra were recorded. The r e s u l t s are presented i n Table V. Table V. Reactions of Polymeric complexes with carbon monoxide i n toluene. Starting Complex,(Symbol) Conversion v(C=0) cm 1 { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 R h C £ } x , ( R 2 _ 0 ) 0.36 1965(s) {[0 3 / 2Si-(CH 2) 8-P.(C 6H 5) 2] 3RhC£} x,(R 8_ 0) 0.40 1965(s) { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C - 6 H 5 ) 2 ] 4 R h 2 C £ 2 } x , ( T 2 _ 0 ) 0.43 1968(B ) , 2080(w) {[0. / oSi-(CH o) o-P(C,H.).]-RhCA.[0 Si-CH 1 } 0.91 1968(s), 1995(s), 3/2 2 2 6 5 2 3 3/2 3 75 x 2080(m) ( R ? _ 7 S ) 100 a 1965(s), 1995(B ) , 2080(m) a: reaction at 70°C. 2-8-2. Reactions of the Polymeric Complexes with CO i n the Absence of any  Solvent. The procedure described below as applied to both the complexes subjected to the test. -48-The polymeric complex { [ 0 3 ^ 2 S i - ( C H 2 ) - P ( C 6 H 5 ) 3 ] R h C U x (0.140 g, 0.15 mmol) was weighed out into a 5 mL round bottom f l a s k , which i n turn was connected to the gas uptake apparatus (Fig. 3) v i a the s p i r a l at the point Q. The complex was degassed and CO was introduced into the system (760 mm Hg pressure). The procedure was repeated twice. The complex remained exposed to the CO atmosphere for 3 days a f t e r which time a sample was removed for IR analysis. The f l a s k with the remaining complex was reweighed and then evacuated for 24h. After t h i s time i t was weighed again and an IR spectrum of the complex was recorded. The degree of conversion was calculated by comparison of the weight gain with the value predicted for consumption of 1 molecule of CO per each atom of Rh. The r e s u l t s are presented i n Table VI. Table VI. Reactions of Polymeric Complexes with Carbon Monoxide without any solvent Starting Before Evacuation After Evacuation Complex v(C=0) Conversion V(CEO) Conversion (Symbol) cm~l cm~l {[0„ / oSi-(CH o) o-P(C,H q) o]„RhCii} (R„ n) 1970(b,vs) 0.27 1970(b,vs) 0.25 3 / 2 2 2 6 5 2 3 x 2-0 2 0 8 0 ( m ) 2 0 8 0 ( m ) { [0 ,„Si- (CH„)„-P (C,H,-) 9 ], Rh„C£„ } . (T„ n) 1970 (b ,vs) 1.30 1970(b,vs) 0.86 i U 1 1 6 ^ Z 4 Z z x z U 2 0 8 0 ( m ) 2080(m) 2-8-3. Reactions of { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 R h C £ . ( 0 3 / 2 S i - C H 3 ) 7 5 > x and U 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 R h C £ } x with H 2 i n toluene suspension. The apparatus shown i n F i g . 3 was used for monitoring the gas uptake. % reacted 100 T 80 -50-The reactions were c a r r i e d out with 0.124 g (1.33 x 10 mmol) of the {[0. / 0Si-(CH 0) 0-P(C,H c)„] 0RhCU and 0.269 g (4.5 x 10~ 2 mmol) of 3/ Z z z O J Z J x . . -{[0 3^ 2Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£.[0 3 / 2S±-CH 3] ^.The a i r s e n s i t i v e homopolymeric complex was weighed out into a bucket i n the f l a s k A under oxygen-free con-d i t i o n s . The copolymer complex was weighed out i n the a i r . Each compound was suspended i n 3 mL of toluene at 60°C. The hydrogen pressure was 690 mm Hg. The gas uptake was monitored according to the pro-cedure described e a r l i e r . A f t e r the reaction was stopped the complexes were f i l t e r e d , washed with benzene, and dried i n a stream of nitrogen for 2h. The IR spectra of the products were recorded. The gas uptake r e s u l t s are reported i n F i g . 5. No peaks i n the IR v(Rh-H) region were observed for either of the products. 2-8-4. Reaction of {[0„ / 0Si-(CH„)„-P(C,H J„] oRhCJ0 with H_ i n the Absence 3/z Z Z o D Z _> x Z of any Solvent. The complex (0.140 g, 0.15 mmol) was weighed out into a 5 mL round bottom f l a s k which was then connected v i a the glass s p i r a l to the gas uptake apparatus (Fig. 3) at the point Q. The contents of the f l a s k were degassed and subsequently flushed with H 2 three times. The complex was exposed to an atmosphere of H 2 for 3 days a f t e r which time an IR spectrum showed no peak i n the v(Rh-H) region. 2-8-5. Reaction of the Polymeric Complexes with HCA(g) i n Toluene Suspension. The modified version of the gas uptake apparatus i n F i g . 3 was used. In the experiments 0.269 g (4.5 x 10~ 2 mmol) of {[0 3 / 2Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£-( 0 3 / 2 S i C H 3 ) 7 5 > x or 0.124 g (1.33 x 1 0 _ 1 mmol) of { [ 0 3 / 2 S i - ( C H 2 ) 2 ~ P ( C ^ ) 2 ] 3 ~ RhC£} and 3 mL of toluene were used. The gas pressure was 760 mm Hg and the -51-temperature 60°C. The solvent and the complex were degassed i n the usual manner. However, a f t e r the bucket containing the complex was dropped into the solvent instead of gas consumption rapid gas evolution persisted for 3h. No net gas absorption was observed at any time. The polymer was f i l t e r e d o f f , washed with benzene and dried i n the stream of N 2 for 2h and f i n a l l y i n the stream of HC£(g) for ca,. 1 min. The IR spectra did not show any noticable increase of the v(Rh-C£) or v(Rh-H) peak i n t e n s i t i e s . 2-8-6. Reaction of {[0 o,„Si-(CH„)„-P(C,H.)_]„RhC£} with HC£(g) i n the 51 Z Z Z O 3 Z 3 X Absence of Solvent. The complex (0.140 g, 0.15 mmol) was weighed out into a 5 mL round bottom f l a s k which was then connected v i a the glass s p i r a l to the modified gas uptake apparatus(Fig. 3). The contents of the f l a s k were degassed and subsequently flushed with HC£(g) three times. The complex was exposed to the atmosphere of HC£(g) for 3 days a f t e r which time the f l a s k was reweighed and an IR spectrum of the polymer was recorded. The f l a s k was weighed evacuated for 24h, and reweighed. The IR spectrum of the polymer was recorded. The observed uptake of HC£(g) was compared with the value predicted f o r absorption of 1 molecule of HC£(g),per atom of Rh. Before pumping: 2.23 of the predicted HC£(g) absorption; no s i g n i f i c a n t increase i n v(Rh-C£) and no appearance of v(Rh-H). After evacuation: 2.17 of the predicted HC£(g) absorption; no change i n the IR spectrum. 2-9. Hydrogenation of Olefins with Soluble Complexes. The reactions were c a r r i e d out i n the gas uptake apparatus shown i n F i g . 3, at 35°C, and 760 mm Hg hydrogen pressure, i n the usual manner. _3 The complex (3.0 x 10 mmol, based on Rh(I) atoms) and styrene % reacted 100 T hours F i g u r e 6. Hydrogenation of styrene i n benzene i n the presence of s o l u b l e complexes H and J . Reaction c o n d i t i o n s ; temp. 35°C; 3 mL benzene; 3.0x10-3 mmol of complex as Rh(I); 3 . 0 x l 0 - 1 mmol of styrene. O H; • J . -53--2 -1 (3.1 x 10 g, 3.0 x 10 mmol) were dissolved i n 3 mL of benzene. Percent conversion as a function of time i s shown i n F i g . 6. 2-10. Hydrogenation of Olefins with Polymeric Complexes. A l l reactions were ca r r i e d out i n the apparatus shown i n F i g . 4, according to the procedure described e a r l i e r . Samples of each c a t a l y s t used i n d i f f e r e n t experiments were taken from the same synthetic batch. 2-10-1. Hydrogenation of Various Olefins with {[0. ,.Si-(CH 0)„-P(C,H C)„] 3/ Z Z Z o 3 Z 3 RhCA.(0, / oSi-CH Q)__} . 3/Z 3 / 5 x In the experiments summarized i n Table VII the o l e f i n (3 mmol) i n benzene sol u t i o n (3 mL) was s t i r r e d with 0.0793 g (1.33 x 10 mmol, based on the number of Rh(I) atoms) of the polymeric ca t a l y s t i n an atmosphere of H£. The temperature was maintained at 25°C. The reaction was stopped a f t e r 23h, and the r e s u l t i n g s o l u t i o n was investigated by GLC. The products were i d e n t i f i e d by comparing the retention times with those of authentic samples. The r e s u l t s are given i n Table VII. Table VII. Hydrogenation of d i f f e r e n t o l e f i n s ' i n the presence of {[03 / 2Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£.(0 3 / 2Si-CH 3 ) 7 5 r , R ^ Substrate Conversion Y i e l d of Y i e l d of isomerization % saturated product product % 7 cyclohexene 8.1 8.1 styrene 88.5 88.5 1-heptene 86.4 46.3 40.1 1-octene 88.8 42.9 45.9 -54-2-10-2. Hydrogenation of Styrene with { [0 3 / 2Si-(CH 2) 2-P(.C 6H 5) 2] 3RhC£. (0„ ,_Si-CH_)-,,-} i n Dif f e r e n t Solvents. 3/2 3 /5 x  Styrene (0.312 g, 3.0 mmol) i n benzene s o l u t i o n (3 mL) was s t i r r e d -2 with 0.179 g (3.0 x 10 mmol) of the catalyst i n an atmosphere of H,,. The temperature was maintained at 35°C. Five d i f f e r e n t solvent systems were tested. The reaction was stopped a f t e r 23h. The r e s u l t s are summarized i n Table VIII. Table VIII. E f f e c t of d i f f e r e n t solvents on the ca t a l y s t R 2 ^ used i n hydrogenation of styrene. Colour of the catalyst, R 2 Solvent system a f t e r the reaction benzene l i g h t orange toluene l i g h t orange b e n z e n e / N ( C 2 H 5 ) 3 ^ grey b e n z e n e / e t h a n o l g r e y ethanol b l a c k ^ (a) i n i t i a l l y l i g h t orange; (b) 3.0 x 10 mole of N ( C 2 H 5 ) 3 i n 3 mL batch; (c) 50:50. (d) blackened immediately a f t e r the addition of the solvent. 2-10-3. Hydrogenation of Styrene with { [ O ^ S i - ( C H 2 ) 2 ~ P ( C g H 5 ) 2 ] 3 R h C & . (°3/2Si-CH3) 75} at 35° and 60°C. Styrene (0.312 g, 3.0 mmol) i n toluene s o l u t i o n (3 mL) was s t i r r e d with -2 the c a t a l y s t (0.179 g, 3.0 x 10 mmol). The progress of the reactions at 35°C and at 60°C were followed. The data are given i n F i g . 7. % reacted 0 5 10 15 20 hours Figure 7. Hydrogenation of styrene i n toluene w i t h R 2-75 a s a f u n c t i o n of temperature. Reaction c o n d i t i o n s : toluene 3 mL; styrene 3.0 mmol; R2-75 3 . 0 x l 0 - 2 mmol. Temperature: O 35°C, and • 60°C. no. moles X 10 reacted 40 1 30 4 h o u r s gure 8. Hydrogenation of styrene with R-2-75 i n benzene at d i f f e r e n t styrene concentrations. Reaction conditions: temp. 35°C; benzene 4 mL; amount of Rh(I) 4.00xl0 - 2 mmol. Amount of styrene: • 3.0xl 0 _ 1 mmol, • 1.0 mmol, • . 3.0 mmol, O 10.0 mmol, ( i . e . Styrene/Rh(I)=7.5,25,75, and 250). no. moles X 10 hours Figure 9. Hydrogenation of styrene i n benzene with d i f f e r e n t amounts of the cat a l y s t R-2-75- Reaction conditions, temp. 35°C. [Styrene]=0.75M; amount of Rh(I) i n the 4 mL solution: • 4.00x10"^ mmol;D 8.00x10"^ mmol; # 1.33xl0~ 2 mmol; O 4.00xl0 - 2 mmol, ( i . e . styrene/Rh(I)= 750,375,225, and 75). -58-2-10-4. Hydrogenation of Styrene with { [ O ^ S i - ( C H 2 ) 2 ~ P ( C ^ ) 2] 3RhC£.-(0„ / 0Si-CH 0)-, c} at Di f f e r e n t O l e f i n and Catalyst Concentrations. 3/2 I 75 x  Styrene i n benzene sol u t i o n (4 mL) was s t i r r e d with the c a t a l y s t at 35°, i n an atmosphere of H,,. In one series of experiments the con-centration of styrene was changed while the amount of the c a t a l y s t suspended i n the reaction s o l u t i o n was maintained constant. In the other series of experiments the concentration of styrene remained constant and the amount of the c a t a l y s t introduced into the 4 mL of the sol u t i o n was varied. The r e s u l t s are summarized i n Figs. 8 and 9. 2-10-5. Hydrogenation of Styrene with D i f f e r e n t Polymeric Complexes of Rh(.I) -2 In each reaction 3.0 x 10 mmol (based on the number of Rh(I) atoms) of the appropriate ca t a l y s t was suspended i n 3 mL of a s o l u t i o n of styrene (0.312 g, 3.0 mmol) i n benzene. The reaction temperature was 35°C. Every c a t a l y s t was recycled a few times. I t was f i l t e r e d o f f , washed with benzene, and dried i n vacuo i n between cycles. A l l the manipulations were done i n an oxygen-free atmosphere. The colour of the reaction s o l u t i o n was noted a f t e r each run. The data are presented i n Figs. 10-19 and Table IX. f 1 1 1 r 0 5 10 15 20 hours Figure 10. F i r s t c y c l e of hydrogenation of styrene i n benzene w i t h d i f f e r e n t polymers. Reaction c o n d i t i o n s : temp.35°C; benzene 3 mL; styrene 3.0 mmol; c a t a l y s t as Rh(I) 3.0x10 mmol. • R 8-100' ' R8-0' •:D .R 2_ 7 5; • R2-0; .A T2-200^ > T 2 - o -% reacted 0 5 10 15 20 25 hours Figure 11. R2_Q.Reaction conditions as i n F i g . 10. Cycles: • 1st; O" A 3rd; . A 4th; • 5 t h . % reacted 0 5 1 0 1 5 2 0 2 5 hours Figure 12. Rs-f j* Reaction c o n d i t i o n s as i n F i g . 10. Cycles: • 1 s t ; O .'2nd; • 3rd; A 4th; • 5th; • 6th; X 1 s t , c a t a l y s t s t i r r e d i n benzene under H 2 f o r 24 h, > p r i o r to i n j e c t i o n of styrene. % reacted 100 1 hours Figure 13. T2_Q.Reaction conditions as i n F i g , 10. Cycles: • 1st; O 2nd; A 3rd. % reacted 100 -i 80 A hours Figure 14. S. Reaction c o n d i t i o n s as i n F i g . 10. Cycles: • 1st; O 2nd; A 3rd; A 4 t h ; • 5th. % reacted 100 i hours Figure 15. R 2_75. Reaction conditions as i n F i g . 10. Cycles: • 1st- O 2nd* A 3rd; A 4th; • 5th. % reacted 100 , hours Figure 16. R2-150* Reaction c o n d i t i o n s as i n F i g . 10. Cycles: # 1 O 2nd; A 3rd; A 4th; • 5th. % reacted 100T A 3rd; A 4th; • 5th. % reacted hours Figure 18. R8-100* Reaction conditions as i n F i g . 10. Cycles: • 1 O .2nd; A 3rd; A 4th. % reacted 100 -80 hours Figure 19. T2_2Q0- Reaction c o n d i t i o n s as i n F i g . 10. Cycles: • 1 s t ; O 2nd; A 3rd. -69-Table IX. Colour of the f i l t r a t e upon r e c y c l i n g the c a t a l y s t . Catalyst R 2-0 R/ 8-0 "2-0 2-75 2-150 2-200 R 8-100 1st 2nd very pale orange Cycle 3rd 4th pale orange very pale orange very pale orange very pale orange 5th strong orange pale orange orange strong orange s trong orange 6th strong orange 2-200 2-10-6. Hydrogenation of Styrene with { [0„ ,„Si- (CH„) „-P(C^H,-) J 0RhC£} Exposed 511 Z Z O 3 Z 5 X to A i r Upon Recycling. The reactions were c a r r i e d out i n 3 mL benzene solutions i n the usual manner with the exception that the c a t a l y s t was f i l t e r e d o ff and dried between cycles as usual but was exposed to a i r for about l h before being used i n the next cycle. The r e s u l t s are shown i n F i g . 20. % r e a c t e d 100 % r e a c t e d hours Figure 21. R2-0* ^ e e^^ect °f t n e s o l u t i o n volume i n the f i r s t c y c l e . Reaction c o n d i t i o n s as i n F i g . 10; the amounts of styrene and c a t a l y s t are p r o p o r t i o n a l to the volume. S o l u t i o n volume: • 3 mL; A 9 mL; A 12 mL. % reacted 100 -\ hours Figure 22. ^2-0' a s ^ i g . 21. Second c y c l e . S o l u t i o n volume: • 3 mL; O 6 mL. % reacted 100 T 80 i hou r s Figure 24. S, as i n F i g . 21. F i r s t c y c l e . S o l u t i o n volume: #3 mL; A 9 mL; A 12 mL. % r e a c t e d 100 .. 80 4 hours Figure 25. S, as i n F i g . 21. Second c y c l e . S o l u t i o n volume:A 9 mL; • -3 mL. % reacted 100 T 80 A 60 \ 40 20 0 hours Figure 26. S, as i n F i g . 21. Third c y c l e . S o l u t i o n volume: • 3 mL; O 7 mL. % reacted 100 , 80 4 60 40 20 1 1 1 1 1 0 5 10 15 20 h o u r s Figure 27. T2-200' a s ^i-S- 21. F i r s t c y c l e . S o l u t i o n volume: • 3 mL, O 6 mL. % reacted 100 i 80 4 % reacted 100 -i hours Figure 29. T2-200> a s i n F i S * 2 1 • Third c y c l e . S o l u t i o n volume: • 3 mL; O 6 mL. % reacted 100 -. 80 -60 -40 -20 4 0 0 5 10 15 20 25 hours Figure 30. Hydrogenation of cyclohexene i n benzene w i t h R2-0* Reaction c o n d i t i o n s temp. 35°C; benzene 3 mL; Rh(I) 3 . 0 x l 0 - 2 mmol; cyclohexene 3.0 mmol. Cycles: • 1 s t ; O 2nd. % re a c t e d 50 i hours Figure 31. The e f f e c t of the s o l u t i o n volume i n the f i r s t c y c l e of hydrogenation cyclohexene^ 1 Conditions as i n F i g . 30; the amounts of cyclohexene and the c a t a l y s t p r o p o r t i o n a l to the volume. S o l u t i o n volume: • 3 mL; • 9 mL; A 12 mL. hours Figure 32. As i n F i g . 31. Second c y c l e . S o l u t i o n volume: • 3 mL; A 9 mL. -83-2-10-7. Hydrogenation of Styrene i n Solutions of D i f f e r e n t Volumes. Styrene was hydrogenated i n the presence of three d i f f e r e n t c a t a l y s t s R2-0 = a 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 R h C £ } x S : { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 7 R h C U x T2-200 : { [ S / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 4 R h 2 C £ 2 - ( 0 3 / 2 S 1 - C H 3 ) 2 0 0 } x i n the same manner as i n the experiments described immediately above except that the volume of the reaction s o l u t i o n was varied from 3 to 12 mL. The amount of the c a t a l y s t (as Rh(I) atoms) was varied i n pro-portion to the volume of the reaction s o l u t i o n . The r e s u l t s are summarized i n Figs. 21-29. -2-10-8. Hydrogenation of Cyclohexene with {[0 3^ 2Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£> x. These reactions were also c a r r i e d out at 35°C i n the apparatus shown _2 i n F i g . 3, using the usual procedure. In a t y p i c a l run 0.028 g (3.0 x 10 mmol) of the ca t a l y s t was s t i r r e d with 0.246 g (3.0 mmol) of cyclohexene i n benzene s o l u t i o n (3 mL). The volume of the s o l u t i o n was varied from 3 mL to 12 mL and the amounts of the c a t a l y s t and cyclohexene were varied i n proportion to the volume of the reaction s o l u t i o n . The percent conversion vs time was recorded and the data are presented i n Figs. 30-32. 2-11. Electron Microscope Studies. A sample of the f r e s h l y prepared complex R2_y^ ,,{ [0.^ 2Si-(CH 2) 2 ~ P(C,H C) „] „RhC£. [0. ,„Si-GH0] } and a sample of the complex from the same D J Z J i l l J o x batch which had been used i n a hydrogenation reaction (benzene/ethanol as a solvent) were examined using an electron microscope. The samples were subjected to the electron beam of power from 2.5 to 20 kV. The magnifications Figure 33. Secondary image E M micrographs of polymer R2-75-(a) before hydrogenation,beam power 5 kV, m a g n i f i c a t i o n 2205(b): a f t e r hydrogenation, 5 kV, magn. 440. -85-i 1 9.1 ym ure 34. E M micrographs of R-2-75 ( a ) : b e f o r e , 5 kV, magn. 1100; (b): a f t e r hydrogenation, 5 kV, magn. 1100. -86-« 1 9.1 ym Figure 35. E M micrographs of R2-75- (a) befo r e , 5 kV, magn. 2200; (b) a f t e r hydrogenation, 5 kV, magn. 1100. -87-i ' 2.3 p Figure 36. E M micrographs of R2-75 a f t e r hydrogenation. (a) beam power 5 kV, magn. 1100; (b) 10 kV, magn. 4400. Figure 37. E M micrograph of R-2-75 a f t e r hydrogenation, 20 kV, magn. 11,200. -89-achieved varied from 220'to Tl,200 f o l d . Samples which were used for micrographs showing the surface of the polymer beads were prepared i n the following way. A few beads were deposited on an aluminum specimen stub which had been coated with a c o l l o i d a l dispersion of graphite i n isopropyl alcohol. Then the s;pubwas placed i n a vacuum carbon evaporator where i t s surface was covered with a t h i n layer of graphite. Samples which were used for taking micrographs showing the cross-section of the polymer beads were embedded i n Spurr Low-Viscosity Epoxy 73 Embedding Medium . The t i p of the epoxy cone containing the polymer beads was shaved off so that the cross sections of the beads could be examined. The reproductions of the micrographs are shown i n Figs. 33-37~. -90-CHAPTER 3  DISCUSSION 3-1. Syntheses and I d e n t i f i c a t i o n of the Ligands and t h e i r Soluble Complexes. The compounds of main i n t e r e s t i n t h i s work are c h l o r o t r i s p h o s p h i n e -rhodium and di-u-chlorotetrakisphosphinedirhodium where the phosphines are Cl2(ClLj)Si-(CH2)2~P(CgH^2, C J ^ S i - ( C H 2 ) n - P ( C g ^ ) 2 (n=2,8) and [ ( C H 3 ) S i - 0 - ] 2 ( C H 3 ) S i - ( C H 2 ) 2 - P ( C g H 5 ) 2 . The syntheses of (NBD)chloro(phos-phine)rhodium and carbonylchlorobisphosphinerhodium w i t h some of these l i g a n d s are a l s o described. The c h l o r o s i l y l p h o s p h i n e s were chosen so that t h e i r complexes could be polymerized and the siloxyphosphine was chosen so that i t would have s t e r i c and e l e c t r o n i c p r o p e r t i e s s i m i l a r to those of the polymeric s i l o x a n e analogues. 3-1-1. Pr e p a r a t i o n of V i n y l Siloxanes. The s y n t h e s i s of 1,1,1,3,5,5,5-hepta m e t h y l - 3 - v i n y l t r i s i l o x a n e reported 72 i n the l i t e r a t u r e i s achieved by c o h y d r o l y s i s of t r i m e t h y l c h l o r o s i l a n e w i t h d i e t h o x y m e t h y l v i n y l s i l a n e . The pr e p a r a t i o n i n v o l v e s the a d d i t i o n of water i n two stages and heating at three d i f f e r e n t temperatures. I n t h i s work, i n order to s i m p l i f y the procedure, the compound i s prepared by co-h y d r o l y s i s of two c h l o r o s i l a n e s i n a l a r g e excess of water, eq. (5); HO (CH 2=CH)Si(CH 3)C2, 2+ 2CJlSi(CH 3) 3 a* > ( C H 3 ) 3 S i - 0 - S i ( C H 3 ) (CH=CH 2)0-Si(CH 3) 3 + ( C H ^ S i - O - S i C C H ^ (5) + ( C H 3 ) 3 S i - 0 - [ S i ( C H 3 ) ( C H = C H 2 ) ] 3 - 0 - S i ( C H 3 ) 3 + higher polymers the temperature of t h i s h i g h l y exothermic r e a c t i o n has to be c o n t r o l l e d only during the a d d i t i o n of the s i l a n e s to water. -91-The d e s i r e d product, l , l , l , 3 , 5 , 5 , 5 - h e p t a m e t h y l - 3 - v i n y l t r i s i l o x a n e was obtained i n 27.5% y i e l d . The other products are as i n d i c a t e d i n equation (5). A l l three v o l a t i l e f r a c t i o n s can be i s o l a t e d by d i s t i l l a t i o n and were i d e n t i f i e d by t h e i r 4 NMR and mass s p e c t r a , and C and H m i c r o a n a l y s i s . The n o n - v o l a t i l e higher polymeric f r a c t i o n s were not c h a r a c t e r i z e d . The m i c r o a n a l y t i c a l data agree w e l l w i t h the c a l c u l a t e d values. Parent peaks i n mass spec t r a correspond w i t h the molecular weights of the compounds; no peaks at m/e values higher than those corresponding to the parent i o n M + are present. The 4 NMR spectrum of 1,1,1,3,3,3-hexa-me t h y l d i s i l o x a n e shows only one s i n g l e peak at 0.076, i n the r e g i o n c h a r a c t e r i s t i c of si l i c o n - m e t h y l groups. The 4 NMR sp e c t r a of both the v i n y l s i l o x a n e s are almost i d e n t i c a l , the only d i f f e r e n c e being, as expected, the r e l a t i v e proportions of the peak areas a s s o c i a t e d w i t h the p a r t i c u l a r groups. The two s i n g l e t s at 0.10 and 0.126 are a t t r i b u t e d to the SiCCH^)^ and SiCCH^) moieties r e s p e c t i v e l y . The unresolved m u l t i p l e t centered at 5.96 i s assigned to the v i n y l protons. I t i s of i n t e r e s t that the v o l a t i l e f r a c t i o n s ( C H 3 ) 3 S i - 0 - [ S i ( C H 3 ) -(CH=CH 2)] n-0-Si(CH 3) 3 c o n t a i n only two compounds w i t h n=l and 3; no compound w i t h n=2 i s produced. 3-1-2. P r e p a r a t i o n of the Phosphines. A general method f o r the prep a r a t i o n of phosphines w i t h d i f f e r e n t r a d i c a l s i s the a d d i t i o n of compounds w i t h phosphorus-hydrogen bonds to molecules c o n t a i n i n g carbon-carbon double bonds. Such r e a c t i o n s can be 74 ,. ,. , , ,75,76 , e i t h e r base or f r e e - r a d i c a l - c a t a l y z e d (eq.6) R 2PH + CH2=CH-R" -> R2P-CH2-CH2-R" (6) -92-A number of silylalkylphosphines have been synthesized by uv l i g h t 28" 77 induced addition of secondary phosphines to o i - alkenylsilanes ' The products always contain phosphorus attached to the terminal carbon atom as i n eq. (6). . In th i s work the uv-induced reactions between diphenylphosphine and different v i n y l - and octenylsilanes are described (eq. (7)). The com-28 7 7 pounds Ci> Si-(CH 0) -P(C,HC)„ (n=2,8) have been previously reported ' . 3 / n o J Z the others are new. uv (C 6H 5) 2PH + R | R 2 ' S i - ( C H 2 ) 2 - C H = CH2 > (7) > R ' R " S i - ( C H 0 ) - P ( C , H c ) 0 1 2 . 2 n 6 5 2 A: R' and R" = CH 3 > n = 2 B: R' = CH3, R" = 0-Si(CH 3) 3, n = 2 C: R' = CH3, R"-CSL, n = 2 D: R' and R" = CI, n = 2 E: R' and R" = CH, n=8 A l l the spectral and other a n a l y t i c a l data show that the products obtained are pure and contain phosphorus attached to the terminal carbon atom. Microanalytical data for C and H, and for CI where applicable agree well with the calculated values. The parent peaks i n the mass spectra correspond with the appropriate molecular weights; no peaks of m/e values + 1 3 1 higher than those calculated for the parent ion M are found. The { H} P NMR spectra of each phosphine contain only one single peak i n the region +9 to +16 ppm upfield from 80% ^ P O ^ . The lack of any peaks due to CH-CH3 moieties i n the 4 NMR spectra confirms the addition of phosphorus to the -93-terminal carbon atom. The aromatic resonances due to the phenyl groups are i n the region 7.36 to 7.456 for a l l the phosphines. The spectra of t r i m e t h y l s i l y l -and methyldichlorosilylphosphines A and C show sing l e resonances for the Si-CH 3 groups at 0.14 and 0.836 res p e c t i v e l y . The two d i f f e r e n t types of methyl groups i n the siloxyphosphine B are responsible for two d i f f e r e n t s i n g l e peaks at 0.08 and 0.116 with r e l a t i v e i n t e n s i t i e s 1:6, for Si-(CH 3) and Si(CH 3> 3 r e s p e c t i v e l y . In the NMR spectrum of B there are two unresolved m u l t i p l e t s of equal i n t e n s i t y which can be assigned to the -Ct^-CH^-moiety. A p a r t i a l l y 31 P decoupled spectrum shows a noticeable d i f f e r e n c e i n the pattern of the m u l t i p l e t centered at 0.606. The m u l t i p l e t centered at 2.096 i s not affected. I t has been r e p o r t e d 7 8 ' 7 9 that J(P_-C-C-H) i s greater than J(P_-C-H). Thus the m u l t i p l e t centered at 0.606 can be a t t r i b u t e d to Si-CH 2- protonsand the one at 2.096 to the P-CH^. The spectra of a l l the other phosphines show two m u l t i p l e t s due to the Si-(CH 2) n-P protons i n the region 0.60 to 2.486. The m u l t i p l e t at higher f i e l d i s a t t r i b u t e d to the S i - ( C H 2 ) n ~ group and that at lower f i e l d to the P-CH2- protons- on the basis of the assignment made for the siloxyphosphine. 3-1-3. Preparation of the Soluble Complexes. Phosphine complexes of Rh(I) are generally prepared by ligand exchange methods where the square-planar symmetry around the metal atom i n the s t a r t i n g compounds i s preserved i n the product. In t h i s work the s i l o x y -and chlorosilylphosphine complexes of general formulae (NBD)RhPC£, P 2Rh(C0)C£, P 3RhC£ and P^Rt^Ci,, were synthesized using these well established procedures. Norbornadienechlorophosphinerhodium complexes -94-80 are prepared i n a r e a c t i o n between stoicheometric amounts of (NBD)2Rh2C£2 and var i o u s l i g a n d s (eq. ( 8 ) ) . II c i I K , | | c i ^ R / \ h / ) + 2L 2 ( R / (8) / \ / v V\ The product of t h i s b r i d g e - s p l i t t i n g r e a c t i o n contains the new l i g a n d L and C£ i n c i s p o s i t i o n s . In the pre p a r a t i o n of the w e l l known V a l l a r i n o complex, .[(C^E^)^P] -68 Rh(C0)C£ and i t s analogues c o n t a i n i n g other phosphines, the s t a r t i n g m a t e r i a l used i s (CO) 4Rh 2C£ 2 (eq. (9)) OC CI CO L CO \ r / + A L — > 2 \ / <9> / \ / \ / \ OC CI CO CI L JL Here the r e a c t i o n product j5 i s of t r a n s - c o n f i g u r a t i o n and the analogues 81 82 of the Wil k i n s o n complex [ (C^H^J^P]^RhCJl can be prepared i n a s i m i l a r b r i d g e - s p l i t t i n g r e a c t i o n using (C^H^) 4Rh 2C£ 2 as the s t a r t i n g compound (eq. (10)). Rh Rh + 6L » 2 Rh ( 1 0 ) When the lig a n d / e t h y l e n e complex r a t i o i s maintained at 4:1 the c h l o r i n e 82 bridge i s r e t a i n e d (eq. (11)). -95-Rh Rh + Ul —> Rh Rh / \ / \ / \ / \ Since the new phosphine l i g a n d s used i n t h i s work are r e l a t i v e l y bulky t h e i r c o o r d i n a t i n g p r o p e r t i e s were t e s t e d by f i r s t attempting the synthesis of { [ ( C H ^ S i - O - ] 2 (CH 3) Si-(CH^-P(C^) 2}Rh(NBD)C£ complex, F. When t h i s was s u c c e s s f u l l y accomplished s i l o x y - and c h l o r o s i l y l p h o s p h i n e complexes {[(CH 3) 3Si-0-] 2(CH 3)Si-(CH 2) 2-P(C 6H 5) 2} 2Rh(CO)C£, G, [C£ 3Si-(CH 2) 2-P(C 6H 5) ]2Rh(CO)C£, K, {[CH 3) 3Si-0-] 2(CH 3)Si-(CH 2) 2-P(C 6H 5) 2} 3RhC£, H, [C£ 3Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£, L, [C£ 3Si-(CH 2) g-P(C 6H 5) 2] 3RhC£, M, { [ ( C H 3 ) 3 S i - 0 - ] 2 ( C H 3 ) S i - ( C H 2 ) 2 - P ( C f i H 5 ) 2 > 4Rh 2C£ 2 J , and [C£ 3Si-(CH 2) 2-P(C 6H 5) 2] 4Rh 2C£ 2, N were synthesized according to the equations ( 9 ) , (10), and (11). The c h l o r o s i l y l p h o s p h i n e complexes thus formed are the precursors f o r the polymeric s i l o x a n e complexes. The siloxyphosphine complexes serve as prototype study models f o r t h e i r polymeric counterparts. I t i s found that the c h l o r o s i l y l p h o s p h i n e complexes become i n s o l u b l e a f t er evaporation of the r e a c t i o n s o l v e n t . This i s most l i k e l y due to a small degree of p o l y m e r i z a t i o n i n the presence of tra c e s of moisture. Consequently, i n order that the NMR spec t r a could be recorded immediately a f t e r formation of the complexes, the preparations have to be c a r r i e d out i n deuterobenzene. -96-The Siloxyphosphine Complexes The i d e n t i t y of the products was confirmed by microanalysis, mass, 1 31 H NMR, P NMR, and IR spectra. The m i c r o a n a l y t i c a l C, H, and CI r e s u l t s for complexes F and G and r e s u l t s for C, H, CI, P and Fh for the complexes H and J agree well with the calculated values. The parent peaks i n the mass spectra of the f i r s t two compounds, F and G, correspond well with the predicted molecular weight, with no m/e peaks at values higher than M+. The mass spectra could not be recorded for H and J because of t h e i r high molecular weights (>1300). The silicon-methyl region of a l l the 4 NMR spectra i s p o t e n t i a l l y the most informative as to the coordination state around the metal centre since the chemical s h i f t s and the r e l a t i v e i n t e n s i t i e s of the peaks due to Si-CH 3 and S i ( C H 3 ) 3 moieties of the free ligand [ ( C H 3 ) 3 S i - 0 - ] 2 ( C H 3 ) -S i - ^ l ^ ^ - P ^ g H ^ ^ * B, may a l t e r on coordination. In the (NBD)PRhCA complex F the chemical s h i f t s and the area r a t i o of the silcon-methyl peaks i s the same as i n the free phosphine. This i s also found i n the spectrum of the carbonyl complex G where the two trans-phosphlnes are equivalent (structure _9); the peaks are s h i f t e d s l i g h t l y downfield from those of the free phosphine by 0.06 and 0,07 ppm for the Si-CH 3 and S i ( C H 3 ) 3 resonances r e s p e c t i v e l y . The pattern changes for the trisphosphine and tetraphosphine complexes. Complex J has four equivalent phosphines as indicated by the structure 10, hence i t s 4 NMR pattern should also look s i m i l a r to that of the free ligand. Instead only one s i n g l e t i s observed i n the s i l i c o n -methyl region at 0.126. The area of the peak accounts for a l l 42 protons -97-i n the Si-CH^ and SiCCH^)^ groups. In the t r i s p h o s p h i n e complex H the two phosphines trans to each other are chemically i n e q u i v a l e n t to the one trans to C£ as can be seen i n the s t r u c t u r e 9_. For a l l the methyl-phosphine and - a r s i n e Rh(III) complexes RhP^X^ of mer-configuration ( s t r u c t u r e 11) two sets of s i g n a l s of r e l a t i v e i n t e n s i t y 2:1 due to a l s o expected f o r the P^RhCJl complex. The s i l i c o n - m e t h y l r e g i o n has two s i n g l e t s at 0.18 and 0.076 of r e l a t i v e i n t e n s i t i e s 2:1. However, as i n complex J , there i s no d i f f e r e n c e i n the chemical s h i f t s of the Si-CH 3 and S i ( C H 3 ) 3 protons. The phenyl region of the "*"H NMR spectra of the complexes G, H, and J contains two d i s t i n c t m u l t i p l e t s which are separated by 0.6-0.8 ppm, and have r e l a t i v e i n t e n s i t i e s between 1:2 and 2:3. In some i r i d i u m complexes the aromatic resonances due to the triphenylphosphine l i g a n d s a l s o show a s i m i l a r p a t t e r n which has been a t t r i b u t e d to a d i f f e r e n t s h i e l d i n g of ortho phenyl protons^^'^^ compared w i t h meta and para protons. The "4i NMR p a t t e r n i n the complexes synthesized i n t h i s work can a l s o be a t t r i b u t e d to a s i m i l a r phenomenon, although i t i s d i f f i c u l t to account f o r r e l a t i v e areas d i f f e r e n t from a 2:3 r a t i o . In the spectrum of complex F a l l the peaks due to the coordinated siloxyphosphine are X two d i f f e r e n t types of phosphines are t y p i c a l 83 S i m i l a r l y t h i s i s -98-s h i f t e d s l i g h t l y downfield r e l a t i v e to the free ligand, but the pattern i s the same as for the free phosphine. The peaks due to NBD are assigned 1 86 on the basis of the reported H NMR spectrum of (NBD)Rh[P(C,H C) Q]C£. b _> J 1 31 Although the H NMR spectra present s l i g h t ambiguities the P NMR spectra confirm the molecular structures of the complexes as indicated by structures 7-10. A l l three complexes F, G, and J contain phosphines which are chemically equivalent and which give r i s e to one doublet due o Rh-P coupling i n each case. Carbonylchlorobis(triphenylphosphine)-87 rhodium has been reported to show a doublet at -29.5 ppm r e l a t i v e to 80% H 3P0 4, J(Rh-P)=124 Hz. Both the NBD and CO complexes containing the siloxyphosphine show doublets i n t h i s region, at -31.45 and -29.65 ppm with J(Rh-P) of 171.6 and 124.6 Hz r e s p e c t i v e l y . The chemical s h i f t of the doublet i n the spectrum of [ (p-CH^-CgH^^P^Rt^C^ complex changes 82 considerably to -49.5 ppm with J(Rh-P) of 196 Hz. The siloxyphosphine analogue follows the same trend by showing a doublet at -47.02 ppm where J(Rh-P) i s 196.5 Hz. 88 89 It i s known ' that J(M-P) values are larger when the phos-phorus atom i s trans to a ligand with low trans-influencing properties, such as halides, than when i t i s trans to a ligand of higher trans-influence, such as PR^, H, or CO. This i s seen i n the present r e s u l t s where the phosphines which are trans to CI i n the tetraphosphine compound J have higher J(Rh-P) values than i s found i n the carbonyl complex G where the two phosphines are trans to each other. The trisphosphine compound H has two inequivalent types of phosphines which give r i s e to two groups of peaks of d i f f e r e n t chemical s h i f t s and d i f f e r e n t J(Rh-P) values. Thus chlorotris(triphenylphosphine)rhodium shows -99-a double doublet at -32.2 ppm and a double t r i p l e t at -48.9 ppm 82 where J(Rh-P) are 146 and 192 Hz r e s p e c t i v e l y .The double doublet i s a t t r i b u t e d to the phosphines trans to each other and the double t r i p l e t to the phosphine trans to Ci. In the siloxyphosphine complex H the same trend i s followed. The phosphine trans to CI gives a double t r i p l e t at lower field.-44.97 ppm and has a higher coupling constant, J(Rh-P)=188 Hz, than the two phosphines trans to each other which give a double doublet at -29.75 ppm and have J(Rh-P) of 140 Hz. The J(P-P) values for the siloxyphosphine complexes are very s i m i l a r , 39 Hz, to Q O those for the Wilkinson complex [(C,H C)^P]„RhC£ , 37.5 Hz. The 0 5 3 3 J(Rh-P) coupling constants are of the magnitude expected from the discussion i n the previous paragraph. 31 The P NMR spectra of G and H contain a single peak at -29.44 and -29.92 ppm r e s p e c t i v e l y . The presence of a s i n g l e t rather than a doublet indicates that the phosphorus atom i s not bound to rhodium. The 79 chemical s h i f t s of phosphine oxides are known to be considerably downfield from those of the corresponding phosphines. For example the 31 8? P NMR s i g n a l due to (p-CH^CgH^) 3P i s observed 9 at +6.8 ppm r e l a t i v e to 80% HoP0. whereas that of (p-CH„-C,H.)„P=0 occurs at -23.7 3 4 3 6 4 3 ppm. The p o s i t i o n of the s i n g l e t i n the spectra of the aforementioned complexes i s around -30 ppm compared with +9.14 ppm for the free phosphine which strongly suggests that some oxide i s present as an impurity. This i s confirmed by the mass spectrum of the carbonyl complex G which shows a parent peak corresponding to the molecular weight of the complex when the sample probe i s heated to 300°C. However, when no heat i s applied to the probe the presence of a substance with a parent peak at m/e 450 i s -100-observed. This value corresponds to the molecular weight of the phosphine oxide [(CH 3) 3SiO] 2(CH 3)Si-(CH 2) 2~P(C f iH ) 0. It has been f o u n d 9 0 , 9 1 that (C,H c) oP=0 i s produced i n the b j j reactions of [ ( C g H ^ ] RhC£, [ ( C 6 H 5 ) 3 P ] 4 R h 2 C £ 2 , and [ (C ^ ) 3 P ] 2 R h ( C 0 ) C £ 31 with molecular oxygen. Since neither P NMR nor the mass spectra of the free siloxyphosphine B indicate the presence of the phosphine oxide i t i s postulated that the oxide i s formed from the phosphine and traces of molecular oxygen during the preparation of the complexes. The reaction i s catalyzed by some intermediate rhodium species present i n the reaction mixture. The IR carbonyl stretching frequency i n the V a l l a r i n o complex, [(C,H.)„P]„Rh(C0)C£, varies between 1960 and 1970 cm"1 depending upon b _) j z 92 —1 the solvent used . A sing l e strong band at 1968 cm i n the spectrum of compound G indicates the presence of one type of carbonyl group i n the molecule with an environment s i m i l a r to that i n the t r i p h e n y l -phosphine complex. The far IR spectra of the Wilkinson complex, [ (C,H..) _P] „RhC£, and D _> J J 93 —1 [ (CgH,-)3P] 4 R h 2 C £ 2 show a medium i n t e n s i t y band at 296 and 303 cm respectively, a t t r i b u t e d to Rh-C£ stretching frequencies. The s i l o x y -phosphine analogues show medium-weak peaks at 260 and 255 cm 1 respectively. Chlorosilylphosphine Complexes The spectroscopic r e s u l t s for carbonylchlorobis(chlorosilylphosphine)-rhodium K, p a r a l l e l • those for the siloxyphosphine analogue. The IR carbonyl stretching frequency at 1970 cm 1 ( i n C^D^) i s almost i d e n t i c a l -1 31 with that of the siloxyphosphine complex G at 1968 cm . The P NMR chemical s h i f t and the J(Rh-P) values are also very s i m i l a r ; -30,00 ppm -101-Figure 38. P NMR spectrum of the product mixture obtained i n the pr e p a r a t i o n of [ C J ^ S i - ( C H 2 ) 2 ~ P ( C ^ ) 2 ] 3 R h C l , L. -102-and J(Rh-P)=127.5 Hz compared with -29.65 ppm and*J(Rh-P)=124.6 Hz. No peak assignable to a phosphine oxide i s observed. The r e l a t i v e i n t e n s i t i e s of the two downfield m u l t i p l e t s i n the 4 NMR spectrum are 2:3 which suggests, as for the siloxyphosphine analogue, d i f f e r e n t s h i e l d i n g of the ortho protons. The m i c r o a n a l y t i c a l data for C, H, CI, P, and Rh agree well with the calculated values. The mass spectrum, as i s the case for the other chlorosilylphosphine complexes, could not be recorded because of high moisture/air s e n s i t i v i t y of the compound. The m i c r o a n a l y t i c a l r e s u l t s (C, H, CI, P, and Rh) for the other chlorosilylphosphine complexes L, M, and N agree well with the calculated values. However, t h i s i s rather meaningless i n view of the f a c t that the NMR spectra show that a mixture of compounds i s produced. The number and the amount of side products can be decreased i f the reaction vessels are pretreated with CA^Si-CH^.This deactivates-the free OH groups on the glass surface. Thus i t i s l i k e l y that the impurities are produced by the p a r t i a l h ydrolysis, possibly followed by an oxidative addition of the l i b e r a t e d HC£ to the Rh(I) centres. 31 As an example, the P NMR spectrum of the products obtained during the attempted preparation of [C& 3Si-(CH 2)-P(C 6H 5) 2] 3RhC£ i s shown i n Fig.38. It contains a double t r i p l e t 1 and a double doublet 2, with coupling constants J(Rh-P) of 186.8 and 140.4 Hz r e s p e c t i v e l y and J(P-P) about 40 Hz. There are four m u l t i p l e t s , 3 and 4 and 3' and 4' (buried under the big peaks) which could possibly consist of at l e a s t one other set of a double t r i p l e t and a double doublet. (They have a very d e f i n i t e dd and dt pattern, and show a greater i n t e n s i t y i n the spectrum of the batch -103-prepared i n unpretreated glassware). The p r i n c i p l e sets 1 and 2 are probably due to the required complex [CJl^Si-(CE^) 2~P(C^H,-)^\^RhCA s i n c e t h i s p a t t e r n i s to be expected f o r the square planar s t r u c t u r e . However, an analogous p a t t e r n would a l s o be expected from the HC£ adducts which 94 95 have been reported ' to e x i s t i n two of the p o s s i b l e isomeric forms, 12_ and 13. H P P X 12 The 4 NMR spectrum of the same product mixture which gives the 31 P NMR spectrum i n F i g . 38 shows that the hydrido complex i s a minor product and of the two p o s s i b l e s t r u c t u r e s the complex has the s t r u c t u r e 12. The h i g h - f i e l d 4 NMR spectrum has an unresolved m u l t i p l e t at -146 whose s p e c t r a l width i s about 65 Hz. This m u l t i p l e t c o l l a p s e s to a doublet, J(Rh-P)=10 Hz, on phosphorus decoupling which i n d i c a t e s the presence of only one of the two p o s s i b l e HC£ adducts. Compounds of 95 s t r u c t u r e L2 and 13 can be d i f f e r e n t i a t e d by t h e i r J(P-H) v a l u e s , 12 having smaller values (ca. 10-20 Hz) than 13 (ca. 200 Hz). Thus on the b a s i s of the s p e c t r a l width of the hydride proton m u l t i p l e t (65 Hz) s t r u c t u r e 12_ can be assigned f o r the im p u r i t y . The r e l a t i v e areas of the - C ^ - C ^ - s i g n a l s to that of the hydride peak i s f a r greater (ca. 33:1) than 12:1 (expected f o r the pure 1:1 HC£ adduct) which i n d i c a t e s -104-that i t i s the HC£ adduct which i s present i n smaller amounts. The presence of the HC£ adduct i s also seen i n the IR spectrum 96 97 where there i s a band assignable to a Rh-H stretching frequency ' at 2095 cm \ and two weak bands i n the v(Rh-C£) region, at 280 and 260 cm \ Since the M-C£ stretching frequencies are strongly 93 98 99 influenced by the nature of the ligand trans to chlorine ' ' but only s l i g h t l y affected by c i s ligands, a mixture of a P 3RhC£ complex and i t s HC£ adduct ]_2_ could contain two, rather than the expected three v(Rh-C£) bands. The frequencies due to Rh-C£ stretches for C£ trans to P would be very s i m i l a r or the same for the two compounds. The chlorine trans to H i n the P^RhHC^ complex should give r i s e to another band at a s l i g h t l y lower f r e q u e n c y 1 0 0 . ^ v Considering the above argument the v(Rh-C£) at 260 cm 1 i s assigned to C£ trans to H, and the degenerate v(Rh-C£) at 280 cm 1 i s assigned to C£ trans to P i n both the complexes, P 3RhC£ and P 3RhHC£ 2 < The spectra of the products obtained i n the preparation of M and N also indicate that a mixture of compounds i s produced. In the attempted preparation of M the desired complex [C£ 3Si-(CH 2) g-P(C 6H 5) 2] 3RhC£ i s the main product as indicated by the NMR spectra of the product mixture. The presence of v(Rh-H) and v(Rh-C£) IR bands as well as hydride "'"H NMR peaks (spectral width ca. 70 Hz) show that the major impurity i s most l i k e l y also an HC£ adduct with the configuration 12. No one major product i s obtained i n the attempted syntheses of N. Instead a number of compounds i s produced i n roughly the same y i e l d s as 31 indicated by the r e l a t i v e i n t e n s i t i e s of the P NMR peaks. Judging by -105-the presence of hydride peaks i n the """H NMR spectrum and by v(Rh-H) and v(Rh-C£) . IR bands some HC£ adduct(s) are formed. Unfortunately no l i t e r a t u r e reports are known for HCJl adducts of T^Rh^Ci^ complexes and the data obtained i n t h i s work do not give conclusive evidence as to the nature of such species. The h i g h - f i e l d NMR spectrum contains a m u l t i p l e t at about -146 and a double t r i p l e t at -15.726, of r e l a t i v e i n t e n s i t i e s 1:4. The small s p e c t r a l width of the m u l t i p l e t (ca. 40 Hz) and the small J(P-H) value of the dt (18 Hz) i n d i c a t e that both the d i f f e r e n t types of rhodium hydride protons are c i s to P. However, no d e f i n i t e structure can be assigned to the products of t h i s reaction. 3-2. Syntheses of the Polymeric Complexes The objective of the next stage i n the synthetic work was to poly-merize the chlorosilylphosphine complexes i n such a way that the chemical environment around the metal centre would not be changed and the product would have good phy s i c a l properties such as high porosity and mechanical and thermal s t a b i l i t y . As mentioned before, the range of physico-chemical a n a l y t i c a l techniques which can be applied to obtain u s e f u l information about insoluble s o l i d s i s very l i m i t e d . In the case of the polymers synthesized i n t h i s study the only r e a d i l y a v a i l a b l e techniques for c h a r a c t e r i z a t i o n were IR spectroscopy and microanalysis. Unlike chlorotrisphosphinerhodium and di-y-chlorotetrakisphosphinedirhodium the complex [C£ 3Si-(CH 2) 2-P(C 6H 5) 2] 2Rh(CO)C£ contains a very convenient IR detectable, b u i l t - i n probe i n the form of the carbonyl group. The C=0 stretching frequency i s very s e n s i t i v e to changes i n the environment of -106-the ce n t r a l metal atom. For e x a m p l e 9 ^ ' v ( C = 0 ) for t rans-{Rh(C0)C£[P(C„H c)(C,H C)„]„} occurs at 1955-1960 cm"1 and at 2107 cm"1 I D b o l l for trans-{Rh(C0)CJl 3[P(C 2H 5) ( C 6 H 5 ) 2 ] 2 > . Also the carbonyl s t r e t c h i n g 103 frequency changes upon oxidative addition of HBr to trans-{Rh(C0)Br[P(C,H c) o] o} from 1980 to 2055 cm"1, o 5 3 I Because of such v(C=0) s e n s i t i v i t y a few polymerization techniques were t r i e d out with [C£-Si-(CH„)-P(C,H C)„]„Rh(C0)C£ and those which gave a 3 / 6 5 I I polymer of the desired physical and chemical properties were then used l a t e r for the polymerization of other macrocomplexes. 3-2-1. D i f f e r e n t Methods of Polymerization of [ C ^ S i - ( C H Q 2~P (C^H^) Q ] 2 ~ Rh(C0)C£. Hydrolysis of chlorosilanes to hydroxysilanes i s followed instan-taneously by polycondensation with the elimination of water. As discussed i n Section 1-2, the nature of the siloxypolymeric products depends on the properties of the s t a r t i n g chlorosilanes and on the re a c t i o n conditions. Three d i f f e r e n t i n t e r f a c i a l polycondensation techniques used i n polymerizing [ C £ 3 S i - ( C H 2 ) 2 ~ P ( C ^ ) 2 ] 2Rh(C0)C£ give products with s a t i s -factory properties. In a l l the three methods the s t a r t i n g c h l o r o s i l y l -phosphine complex dissolved i n the minimum amount of benzene i s introduced into the hydrolyzing medium. The reaction should proceed according to eq. (12); D+HpO 2)-H 0 [C£ 3Si-(CH 2) 2-P(C 6H 5) 2] 2Rh(C0)C£ > { [ O ^ S i - ( C H 2 ) 2~P ( C ^ ) 2 ] 2Rh-(C0)C£) (12) In two methods which involve base-catalyzed processes the hydrolyzing medium consist of water i n a very large excess. The bases used are N(C 2H^) 3 and KOH(aq). No soluble low-molecular weight polymers are produced since -107-the f i l t r a t e a f t e r the i n i t i a l polymer p r e c i p i t a t i o n as well as the further washings are a l l colourless. Both of the products exhibit a strong IR band at 1965 cm \ The small s h i f t from the v(C=0) at 1970 cm 1 i n the s t a r t i n g chlorosilylphosphine complex can be a t t r i -buted to the d i f f e r e n c e i n the IR sample dispersion media (Nujol vs. C,D, solution) and/or to the remote influence of the Si-O-Si vs. Si-C& o D — groups of the ligands. When pure water i s used as the hydrolyzing medium the reaction i s extremely vigorous. D i l u t i n g the water with some other m i s c i b l e solvent permits more cont r o l ; i n the t h i r d successful polymerization method water mixed with dioxane i s found to be a good hydrolyzing medium. The optimal proportion of dioxane to water i s 4:1 (v/v) and gives high-molecular weight products. The r e a c t i o n i s e f f e c t i v e l y acid-catalyzed since HCJi i s evolved. The insoluble polymer P i s obtained i n good y i e l d and i t s IR carbonyl stretching frequency at 1965 cm 1 indicates that the environment of the metal centre i s not a l t e r e d i n the process of polymerization. The m i c r o a n a l y t i c a l data (C,H,P, and Rh) for the polymer P obtained by hydrolysis i n water/dioxane mixture agree w e l l with the values calculated for the formula {[0. ,_Si-(CH„)„-P(C,H C)_] oRh(C0)C£} . However, the Ci 3/2 2 2 6 5 2 2 x content found (12.3%) i s more than twice that predicted. Since the v i r t u a l l y unchanged IR v(C=0) shows that the Rh(I) centres remain un-affected i t seems that the excess of chlorine detected by microanalysis i s due to three possible f a c t o r s : (a) some interference from other element(s) i n the a n a l y t i c a l measurements, (b) incomplete hydrolysis of the S±-Ci moieties, and/or (c) adsorption of evolved HC& onto the polymer. -108-Interference from S i has to be considered i n p o s s i b i l i t y (a). Total CI content i n the polymer P i s determined i n the following way. The sample i s burnt i n an oxygen f l a s k i n the presence of an absorbent (NaOH and . Then the excess of H^O^ i s destroyed by b o i l i n g 2+ and the phosphorus i s removed by p r e c i p i t a t i o n with Ca (as phosphate or phosphite). Then the s o l u t i o n , a c i d i f i e d with HNO^ and d i l u t e d with acetone, i s t i t r a t e d with AgNO^(aq). There i s the complicating p o s s i -b i l i t y of formation of sodium s i l i c a t e s (during the f i r s t stages of the procedure) which can subsequently c o p r e c i p i t a t e with AgC£ as s i l v e r s i l i c a t e s . A l l s i l v e r s i l i c a t e s are known to have very low s o l u b i l i t y 1 ^ Unfortunately s e l e c t i v e removal of s i l i c a t e s i s not possible, i n the a n a l y t i c a l method described. Since the high CSL content i s found only for the polymeric complexes (see also section 3-2-3) and not for the soluble ones i t i s concluded that the S i interference i s most l i k e l y imposed by the polymeric nature of the siloxane network. Unfortunately no standard compound i s a v a i l a b l e to prove the above t h e s i s . T r i a l and error c a l c u l a t i o n s f or possible products r e s u l t i n g from (b) and (c) ind i c a t e that the chlorine content found for the polymeric carbonyl complex P (12.3%) may correspond with two possible formulae: {[0 3 / 2Si-(CH 2) 2-P(C 6H 5) 2] 2Rh(CO)C£.(HC£) 1 5> x and/or { [ 0 9 / 8 ( C £ 3 / 4 ) S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 2 R h ( C O ) C £ } x . The C, P, and Rh values for these formulae are d i f f e r e n t from those for the o r i g i n a l formula P, {[0 o ,„Si-(CH„)„-P(C,H C)J_Rh(C0)C£} , being low by about 3-4, 5/2 2 2 o D 2 2 x 1, and 1 percent r e s p e c t i v e l y , and thus are s e n s i t i v e to the changes i n C£ content. Since the percentage of C, P, and Rh found agrees well with -109-the formula P i t seems u n l i k e l y that a r e a l increase i n CH content i s encountered. In some other polymers discussed i n the following sections, problems with C analysis are experienced. However, i n those cases the values found are always lower than those expected. Thus i t i s concluded that the formation of not only {[0» , 0Si-(CH„)„-P(C,H C)„]„Rh(C0)C£.(HC£), r} 3/1 1 1 D D I I 1.5 X and {[0 g^ 2(C£ 3 / 4)Si-(CH 2) 2-P(C 6H 5) 2] 2Rh(CO)C£} x, but also of the HCJl oxidative a d d i t i o n product, { [ O ^ S i - (CH 2) 2~P ( C ^ ) 2 ] 2Rh(CO)HC£ 2) x i s u n l i k e l y . Polymerization of CJl^Si-(CH 2) 2~P(C^H^) 2 alone c a r r i e d out i n the same manner as that of the carbonyl complex y i e l d s a polymeric product with C£ content 9.2% which i s higher than expected (0%) for {0„ / 0Si-(CH 0) 0-P(C,H r) 0} . This indicates that the high CI percentage j / l l l b j l ' x . i s not neces s a r i l y due to the reaction of HC£ with Rh(I) centres. It can be concluded on the basis of the above discussion that factor (a) i . e . the interference from other element(s), probably S i , i s most l i k e l y responsible for the high C£ content found for the polymeric complex P, although some degree of (b) and (c) cannot be completely excluded. It should be stressed that no Rh(III) HC£ adduct i s present i n the polymer since no Rh-H and no changed C=0 IR stretching frequencies are observed. 3-2-2. D i f f e r e n t Methods of Polymerization of [CJ^Si-(CH 2) 2~P(CgH^ 2] 3RhC&. A seri e s of homo- and copolymeric complexes was synthesized using the three s a t i s f a c t o r y polymerization methods described above. Since the macrocomplexes were to be used as hydrogenation c a t a l y s t s i t was important to e s t a b l i s h t h e i r s t a b i l i t y to hydrogen. I t has previously been established -110-26 by EM studies that the darkening of the sil i c a - s u p p o r t e d trisphos-phinerhodium(I) complexes during hydrogenation reactions i s a r e s u l t of reduction of Rh(I) to.Rh(O) with the subsequent formation of metal c r y s t a l l i t e s . Therefore, any noticable darkening of the siloxypolymer exposed to hydrogen was taken to be an i n d i c a t i o n of the same process and, i f t h i s happened, the polymerization technique by which the polymer was obtained was not studied further. When the chlorosilylphosphine complex i s h y d r o l y t i c a l l y polymerized and copolymerized with CA^Si-CH^ i n d i f f e r e n t proportions the reaction proceeds according to the general equation (13). D+H 0 2)-H 20 [C£ 3Si-(CH 2) 2-P(C 6H 5) 2] 3RhCJl + mCJ^Si-QL^ (13) > { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 R h C £ . ( 0 3 / 2 S i - C H 3 ) m } x m=0-200; x=large, unspecified. Table I shows the r e s u l t s obtained with the polymers prepared by base-catalyzed, N(C 2H^) 3, hydrolysis. The hydrolyzing medium i s pure water i n a large excess. Most of the products are unstable to hydrogen as judged by the darkening of the polymer. The reaction of the Wilkinson complex, [(C^H^) 3P] 3RhC£, and i t s analogues with hydrogen involves formal oxidative a d d i t i o n to Rh(I) thereby forming Rh(III) . 81,82,105,106 species RhP 3C£ + H 2 > RhH 2P 3C£ (14) Since the darkening of the polymer i s accompanied by the hydrogen uptake which i s greater than calculated for one molecule of H 2 per atom of -111-Rh(I) t h i s reinforces the idea that decomposition to m e t a l l i c rhodium takes place. The r e s u l t s are not always reproduceable as i s found f o r example i n the complex of formula with m=100. For one preparation batch the hydrogen uptake i s almost 1:1 and there i s no di s c o l o u r a t i o n yet a sample from another preparation batch of the same complex darkens and the hydrogen uptake i s more than predicted. The l a r g e l y negative r e s u l t s and the inconsistencies observed lead to the abandonment of t h i s polymerization technique as a v i a b l e method. In a s i m i l a r method KOH(aq) i s used as the c a t a l y t i c base. The re s u l t s obtained for these polymers are summarized i n Table I I . Again, most of the products darken upon exposure to hydrogen and consume more hydrogen than that calculated on the basis of one YL^ per Rh atom. This polymerization technique was also rejected. When the hydrolyzing medium consists of water d i l u t e d with solvents 53 of electron .donating properties , DMF or dioxane without the addition of base or acid c a t a l y s t , polymers are obtained whose properties are summarized i n Table I I I . Although neither of the two products obtained by polymerization i n the DMF/water mixture decompose to m e t a l l i c rhodium the amount of hydrogen consumed i s very small which indicates i n view of eq. (14) that only very few m e t a l l i c centres are a v a i l a b l e for reaction. The small extent of hydrogen reaction i s also indicated by the fac t that the o r i g i n a l orange colour, c h a r a c t e r i s t i c of Rh(I) species, does not become yellow, t y p i c a l for Rh(III) species. When a water/dioxane mixture i s used as the hydrolyzing medium the products have s a t i s f a c t o r y properties. As can be seen i n Table I I I . none of the polymers darken upon exposure to hydrogen, a l l of them change -112-colour from orange to yel l o w , and the amount of hydrogen consumed does not exceed the maximum expected value. The general trend i s that the amount of hydrogen taken up increases w i t h the content of the copoly-meric component O^^SiCH^. When m=0 the observed hydrogen uptake i s only 0.27 of the a n t i c i p a t e d amount; f o r m=50 i t i s 0.75; and when m=200 i t i s 100%. The s y n t h e s i s of the polymer w i t h m=100 was repeated but the hydrogen uptake values vary over a wide range (Table I I I ) . This leads to a b e l i e f that e i t h e r the r e a c t i o n i s not reproduceable or that p o s s i b l y the content of p a r t l y s o l u b l e polymers of lower molecular weights d i f f e r s from one preparation batch to another. D i f f e r e n t contents of these compounds would g r e a t l y a f f e c t the r e a c t i v i t y of the macrocomplex towards hydrogen. In order to ensure that the f i n a l product c o n s i s t s of high-molecular polymers only, the product obtained by the h y d r o l y s i s i n water/dioxane (1:4 v/v) mixture i s separated, d r i e d , and then Soxhlet e x t r a c t e d w i t h dichloromethane f o r 24h. I t i s found that the r e s u l t s obtained w i t h d i f f e r e n t batches of the same macracomplexes prepared i n t h i s way are reproduceable (Table I V ) . Both the homo- and the copolymers change t h e i r colour upon exposure to hydrogen from strong orange to l i g h t orange, and do not show any signs of decomposition to m e t a l l i c rhodium. The amount of hydrogen consumed increases w i t h increased content of the copolymeric component O^^SiCH^. This procedure was t h e r e f o r e adopted f o r the p r e p a r a t i o n of a l l the polymeric chloro(siloxyphosphine)rhodium complexes. -113-3-2-3. Homopolymerization of Phosphine Complexes of Rh(I) and t h e i r  Copolymerization with Cl^Si-CH^. Apart from the polymers described i n the previous section a l l other polymeric complexes described i n t h i s work were synthesized by hydrolysis i n a water/dioxane (1:4 v/v) mixture followed by Soxhlet extraction with dichloromethane. Only i n one case does the method f a i l to produce an insoluble polymer. This i s the polymer produced from [C£ 2(CH 3)Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£, which dissolves upon extraction with dichloromethane. The lower cross-linked structure of the polymer produced by hydrolysis of SiC& 2 groups probably accounts f o r t h i s s o l u b i l i t y . Four types of insoluble s o l i d polymeric complexes were synthesized s u c c e s s f u l l y . Their general formulae can be written as follows: { [ 0 3 / 2 S i - ( C H 2 ) n - P ( C 6 H 5 ) 2 ] 3 R h C £ . ( 0 3 / 2 S i - C H 3 ) m } x n=2 ; m=0,75,150,200 ; R2-0,75,150,200. n=8 ; m=0,100 ; R 8-0,100. { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 > 7 R h C £ > x ; S { [ 0 3 / 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 4 R h 2 C £ 2 . ( O , / 2 S i - C H 3 ) m } x m=0,200 ; T2-0,200. In a l l the complexes x i s probably very large but i t i s undetermined. The macrocomplexes were examined by microanalysis, mp determination and far IR spectroscopy. -114-Th e m i c r o a n a l y t i c a l data which were obtained are far from adequate for proving the predicted formulae of the polymers but when combined with the IR evidence they give a good i n d i c a t i o n as to the id e n t i t y of the macrocomplexes. The oxidation state of rhodium seems to be (I) i n the polymeric complexes and very l i t t l e i f any Rh(III) products of HC£ oxidative addition to rhodium(I) are present. The homopolymeric complexes show weak broad bands i n the v(Rh-CA) -1 -1 region, at 285 cm with a shoulder at 255. cm (R and R ) and 2—U o—U at 290 cm 1 with a shoulder at 265 cm 1 (I^.Q) • There i s no peak i n the region t y p i c a l for v(Rh-H) around 2100 cm 1 . The combination of the i n t r i n s i c a l l y small i n t e n s i t y of these peaks together with the high " d i l u t i o n " of the complex by O^^Si-CH^ i n the copolymers i s the cause of the absence of v(Rh-CJl) (and v(Rh-H)) i n the IR spectra of the copolymers. It was noted that i n the course of the polymer preparation the yellow colour ( c h a r a c t e r i s t i c of Rh(III)) of the o r i g i n a l p r e c i p i t a t e changes to orange ( c h a r a c t e r i s t i c of Rh(I)) for the homopolymers and darker yellow f o r the copolymers ( d i l u t i o n by colourless O^^Si-CH^ moieties). The C£ content found f o r a l l the homopolymers and for some copoly-mers (R 2_y^) i s higher than expected. The S i content found i s i n good agreement with the calculated values f o r the polymers tested. So are the values for P and Rh found i n the homopolymers and copolymers ^ - 7 5 and ^2-200'' ^ o r a 1 1 t* i e o t n e r copolymers the percentage of P, Rh, and C£ i s lower than the accuracy of the determination hence these elements were not analyzed. The carbon content i n a l l the copolymers and T 2_Q i s found -115-as predicted but i t i s low i n a l l the other homopolymers. Since no c o r r e l a t i o n i s found between the high CI and low C values i n the series of polymers i t i s concluded by analogy with polymer P that the high C% values are most l i k e l y due to S i interference i n the a n a l y t i c a l procedure. In view of the above discussion higher emphasis must be put on the IR r e s u l t s and the colour of the products which indicate that the homopolymers do not contain Rh(III) products r e s u l t i n g from HC£ oxidative addition. This conclusion can also be extrapolated to the copolymers. As mentioned before the carbon content i n the homopolymers R„ o J R D and S i s lower than expected i n s p i t e of an improved Z—U o—0 a n a l y t i c a l method 1 0 7 which gives much better r e s u l t s than the 108 standard a n a l y t i c a l procedures . The improvement provides a method of eliminating the formation of s i l i c o n carbide which would lead to low carbon values calculated on the basis of CO^ evolved. There i s a p o s s i b i l i t y that higher cross-linked polymeric networks promote s i l i c o n carbide formation. As discussed i n the previous section the a c c e s s i b i l i t y of Rh centres to hydrogen i s lower for the homopolymers and increases with the 0^^S±-CE^ content i n the copolymer. If t h i s i s taken as an i n d i c a t i o n of the "tightness" or the degree of cross-l i n k i n g of the network (see also sections 4-1-1 and 4-2) i t may explain why the carbon content found for the copolymers i s as calculated although i t i s lower for the homopolymers. An i n t e r e s t i n g trend i n the values for the decomposition points of the polymers i s seen i n the data i n Table V. -116-Table V. Decomposition points of the polymeric complexes R , S, and T„ n-m z-m Polymer Decomp. point °C R2-0 220-230 R8-0 185-195 S 260-265 T 2-0 220-230 R2-75 255-265 R2-150 255-265 R2-200 255-265 R8-100 250-260 T2-200 270-280 None of the polymers a c t u a l l y melt; they a l l decompose over a range of about 10°C leaving either black or grey residues. A l l the homopoly-mers decompose at temperatures 30-50°C lower than the corresponding copolymers. For example R2_o decomposes at 220-230°C whereas R^_^^, ^-150' and R at 255-265°C. The homopolymer R„ n with 8-carbon ligands Z—ZUU o—U decomposes at the lowest temperature whereas the copolymer with an excess of the phosphine, S, i s almost as stable as ^-^uo w n ^ c n n a s the highest decomposition temperature of a l l . A l l the other copolymers decompose at roughly the same temperature (ca. 260°C) regardless of t h e i r -117-composition, and a l l lower than S and T2-200* The a n a l y t i c a l r e s u l t s obtained give only an incomplete i n -d i c a t i o n of the i d e n t i t y of the macrocomplexes produced. Therefore, i n the course of t h i s study a number of experiments were c a r r i e d out i n order to c h a r a c t e r i z e them more f u l l y by means of t h e i r chemical r e a c t i v i t y . These experiments are d e a l t w i t h i n the next chapter of t h i s work. -118-CHAPTER 4 82 Reactions of the Complexes w i t h H^, CO, and HCft(g). The chemical i d e n t i t y of compounds can o f t e n be e s t a b l i s h e d by i n d i r e c t methods f o r example by checking t h e i r r e a c t i v i t y towards c e r t a i n reagents. Both [ (C,HC),,P] „RhC£ and [ (C£H..)„P] .Rh„C£0 and t h e i r analogues undergo a v a r i e t y of 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 . Hydrogen adds o x i d a t i v e l y t o the di-p-chlorotetrakisphosphinedirhodium , • , 81,82,105,106 and to the chlorotrisphosphxnerhodium complexes P CI CI ^ P Rh + H 0 z=> Rh ( 1 5 ) / \ 2 / | \ P P P p H P • CI P Pv CI ?\ H /* \ / R \ + 2 / \ /\\ ( 1 6 ) P CI P P CI I H •35. P Two of the p o s s i b l e s t r u c t u r e s of the ECU adducts of the c h l o r o t r i s p h o s -u- u J - i u • 94-97,100 J phinerhodium complexes have been p r e v i o u s l y reported and were discussed i n Se c t i o n 3-1-3 of t h i s work. Pv .CI P v H CI .CI P. H Rh • H C l < I ± Rh • Rh U 7 ) P - P P 1 P P 1 P r r CI CI 12 13 -119-The above reactions allow a d i s t i n c t i o n to be made between Rh(I) and Rh(III) species since the l a t t e r do not undergo oxidative addition to rhodium. Both the complexes P^RhCJl and P^Rl^C^ react with electron-donor species. The r e a c t i v i t y of [(C^H^)^P]^RhCA i s probably due to the ease of P 2RhC£ formation i n s o l u t i o n ^ 1 ' 1 0 9 . The reaction with CO i s reporte d ^ 1 to be i r r e v e r s i b l e . P^ / P P /CO Rh^ + C O — " ^ R h + P (18) C£ X ^ P C £ X ^ P 16 In the case of di-u-chlorotetrakisphosphinedirhodium complexes a bridge-82 s p l i t t i n g r eaction takes place i n the presence of donors such as C2^4 and CO (eq 19) , y i e l d i n g a product with the same structure 1_6 as shown i n equation (18). Carbon monoxide has been reported to d i s p l a c e 1 1 0 a l l four phosphines i n ( F ^ ^ R t ^ C ^ giving (CO^Rt^CJ^. Rh Rh + 2C0 ^  2 RK (19) p / ^ c r ^ ^ P C£^ ^ P 16 Both the model complexes and the polymeric analogues were subjected to reactions (15) - (19) and the r e s u l t s obtained for the two groups of compounds were compared. Because of the high s o l u b i l i t y of the model complexes even i n solvent vapours quantitative uptake measurements using the gas uptake apparatus could not be made. The reactions were therefore followed s p e c t r o s c o p i c a l l y . -120-4-1. Reactions w i t h H^. 4-1-1. Reactions of P^RhCA Complexes . The r e a c t i o n of the s o l u b l e complex H was followed w i t h IR, 1 31 H NMR, and P NMR spectroscopy. The molecular s t r u c t u r e lb_ has been assigned to the hydrogen adduct of [ (C^H^^PJ^RhCJi and CU Rh 'Pa p / I \ u 81 82 i t s analogues ' . They show a broad medium i n t e n s i t y v(Rh-H) peak around 2050 cm 1 w i t h a broad shoulder at a frequency about 50 cm 1 greater than the main peak. The s o l u b l e siloxyphosphine compound obtained i n the r e a c t i o n of H w i t h hydrogen shows a s i m i l a r peak at 2075 cm 1 w i t h a shoulder at 2160 cm \ The h i g h - f i e l d 4 NMR spectrum of the adduct of the W i l k i n s o n complex contains three p e a k s 8 ^ - f ^ ^ around -9, -11, and -286 w i t h r e l a t i v e i n t e n s i t i e s 1:1:2. An analogous p a t t e r n of peaks, at -8.5, -10.1 and -17.9 6 r e s p e c t i v e l y , i s observed f o r the siloxyphosphine compound. Upon p a r t i a l phosphorus decoupling the two smaller peaks c o l l a p s e i n t o one m u l t i p l e t and the b i g one i n t o a doublet; the r a t i o of t h e i r i n t e g r a t e d areas being 1:1. The 3 1 P NMR spectrum of (Ph 3P) 3RhH 2C£ c o n t a i n s 1 0 6 a double doublet of -48.92 ppm due to the phosphorus P a and a double t r i p l e t f u r t h e r u p f i e l d at -32.21 ppm due to P^. An analogous spectrum i s found f o r the siloxyphosphine hydrogen adduct w i t h a double doublet at -41.03 ppm -121-and a double t r i p l e t at -20.17 ppm, with a l l the coupling constants considerably smaller than those for the triphenylphosphine complex. The s i n g l e t due to siloxyphosphine oxide which i s observed i n the spectrum of the s t a r t i n g complex i s also noted i n that of the product. The hydrogenation process, as for the Wilkinson complex, i s completely r e v e r s i b l e . Upon removal of the solvent i n vacuo a l l the IR and NMR s p e c t r a l features due to the hydride species disappear and the pattern t y p i c a l of the s t a r t i n g P^RhCJi reappears. The recovered complex can s u c c e s s f u l l y be rehydrogenated, as indicated by the spectra. The polymeric R^-rj a n < * R2-75 c o m P l e x e s w e r e exposed to H 2 both i n a toluene suspension and i n the s o l i d state. Data i n F i g . 5 show the amount of uptake vs. time for the reaction c a r r i e d out i n toluene. After 33h the homopolymer consumes 11.5% and the copolymer 56% of the as compared with the amounts calculated f or 1:1 uptake. The fa c t that the homopolymer consumes les s hydrogen (per calculated number of rhodium atoms) may be a ref l e c t i o n of the degree of a c c e s s i -b i l i t y of rhodium atoms which i s a r e s u l t of the degree of c r o s s - l i n k i n g and d i l u t i o n with O^^Si-CH^ moieties. However, the IR spectra of a l l the hydrogenated products show no v(Rh-H) peaks i n the expected region, 2050-2150 cm There are two possible reasons for t h i s . One i s the high i n s t a b i l i t y of the hydrido species which could revert to the s t a r t i n g compound during the IR mull preparation i n a N 2 atmosphere. The other i s the i n t r i n s i c a l l y small i n t e n s i t y of the v(Rh-H) IR absorption combined with the small amount of H 2 uptake by the homopolyme A d d i t i o n a l l y there i s the problem of the " d i l u t i o n " by O^^Si-CH^ for th copolymer. -122-(a) 2 3 -123-4-1-2. Reaction of P^Rh^CJ^ Complex, J . The compounds (Ar 3P) 4Rh 2CA 2(Ar=C 6H 5,p=CH 3-(C 6H 4) are reported to give only one complex 15 on r e a c t i o n w i t h hydrogen. P P CI H \ / \ / Rh Rh / \ / \ P CI H 15 P 8 2 This s t r u c t u r e has been e s t a b l i s h e d by extensive IR and NMR s t u d i e s of the p-tolylphosphine complex. The IR spectrum shows a broad -1 31 band about 2115 cm . The proton decoupled P NMR spectrum c o n s i s t s of two doublets, J(Rh-P)=195 and 118 Hz, and the h i g h - f i e l d 1H NMR spectrum has a doublet (J(Rh-H)=22 Hz) of t r i p l e t s J(P-H)=17 Hz. 31 1 The P and the h i g h - f i e l d H NMR spectra of the H 2 adduct of complex J are shown i n F i g . 39a and 39b. The four resonances 1-4 i n 31 the P NMR spectrum can be assigned to the two doublets of a species w i t h the same s t r u c t u r e as 15_. I t i s not immediately c l e a r , however, which peaks belong to which doublets. The formation of such a hydrido species i s however confirmed by the double t r i p l e t a_ and b_ i n the high-f i e l d XH NMR spectrum at -20.16, J(Rh-H)=24 Hz and J(P-H)=16 Hz, which c o l l a p s e s to a doublet on phosphorus decoupling. In view of the information a v a i l a b l e i n the e x i s t i n g l i t e r a t u r e 31 p o s s i b l e assignments f o r the other P NMR peaks present somewhat of a d i f f i c u l t y , when compared w i t h the peaks i n the 4 NMR spectrum. The -124-31 four P NMR peaks of lower i n t e n s i t y , 5-8, which look l i k e a shadow of peaks 1-4 could p o s s i b l y be assigned to an isomer 1_7 of the complex 15. Rh Rh / \ / I \ P CI I P 17 H Such a s t r u c t u r e a l s o c a l l s f o r a double t r i p l e t i n the h i g h - f i e l d "*"H NMR spectrum. Only one t r i p l e t c was observed at -19.86; there i s the p o s s i b i l i t y that i t s " t w i n " t r i p l e t i s buried under the l a r g e peaks of the double t r i p l e t a-b_. However, so f a r no t r a n s i t i o n metal complex w i t h two H atoms trans to each other has been reported. The peaks 5 and 6 show the same frequency as the doublet of the s t a r t i n g siloxy-complex P^RT^CJ^- The two small m u l t i p l e t s 10 and 11 have the same chemical s h i f t s as the doublet of t r i p l e t s of the s i l o x y P^Rh^ C J l and the chemical s h i f t s of 7,3,8, and 4 are the same as those of the double doublet peaks of the same P Rhl^Cfc complex. The small s i n g l e t , 9 i s due to the siloxyphosphine oxide. The NMR contains two small m u l t i p l e t s e^  and d_ at -16.1 and -17.86 each of which forms a doublet p a t t e r n on p a r t i a l phosphorus decoupling. The one at -17.86 i s i d e n t i f i e d as the l a r g e peak of the three i n the P^Rhi^CJi spectrum. The small m u l t i p l e t at .-16.26 cannot be assigned. Although a p r e c i s e assignment of a l l the complexes formed cannot be unequivocably made, the spectra show that complex 1_5 i s the main product of hydrogenation of complex J . The hydrogenation of J i s -125-r e v e r s i b l e , s i m i l a r to H. 4-2. Reactions with CO. As shown by equations (18) and (19) both P,jRhCJt- and P^Rt^CJ^ (P=P(C,H C)„, P(p-CH -C,H.) 0) react with CO giving trans P oRh(C0)C£ complexes only. The same products are obtained i n the reaction between (CO^Rt^CJ^ .and the phosphines (eq.9). For some chelating . . . , • ^  • r - - t - u ,102,111 phosphxnes, complexes wxth a c i s configuration have been reported The v(C=0) of Rh(C0)CA[(C 6H 5) 2P-(CH 2) 2-P(C 6H 5) 2] with a -1 _ -1 c i s configuration i s higher, at 2010 cm , than v(C=0), at ca. 1960 cm , of the dimeric complexes (Rh(CO)C£[(C,H C)_P-(CH„) -P(C,H C)„]}„ (n=l,3,4) o 5 z z n D j z z i n which P atoms of the bridging phosphines are trans to each ether. When (CO) R h 0 C £ 0 reacts with either soluble or polymeric phosphines with a 4 z z 31 112 113 P:Rh r a t i o of 1:1, ci s - d i c a r b o n y l complexes are formed ' ' , t h e i r IR spectra show two v(C=0) bands i n the 2000 cm 1 region. The IR spectra of the solutions of both the soluble siloxyphosphine complexes H and J exposed to, CO contain a strong band at 1965 cm 1 which i s i d e n t i c a l with the v(C=0) of complex G, trans- { [ ( C H ^ S i - O - J ^ C l L j ) S i -(CH 2) 2-P(C 6H 5) 2} 2Rh(CO)C£, synthesized according to eq.(9). The 3 1 P NMR spectrum of the product obtained from J i s i d e n t i c a l with that of G, ex h i b i t i n g a doublet at -29.81 ppm with J(Rh-P)=124.7 Hz. A small s i n g l e t at -30.00 ppm i s due to a small amount of the phosphine oxide. However, the oxide i s not a product of the reaction with CO since i t i s also present i n the s t a r t i n g complex J . 31 The P NMR spectrum of the s o l u t i o n containing complex H with CO shows a very broad intense m u l t i p l e t from -30 to -3 ppm (plus the s i l o x y --126-phosphine oxide s i n g l e t at -29.94 ppm) instead of the doublet at -29.81 expected for the trans -P2Rh(C0)C£ complex and the s i n g l e t at +9.14 due to the displaced phosphine. The spectrum recorded i n deuteroacetone at -60°C has a s i m i l a r m u l t i p l e t but s h i f t e d downfield. The proton NMR signals at 35°C are also broad with no separate set of peaks for the complex and the free phosphine. The broadening of the signals i s most l i k e l y due to ligand exchange between the new carbonyl complex formed and the released free phosphine. When carbonyl complex G and free phosphine B are mixed i n a 1:1 molar 31 r a t i o the P NMR spectrum of the so l u t i o n shows a broad m u l t i p l e t (-20 to -3 ppm) and the siloxyphosphine oxide s i n g l e t at -29.41 ppm. This r e s u l t thus confirms the postulated ligand exchange between the carbonyl complex and the free displaced phosphine i n the reaction discussed above. In the case of the polymeric complexes the IR spectra of a l l these a f t e r the reaction with CO contain a strong peak around 1965-1970 cm \ The chlorine-bridged homopolymer Q and the copolymer R^ y^ also show a medium to weak peak at 2080 cm \ and R^ y^ exhibits a d d i t i o n a l l y a strong peak at 1995 cm 1 (Tables V and VI). When the reaction with CO i s c a r r i e d out i n the absence of any solvent the product obtained from R 2 Q also exhibits a medium i n t e n s i t y peak at 2080 cm 1 . The absorption at 1965 cm 1 i s at the same frequency as found for the polymeric carbonyl complex P synthesized from t r a n s - [ C ^ ^ S i - ( C ^ ) ^ ~ P(C,H C)„] oRh(C0)C£. Hence i t i s assumed that a l l the polymers R„ R 0 n , o D Z Z z - U o - U R"2 yi-, and T2 Q form a trans carbonyl complex with structure 16_ (same as 8). As mentioned before, the C=0 stretching frequency for the carbonyl complex with c i s configuration i s higher than that for the trans compounds. -127-The frequencies of both the bands at 2080 and 1995 cm 1 are higher than v(C=0) for the trans-(CO)P 2RhC£ products (1965 cm"1) and hence either of the two could be a t t r i b u t e d to the more unusual c i s configuration, the p o s s i b i l i t y being that the polymeric ligands act as chelates. The p r o b a b i l i t y of the 2080 cm"1 band being due to cis-(C0)P 2RhC£ i s greater because, as discussed below, the 1995 cm 1 band i s more l i k e l y due to the cis-(CO) 2PRhC£ species. The 1995 cm 1 band appears only i n the spectrum of the product of the reaction of R^_j^ with CO. At the same time, as seen i n Table V, R2_^^ absorbs more CO than any other polymer tested. Formation of some cis-bis ;carbonylchloro(phosphine)rhodium probably takes place and thus the apparent 100% absorption, counting one molecule of CO per rhodium atom, i s i n fact probably lower when counting 2:1 for some rhodium centres. The cis-(CO) 2PRhC£ complexes exhibit two v(C=0) bands and therefore another band apart from that at 1995 cm 1 i s expected. However, no fourth v(C=0) band i s present i n the spectrum of t h i s product. It i s possible that i t has a frequency coincident with either the 1965 cm 1 or 2080 cm - 1 peaks, already assigned to the (C0)P 2RhC£ species. The CO uptake data i n Tables V and VI show a wide v a r i a t i o n which probably r e f l e c t s the a c c e s s i b i l i t y of Rh(I) centres i n the polymers tested. The degree of a c c e s s i b i l i t y , as mentioned before (section 4-1-1), i s most l i k e l y a r e s u l t of the degree of c r o s s - l i n k i n g . The low values observed are probably due to the fa c t that some metal centres are p h y s i c a l l y blocked. The high CO uptake i n case of R 2 ^ may also be the r e s u l t of increased a c c e s s i b i l i t y of rhodium centres by " d i l u t i o n " with O^^Si-CH^ - 1 2 8 -moieties. Some p r i o r oxidation to Rh(III) would also r e s u l t i n low uptake values but t h i s seems less l i k e l y (Section 3 - 2 - 3 ) . 4 - 3 . Reactions with HC£(g). As discussed e a r l i e r (Section 3 - 1 - 3 ) HC£ adds o x i d a t i v e l y to both chlorotrisphosphinerhodium and di-u-chlorotetrakisphosphinedirhodium complexes. There are two possible structures 1_2 and J-3_ for the product P3RhH2C&. Isomer jL2 exhibits an IR v(Rh-H) b a n d 9 6 ' 9 7 around 2 1 0 0 -2200 cm"1 and two v(Rh-Cfc) b a n d s 9 4 ' 9 5 ' 1 0 0 ' 1 0 1 i n the 225 -290 cm"1 region. The Rh-H stretches i n the isomer 13_ give r i s e to peaks at 95 97 —1 lower frequencies ' 1 9 6 0 - 1 9 9 0 cm . The v(Rh-C£) region shows only one band 9 5'"'" 0 0 at a frequency higher than that f o r 1_2, 3 2 0 - 3 3 0 cm \ c h a r a c t e r i s t i c of CI trans to CI. Upon reaction with HC£(g) both soluble siloxyphosphine complexes H and J give s o l i d products insoluble i n common solvents hence the analyses were r e s t r i c t e d to IR and microanalyses. The presence of two v(Rh-C£) bands (273 and 253 cm 1 ) and the po s i t i o n of the v(Rh-H) band well above 2000 cm 1 (2110 cm 1 ) suggest formation of an adduct of structure 1_2 i n the reaction of trisphosphine complex H with HC£. The product of the reaction with the tetraphosphine complex also shows two IR v(Rh-C£) bands at 255 and 275 cm 1 and one v(Rh-H) at 2100 cm 1 but i t s structure cannot be determined on the basis of these data. The addition of HC£ i s p a r t l y r e v e r s i b l e for both the adducts and upon pumping the HG£(g) o f f , the peaks due to the Rh-H and Rh-C£ stretching frequencies diminish and the yellow colour of the adducts -129-( c h a r a c t e r i s t i c of Rh(III)) changes to orange ( c h a r a c t e r i s t i c of Rh(I)) . The formation of an insoluble s o l i d i n the reaction between the soluble complexes H and J and HC£(g) was rather unexpected. The mechanism of the acid-catalyzed r e d i s t r i b u t i o n of siloxane linkages i s not well understood,but anhydrous or concentrated acids such as H^SO^ j TT^„ , , _,47,48,114,115 , , , and HC£ have been reported to break siloxane bonds. The r e v e r s a l of t h i s process, involving new partners, leads to the r e d i s t r i b u t i o n of the siloxane linkages. A s i m i l a r process most l i k e l y takes place i n the reaction of the siloxyphosphine complexes with HC£(g) The high H and CZ m i c r o a n a l y t i c a l values found f o r the products may be explained i n terms of HC£ chemisorption to the surface of the s o l i d . The explanation of formation of an insoluble s o l i d from H and J upon exposure to HC£(g) i n terms of siloxane linkage rearrangement and polymerization i s supported by the fac t that l,l,l,3,5,5,5-heptamethyl-3-v i n y l s i l o x a n e forms an insoluble gel when treated with HC£(g). Exposure of the polymeric complexes R^-O a n c* R2-75 t o ^^^s) at 25°C gives products with no v(Rh-H) or v(Rh-C£) peaks c h a r a c t e r i s t i c of an HC£ adduct, although a considerable increase i n the weight of the samples i s observed, up to a 2:1 r a t i o of HC£ per rhodium atom. Such IR r e s u l t s i n d i c a t e that l i t t l e or no HC£ reacts with the Rh(I) centres. However, the p o s s i b i l i t y e x i s t s that, as explained for the reaction with hydrogen, absorptions due to an adduct are too weak i n i n t e n s i t y ( a c c e s s i b i l i t y of rhodium centres and"dilution"by Q^/2 ^i-CH^) t o ^ e observed. The strong chemisorption of HC& to the matrix i s indicated by the high m i c r o a n a l y t i c a l values for H and CI. The chemisorption seems strong and not e a s i l y reversed by pumping at 25°C. When s o l i d polymer -130-which has been exposed to HC£(g) i s added to toluene at 60°C gas e v o l u t i o n occurs. This i s probably due to r e v e r s i b l e chemisorption perhaps aided by s w e l l i n g of the polymer network. -131-CHAPTER 5 Catalytic Hydrogenation of Olefins The mechanism of o l e f i n hydrogenation catalyzed by Wilkinson 81 complex [(C,HC)0P]„RhC£ has been postulated to be as outlined i n the O J J J reaction scheme (20) and (21) RhC£(PPh„)„ g > RhC£(PPhQ)„ + PPh. (20) RhC£(PPh3)2 + H 2 ^ H2RhC£(PPh3)2 K 2 o l e f i n *1 o l e f i n (21) H 2 RhC£(PPh3)2(olefin) RhC£(PPh3)2+ paraffin lift More recent studies indicate that the reaction more l i k e l y proceeds v i a the "hydride" path. The high c a t a l y t i c a c t i v i t y of (Ph3P)3RhC£ i s due to the extreme r e a c t i v i t y of complex 1_8_. The a v a i l a b i l i t y of which 105 i s affected by the equilibrium (22) which l i e s far to the right 2RhC£(PPh3)2 — ^ — > Rh 2C£ 2(PPh 3) 4 (22) In the presence of hydrogen the interception of 18^  by H 2 precludes formation of the tetraphosphine complex. The dimer i t s e l f i s described as a good on hydrogenation catalyst but with l i t t l e substantiation. A wide range of studies have been done on the Wilkinson complex whose very high c a t a l y t i c efficiency i s comparable with that of Raney n i c k e l . Quantitative studies of the hydrogenation of some ole f i n s with [(C,HC)„P]0RhC£ have shown the dependence of the reaction rate on substrate -132-and c a t a l y s t concentrations^temperature, and pressure0"'"'^"'"'. The rate law can be expressed as follows: ..kU [P][S][C] Rate 1+K^P] + K 2[S] where [S] and [C] are the o l e f i n and c a t a l y s t concentrations, [P] i s the hydrogen concentration i n s o l u t i o n and K^, K^, and -are the equilibrium and rate constants for the reactions (20)-(21). The reaction rates increase with increased concentration of both o l e f i n and c a t a l y s t as w e l l as with an increase of hydrogen pressure and the reaction temperature. These reactions were ca r r i e d out i n benzene solutions and i t was found that the addition of polar cosolvents such as alcohols speeds up the reaction rate s u b s t a n t i a l l y . Terminal o l e f i n s are hydrogenated more r a p i d l y than i n t e r n a l and c y c l i c o l e f i n s ; the rate 118 decreases for the c y c l i c ones with increasing r i n g s i z e Similar dependence of the reaction rates on the above mentioned factors has been found for analogues of the Wilkinson complex supported on polystyrene and on silica 2^>119,120^ ^ n g e n e r a i terminal o l e f i n s are hydrogenated more r a p i d l y than i n t e r n a l and c y c l i c o l e f i n s , although here the s i z e of the o l e f i n vs the pore s i z e of the support plays an important r o l e also. Larger o l e f i n s , are l e s s r e a c t i v e because t h e i r access to the a c t i v e c a t a l y t i c s i t e s i s r e s t r i c t e d by the pore s i z e . As found for [ (C^B.^)^P] ^ RhCA hydrogenation of terminal o l e f i n s by the 120 121 supported c a t a l y s t s i s accompanied by isomerization ' . Polymer-swelling properties of polar solvents have an a d d i t i o n a l p o s i t i v e influence on the reaction rates. Reaction rates also increase with increased -133-temperatures but higher temperatures (100°C) have been found to decompose the s i l i c a supported [!^-0-Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£ complex to m e t a l l i c U A- 2 6 rhodxum 9 It i s claimed '• that the a c t i v i t y of a supported Wilkinson complex should be higher than that of the corresponding soluble [(CgH^) 3P] 3RhC£ complex. The a c t i v i t y of the c a t a l y s t i s dependent on the phosphine d i s s o c i a t i o n equilibrium (eq 20) and i n a polymeric system the rea s s o c i a t i o n of the phosphine with the rhodium centre i s le s s l i k e l y than i n the soluble species where an o l e f i n has to compete with the free 122 mobile phosphine for the free coordination s i t e . However, i n the supported c a t a l y s t s some of the metal centres are inside the small pores of the polymer which makes them either completely substrate-inaccessible or else the d i f f u s i o n of the substrates to the a c t i v e s i t e s becomes a rate 3 119 determining factor ' . The comparison of reaction rates and turnover 123 124 37 numbers ' shows, with one exception , that the a c t i v i t y of the Wilkinson type complexes supported on various polymers i s far i n f e r i o r to that of the soluble [(CgH^ 3P] 3RhC£ complex. Various polymer supported Rh(I) systems can be recycled but no pattern of the maintained l e v e l of a c t i v i t y has been noted. Some ca t a l y s t s . . . . . J 37,125,1-2-6-decrease i n t h e i r a c t i v i t y to various degrees on r e c y c l i n g . • , -, , • i _ r - r i 12,37,126 others r e t a i n i t at the same l e v e l i n the f i r s t few cycles and i n some cases the a c t i v i t y of the c a t a l y s t increases s l i g h t l y a f t e r the 3 6 12 32 127 f i r s t cycle ' ' . S i l i c a supported systems have been reported ' to maintain t h e i r a c t i v i t y over c_a. 70h period under continuous flow conditions. The e f f e c t of the length of the anchoring "arms" of phosphines has -134-28 77 been studied and i t has been shown ' that i n general,,complexes with longer "arms" are c a t a l y t i c a l l y more act i v e than those with short ones, and can be recycled more times. One i r r e g u l a r i t y i n t h i s pattern has been found f o r the hydroformylation reaction by s i l i c a supported Rh(I) 28 complex . After attachment of [(C_H c0)„Si-(CH„) -P(C,H c)„]Rh(C0D)C£ z D 3 z n fa _> z (n=2,8) to s i l i c a the complex with the chain i s more act i v e than the one with the C 0 chain. The EPR studies of polysaccharide supported o 128 129 nitroxides have shown ' that longer spacer "arms" give more freedom of mobility to the anchored s i t e s and the spectra become si m i l a r to that of the species i n a sol u t i o n ; the extended distance from the support makes the anchored s i t e s l e s s s e n s i t i v e to the geometry of the support. The increase of the spacer "arms" beyond a c e r t a i n length (equivalent to a C D chain) causes no further change, o Homo geneous c a t a l y s t s prepared i n s i t u from [(olefin) 2RhC£] 2 a n d various phosphines, including P(C,H,.)0, exhibit highest a c t i v i t y when fa J J P/Rh r a t i o i s 2; with added phosphine, the a c t i v i t y of the c a t a l y s t 5 118 decreases ' probably because of the s h i f t of equilibrium (20) to 130 the l e f t . A s i m i l a r trend i s observed for the supported complexes On addition of either soluble or polymeric phosphine to the supported complexes of the P^RhCA type the ca t a l y s t ' s a c t i v i t y decreases consider-i - i 12,37 ably It has been shown that higher P/Rh r a t i o s , on the other hand, have a s t a b i l i z i n g e f f e c t on the supported c a t a l y s t s . S t e r i c s t r a i n around the metal centre caused by the r i g i d i t y of the polymeric ligands 6 '131—133 i s believed ' _ to be responsible for decomposition to m e t a l l i c rhodium. Complexes of the type {[Rh(NBD)polyP(C &H 5) 2] 2> + i n which rhodium--135-3? 32 thought to be responsible for rhodium e l u t i o n from a matrix content i s varied do not decompose to the metal when the P/R.h r a t i o i s higher (7.8-31 vs. 2.7-4.4). This i s explained i n terms of formation of complexes with the le a s t strained configuration when a greater choice of ligands i s possible (higher P content). It i s possible that such polymer-imposed s t r a i n causes cleavage of Rh-P bonds. The l a t t e r e f f e c t i s The r e s u l t s of recent studies of hydroformylation with c i s - R M C O ^ -(poly-P)C£ suggest that the s h i f t s i n equilibrium between phosphine, carbonyl,hydrido phosphine, and hydrido carbonyl complexes (soluble and anchored) of d i f f e r e n t s t a b i l i t i e s are responsible for rhodium e l u t i o n from the r e s i n A high metal loading of the supported systems P^RhC^5' P^RhBr 1 3 5 and' Cp TiCi!^"^ leads to formation of dimeric species. As a re s u l t of i t , a c t i v i t y of the c a t a l y t i c species decreases. For example s p e c i f i c a c t i v i t y of the ca t a l y s t s synthesized from Rl^C^(C^H^)^ and phosphinated polystyrene polymers decreases with increasing rhodium 9 content i n the polymer . X-ray absorption studies show that s i t e i s o l a t i o n i n P^RhBr supported on a styrene-DVB copolymer with higher DVB contents (20%) r e s u l t s i n greatly reduced P^Rl^Br dimer formation. S i t e i s o l a t i o n i n CP2T1C&2 supported on highly-crosslinked polymers also prevents formation of dimeric species r e s u l t i n g i n a substantial increase of i t s c a t a l y t i c a c t i v i t y as compared with the soluble complex. A l l of these r e s u l t s allow some predictions to be made with regard to the c a t a l y t i c behaviour of the polymeric siloxyphosphine complexes synthesized i n t h i s work. Their a c t i v i t y i s expected to be lower than that of the soluble siloxyphosphine model analogues with the copolymers -136-showing higher o v e r a l l a c t i v i t y than the homopolymers. The complexes with C D spacer "arms" should be more a c t i v e than those with C 0 "arms". o Z The macrocomplex S, with an excess of the phosphine, ^RhC£ should be less a c t i v e but more stable than P^RhCA. As mentioned before no actual study has been reported on the c a t a l y t i c a c t i v i t y of P^Rt^CA,, D u t i t s formation on supports i n the preparation of the Wilkinson c a t a l y s t bound to phosphine polymer has 136 been documented . It has been implied that the a c t i v i t y of P^Rt^C^ i s lower than that of P^RhC^ i n s o l u t i o n 1 1 ^ and the same pattern can be expected for the polymeric siloxyphosphine analogues. 5-1. Hydrogenation of Styrene with the Soluble Siloxyphosphine Complexes. The two new soluble siloxyphosphine complexes {[(CH 3) 3Si-0-] 2(CH 3)Si-(CH 2) 2-P(C 6H 5) 2} 3RhC£ and { [ (CH 3) 3Si-0-] 2 ( C H 3 ) S i - ( C H 2 ) 2 ~ P ( C ^ ) 2 > 4 R h 2 C £ 2 H and J , were tested as to t h e i r a b i l i t y to catalyze hydrogenation of styrene. The r e s u l t s plotted i n F i g . 6 show that both the complexes are e f f e c t i v e c a t a l y s t s , the reaction rate being higher for the trisphosphine complex H than for the tetraphosphine one J . As w i l l be seen l a t e r , com-parable rates are obtained when using the polymeric analogues only i f the concentrations of both o l e f i n and c a t a l y s t (per rhodium centers) are i n -creased by a factor of 10. 5-2. Hydrogenation of Olefins with Polymeric Complex R 2 { [ 0 3 / 2Si-(CH 2) 2-P(C 6H 5) 2] 3RhC£. ( 0 3 / 2 S 1 C V 7 5 } x -A series of experiments was c a r r i e d out with the polymeric c a t a l y s t -137-"*"n o r d e r t o determine the i n f l u e n c e of f a c t o r s such as s u b s t r a t e and c a t a l y s t c o ncentrations, temperature, s o l v e n t , and nature of the o l e f i n on the r e a c t i o n r a t e s . This s e r i e s of experiments was a l s o done i n the b e l i e f that the r e s u l t s would be of value i n choosing the most convenient experimental c o n d i t i o n s f o r f u r t h e r work w i t h t h i s and other polymers. 5-2-1. V a r i a t i o n of O l e f i n s . A range of o l e f i n s was hydrogenated at atmospheric pressure using a constant amount of the c a t a l y s t and benzene as a solvent (Table V I I ) . The r e a c t i o n was stopped a f t e r 23h and y i e l d s of products determined w i t h GLC. Cyclohexene, styrene, 1-heptene, and 1-octene were chosen as r e -pr e s e n t a t i v e s of i n t e r n a l and primary o l e f i n s . The f i r s t two do not all o w i s o m e r i z a t i o n whereas the l a t t e r two do. The r e s u l t s obtained f o r these o l e f i n s were expected to p a r a l l e l those which have been reported f o r s i m i l a r supported c a t a l y s t s . For 120 example 1-pentene y i e l d s n-pentane and c i s - and trans-2-pentene and 120 1-heptene y i e l d s n-heptane and 2- and 3-heptenes i n v a r i o u s pro-p o r t i o n s when hydrogenated w i t h polystyrene and s i l i c a supported W i l k i n s o n -type c a t a l y s t s . Hydrogenation r a t e s f o r styrene are not much lower than T-20 those of 1-pentene . Although i n general i n t e r n a l o l e f i n s are _ . - _ , . , 26,81,120 , . , hydrogenated slower than the t e r m i n a l ones j i t has been reported that when ethanol i s used as a solvent hydrogenation of cyclohexene proceeds f a s t e r than that f o r styrene. In t h i s work r e d u c t i o n of cyclohexene, f o l l o w i n g the general trend expected of i n t e r n a l o l e f i n s , proceeds at a r a t e slower than f o r any of the primary o l e f i n s , the conversion a f t e r 23h being about ten times lower than -138-that of the other substrates. A l l three primary o l e f i n s are hydrogenated to the same extent. However, both 1-heptene and 1-octene give products composed of a ^a. 1:1 mixture of the paraffin and the unsaturated isomers. Styrene, although more bulky, reacts to the same extent giving: s o l e l y ethylbenzene. 5-2-2. V a r i a t i o n of Solvent. Suspensions of R^ i n various solvents containing styrene were exposed to hydrogen. The hydrogen uptake was not monitored and only colour changes of the ca t a l y s t were noted (Table VIII) . Only when benzene or toluene are used as solvents does the colour of the polymer remain orange. Addition of polar cosolvents, triethylamine and ethanol, causes the polymer to change i t s colour from orange to grey; i n pure ethanol the polymer turns black immediately upon addition. This e f f e c t of ethanol or triethylamine has not been reported previously. The darkening of the polymer i s assumed to be due to the reduction of Rh(I) to m e t a l l i c Rh(0).Thus triethylamine and ethanol were not used as solvents i n further studies of o l e f i n hydrogenation with the polymeric siloxyphosphine Rh(I) complexes. 5-2-3. V a r i a t i o n of Temperature. As mentioned before , hydrogenation rates increase with increased temperature. For example while only traces of isoprene are hydrogenated 2 6 at 50° with a s i l i c a supported P^RhCA ca t a l y s t the y i e l d s increase to 11% when the temperature i s raised to 80°C. The rate of styrene hydrogenation i n toluene as a solvent exhibits s i m i l a r tendency as seen i n F i g . 7 where an increase from 35° to 60°C causes the reaction rate to increase by about a factor of two. -139-5-2-4. V a r i a t i o n of Concentrations of O l e f i n and Catalyst. As was described f o r the soluble and polymeric systems 8 1' 1"^ mentioned e a r l i e r , the hydrogenation rate using -j^ increases with increased concentration of o l e f i n . The rate of hydrogenation of a given amount of styrene also increases as the amount of the polymeric c a t a l y s t i n a constant s o l u t i o n volume i s increased (Fig,.8 and 9). The r e s u l t s shown i n F i g . 8 show that the degree of conversion i n a given time increases with an increase of styrene concentration but the dependence i s not l i n e a r . This e f f e c t i s much more pronounced f o r the lower styrene/Rh r a t i o s (7.5 vs. 75) than f o r higher (75 vs. 250). When dealing with heterogeneous c a t a l y s t s the term "concentration" i s not s t r i c t l y appropriate but instead the amounts of the ca t a l y s t i n given so l u t i o n volumes should be s p e c i f i e d . The r e s u l t s p lotted i n F i g . 9 show that the degree of styrene reduction a f t e r a given time also increases with the amount of the ca t a l y s t introduced. However, unl i k e the r e s u l t s for increasing o l e f i n concentrations (Fig. 8), as the amount of the cat a l y s t i s increased the degree of conversion i n a given time becomes greater than expected f o r a l i n e a r r e l a t i o n s h i p . Since the degree of conversion rather than reaction rate i s being measured the term "order of reacti o n " i s not s t r i c t l y a pplicable. However, for lack of a better terminology i t can be stated that the degree of conversion i s lower than " f i r s t order" with regard to styrene concentration and higher than " f i r s t order" with regard to the amount of the ca t a l y s t introduced. 5-3. Hydrogenation of Styrene with the Polymeric Complexes. The r e s u l t s of the experiments discussed i n the previous sections -140-(Sections 5-2) allow the choice of the most convenient experimental conditions for use i n further studies. Styrene was chosen as the reference o l e f i n because of the convenient hydrogenation rate and formation of only one product, ethylbenzene. Of the two s u i t a b l e solvents benzene and toluene, the former was chosen for the reason that i t s value i n GLC does not coincide with either that of styrene or e t h y l -benzene. The reaction conditions were standardized i n the whole serie s of experiments; the s o l u t i o n volume was 3 mL and i n order that a few runs could be monitored concurrently over a convenient period of time the temperature was maintained at 35°. The amount of styrene was 0.319g -2 (3.0 mmol), and the amount of each c a t a l y s t was always 3.0x10 mmol (based on the number of Rh atoms). The only d i f f e r e n c e between runs was the nature of the c a t a l y s t introduced. In t h i s way i t was ensured that no factors other than the i n t r i n s i c properties of the polymeric c a t a l y s t i t s e l f would influence the course of each i n d i v i d u a l reaction. The data presented i n F i g . 10 present a picture of the r e l a t i v e a c t i v i t i e s of d i f f e r e n t polymeric c a t a l y s t s i n t h e i r f i r s t c ycle. Re-gardless of the fa c t that they are homo- or copolymers a l l the chloro-trisphosphinerhodium complexes are considerably more act i v e c a t a l y s t s than the di-y-chlorotetraphosphinedirhodium ones. The i n i t i a l reaction rates do not d i f f e r very much but a f t e r about 40% conversion has been achieved the dimers' curves depart from those of the trisphosphine complexes. With the exception of R 0 which exhibits s l i g h t anomalous behaviour which o—U w i l l be discussed l a t e r , t h e hydrogenation with the homo- and copolymeric trisphosphine compounds proceeds very fast to completion (Fig. 10, 15-18) without reaching a plateau. The degrees of conversion when the tetraphosphine -141-complexes are employed (Fig. 10) s t a r t d e c l i n i n g p a r t i c u l a r l y quickly i n the case of the copolymer T2_2QQ- This pattern of a c t i v i t y follows that of the soluble complexes (Fig. 6) where the reaction rates are higher for trisphosphine complex H than for the tetraphosphine complex J , the r e l a t i v e a c t i v i t y of the soluble complexes being considerably higher than the polymeric ones. On r e c y c l i n g a l l the c a t a l y s t s show decrease in a c t i v i t y but the a c t i v i t i e s of the tetraphosphine compounds are always lower than those of the trisphosphine ones, i n the corresponding cycles. The data plotted i n Figs. 11-14 show the deactivation pattern of the complexes which were not copolymerized with CJ^Si-CH^. Macrocomplex ( Fi-8- H ) maintains i t s a c t i v i t y i n the second cycle almost to the same extent as i n the f i r s t one but loses i t gradually i n the subsequent runs u n t i l i t reaches a n e g l i g i b l e l e v e l i n the f i f t h run. Judging by the colour of the s o l u t i o n a f t e r the reaction (Table IX) there i s some e l u t i o n of rhodium from the polymer i n the fourth cycle but none i n the f i r s t three. Therefore the deactivation i n at l e a s t the i n i t i a l three runs i s not caused by metal l o s s . Homopolymer Rg_Q (Fig. 12) shows s l i g h t l y anomalous behaviour compared with a l l the other trissiloxyphosphine c a t a l y s t s . I t s a c t i v i t y i n the f i r s t run i s r e l a t i v e l y low but most i n t e r e s t i n g l y i t increases i n the second and'third ones. I n i t i a l l y i t was thought that i t i s a d i f f u s i o n b a r r i e r which causes such behaviour but preconditioning the polymer i n benzene suspension, under an atmosphere of hydrogen, and i n the absence of styrene makes only a s l i g h t d i f f e r e n c e to the rate i n the f i r s t cycle. This c a t a l y s t can be used s i x times; the l o s s of a c t i v i t y i n the f i r s t four cycles i s not caused by rhodium loss since e l u t i o n i s -142-noticed only a f t e r the l a s t two runs. Similar cases of an increased c a t a l y t i c a c t i v i t y a f t e r the f i r s t cycle for RhCA^ supported on phosp-12 + hinated s i l i c a and (Rh(NBD)[poly-P(C^K^) 2]} supported on poly-styrene^ have been reported. Tetraphosphine complex T 2_Q (Fig. 13) can be used e f f e c t i v e l y only twice. The conversion which i s r e l a t i v e l y slow i n the f i r s t run diminishes i n the second, and i n the t h i r d one i s p r a c t i c a l l y zero. Rhodium e l u t i o n i s noticed only a f t e r the f i r s t run therefore the almost complete deactivation a f t e r the second one must be due to some other f a c t o r ( s ) . Copolymerization of the trisphosphine complexes with CA^Si-CH^ also helps maintain the a c t i v i t y . For the ser i e s (Figs. 11, 15-17) a l l the polymers were used f i v e times, with the copolymers being more act i v e i n the l a s t run than the homopolymer. The deactivation pattern changes gradually with the increasing content of 0^/2 ^i-CH^. A c t i v i t y of the homopolymeric R2_o decreases gradually i n every subsequent cycle whereas the copolymers maintain high a c t i v i t y i n more cycles. This i s then followed by a drop of a c t i v i t y i n subsequent cycles. The larger the 0^/2 ^i-CH^ content the longer the c a t a l y s t retains i t s high a c t i v i t y . There i s some rhodium e l u t i o n noticed f o r a l l three copolymers i n the t h i r d c y c l e , none i n the fourth, only to become strong i n the f i f t h run. There i s no d i s t i n c t c o r r e l a t i o n between the deactivation and the rhodium e l u t i o n . In contrast, the diff e r e n c e i n the deactivation pattern of the homo- (Fig. 13) and the copolymeric (Fig. 19) tetraphosphine complexes, T^_Q and ^2-200 1 s n o t large. Their a c t i v i t y decreases gradually to a very low l e v e l f o r the copolymer and almost zero for the homo i n three -143-Figure 40. Schematic r e p r e s e n t a t i o n of pores w i t h i n the polymeric matr i x of the complexes (a) R2-0 a n d  R8-0> a n d 0>) R2-75,150,200 a n d R8-100--144-consecutive cycles, always being lower i n the corresponding runs than the trisphosphine complexes. A possible explanation for the deactivation pattern of the homo- and copolymeric trisphosphine macrocomplexes and the f a c t that the a c t i v i t y of the tetraphosphine compounds i s always lower than that of the trisphosphine i s schematically depicted i n F i g . 40. The equilibrium between the c a t a l y t i c a l l y a ctive species P2RhC£ and the less active dimer [?2RhC£]2 exemplified by eq (22) should depend on the distance between the rhodium centres. The siloxane polymeric network appears to be r i g i d . In the homopolymeric phosphine complex metal centres are probably close to each other within a pore (Fig. 40a). Hence the dimerization can e a s i l y occur. On the other hand the r i g i d i t y of the matrix can prevent the dimerization of the copolymeric species. Here the rhodium centres i n most cases are separated from each other by 0^^S±-CR^ moieties (Fig. 40b) and thus the dimerization process i s hindered. It i s also found that the separation of rhodium centres i n the dimeric P^Rt^CJ^ complexes by copolymerization with Ci^Si-CH^ does not improve the a c t i v i t y and r e c y c l a b i l i t y of the complex. The above r e s u l t s seem to indicate that the dimerization to P^Rl^C^ i s one of the reasons for deactivation of the trisphosphine macrocomplexes P^RhCA, whose o v e r a l l a c t i v i t y depends on the serie s of reaction e q u i l i b r i a (23), analogous to (16), (20) and (21). -145-P — Rh CI p / P —RhCl P \ / C l \ ^ p -Rh Rh x ci ^ \ p - 1 (23) I p ^RhH 2 C I P :RK CI Cl H 2 ^ P -Rh \ P -The s t a b i l i t y of the c a t a l y s t S w i t h the formula { [ O ^ ^ S i - ( C H ^ -P(C,H,.) 0], 7RhC£} i s g r e a t l y improved as compared w i t h R and R D . As o .> 2 J • / x 2—(J o—0 mentioned e a r l i e r the increased P/Rh r a t i o i n f l u e n c e s adversely the a c t i v i t y of the c a t a l y s t and indeed the a c t i v i t y f o r styrene hydrogenation w i t h S i s lower even i n the f i r s t run than that of the tetraphosphine complex T^ 2QQ ( F i g . 14). Due t o the r i g i d i t y of the polymeric network the e x t r a phosphines (over the s t o i c h i o m e t r i c 3:1 of P/Rh r a t i o ) are r e l a t i v e l y c l o s e to the rhodium atoms as roughly shown i n F i g . 41. -146-F i g . 41. Schematic r e p r e s e n t a t i o n of a pore w i t h i n the polymeric matrix of the complex S, { [ 0 3 y 2 S i - ( C H 2 ) 2 - P ( C 6 H 5 ) 2 ] 3 - ? R h c ^ x -The proximity of the phosphines w i t h i n a pore s h i f t s the d i s s o c i a t i o n e q u i l i b r i u m (20) RhCAP, «c ^ RhCJIP. + P (20) -147-to the l e f t thereby p r o h i b i t i n g the formation of the a c t i v e bisphosphine species and decreasing the chances of the o l e f i n competing for the coordination s i t e . On the other hand the presence of the a d d i t i o n a l ligands has a p o s i t i v e e f f e c t . The a c t i v i t y which i s the same i n the f i r s t two cycles decreases i n the t h i r d one and stays at t h i s l e v e l i n at least two more cycles. Although the extra phosphines i n the polymer lower the c a t a l y s t ' s a c t i v i t y i n the f i r s t cycles they help to maintain i t a steady l e v e l i n the subsequent runs. Due to the proximity of free phosphines the competition of equilibrium (20) with (22) somehow prevents the formation of le s s active dimeric species P^Rl^C^-No rhodium e l u t i o n at any time (Table IX) suggests that the extra phosphines within the polymer have a s t a b i l i z i n g e f f e c t on the complex. This r e s u l t i s s i m i l a r to those obtained for the polymeric {Rh(NBD)[poly-7(.C^B.^)^]}+ where higher P/Rh r a t i o s seem to prevent decomposition to the metal . - The r i g i d i t y of the polymeric backbone d e s t a b i l i z e s the macro-complex by imposing s t e r i c s t r a i n on the metal centre. This i n turn may r e s u l t i n d i s s o c i a t i o n of the ligands followed eventually by e l u t i o n of the metal, probably i n the form of some solvated species, from the polymer's network. The c a t a l y s t with the higher P/Rh r a t i o , S, i s more stable; here the diss o c i a t e d ligands can be replaced by others i n the v i c i n i t y of the metal atom and thus preventing the e l u t i o n . The fa c t that a l l the polymers deactivate to d i f f e r e n t degrees upon r e c y c l i n g , including the tetraphosphine complexes, indicates that factors other than dimerization of P^RhCJi and rhodium e l u t i o n from the matrix play a r o l e i n the deactivation process. Complex R2-0 ^ o r e x a m P l e i s oxygen s e n s i t i v e and when exposed to a i r between cycles (Fig. 20) loses -148-i t s a c t i v i t y r a p i d l y . It i s possible that i n sp i t e of great precautions taken the polymers come into contact with traces of oxygen, when handled between cycles, and are deactivated t h i s way. Since upon r e c y c l i n g the surface area of the ca t a l y s t s increases, as indicated by EM micrographs (Figs. 33-37 and Section 5-5.), oxygen has probably easier access to metal centres and thus can "poison" the ca t a l y s t easier. Migration of a c t i v e metal centres on the surface of the polymer 6 12 A and/or a change of nature of the act i v e species have been suggested ' as being possibly responsible for the change i n the properties of the supported phosphine rhodium c a t a l y s t s . A s i m i l a r phenomenon i s possible i n the case of the siloxyphosphine macrocomplexes where the s t r a i n around the metal centre imposed by the r i g i d ligands may cause d i s s o c i a t i o n of some ligands with the subsequent formation of some other, s t i l l attached to the polymer, but less a c t i v e species. 137 On the other hand i t has been reported . that i n the c a t i o n i c 2+ species {Rh^[1,2-bis(diphenylphosphino)ethane] } each Rh atom i s bonded to two P atoms and through the symmetrical II-arene coordination to a phenyl r i n g of the ligand; each Rh atom maintaining thus an "18-electron 138 valence s h e l l " . By analogy, the p o s s i b i l i t y of the de a c t i v a t i o n of the polymeric c a t a l y s t s i n the hydrogenation of styrene due to the styrene coordination v i a the aromatic r i n g was considered. Since the phenyl r i n g i s a 6-electron donor i t would have to displace other ligands so that the "18-" or "16-electron r u l e " could be preserved. The c a t a l y t i c a c t i v i t y of such a newly formed complex would be considerably d i f f e r e n t from that of the s t a r t i n g phosphine complex. -149-This may be checked by changing styrene to cyclohexene as the hydrogenation substrate and so eliminating the p o s s i b i l i t y of II-arene coordination to Rh(I). F i g . 30 shows that with cyclohexene the a c t i v i t y of the polymeric c a t a l y s t R^-O decreases on r e c y c l i n g also. In a fashion s i m i l a r to r e s u l t s obtained with ^-75 e a r l i e r i - n the course of t h i s work (section 5-2-1) the degrees of conversion with a r e a^- s o m u c n lower than for styrene. No rhodium e l u t i o n i s observed. What i s most relevant i s the fact that a noticeable deactivation of the c a t a l y s t takes place when going from the f i r s t cycle to the second, i n fac t even more so than for styrene. This indicates that even i f there i s any styrene coordination to Rh(I) i t i s not the main cause of deactivation of the c a t a l y s t . The e f f e c t of the length of the spacer "arm" between the metal atom and the matrix discussed e a r l i e r i n t h i s chapter i s also noticed i n the polymeric siloxyphosphine complexes R n _ m ; the e f f e c t i s p a r t i c u l a r l y pronounced when R and R are compared. Complex R maintains i t s z—U o—0 o—0 a c t i v i t y over a greater number of cycles than R^-O ^ i g s 11 and 12). Even though rhodium e l u t i o n takes place f o r Rg_Q i n the l a s t two runs the a c t i v i t y i n the s i x t h cycle i s s t i l l greater than that of R 2 _ Q i n the f i f t h . The presence of longer C Q chains i n R _ as compared with C„ chains o o—U z i n R^ Q r e s u l t s most l i k e l y i n a spreading of the ac t i v e rhodium centres further apart thus preventing dimerization and i n turn allowing the ca t a l y s t to be ac t i v e over a larger number of cycles than R 2 _ Q ' Also, as mentioned before, the e f f e c t of longer spacer "arms" i s such that the anchored s i t e s which gain more freedom of mobility behave more l i k e species soluble i n sol u t i o n . The soluble siloxyphosphine complex H i s found to be more ac t i v e -150-than any of the polymeric siloxyphosphine complexes studied. It i s therefore possible that the fact that the o v e r a l l l i f e t i m e of Rg_Q (C 0 chain) i s longer than that of R„ _. (C„ chain) i s influenced by o z—U z s i m i l a r f a c t o r ( s ) . The a c t i v i t y of the copolymer R (Fig. 18) i s higher i n the o—1UU f i r s t two cycles than the a c t i v i t y of R c _ (Fig. 12). However, on o—U subsequent r e c y c l i n g the a c t i v i t y of R g declines more r a p i d l y than that of R„ „. The phenomenon i s not well understood and at t h i s point o—U may be explained i n terms of some changes within the polymer. 5-4. Hydrogenation of Styrene and Cyclohexene with the Polymeric Complex R^ i n Solutions of D i f f e r e n t Volumes. An unusual phenomenon i s observed when reactions are run with s o l u t i o n volumes d i f f e r e n t from the standard 3 mL previously used. This i s most evident for the homopolymeric trisphosphine complex but i s also observed with other polymers. Data plotted i n F i g . 21 show that the degrees of conversion of styrene over the reaction time-span are d i f f e r e n t f or d i f f e r e n t s o l u t i o n volumes when using R _ ,. although a l l the concentrations are the same. The degree of conversion at a given time i s smaller for larger volumes i n the f i r s t c y c l e . In the second cycle the d i f f e r e n c e between two runs of volumes 3 and 6 mL i s n e g l i g i b l e (Fig. 22). F i n a l l y i n the t h i r d cycle the degrees of conversion are smaller for the s o l u t i o n with the smaller volume (Fig. 23). Polymer S shows a s i m i l a r tendency (Figs. 24-26) but to a much smaller extent. The degrees of conversion of styrene at a given time -151-are very s i m i l a r with d i f f e r e n t volumes but i n a l l three cycles the runs with larger volume give s l i g h t l y lower conversions than those with smaller volumes. The s i t u a t i o n i s s i m i l a r for the dimeric copolymer ^QQ when used i n hydrogenation of styrene (Figs. 27-29). In the f i r s t cycle the d i f f -erence between the 3 and 6 mL volume runs i s evident, as for R^-rj' t l i e run giving a greater conversions than the 6 mL one. In the second and t h i r d cycles the percentage conversion are i d e n t i c a l over the re a c t i o n time span regardless of the solution's volume. Figures 31 and 32 show that when cyclohexene i s hydrogenated with R2-0 t' i e d e 8 r e e s °f conversion over a given time period do not vary very much with d i f f e r e n t s o l u t i o n volumes. Here the trend both i n the f i r s t and the second cycle i s such that i n runs of larger s o l u t i o n volumes the degrees of conversion are s l i g h t l y higher than i n those with smaller volumes. The trend i s opposite to that observed for styrene. These r e s u l t s are quite reproduceablebut there i s no r e g u l a r i t y nor any apparent l o g i c a l pattern. Increased s t i r r i n g speed of a suspen-37 sion of supported phosphine rhodium c a t a l y s t has been reported to r e s u l t i n higher a c t i v i t y of the c a t a l y s t (expressed i n turnover numbers). But i n t h i s work v a r i a t i o n of s t i r r i n g rate does not have any influence. The observed changes of the degrees of conversion over a given time, with d i f f e r e n t s o l u t i o n volumes i s most l i k e l y caused by some processes a f f e c t i n g the polymeric network rather than the a c t i v e metal centres. However, no s u i t a b l e explanation of the observed phenomenon has yet been found. 5-5. Electron Microscope Studies . 2 6 It has been established by EM studies that the darkening of -152-the silica-supported trisphosphinerhodium(I) complexes during hydro-genation reactions i s a r e s u l t of reduction of Rh(I) to Rh° with the subsequent formation of rhodium metal c r y s t a l l i t e s . Two samples of the polymer R 2-75 - w e r e examined with the electron microscope. One was the f r e s h l y prepared c a t a l y s t and the other was the c a t a l y s t from the same batch which had been used i n the hydro-genation of styrene i n a benzene/ethanol (1:1 v/v) solvent mixture. The ca t a l y s t changed i t s colour from orange to l i g h t grey during the reaction. As discussed i n Section 3-2-2 the darkening i s a t t r i b u t e d to Rh° metal c l u s t e r formation and i t was hoped that t h i s could be established from X-ray and/or secondary image EM micrographs. The power of the applied electron beam had to be maintained at a low l e v e l so that the electrons themselves would not reduce the Rh(I) species to Rh(0) At the same time maximum magnification was required. Attempts to obtain secondary image micrographs of cross-sections of the polymeric beads at higher beam power and at a magnification factor 900 proved to be unsuccessful due to strong discharges. Rhodium d i s t r i b u t i o n , as observed on the X-ray micrographs, of the polymer used i n hydrogenation was not d i f f e r e n t from that of the fresh species and did not indi c a t e formation of metal c l u s t e r s ; at the maximum magnification achieved (11,200 fold) the r e s o l u t i o n was about 0.1 pm. The secondary image micrographs of the polymer surface, shown i n Figs. 33-37, do not reveal any m e t a l l i c rhodium c l u s t e r formation eit h e r , but they give i n t e r e s t i n g information as to the phy s i c a l nature of the polymer. A considerable d i f f e r e n c e between the appearance of -153-the new c a t a l y s t and a f t e r i t has been used i n hydrogenation can be seen i n Figs. 33 and 34. The f r e s h l y prepared polymer consists of r e l a t i v e l y smooth globules clustered together i n bigger conglomerates. Aft e r the c a t a l y s t has been used i n hydrogenation i t shows signs of deep cracks and ruptures. This could be due to two e f f e c t s . (a) The polymer i s suspended i n the reaction s o l u t i o n and s t i r r e d vigorously for 23h; thus i t s surface could be damaged mechanically, (b) In the course of the reaction hydrogen d i f f u s e s inside the polymer's pores and remains there i n the form of either a Rh hydride complex or as hydrogen gas. A f t e r the r e a c t i o n i s terminated the polymer i s f i l t e r e d , washed, and dried by evacuation. The rapid removal of a considerable amount of gas adsorbed i n s i d e the polymer could cause rupture of the beads. L i t t l e craters seen i n F i g . 35b could possibly form by the rupture of lumps from the surface of the beads. In the l e f t bottom corner of t h i s photo-graph there are surface cracks which could be the i n i t i a l stages of such a rupture. Similar magnification of a bead of the fresh polymer shows a very uneven surface but without any signs of cracking. At higher magnifications (>1100) and higher beam powers ( F i g . 36) another aspect of the structure of the used polymer can be seen. In the surface of the open cracks there are numerous holes of rectangular shape. At even higher magnifications (>11,200)(Fig. 37) small pieces of rectangular cross-section can be seen i n the same polymer. The X-ray images do not show any increased concentration of rhodium atoms along the edges of the c a v i t i e s . At t h i s stage no explanation as to the cause of t h i s phenomenon has been found. Unfortunately the attempt to prove, using EM, that darkening of the polymer i s r e l a t e d to m e t a l l i c rhodium c l u s t e r formation f a i l e d . Most -154-l i k e l y d i f f e r e n t and s p e c i f i c instrumental c o n d i t i o n s are r e q u i r e d to detect the presence of small m e t a l l i c c r y s t a l l i t e s . However, a very i n t e r e s t i n g i n s i g h t has been gained w i t h regard to the p h y s i c a l s t r u c t u r e of the polymer and the e f f e c t of handling and using i t i n the hydro-genation r e a c t i o n . -155-CONCLUSIONS The synthesis of polysiloxyphosphine complexes of rhodium(I) was achieved by hydrolysis of the chlorosilylphosphinerhodium precursors. The process of h y d r o l y t i c polycondensation does not change the environ-ment around the c e n t r a l metal atom; the macrocomplexes produced contain mainly, i f not e x c l u s i v e l y , rhodium(I) species of the predicted formulae. This i s concluded on the basis of the m i c r o a n a l y t i c a l and IR data, and the r e a c t i v i t y of the non-carbonyl complexes towards hydrogen and carbon monoxide. A l l the complexes which do not contain a carbonyl group are e f f e c t i v e r ecyclable c a t a l y s t s i n hydrogenation of styrene and cyclohexene, but t h e i r a c t i v i t y decreases upon r e c y c l i n g . The deactivation of the c a t a l y s t s seems to be caused by: (a) dimerization to di-u-chlorotetraphosphine species i n the case of the trisphosphine complexes; (b) "poisoning" of the c a t a l y s t s by traces of oxygen; (c) e l u t i o n of rhodium from the matrix; and/or (d) other changes i n the nature of the o r i g i n a l c a t a l y t i c species. However, i t i s possible that some of the deactivation i s caused by p h y s i c a l changes i n the polymeric matrix of the c a t a l y s t s which occur either during the hydrogenation r e a c t i o n or i n the handling between cycles. Copolymerization of trisphosphine complexes with CA^Si-CH^ r e s u l t s i n maintaining high a c t i v i t y i n more cycles, which i s believed to be due to metal centre i s o l a t i o n thereby preventing dimerization. Copolymerization with an excess of a phosphine prevents rhodium e l u t i o n from the matrix and r e s u l t s i n maintaining i t at a steady l e v e l upon r e c y c l i n g , although lowers the c a t a l y s t ' s i n i t i a l a c t i v i t y . Extension of the spacer "arm" between the backbone and the metal centre from a two-carbon to an eight-carbon chain gives a c a t a l y s t with an o v e r a l l longer l i f e t i m e ; t h i s i s also most l i k e l y the r e s u l t of better separation of the -156-active s i t e s . The r e s u l t s show that i n order to extend the l i f e - t i m e of these a i r - s e n s i t i v e c a t a l y s t s the polymers have to be handled i n such a way as to ensure more rigorous exclusion of oxygen. Probably a continuous-flow process with an exclusion of traces of oxygen from the o l e f i n s o l u t i o n feed-stock would be more successful i n t h i s respect than r e c y c l i n g the c a t a l y s t a f t e r i n d i v i d u a l hydrogenation runs. Also, the l i f e - t i m e of a c a t a l y s t with P/Rh>3 and with C 0 spacer "arms" would o probably be considerably increased. However, i t should be pointed out that large P/Rh r a t i o s would considerably lower the c a t a l y t i c a c t i v i t y . Unfortunately, i n s p i t e of expectations, not enough information could be garnered about the actual nature of the polymeric c a t a l y s t s to permit del i b e r a t e improvements. It i s recommended that the poly-merization procedure be more standardized by using either p e r i s t i l t i c or syringe pumps for introducing the s o l u t i o n of the c h l o r o s i l y l -phosphine complexes into the hydrolyzing medium. 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