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Synthesis and reactivity of terminal phosphido complexes of iridium(III) Bhangu, Kiran 1987

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SYNTHESIS AND REACTIVITY OF TERMINAL PHOSPHIDO COMPLEXES OF IRIDIDM(III) by KIRAN BHANGU .Sc. (Honours) University of B r i t i s h Columbia, 1985 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of Chemistry) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA June 1987 © Kiran Bhangu, 1987 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 D E - 6 ( 3 / 8 1 ) Abstract The i r i d i u m ( I I I ) methyl dlarylphosphido complexes, I r ( C H 3 ) ( P R 2 ) -[N(SiMe 2CH 2PPh2)2] (2a: R = phenyl, 2b: R = meta-tolyl), have been successfully prepared by transmetalation of the ir i d i u m ( I I I ) methyl iodide complex, Ir(CH 3)(I)[N(SiMe 2CH 2PPh 2) 2], with the corresponding lithium diarylphosphide. Based primarily on a nuclear Overhauser e f f e c t difference experiment, these complexes are assigned a stereochemistry intermediate between square pyramidal and t r i g o n a l bipyramidal forms. The pyramidal geometry at the phosphido ligand i s evident from the 3 1P{ 1H) NMR spectral data. The complex 2a affords a mixture of at least three, as yet uncharacterized complexes when heated to 60°C for 5 hours i n benzene sol u t i o n ; however, clean formation of the planar iridium(I) methyl-diphenylphosphine complex, Ir(PCH 3Ph 2)[N(SiMe 2CH 2PPh 2) 2], 3a, takes place when 2a i s exposed to l i g h t for 24 hours i n benzene s o l u t i o n . A crossover experiment indicates that the l a t t e r reaction involves an i n t r a -molecular mechanism. The n u c l e o p h i l i c i t y of the phosphido ligand i s evident from the reaction of 2a with CH 3I; the product afforded i n th i s reaction Is Ir(CH 3)(PCH 3Ph 2)(I)[N(SiMe 2CH 2PPh 2) 2], 4 . A l a b e l l i n g experiment with CD 3I shows that the reaction i s intermolecular as the product observed i s Ir(CH 3)(PCD 3Ph 2)(I)[N(SiMe 2CH 2PPh 2) 2]. i i i Exposure of 2a at room temperature to one atmosphere of H 2 produces a mixture of the i r i d i u m ( I I I ) dihydride Ir(H) 2(PHPh 2)[N(SiMe 2CH 2-P P h 2 ) 2 ] , 5, and methyl hydride Ir(CH 3)(H)(PHPh 2)[N(SiMe 2CH 2PPh 2) 2], 6, i n 70 and 30% y i e l d s , r e s p e c t i v e l y . The analogous reaction with one atmosphere of D 2 reveals that the formation of the methyl hydride complex involves an intramolecular proton abstraction by the phosphide ligand from the bound methyl group, as the minor product observed i n t h i s reaction i s Ir(CH 2D)(D)(PHPh 2)[N(SiMe 2CH 2PPh 2) 2]. A mechanism i s proposed involving the formation of Ir(=CH 2)(PHPh 2)[N(SiMe 2CH 2PPh 2) 2] followed by trapping with D 2 to give the methyl hydride product. The dihydride complex observed i n these reactions i s apparently produced by h e t e r o l y t i c cleavage of dihydrogen. Under excess CO, complex 2a i s converted to an octahedral carbonyl complex Ir(CH 3)(CO)(PPh 2)[N(SiMe 2CH 2PPh 2) 2], 9; the carbonyl and the phosphide ligands i n t h i s complex are i n c i s arrangement. Upon removing the excess CO from the reaction mixture, another stereoisomer, 10, i s produced In which the carbonyl and the phosphide ligands are trans to one another. It i s suggested that the carbonyl complex 9 observed under excess CO i s the k i n e t i c a l l y favoured isomer which rearranges to the more thermodynamically stable isomer, 10, upon removal of the excess CO. Both of the carbonyl Isomers are unstable In s o l u t i o n at room temperature as they convert to the planar iridium(I) complex Ir(CO)[N(SiMe 2CH 2PPh 2) 2] and methyldiphenylphosphine. i v Table of Contents Page Abstract i i Table of Contents i v L i s t of Figures v i i L i s t of Tables i x Glossary of Abbreviations x Acknowledgement x i i Chapter 1 Introduction 1 1.1 Synthesis 3 1.1.1 Metal carbonylate n u c l e o p h i l i c attack 4 1.1.2 Transmetalation 4 1.1.3 Diphosphine cleavage 5 1.1.4 Oxidative addition 5 1.1.5 Dehydrohalogenation 5 1.2 R e a c t i v i t y 6 1.2.1 N u c l e o p h i l i c i t y 7 • 1.2.2 E l e c t r o p h i l i c i t y 8 1.2.3 Other reactions: Hydrogenolysis and Carbonylation 8 V Page 1.3 Applications of phosphido complexes 10 1.3.1 Phosphido-bridged complexes 10 1.3-2 Phosphinidene complexes 12 1.4 Hybrid ligand strategy 13 1.5 Dihydrogen A c t i v a t i o n 14 1.5-1 H e t e r o l y t i c a c t i v a t i o n of dihydrogen . . 15 1.6 Objectives 16 Chapter 2 Synthesis and R e a c t i v i t y 18 2.1 Synthesis 18 2.2 R e a c t i v i t y 25 2.2.1 Thermolysis 25 2.2.2 Photolysis 26 2.2.3 Reaction with methyl iodide 30 2.2.4 Hydrogenation 34 2.2.5 Carbonylation 42 Chapter 3 Conclusions and Suggestions f o r Future Work 49 3.1 Conclusions 49 3.2 Suggestions for future work 51 v i Page Chapter 4 Experimental 52 4.1 General Information 52 4.2 Synthesis 53 Chapter 5 References 62 Appendix 68 v i i L i s t of Figures Page F i g . 1.1 A t r a n s i t i o n metal complex Incorporating (a) a pyramidal phosphido ligand, and (b) a planar phosphido ligand . . 2 F i g . 1.2 C r y s t a l structure of ( n 5 - C 5 H 5 ) 2 H f ( P E t 2 ) 2 3 F i g . 1.3 Three valence forms of Cp*HfCI 2{n 2-C(0)P(CMe 3) 2) . . . 10 F i g . 1.4 Tridentate hybrid ligand bound to a metal center . . . 14 F i g . 2.1 XH NMR spectrum (C 6D 6, 400 MHz) of Ir(CH 3)(PPh 2)-[N(SiMe 2CH 2PPh 2) 2], 2a 20 F i g . 2.2 Possible geometries for Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2], 2a 22 Fi g . 2.3 (a) lE NMR spectrum (C 6D 6, 400 MHz) and (b) N0EDIFF spectrum of Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2], 2a . . . . 23 F i g . 2.4 Ir(CH 3)(PR 2)[N(SiMe 2CH 2PPh 2) 2] complex incorporating (a) a pyramidal phosphido ligand, and (b) a planar phosphido ligand . . . . . . . . . 24 F i g . 2.5 XH NMR spectrum (C 6D 6, 400 MHz) of the thermolysis products of Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2], 2a . . . . 25 F i g . 2.6 XH NMR spectrum (C 6D 6, 400 MHz) of Ir(PCH 3Ph 2)-[N(SiMe 2CH 2PPh 2) 2], 3a 27 F i g . 2.7 AH NMR spectrum (C gD 6, 400 MHz) of Ir(CH 3)(PCH 3Ph 2)(I)-[N(SiMe 2CH 2PPh 2) 2], 4 30 v i i i Page F i g . 2.8 Possible stereochemistries for Ir(CH 3)(PCH 3Ph 2)(I)-[N(SiMe 2CH 2PPh 2)2] 3 1 F i g . 2 .9 XH NMR spectrum (C 6D 6, 400 MHz) of Ir(H) 2(PHPh 2)-[N(SiMe 2CH 2PPh 2) 2], 5, and Ir(CH 3)(H)(PHPh 2)-[N(SiMe 2CH 2PPh 2) 2], 6 35 Fig . 2.10 2H{--H} NMR spectrum (CH 3C 6H 5, 40 MHz) of Ir(D) 2(PDPh 2)-[N(SiMe 2CH 2PPh 2) 2], 7, and Ir(CH 2D)(D)(PHPh 2)-[N(SiMe 2CH 2PPh 2) 2], 8 38 Fi g . 2.11 XH NMR spectrum (C 6D 6, 400 MHz) of Ir(CH 3)(CO)(PPh 2)-[N(SiMe 2CH 2PPh 2) 2], 9 43 Fi g . 2.12 1 3C{ 1H} NMR spectrum (C 6D 6, 75 MHz) of Ir(CH 3)( 1 3 C 0 ) -(PPh 2)[N(SiMe 2CH 2PPh 2) 2], 9 43 Fi g . 2.13 *H NMR spectrum (C 6D 6, 400 MHz) of Ir(CH 3)(C0)(PPh 2)-[N(SiMe 2CH 2PPh 2) 2], 10 . . . . . 46 Fi g . 2.14 1 3C{ 1H} NMR spectrum (C 6D 6, 75 MHz) of Ir(CH 3)( 1 3 C 0 ) -(PPh 2)[N(SiMe 2CH 2PPh 2) 2], 10 46 i x L i s t of Tables Page Table 1 1H NMR spectral data 58 Table 2 T r a n s i t i o n metal phosphide complexes reported i n the l i t e r a t u r e 68 X Glossary of Abbreviations A p angstrom unit, 10 cm atm atmosphere br broad n-Bu n-butyl °C degree c e l s i u s cm -! wavenumber COE cyclooctene, TI - C S H J ^ Cp cyclopentadienyl, C 5H 5~ * Cp pentamethylcyclopentadienyl, (CH3)5C5-d doublet decomp decomposition dt doublet of t r i p l e t s Et ethyl, C 2H 5 FAB fast atom bombardment fac f a c i a l gem geminal g gram(s) proton decoupled (NMR) Hz hertz, s e c - 1 h hour(s) IR Infrared i - p r isopropyl, (CH 3) 2CH J coupling constant x i J f lpp apparent coupling constant ( v i r t u a l coupling) L a neutral unidentate ligand m moderate i n t e n s i t y (IR) multiplet (NMR) M the central metal atom i n a complex Me methyl, CH 3 mer meridional min minute(s) mmol mil l i m o l e ( s ) m.p. melting point m-tol meta-tolyl, CH 3C 6H^ mL m i l l i l i t r e NMR nuclear magnetic resonance NOEDIFF nuclear Overhauser e f f e c t difference o - t o l o r t h o - t o l y l , CH 3C 6H 4 Ph phenyl, C 6H 5 ppm parts per m i l l i o n (chemical s h i f t ) q quartet s strong i n t e n s i t y (IR) sin g l e t (NMR) t t r i p l e t UV-Vis u l t r a v i o l e t - v i s i b l e w weak i n t e n s i t y W watt x i i Acknowledgements I am extremely g r a t e f u l to Dr. M.D. Fryzuk for his expert guidance and utmost patience throughout the course of this work. I also thank members of the Fryzuk group for t h e i r support and fr i e n d s h i p . I wish to express my gratitude to the proof-readers for t h e i r excellent c r i t i c i s m . The assistance and cooperation of various departmental services are g r a t e f u l l y acknowledged. 6 1 CHAPTER 1 INTRODUCTION During the l a s t two decades, in t e r e s t i n t e r t i a r y phosphine com-plexes of the t r a n s i t i o n metals (L nM-PR 3; R = a l k y l , a r y l and hydride) has grown tremendously. This has been due, i n part, to the observations that many of these derivatives are ca t a l y s t precursors for such i n d u s t r i a l l y s i g n i f i c a n t processes as hydrogenation, hydroformylation and polymeriza-tion.^" As a r e s u l t , the examples of phosphine-derived complexes are numerous. In addition to the well known t e r t i a r y phosphines, ligands for other valences of phosphorus are known but less studied. These include metallated phosphoranes (-PR^), phosphides (-PR2) and phosphinidenes 2 (=PR). Although phosphorane and phosphinidene complexes are s t i l l extremely rare, the chemistry of t r a n s i t i o n metal phosphide complexes has become a rap i d l y growing research area. Structural data indicate that a terminal phosphido ligand PR2~ (R = a l k y l , a r y l , halide and hydride) i n the complex L nM-PR 2 can have one of two possible geometries: i t can either be pyramidal,^ or planar^ ^ (Fig-1.1). A simple bonding scheme distinguishes these two configurations, 2 F i g . 1.1 A t r a n s i t i o n metal complex incorporating (a) a pyramidal phosphido ligand, and (b) a planar phosphido ligand as shown by (a) and (b), according to the number of electrons donated to 3 the metal by the phosphorus atom. In the case of pyramidal geometry, the PR2~ ligand i s a 2 electron donor and possesses a o-bond with the metal; i n planar geometry, the ligand i s a 4 electron donor and i s capable of n-bonding with the metal because of the a v a i l a b i l i t y of the f i l l e d phosphorus 3p o r b i t a l . An obvious distinguishable feature of the two configurations i s the metal-phosphorus bond lengths: complexes containing planar phosphido group possess a shorter M-P bond length compared to that of complexes containing pyramidal phosphido group. Another d i s t i n c t i o n Is found i n metal-phosphorus-substituent bond angles; the respective ranges are 6-14 4 5 reported to be 127-140° and 106-114° for planar and pyramidal ' phosphido complexes. These two modes of bonding are best exemplified by the b i s ( c y c l o -12 pentadienyl)bis(diethylphosphido)hafnium(IV) complex ( F i g . 1.2). In t h i s complex, the geometry about P(2) i s pyramidal with a non-bonding 3 C2« F i g . 1.2 Cry s t a l structure of (T) 5-C 5H 5) 2Hf(PEt 2)2 pair of electrons, while that at P ( l ) i s planar with the lone pair being involved i n it-bond formation with hafnium. This n-donor i n t e r a c t i o n i s quite substantial as evidenced from the shorter Hf-P(l) bond length of 2.488A compared to the Hf-P(2) bond length of 2.682A. In addition to the hafnium complex mentioned above, a wide var i e t y * < 9,15 , . 9,12 . , , 15-18 fc t 15-18 of titanium, zirconium, molybdenum, tungsten, . , 9,19 . 17,21-23 , 3,18 . . . 26 . ... 5,27,28 rhenium, ' i r o n , ' osmium ' , rhodium, ir i d i u m ' ' and 25 n i c k e l phosphido complexes have been reported i n the l a s t few years. The majority of these complexes possess pyramidal geometry at the phosphido ligand with very few examples of the complexes containing a planar phosphido group. 1.1 Synthesis A l i m i t i n g factor i n the syntheses of t r a n s i t i o n metal complexes containing terminal phosphido groups i s t h e i r strong tendency to undergo 29 dimerization; only In a few s t e r i c a l l y or e l e c t r o n i c a l l y favourable 4 cases are they preparatively accessible i n the terminal mode. Typical methods used i n t h e i r preparation are summarized below. 1.1.1 Metal carbonylate n u c l e o p h i l i c attack Nucleophilic attack of t r a n s i t i o n metal carbonylate anion species on halophosphines has been used most extensively i n the formation of terminal phosphido complexes of group 6 metals (Eq. l . l ) . ^ a [Cp(CO)3M]Na + PCA 3 -NaCA Cp(CO) 3M(PCA 2) M = Cr, Mo, W (1.1) 1.1.2 Transmetalation A v a r i e t y of hafnium and zirconium phosphide complexes, synthesized i n the early e i g h t i e s , involved transmetalation of the respective group 4 bis(cyclopentadienyl) d i c h l o r i d e complexes with l i t h i u m phosphides (Eq. 1.2). 1 2 Cp 2MCl 2 + 2 LiPR 2 ^ Cp 2M(PR 2) 2 + 2 LiCA (1.2) M = Zr, Hf R = Me, Et, Ph, Cy, t-Bu 5 1.1.3 Diphosphine cleavage The iron complex ( T| 5-C 5H 5)Fe(CO) 2{P(CF 3) 2) was prepared by the action of tetrakis(trifluoromethyl)-diphosphine on the 30 bis(cyclopentadienyldicarbonyliron(II)) complex (Eq. 1.3). [(Ti 5-C 5H 5)Fe(CO) 2] 2 + ( C F 3 ) 2 P ' P ( C F 3 ) 2 ^ 2 (n 5-C 5H 5)Fe(CO) 2{P(CF 3) 2> (1.3) This route i s analogous to that reported for the preparation of the arsenido complex (n 5-C 5H 5)Fe(CO) 2{As(CF 3) 2>. 1.1.4 Oxidative a d d i t i o n The f i r s t six-coordinate rhodium(III) and Iridium(III) complexes containing PX 2 (X = F,C1,H) ligands were prepared by a method which involved oxidative addition of a PX 2Y species to low valent Vaska-type 5 26—28 rhodium(I) and iridium(I) substrates (Eq. 1.4). ' trans-[M(CO)(U(PEt 3) 2] + PX 2Y •trans-[M(CO)CAY(PEt 3) 2(PX 2)] (1.4) M = Rh, I r X = F; Y = CA,Br,I,H X = CA; Y = C". X = H; Y = H 1.1.5 Dehydrohalogenation A general synthetic route used to prepare terminal phosphido complexes of ruthenium and osmium involves dehydrohalogenation of an i o n i c 6 halo-metal-alkyl(or a r y l ) phosphine species with a strong non-nucleophilic 24 base such as l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (Eq. 1.5). PPh, 3 / OC I P — H O C ^ \ ^ C l Ph PPh, R CIO, DBU 3 / DBU.HCI04 PPh, OC I P OC M Ph / l \ (1.5) CI PPh, M = Ru; R = H M = Os; R - H, Ph, I, OMe This dehydrohalogenation route has also been used i n the syntheses 32 of tungsten phosphido complexes with planar phosphido groups (Eq. 1.6). W R 0 C CI \ H DBU -DBU.HCI W - 7 (1.6) R R - i-pr, t-Bu 1.2 R e a c t i v i t y The r e a c t i v i t y patterns observed for terminal phosphido complexes depend mainly on the geometry of the phosphido ligand. N ucleophilic properties of the phosphorus centre are normally associated with the pyramidal configuration due to the presence of a lone pair of electrons; 7 however, the formal charges present i n planar phosphido derivatives suggest that the phosphorus centre should display e l e c t r o p h i l i c character. 1.2.1 N u c l e o p h i l i c i t y Molybdenum and tungsten complexes containing pyramidal phosphido ligands, trans-[Cp(CO) 2(PMe 3)M(PPh 2)], demonstrate the high n u c l e o p h i l i c i t y of the phosphido ligand by formation of [Cp(CO) 2(PMe 3)M(PPh 2R)] +X - (R = H, Me, Br) upon reaction with the e l e c t r o p h i l e s Mel, HCA and B r 2 (Eqs. 1.7).^ trans-[Cp(CO) 2(PMe 3)M(PPh 2)] B r ? ^ [Cp(CO) 2(PMe 3)M(PPh 2Br)J+Br -The i r i d i u m ( I I I ) complex, t r a n s - [ I r ( C O ) C A 2 ( P E t 3 ) 2 ( P C * 2 ) ] , can e a s i l y be converted to trans-[Ir(CO)CA 2(PEt 3) 2(P(U 2Y)] (Y = 0, S or Se) as the n u c l e o p h i l i c phosphido ligand reacts with 0 2, S 8 or Se 8 (Eqs. 1.8)."* Mel (1.7) [Cp(CO) 2(PMe 3)M(PPh 2Me)] +I - [Cp(CO)2(PMe 3)M(PPh 2H)] +C JT M = Mo, W t r a n s - [ I r ( C O ) C l 2 ( P E t 3 ) 2 ( P C l 2 ) ] t r a n s - [ I r ( C 0 ) C l 2 ( P E t 3 ) 2 ( P C 1 2 S e ) ] tra n s - [ I r ( C 0 ) C l 2 ( P E t 3 ) 2 ( P C 1 2 0 ) ] 8 1.2.2 K l e c t r o p h l l i c l t y Complexes containing planar phosphido groups are rare, hence l i t t l e i s known about t h e i r r e a c t i v i t y . Studies done on the complex Cp(CO)2W{P(CMe3)2} suggest that the phosphorus center has e l e c t r o p h i l i c 32 character (Eq. 1.9). This complex undergoes spontaneous reaction with ROH to form the d e r i v a t i v e i n which the alcohol has formally added across the tungsten-phosphorus double bond. CMe, Cp(CO)2W = P ROH \ Cp(CO)2HW OR CMe, -CMe 3 CMe, (1.9) R - H, Me, Et 1.2.3 Other reactions: Hydrogenolysis and Carbonylatlon Hydrogenolysis and carbonylatlon studies attempted on planar hafnium 33 phosphido complexes have produced i n t e r e s t i n g r e s u l t s . The reaction of a dialkyl(di- t e 2 ,*-butylphosphido)hafnium(IV) complex with H 2 induces clean loss of methane and formation of a dimeric phosphido-bridged complex (Eq. 1.10). 2 Cp*HfMe 2{P(CMe 3) 2} + 2 H 2 ^ [Cp*Hf(H)Me{P(CMe 3) 2}] 2 + 2 CH H (1.10) The phosphido ligand acts as an a n c i l l i a r y ligand i n t h i s r e a c t i o n . However, i t i s susceptible to hydrogenolysis as shown when the complexes 9 Cp*HfCA{p(CMe 3) 2}2 a n d Cp*Hf C A2(P(CMe 3) 2) are exposed to H 2 (Eqs. 1.11, 1.12). The bis(di-£ert-butylphosphido)hafnium complex reacts very r a p i d l y with H 2 to generate both di-tert-butylphosphine, and a dimeric complex with hydride and phosphido bridges (Eq. 1.11). However, the r e a c t i v i t y Cp*HfCl{P(CMe 3) 2>2 + H 2 • [Cp*HfCl( H-H){u-P(CMe 3) 2>] 2 + HP(CMe 3) 2 (1.11) Cp*HfCl 2{P(CMe 3) 2} + H 2 ~ H p ( C M e 3 ^ [Cp*HfCl 2H] •»• Cp*HfCl 3 + (Cp*HfH 2CA) + (1-12) of the mono(di-£ert-butylphosphido)hafnium complex i s much slower (Eq. 1.12); the reaction proceeds over days to produce di-teri-butylphosphine and disproportionation products, Cp H f C l 3 and (Cp HfH 2CA) x» plus 40% decomposition. Carbonylation studies done on the mono(di-tert-butylphosphido) hafnium complex, Cp HfCl 2(P(CMe 3) 2/> show that i t reacts very r a p i d l y with CO to a f f o r d a carboxyphosphide complex, Cp*HfCI 2{n 2-C(0)P(CMe 3) 2} (Eq. 1.13) Cp*HfCl 2{P(CMe 3) 2} + CO • Cp*Hf Cl 2{(i1 2-C(0)P(CMe 3) 2> (1.13) The l a t t e r complex i s the f i r s t carboxyphosphide d e r i v a t i v e of a t r a n s i t i o n element to be reported. Three valence forms for t h i s complex are possible 10 + - M (c) -M M = Cp*HfCI2 -M (e) F i g . 1.3 Three valence forms of Cp*HfCI 2{i1 2-C(0)P(CMe 3) 2> (F i g . 1.3). Spectroscopic data suggest that form (c) i s the preferred structure for this complex i n which s i g n i f i c a n t it-bonding between the carbonyl carbon and the phosphorus atom takes place. Diagnostic of t h i s resonance form i s the u p f i e l d *3C(*H} NMR s h i f t of the carbonyl carbon atom (3.03 ppm, = 101 Hz) when compared to the c h a r a c t e r i s t i c low f i e l d 34 values for "carbene-like" or "carbenium-like" acyl complexes. 1.3 Applications of phosphido complexes Terminal phosphido complexes have been u t i l i z e d as precursors to phosphido-bridged complexes and terminal phosphinidene complexes. 1.3.1 Phosphido-bridged complexes BInuclear t r a n s i t i o n metal complexes have been the subject of intense research since they f i n d extensive use i n the designed syntheses of 35 39 metal c l u s t e r s ' and i n studies related to c a t a l y s i s by adjacent metal s i t e s . Phosphide ligands as bridging groups are of p a r t i c u l a r 11 inte r e s t i n b i m e t a l l i c systems since they enhance the s t a b i l i t y of the binuclear systems with respect to d i s s o c i a t i o n to mononuclear * - 3 5 - 3 9 fragments. Phosphido bridged di-cobalt and di-manganese complexes have been 38 known since the early s i x t i e s . The dimer Co 2(C0) 6 ( n~PPh 2) 2 was synthesized v i a phosphorus-phosphorus bond cleavage of Ph 2P*PPh 2 by Co 2(CO) 8 (Eq. 1.14). PPh 2 Co2(CO)8 + Ph 2P.PPh 2 ( C O ) 3 C o ' ^ C o ( C O ) 3 + 2 CO (1.14) PPh, '2 35 More recently, Geoffroy has reported a number of heterodinuclear complexes which can be synthesized e a s i l y from t h e i r terminal phosphido counterparts. The d i r e c t reaction of the anionic monophosphido tungsten Li[W(CO)4(PHPh2)(PPh2)] + trans-RhCI(CO)(PPh3)2 (1.15) (CO)4 W P P h 2 . . . . H PPh, Rh CO + LiCI PPh 3 reagent with rhodium halide affords the diphenylphosphide bridged tungsten-35a rhodium complex (Eq. 1.15). The corresponding tungsten-iridium phosphido 35b bridged complexes can also be prepared e a s i l y by a s i m i l a r r e a c t i o n . 12 1-3.2 Phosphinidene complexes The understanding of t r a n s i t i o n metal-main group element multiple bonding has made continuous progress, gaining a strong impetus e s p e c i a l l y 41 42 from the findings i n carbene, carbyne, and nitrene and n i t r i d e c o o r d i -nation chemistry. T r a n s i t i o n metal double bonding to the phosphorus homologues of carbenes (CR 2), namely PR, i s a new f i e l d of research. The ligand PR, i n a complex LnM=PR, i s named a phosphinidene. Terminal phosphinidene complexes have been implicated as intermediates i n reactions 3 24 involving terminal phosphido complexes, ' but a stable example i s yet to be i s o l a t e d . Terminal monohalophosphido complexes, LnMPXR, are of p a r t i c u l a r i n t e r e s t since they are, through halide loss, p o t e n t i a l precursors for terminal phosphinidene complexes, (L nM=PR) +. ' Roper has reported an osmium(II) complex with a pyramidal iodophenylphosphido ligand; i t s reaction with s i l v e r s a l t leads to a product i n d i c a t i v e of a ca t i o n i c phosphinidene intermediate (Eq. 1.16). I OC PPh3 / I P \ / \ Os Ph Ag.SbF6 O C ^ | \ d m PPh3 Ag I \ / [Os] P >Ph SbF c I (g) -Agl (1.16) [Os] OMe / P _ H \ p h SbFc (i) MeOH [Os] P — P h SbF c (h) [Os] = OsCI(PPh3)2(CO)2 13 The osmium phosphido complex (f) upon coordination with s i l v e r ( I ) produces intermediate (g). Intramolecular elimination of Agl from the l a t t e r would produce the c a t i o n i c phosphinidene intermediate (h); i n s e r t i o n of such a species into the 0-H bond of methanol affords ( i ) . A l l attempts to trap (h) were unsuccessful. Bridging phosphinidene complexes, [L QM] 2PR, have been well 43 characterized. The f i r s t bridging phosphinidene complex to be reported, 44 [Cp(CO) 2Mn] 2PPh, was prepared by a sequence of metalation and demetala-tio n reactions as shown below (Eq. 1.17). R / ., 2 LiBu l M P H • LnMPRLi2 \ -2BuH > H R L M P - M L n " \ / I T (1-17) P' | - * {LnMPR} R V - M l _ n R R / I A ' 1 — • p LnM = CP(CO)2Mn L M ML R = Ph R' = c-CgH^ The treatment of Na 2M 2(CO) 1 0 with RPCJl2 i s a general synthetic route for 43 the syntheses of bridging phosphinidene complexes. 0.5 RN=NR NCI2 - 2 LiCI 1.4. Hybrid ligand strategy A subtle v a r i a t i o n i n ligand design can dramatically influence the r e a c t i v i t y of t r a n s i t i o n metal complexes. For t h i s reason, considerable e f f o r t has been directed towards the syntheses of new ligands. 14 The chelating hybrid ligand shown below ( F i g . 1.4) was f i r s t 45 synthesized i n our laboratory. The impetus for the design of this ligand PR2 Me 2Si^ j N M L n Me 2 Si^ | 2^ F i g . 1.4 Tridentate hybrid ligand bound to a metal center was the fact that soft t e r t i a r y phosphines form r e l a t i v e l y few derivatives 46 47 of the hard early t r a n s i t i o n metals, ' while the hard amide donors 48 provide very few stable, l a t e metal d e r i v a t i v e s . Thus, i t was thought that incorporation of the amido donor NR2 into a chelating array of phosphines might allow ligand coordination to a wide range of t r a n s i t i o n metals. This indeed was the case as a v a r i e t y of amido phosphine complexes 49 50 51 52 53 of N i ( I I ) , Pd(II), P t ( I I ) , ' Zr(IV), Hf(IV), I r ( I ) and Rh(I) ' have been synthesized. 1.5 Dihydrogen a c t i v a t i o n A c t i v a t i o n of dihydrogen may involve a) homolytic cleavage, b) oxidative addition or c) o v e r a l l h e t e r o l y t i c s p l i t t i n g ; these can be 54a represented by general equations 1.18 - 1.20. 15 Homolytic s p l i t t i n g 2Mn + H 2 2 HM n + 1 (1.18a) M 2 n + H 2 2 HM n + 1 (1.18b) Oxidative addition M n + H 2 H^in+2 (1-19) He t e r o l y t i c s p l i t t i n g M n + H 2 H~Mn + H + (1-20) These d i f f e r e n t processes of hydrogen a c t i v a t i o n have been discussed i n d e t a i l i n a number of review a r t i c l e s on h y d r o g e n a t i o n . ^ ' ^ Of p a r t i c u l a r relevance to the hydrogenation r e c t i o n described i n t h i s thesis i s the he t e r o l y t i c s p l i t t i n g of dihydrogen, which w i l l be considered b r i e f l y i n the following section. 1.5.1 H e t e r o l y t i c a c t i v a t i o n of dihydrogen H e t e r o l y t i c a c t i v a t i o n of dihydrogen involves the cleavage of the hydrogen molecule into a hydride (coordinated to the metal) and a proton 54a (usually s t a b i l i z e d by a base) (Eq. 1.20). Hete r o l y t i c H 2 cleavage i s d i f f i c u l t to d i s t i n g u i s h from oxidative addition of H 2 (step a, Eq. 1.21), 54a followed by deprotonation of a hydride with a base (step b, Eq. 1.21). H H M H 0 (a) M / | \ (b) Base H M -/ \ (1.21) H-Base+ 16 Hydrogenatlon of the complex Ir(CH 3)(I)[N(SiMe 2CH 2PPh 2) 2] (containing the basic amido ligand) generates a mixture of the iri d i u m ( I I I ) amine monohydride complex and the corresponding amine dihydride d e r i v a t i v e 53 (Eq. 1.22). This reaction proceeds v i a an apparent h e t e r o l y t i c cleavage of dihydrogen; however, the mechanism involved i n this transformation i s not c l e a r l y understood. Ph 2 M e * S i v \ s ° " 3 H2(1atm), 25°C N — | r 1 1 M e 2 s / *P P h2 P h2 Ph, ^ " / / i H Me 2Si^ | / Me 2Si ( H ^ N — lr CH3 + H ^ N — l r H (1.22) Me2Si | * | Me2Si | ' | •P Ph 2 Ph 2  m a J ° r 0 . minor | H2(1atm), 80 C ^ 1.6 Objectives Iridium phosphido complexes are of in t e r e s t for three major reasons: 5 27 28 1) there are very few examples of iri d i u m phosphides, ' ' despite the r e l a t i v e l y large l i t e r a t u r e dealing with t r a n s i t i o n metal phosphido complexes. 2) our research group has been involved for a number of years with 45 49-53 complexes containing the basic amide ligand, [N(SiMe 2CH 2PPh 2) 2] ; ' i t was of in t e r e s t to prepare complexes i n which both the above mentioned 17 amide donor as well as another basic phosphide ligand bind to the same metal, and hence observe the competing r e a c t i v i t y of these two ligands. 33 3) except for one example of early t r a n s i t i o n metal phosphido complex, there are no other complexes known i n which both an a l k y l and a terminal phosphide ligand are bound to the same metal. Such complexes may provide some information regarding metal mediated carbon-phosphorus bond formation. This thesis describes the syntheses of ir i d i u m ( I I I ) methyl d i a r y l -phosphido complexes, Ir(CH 3)(PR 2) [N(SiMe 2CH 2PPh 2) 2] (R - phenyl, m - t o l y l ) . The r e a c t i v i t y of the diphenylphosphido derivative was studied In d e t a i l . The n u c l e o p h i l i c i t y of the phosphido ligand i n this complex, i t s reaction with dihydrogen along with carbon monoxide addition are presented. 18 CHAPTER 2 SYNTHESIS AND REACTIVITY 2.1 Synthesis The i r i d i u m ( I I I ) methyl diarylphosphido complexes, I r ( C H 3 ) ( P R 2 ) -[N(SiMe 2CH 2PPh 2)2] (2a: R = Ph, 2b: R = m-tol), were synthesized by 52 transmetalation of the previously reported square pyramidal i r i d i u m ( I I I ) methyl iodide d e r i v a t i v e , Ir(CH 3)(I)[N(SiMe 2CH 2PPh 2) 2], 1, with stoichiometric amounts of the corresponding lithium diarylphosphide (Eq. 2.1). The reaction proceeds within minutes at room temperature with a M e 2 S i s | # , C H 3 N Ir' I + MeoSi Ph, Li PR. Toluene/ Me2Si CH, Ph, THF (-Lil) N Ir' PR 2 (2.1) Me2Si Ph, 2a: R = Ph 2b: R = m-tol dramatic colour change. The deep green colour of the methyl iodide deriva-t i v e changes quickly to the dark purple of the phosphido complex. The v i s i b l e spectrum of the diphenylphosphido derivative 2a shows a strong absorption band at 536 nm (e = 3.11x10 3 M - 1 cm - 1). This band i s presumably 19 a d-d t r a n s i t i o n , which i s c h a r a c t e r i s t i c of most f i v e coordinate d i , 52,55 molecules. There l i k e l y exists some s t e r i c hindrance between the a l k y l ligand on the metal and the a r y l unit of the phosphide donor. For example, when the methyl ligand on the metal was replaced by a phenyl group, the s t a r t i n g material I r ( P h ) ( I ) [ N ( S i M e 2 C H 2 P P h 2 ) 2 ] 5 6 f a i l e d to react with L i P P h 2 (Eq. 2.2). Ph, Me 2Si^ N- 1 Ir I + Li PR, Toluene/ Me2Si •P Ph, • THF R Rf CH3 o- to l CH3 i-pr Ph Ph CH 2 Ph Ph No Reaction (2.2) The H NMR spectra for the terminal phosphido complexes 2a and 2b are straightforward. The spectrum of 2a ( F i g . 2.1) w i l l serve to I l l u s t r a t e . The S i ( C H 3 ) 2 resonances are observed as two sharp s i n g l e t s of equal i n t e n s i t y i n d i c a t i n g inequivalent environments above and below the metal tridentate plane. An AB quartet of v i r t u a l t r i p l e t s " * ^ for the CH2P protons i s i n d i c a t i v e of a trans o r i e n t a t i o n of the chelating phosphine. Shaw^ has demonstrated that v i r t u a l coupling arises i n such AA'BB'XX' spin systems when Jyvt * s very large. For 2a and 2b , i n which the 20 phosphines are strongly coupled, an apparent A 2 B 2 X 2 pattern i s observed for Si(CH3)2 Ir — CH 3 F i g . 2.1 AH NMR spectrum (C 6D 6, 400 MHz) of Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2], 2a ( a s t e r i k indicates solvent protons) the CH2P protons. Signals for the para and meta protons of the phenyl rings are observed as a multiplet and are separated from the signals for the ortho protons by 0.75 ppm. A chemical s h i f t difference of 0.6 - 1.0 ppm between the ortho and para/meta protons of the phosphine phenyl groups ( i n deuterated aromatic solvents) i s also i n d i c a t i v e of trans disposed phosphines. 21 The above mentioned spectral data do not r e a d i l y d i s t i n g u i s h between the two basic geometries possible for the f i v e coordinate molecule: (a) t r i g o n a l bipyramidal (tbp) or (b) square pyramidal (sqp). For the l a t t e r case, there i s also uncertainty as to which ligand i s a p i c a l : methyl (sqp 1), diphenylphosphide (sqp 2), or amide (sqp 3) (F i g . 2.2). The *H NMR spectrum ( F i g . 2.1) r e a d i l y rules out the sqp 3 geometry, as the methyl ligand would be expected to resonate as a doublet of t r i p l e t s for this stereochemistry because of i t s larger trans coupling with the phosphide group than i t s c i s coupling with the chelating phosphine donors; rather i t i s observed to be a four l i n e pattern ( 3J_„ „„, = CH jPPh 2 ,H 6.0 Hz, 3Jppk H = 3.0 Hz). A nuclear Overhauser e f f e c t d i f f e r e n c e (NOEDIFF) experiment ( F i g . 2.3) was conducted i n order to d i s t i n g u i s h among the other three isomers. On i r r a d i a t i n g the downfield methylene proton resonance of 2a, small enhancement of the methyl resonance i s observed. Furthermore, no enhancement of the methyl protons occurs when the u p f i e l d methylene resonance i s i r r a d i a t e d ; therefore, the sqp 2 stereo-chemistry for which the methyl group i s trans to the amide i s eliminated. Similar NOEDIFF experiments for the sqp 1 i r i d i u m ( I I I ) methyl bromide complex, Ir(CH 3)(Br)[N(SiMe 2CH 2PPh 2) 2], show a f a i r l y large enhan-cement (~3x compared to that observed for the methyl protons of 2a) of the a p i c a l methyl protons; i n comparison, the tbp i r i d i u m ( I I I ) dimethyl complex, Ir(CH 3) 2[N(SiMe2CH 2PPh2) 2]> displays no enhancement of the methyl 59 resonance on i r r a d i a t i n g the methylene protons. Thus the extent of enhancement observed for the methyl protons i n the present study suggests 22 a) Trigonal bipyramidal Ph-Me,Si. CH, Me2Si N Ir ' l \ tbp PPh, Ph, b) Square pyramidal M e 2 S i v Me2Si Ph, | .CH3 Ir'' PPh 2 Sqp 1 •P Ph, Ph, Me 2 Si ' ,» P P h2 N — Ir CH, Me, Si Ph, Ph, Me 2Si^ N Ir M e 2 S i ' S I ^ CH, ' PPh, Ph, sqp 2 sqp 3 F i g . 2.2 Possible geometries for Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2]» 2a Fig. 2.3 (.a).  lH NMR spectrum (C 6D 6, 400 MHz) and (b) NOEDIFF spectrum of Ir (CH3) (PPh 2)-[N(.SiMe2CH2PPh2) 2] > 2a 24 the complex Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2)2 ] possesses a stereochemistry intermediate between the tbp and sqp 1 forms. However, i n th i s t h e s i s , t h i s complex has been represented by the sqp 1 form. As pointed out e a r l i e r , the phosphido ligand i n complexes 2a and 2b can possess ei t h e r (a) pyramidal or (b) planar geometry ( F i g . 2.4). So i t was of in t e r e s t to determine which applied i n th i s work. (a) (b) F i g . 2.4 Ir(CH 3)(PR 2)[N(SiMe 2CH 2PPh 2) 2] complex incorporating (a) a pyramidal phosphido ligand, or (b) a planar phosphido ligand The respective 3 1P{ 1H} chemical s h i f t s for pyramidal and planar phosphido complexes reported i n the l i t e r a t u r e range from -270 - +420 ppm and 200 - 400 ppm (See Appendix). The 31P{*-H} s h i f t s of 105.65 and 117.84 ppm for complexes 2a and 2b, respectively, although not conclusive i n d i s t i n g u i s h i n g the geometry at the phosphido ligand, point to the presence of a pyramidal phosphido donor i n these complexes. The a b i l i t y of the phosphido group to act as a nucleophile also supports this view (See Section 2.2.3). 25 2.2 R e a c t i v i t y 2.2.1 Thermolysis The i r i d i u m ( I I I ) methyl diphenylphosphido complex, Ir(CH 3)(PPh 2)-[N(SiMe 2CH 2PPh2)2]» 2a, i n the s o l i d state i s very temperature-se n s i t i v e as i t decomposes to a black tar at temperatures above 60°C. The benzene sol u t i o n of this complex, when heated at 60°C for f i v e hours, affords a mixture of at least three complexes which i s yet to be i s o l a t e d and characterized. The high f i e l d resonance at -20 ppm i n the lE NMR spectrum ( F i g . 2.5) of the mixture indicates that one of the complexes i s a hydride containing species. Further work on this reaction was not pursued. 20 5 1 F i g . 2.5 AH NMR spectrum (C 6D 6, 400 MHz) of the thermolysis products of Ir(CH 3)(PPh2)[N(SiMe2CH 2PPh2)2]» 2a 26 2.2.2 Photolysis The i r i d i u m ( I I I ) methyl diphenylphosphido complex, Ir(CH 3)(PPh 2)-[N(SiMe2CH2PPh2)2]» 2a, i n the s o l i d form shows no photochemical r e a c t i v i t y on i r r a d i a t i o n with a 275-W sunlamp; however, complete conver-sion to the corresponding iri d i u m ( I ) methyldiphenylphosphine complex, Ir(PCH 3Ph2)[N(SiMe2CH 2PPh2)2]» 3a, occurs on photolysis of 2a i n benzene sol u t i o n for 24 hours (Eq. 2.3). Ph, Ph, Me 2 Si s | y C H 3 N — Ir' PPh2 hv Me2Si 24 h C 6 D 6 Me, Si. Me, Si Ph, N — Ir — PCH 3Ph 2 Ph, (2.3) 2a 3a The synthesis of 3a can be achieved independently by the displacement of the cyclooctene ligand (COE) from the r e a d i l y a v a i l a b l e complex Ir(COE)[N(SiMe 2CH 2PPh 2) 2] 5 2 by PCH 3Ph 2 (Eq. 2.4). Ph, Ph, Me,Si Me2Si N Ir COE + PCH 3Ph 2 Ph, Toluene Me2S\^ (-COE) N — I r — PCH 3Ph 2 (2.4) Me2Si Ph, 3a 27 At least two possible mechanistic pathways for the synthesis of 3a can be envisaged. The reaction may occur v i a either (a) an i n t r a -molecular mechanism or (b) an intermolecular reductive elimination with a second mole of i r i d i u m ( I I I ) phosphide, 2a. A crossover experiment was performed i n order to d i s t i n g u i s h between these two p o s s i b i l i t i e s . A 50:50 mixture of the complexes Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2)2 ]» 2a, and Ir(CD 3){P(m-tol) 2}[N(SiMe 2CH 2PPh 2) 2], 2b, was photolyzed i n benzene. The r e s u l t s observed are outlined i n Scheme 2.1. The --H, 2H{-"H} and 3 1p{ 1H} NMR spectroscopy did not provide any information on examining the photolysis products of 2a and 2b since various n u c l e i within 3a and 28 Ph, Me,Si CH, Ph, N Ir PPh2 Me2Si Me 2Si^ + N Ir CD, P(m-tol)2 50 Ph2 2a Ph, hv Me2Si 50 X ^ Ph, 24 h 2 2b Ph, Me 2Si^ Me, Si Me2Si N Ir Ph, PCH 3Ph 2 + N — Ir PCD 3(m-tol) 2 Me2Si 3a CO(1 atm) ^ P h 2 3b Ph, Me 2Si^ N Ir CO Me2Si Me2Si Ph, Ph, CH, N Ir CO Me2Si I / j + PCH 3Ph 2 CH3I + PCD 3(m-tol) 2 + [P(CH3)2Ph2]+r + [P(CH3)(CD3)(m-tol)2]+r Ph, Scheme 2.1 Crossover experiment 29 3b resonate at approximately the same chemical s h i f t s . Thus, i t was decided to add CO to the photolysis products which generated the planar 52 iridium(I) carbonyl complex, Ir(CO)[N(SiMe 2CH 2PPh 2) 2]» and free phosphines. Since both the carbonyl complex and the phosphines possess high s o l u b i l i t y i n benzene, t h e i r further reaction with methyl iodide was necessary. The carbonyl derivative reacted with methyl iodide to generate 52 the previously reported complex Ir(CH 3)(I)(CO)[N(SiMe 2CH 2PPh 2) 2]; the free phosphines reacted with methyl iodide to give phosphonium s a l t s which pre c i p i t a t e d from so l u t i o n and were i s o l a t e d . The FAB mass spectrum obtained for the l a t t e r showed two peaks at 215 and 246 mass un i t s . These signals can c l e a r l y be assigned to the P(CH 3) 2Ph 2+ and P(CH 3)(CD 3)-( m - t o l ) 2 + ions, r e s p e c t i v e l y . No peaks for the possible crossover products P(CH 3)(CD 3)Ph 2 + and P ( C H 3 ) 2 ( m - t o l ) 2 + were observed; thus, the i n t e r -molecular mechanism (b) can be disregarded. Hence, the photolytic reaction (Eq. 2.3) involves an intramolecular pathway (a); no other information i s av a i l a b l e on the mechanism at t h i s time, but a simple reductive elimination of the methyl and the phosphide ligands i s reasonable. The formation of a metal mediated carbon-phosphorus bond i s observed i n t h i s reaction. 30 2.2.3 Reaction with methyl iodide The n u c l e o p h i l i c character of the phosphido ligand i n the complex Ir(CH 3)(PPh2)[N(SiMe2CH 2PPh2)2]> 2a, i s i l l u s t r a t e d by reaction with the e l e c t r o p h i l e methyl iodide (Eq. 2.5). The reaction proceeds within minutes at room temperature and affords an octahedral i r i d i u m ( I I I ) methyldiphenylphosphine complex 4. The -"H and 31P{--H} NMR spectra show the formation of only one isomer i n the reaction. The presence of v i r t u a l coupling for the methylene protons i n the **H NMR ( F i g . 2.7) i s consistent with trans phosphine donors Toluene (2.5) P C H 3 P h 2 P C H 3 P h 2 5 1 F i g . 2.7 XH NMR spectrum (C 6D 6, 400 MHz) of Ir(CH 3)(PCH 3Ph 2)(I)-[N(SiMe 2CH 2PPh 2)2]» 4 31 of the tridentate ligand, thus establishing that the tridentate ligand i s bound i n a meridional fashion i n the octahedral complex. Thus, there are only three possible stereoisomers for the structure of this complex i n so l u t i o n : o l , o2, or o3 ( F i g . 2.8). The lR NMR spectrum r e a d i l y rules out the isomer o3, as the methyl ligand would be expected - P h z >^ P h 2 P h 2 P Me2S\[ | ^ C H 3 M e 2 S i ' \ y ™ 3 ™ 2 Mo2S\^ °\ \ N Ir'-— PCH 3Ph 2 N— Ir'' CH, N— | r I Me 2s/ / \ Me2s/ | / | Me 2Si' I \ C H P h P \ ^ * P 3 2 Ph 2 Ph 2 ^ Ph 2 o1 o2 o3 F i g . 2.8 Possible stereochemistries for Ir(CH 3)(PCH 3Ph 2)(I)[N(SiMe 2CH 2PPh 2) 2 to resonate as a doublet of t r i p l e t s for this stereochemistry because of i t s larger trans coupling with the methyldiphenylphosphine ligand than i t s c i s coupling with the chelating phosphine donors; rather i t i s observed to be a four l i n e pattern. I n t e r e s t i n g l y , the isomer o3 was prepared by a straightforward addition of methyldiphenylphosphine to the coordi n a t i v e l y unsaturated i r i d i u m ( I I I ) methyl iodide complex 1 (Eq. 2.6). The pro-duct i s iso m e r i c a l l y pure and as mentioned above has a doublet of t r i p l e t s for the methyl resonance ( 3 j P C H 3 p h 2 H = 2 0 , 0 H 2» ^ C H ^ p h j H = 6 - 0 ^ ' 32 P h 2 . Ph2 Mp^^i I CH 3 / CH, i 2 \ , IX Toluene M ° ^ \ < N — lr I + PCH 3Ph 2 • N — | r — I (2.6) M e 2 \ I Me 2Si' | \ \ ^ - P \ ' P C H 3 P h 2 Ph '2 ^ Ph2 03 A d i s t i n c t i o n between the isomers o l and o2 was accomplished via an independent experiment. Given that the oxidative addition of a l k y l 54b halides proceeds k i n e t i c a l l y to generate trans adducts, the reaction between CH 3I and the square planar complex Ir(PCH 3Ph2)[N(SiMe 2CH2PPh2)2] should r e s u l t i n the formation of isomer o l (Eq. 2.7). This, indeed, i s the res u l t observed. The *H NMR spectrum of the product obtained from the reaction 2.7 was i d e n t i c a l to that of 4 , which allowed assignment of structure o l to 4 . Ph, Ph, Me2Si N -Me2Si y Ir PCH 3Ph 2 + CH3I Toluene Me 2Si v | j CH, Me 2Si / j y | N Ir PCH 3Ph 2 •P Ph, •P Ph2 01 (2.7) In order to discover the source of the methyl group i n the methyldiphenylphosphine ligand for complex 4 , the analogous reaction 33 with. CD 3I was carried out (Eq. 2.8). Ph, Me 2Si^ | , , C H 3 N — I r * PPh 2 + CD3I Toluene Me*S\ I CH, Me 2Si N — I r PCD 3Ph 2 (2.8) M e 2 S i ' 1 f Ph, Ph, This experiment showed that the methyl group i n the methyldiphenylphosphine ligand originated from the intermolecular reaction with C D 3 I , since the product observed i n th i s reaction i s Ir(CH 3)(PCD 3Ph2)(I)[N(SiMe 2CH 2PPh 2) 2]• The 1H NMR spectrum for the product of equation 2.8 did not show the doublet at 1.58 ppm ( 2 J p H = 10.6 Hz) as observed for the PCH 3Ph 2 ligand i n the analogous reaction with CH 3I; however, a broad peak centered at the same chemical s h i f t was present i n the 2 H { " - H} NMR spectrum, which i s obviously assigned to the PCD 3Ph 2 moiety. This l a b e l l i n g experiment thus shows that the reaction of the phosphido complex 2a with CH 3I involves n u c l e o p h i l i c attack of the phosphido ligand on the e l e c t r o p h i l e C H 3 I r e s u l t i n g i n the formation of complex 4. Such n u c l e o p h i l i c i t y of pyramidal phosphido ligand i s well documented (See Section 1.2.1). 34 2.2.4 Hydrogenation At room temperature, the reaction of a toluene so l u t i o n of Ir(CH 3)(PPh2)[N(SiMe2CH 2PPh2)2]» 2a, with one atm of dihydrogen produces a mixture of the i r i d i u m ( I I I ) dihydride complex 5 and the methyl hydride complex 6 i n the r a t i o of 70:30 as determined by % NMR spectroscopy (Eq. 2.9). Upon s t i r r i n g the mixture of 5 and 6 under excess dihydrogen for an a d d i t i o n a l 24 hours, the methyl hydride complex 6 i s completely converted to the dihydride complex 5. The **H NMR spectrum provides an excellent handle on the i d e n t i t y and stereochemistry of these hydride species ( F i g . 2.9). Once again, the methylene resonances, observed as an AB quartet of v i r t u a l t r i p l e t s f o r CH 3 H2(1atm), 5min N — Ir PPh 2 Toluene 2a CH 4 + 70% 5 30% £ t H2(1atm), 24h (-CH4) 35 both 5 and 6, are i n d i c a t i v e of trans disposed phosphines of the trid e n t a t e ligand. The diphenylphosphido ligand i n 2a i s converted to diphenylphosphine ligand i n 5 and 6 by a c q u i s i t i o n of a proton and the resonances are observed as doublets of t r i p l e t s centered at 5.84 ppm C1^ _ = 334.7 Hz, 3J„ „ = 9.7 Hz) for 5 and at 5.76 ppm ( J J_ „ = 334.7 Hz, 3 J T 1 „ = 8.4 Hz) for 6 . The hydride resonance for the methyl hydride complex 6 i s a doublet of t r i p l e t s centered at -9.06 ppm ( 2 jPHPh 2,H = 1 5 0 , ° H Z ' 2 jCH2PPh 2,H = 1 0 , 1 V z ) m ^ d l h v d r i d e complex 5 displays a doublet of t r i p l e t s of doublets at -9.75 ppm ( J p„ p, „ = 140.4 5 1 F i g . 2.9 XH NMR spectrum (C gD 6, 400 MHz) of Ir(H) 2(PHPh 2)[N(SiMe 2CH 2PPh 2) 2]» 5, and Ir(CH 3)(H)(PHPh 2)[N(SiMe 2CH 2PPh 2) 2], 6 36 Hz, 2 J _ __, „ = 18.2 Hz, and 2J„ „ = 5.0 Hz) for the hydride trans to the 2£_"n 2»" n, rl diphenylphosphine ligand, and a quartet of doublets at -19.17 ppm ( 2 J = F,H 15.1 Hz, 2 J n „ = 5.2 Hz) for the hydride trans to the amide ligand. The n, n hydride resonances i n the region of -8 to -30 ppm have been reported for a 53 number of rhodium and irid i u m amine and amide hydride complexes. The IR stretches at 2220 cm - 1 for 5 and 2242 cm - 1 for 6 are also t y p i c a l 53 of late t r a n s i t i o n metal hydride complexes. Complex 5 was also prepared by the addition of PHPh 2 to the coordinatively unsaturated i r i d i u m ( I I I ) dihydride complex, I r ( H ) 2 -[N(SiMe 2CH 2PPh2)2] 6 0 (Eq- 2.10). ' P PHPh, Me, Si. 2 Toluene PHPh2 • N — I r — H (2.10) M e 2 S i ' | In order to obtain some Information on the mechanism involved i n the formation of the hydride complexes 5 and 6, the analogous reaction with one atm of D 2 was ca r r i e d out (Scheme 2.2). Some very i n t r i g u i n g r e s u l t s were revealed. The *H NMR spectrum for the reaction products s t i l l showed the PHPh 2 resonance for the methyl hydride complex; furthermore, the resonance of the iridium-methyl protons was broadened instead of the doublet of t r i p l e t s observed for the previous reaction with H 2- The "^{^H} NMR spectrum ( F i g . 2.10) was also completely consistent with the 37 Ph, M e 2 S i v CH, N Ir • PPh, Me2Si D2(1atm), 5min Toluene Ph, 2a CH3D Ph, S \ PDPh, Me 2Si^ | / 2 + N — I r ' D M e 2 S i / {f I 70% Ph, Me2Si Ph, M e 2 S i ' | PHPh, N J r CH2D 30% •P Ph, 8 D2(1atm), 24h I Toluene Ph, M e 2 S i v | / 2 N Ir' D M e 2 S i ' / | + CH 2 D 2 Ph, Scheme 2.2 Deuteration of Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2]» 2a 38 structures 7 and 8 shown i n Scheme 2.2. The gaseous products evolved i n this reaction were CH3D and CH 2D 2, as confirmed by mass spectro-metry. The reaction of 2a with D 2 was also followed by variable temperature *H NMR spectroscopy. From -70°C to +10°C, only the s t a r t i n g phosphide was detected, but as the temperature was increased to 20°C, the complexes 7 and 8 appeared almost simultaneously i n t h e i r respective y i e l d s of 70 and 30%. This experiment along with the previous deuterium-l a b e l l i n g study indicate that the methyl hydride complex i s not an i n t e r -mediate i n the formation of the dihydride complex, even though i t i s u l t i -mately converted to the dihydride complex upon being s t i r r e d under excess H 2 for 24 hours. Ph, / — Me,Si PDPh, Me2Si r N — Ir Me 2Si' j r PHPh, CH2D PDPh 2 u > CH 2D 10 -10 - 2 0 F i g . 2.10 2H{ 1H} NMR spectrum (CH 3C 6H 5,40 MHz) of Ir(D) 2(PDPh 2)[N(SiMe 2CH 2PPh 2) 7, and Ir(CH 2D)(D)(PHPh 2)[N(SiMe 2CH 2PPh 2) 2], 8 39 To account for the observed d i s t r i b u t i o n of deuterium, an e q u i l i -brium between the methyl diphenylphosphide complex 2a and the methylidene diphenylphosphine species 11 i s proposed as shown i n Scheme 2.3. Such an intramolecular proton transfer from a hydrocarbyl ligand to phosphido donor i s extremely r a r e . ^ Although, there Is no evidence for 11 at the present, the suggested reaction of D 2 across the i r i d i u m -carbon double bond would generate 8, the correct methyl hydride isotopomer. The sequence of reactions to convert 2a to the dideuteride 7 i s speculative but draws on e a r l i e r observations of a n c i l l i a r y ligand 53 involvement i n the a c t i v a t i o n of dihydrogen. In p a r t i c u l a r , addition o D 2 produces the amine deuteride 12 which can rearrange to the isomer 13 by amine d i s s o c i a t i o n , inversion at nitrogen, and reassociation; elimination of C H 3 D from 13 to give the phosphido deuteride 14 followed by addition of D 2 generates the observed major product 7. Some preliminary mechanistic studies have been done. It can be shown that the proposed phosphido deuteride 14 could not reductively eliminate to the ir i d i u m ( I ) diphenylphosphine complex Ir(PDPh 2)-[N(SiMe 2CH 2PPh 2) 2] p r i o r to D 2 addition, since reaction of the complex Ir(PHPh 2)[N(SiMe 2CH 2PPh 2) 2] 6 2 with H 2 does not y i e l d the me^dihydride 5, rather fac-lr(H) 2(PHPh 2)[N(SiMe 2CH 2PPh 2) 2] i s the only product observed (Eq. 2.11). Attempts to prepare the proposed Intermediate 11 40 / ^ P M e 2 S i v | # . C H 3 N Ir Me2Si y PPh, I" Ph, Me,Si C H , N — Ir • P P h , M e 2 S i ' ^ / Inversion t P 12 Ph 2 at N Ph, C H , N ' — Ir P P h 2 • P 13 \ | (-CH 3D) t Ph, Me 2Si^ N Ir M e ^ i ' ^ | • P P h , •P 14 Ph, Ph, Me2Si Me,Si PHPh, N — | r = C H , Ph 11 J2 Ph, Me2Si PHPh, N — Ir CH2D M e 2 S i ' xf | \ ^ P 8 Ph 2 Minor o ' f PDPh 2 N Ir ' D M e 2 S i ' £ j P 7 Ph 2 Major Scheme 2.3 Mechanism proposed for deuteration of Ir(CH 3)(PPh 2)-[N(SiMe 2CH 2PPh 2)2]» 2a 41 Ph, Me, Si Me2Si Ph, N Ir H2(1 atm) Me2Si • PHPh, Toluene Me2Si Ph, N — I r PHPh2 (2.11) by either the addition of one equivalent of PHPh 2 to the previously 63 reported methylidene complex, Ir(=CH 2)[N(SiMe 2CH 2PPh 2) 2]» or by the 64 reaction of CH 2N 2 with Ir(PHPh 2)[N(SiMe 2CH 2PPh 2) 2] have been unsuccessful; i n the former reaction, a complex mixture r e s u l t s , while i n the l a t t e r case, the irid i u m ( I ) d e r i v a t i v e Ir(PCH 3Ph 2)[N(SiMe 2CH 2PPh 2) 2] i s the only product. C l e a r l y , neither of these procedures i s k i n e t i c a l l y f e a s i b l e for accessing the proposed equilibrium i n Scheme 2.3. Further studies are underway to provide evidence for the rev e r s i b l e intramolecular proton transfer from an a l k y l to a terminal phosphide ligand. 42 2.2.5 Carbonylation The coordinatively unsaturated phosphido complex Ir(CH 3)(PPh 2)-[ N ( S i M e 2 C H 2 P P h 2 ) 2 ] » 2a, reacts under one atm of carbon monoxide within minutes at room temperature to afford an octahedral carbonyl d e r i v a t i v e , Ir(CH 3)(CO)(PPh 2)[N(SiMe 2CH 2PPh 2)2], 9 (Eq. 2.12). Upon contact with CO, the intense purple colour of the s t a r t i n g material i s lo s t leaving a Ph, Me 2 Si s j , , C H 3 Ph, N — Ir PPh, Me2Si CO(1atm) C6 D 6 Ph 2 2a N — |r* PPh 2 M e 2 S i ' Qrf] (2.12) Ph, yellow carbonyl complex. The •'H and 31P{""H} NMR spectra show the formation of only one isomer i n the reaction. The presence of v i r t u a l coupling for the methylene protons i n the *H NMR spectrum ( F i g . 2.11) i s consistent with the trans phosphine donors, thereby e s t a b l i s h i n g that the tridentate ligand i s bound 43 lU NMR spectrum (C 6D 6, 400 MHz) of Ir ( C H o ) ( C O ) ( P P h o ) -[N(SiMe 2CH 2 P P h 2 ) 2 ] , 9 2 JUJI in|inninijnmiiiijmmiil|miri,1,.li,,|ljl. tl T1T1 178 176 174 172 170 168 VPU 1 3C{ XH} NMR spectrum (C 6D 6, 75 MHz) of Ir(CHo ) ( 1 3C0)(PPh [N(SiMe 2CH 2PPh 2) 2], 9 3 M 44 i n a meridional fashion i n the octahedral complex. The 1 3C{ 1H} NMR spectrum (Fig. 2.12) of the l a b e l l e d complex, Ir(CH 3)( 1 3CO)(PPh 2)-[N(SiMe 2CH 2PPh 2) 2], displays a doublet of t r i p l e t s at 173.2 ppm ( 2 j C H 2 P P h 2 , 1 3 C = 9 a H Z ' 2 j P P h 2 , 1 3 C = 5 1 - 8 H Z ) ' a t t r i b u t a b l e to the carbonyl carbon atom. This observed s h i f t i s t y p i c a l of late t r a n s i t i o n metal carbonyl complexes. 6 5 Complex 9 exhibits a strong absorption at 2009 cm-* i n benzene, which s h i f t s to 1960 cm - 1 upon i s o t o p i c s u b s t i t u t i o n with 1 3C0. Completely d i f f e r e n t spectroscopic r e s u l t s are observed when the excess CO i s pumped off from the reaction mixture. The *H NMR spectrum i n F i g . 2.13 w i l l serve to I l l u s t r a t e t h i s f a c t . The S i ( C H 3 ) 2 resonances have s h i f t e d considerably i n this spectrum when compared to that of complex 9; the methylene protons are at d i f f e r e n t chemical s h i f t s , but s t i l l are observed as an AB quartet of v i r t u a l t r i p l e t s , thus i n d i c a t i n g a meri-dional arrangement of the tridentate ligand i n the new complex. The most anamolous feature of t h i s spectrum i s that even i n the presence of the three phosphorus containing ligands, the methyl resonance i s only s p l i t into a t r i p l e t ! The 1 3C{ 1H> NMR spectrum ( F i g . 2.14) for the 1 3C-enriched carbonyl d e r i v a t i v e displays a doublet of t r i p l e t s at 177.5 ppm ( 2 jCH2PPh 2 1 3 C = 1 1 , 5 H Z > 2 j P P h 2 1 3 C = 6 5 6 ' 8 H Z ) ' T 1* e i m P ° r t a n t features of t h i s spectrum are i ) the observed s h i f t , which indicates that the CO i s present as a terminal carbonyl ligand i n the new complex, and i i ) the very high 2 J p p V l 13 r value, which suggests that the phosphide and the carbonyl 45 ligands are In a trans d i s p o s i t i o n . Further evidence for the presence of CO as a terminal carbonyl ligand comes from the strong absorption at 1944 cm-* i n the i n f r a r e d spectrum. These r e s u l t s suggest that the complex 10 i s an isomer of complex 9 with the phosphido and carbonyl ligands trans to one another (Eq. 2.13). Complex 10 was also obtained when the previously 52 characterized complex Ir(CH 3)(C0)(I)[N(SiMe 2CH 2PPh 2) 2] was reacted with one equivalent of L i P P h 2 (Eq. 2.13). Me2Si Me2Si PPh, CO(excess removed) Me2Si C 6D 6 Ph, / ^ P N Ir I (2.13) Toluene/ THF LiPPh, Ph 2 An alternate formulation of 10 (shown below) i s the product of CO i n s e r t i o n into the phosphide-metal bond. As mentioned e a r l i e r , such carbonyl i n s e r t i o n has been reported for a hafnium di-teri-butylphosphido 46 F i g . 2.14 1 3C{ 1H> NMR spectrum (C 6D 6, 75 MHz) of Ir(CH 3)( 1 3CO)(PPh 2)-[N(SiMe 2CH 2PPh 2)2]» 10 47 CH3 Me2Si • CPPh2 N — Ir Me2Si complex. 33 This a l t e r n a t i v e does explain the presence of the methyl resonance as a t r i p l e t In the H NMR spectrum; however, i t does not account for the 1 3C( 1H} NMR and IR data. The carbonylation of the phosphido complex 2a i s summarized i n Scheme 2.4. The conversion of the c i s carbonyl-phosphido geometry in complex 9 to the trans carbonyl-phosphido arrangement i n the complex 10 can be accounted for as follows: the carbonylation of 2a gives 9 as the k i n e t i c a l l y favoured product, which rearranges to the more thermodynamically stable product 10 via CO d i s s o c i a t i o n , followed by reassociation when excess CO i s removed. However, this reaction mechanism i s no way c l e a r l y understood. Both carbonyl derivatives 9 and 10 are unstable i n solution at room temperature. Within minutes of their formation, they s t a r t converting to the planar iridium(I) complex, Ir(CO)-52 [N(SiMe2CH 2PPh 2) 2] (which has been previously characterized ) and free methyldiphenylphosphine (Scheme 2.4). Once again, the formation of a carbon-phosphorus bond i s observed in this reaction. 48 Scheme 2.4 Carbonylation of Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2)2]» 2a 49 CHAPTER 3 CONCLUSIONS AND SOME SUGGESTIONS FOR FUTURE WORK 3.1 Conclusions The i r i d i u m ( I I I ) methyl diarylphosphido complexes, Ir(CH 3)(PR 2)-. tN(SiMe 2CH 2PPh 2)2] (2a: R = Ph, 2b: R = m-tol), were synthesized by treatment of the ir i d i u m ( I I I ) methyl iodide d e r i v a t i v e , I r ( C H 3 ) ( I ) -[N(SiMe 2CH 2PPh 2) 2], with the corresponding l i t h i u m diarylphosphide. Based primarily on a nuclear Overhauser e f f e c t difference experiment, these complexes are assigned a stereochemistry intermediate between the square pyramidal and t r i g o n a l bipyramidal forms. The 3 1P{*H} chemical s h i f t s f o r 2a and 2b indicate pyramidal geometry at the phosphido ligand. The diphenylphosphido d e r i v a t i v e 2a affords a mixture of at least three u n i d e n t i f i e d complexes upon thermolysis i n benzene s o l u t i o n ; however, clean formation of the planar iridium(I) complex, Ir(PCH 3Ph 2)-[N(SiMe 2CH 2PPh 2) 2], 3a, takes place upon photolyzing a benzene solution of 2a. A crossover experiment indicates that the formation of 3a is achieved v i a an intramolecular mechanism. The formation of a carbon-phosphorus bond i s observed i n the l a t t e r reaction. The n u c l e o p h i l i c i t y of the phosphido ligand i s evident from the reaction of 2a with CH 3I; the product of th i s reaction i s I r ( C H 3 ) -(PCH 3Ph 2)(I)[N(SiMe 2CH 2PPh 2) 2], 4. The l a b e l l i n g experiment with CD 3I shows that the reaction i s intermolecular as the product observed i n t h i s reaction i s Ir(CH 3)(PCD 3Ph 2)(I)[N(SiMe 2CH 2PPh 2) 2]. 50 Exposure of 2a to one atm of H 2 at room temperature produces a mixture of the i r i d i u m ( I I I ) dihydride complex Ir(H) 2(PHPh 2 ) ~ [N(SiMe 2CH 2PPh 2) 2], 5, and the methyl hydride complex Ir(CH 3)(H)(PHPh 2)-[N(SiMe 2CH 2PPh 2)2l. 6. i n 70 and 30% y i e l d s , r e s pectively. The analogous reaction with one atm of D 2 reveals that the formation of the methyl hydride complex, 6, involves an intramolecular proton abstrac-tion by the phosphide ligand from the bound methyl group, as the minor product observed i n this reaction i s Ir(CH 2D)(D)(PHPh 2)-[N(SiMe 2CH 2PPh 2) 2], 8. A mechanism i s proposed which involves the formation of Ir(=CH 2)(PHPh 2)[N(SiMe 2CH 2PPh 2) 2] followed by trapping with D 2 to give the methyl hydride complex. The dihydride complex observed i n these reactions i s produced by an apparent h e t e r o l y t i c cleavage of dihydrogen. Under excess CO, at room temperature the complex 2a i s converted to an octahedral carbonyl species Ir(CH 3)(C0)(PPh 2)[N(SiMe 2CH 2PPh 2) 2], 9; the carbonyl and the phosphido ligands i n this complex are i n c i s proximity. Upon removing the excess CO from the reaction mixture, another stereoisomer, 10, of the complex 9 i s formed i n which the carbonyl ligand and the phoshido donor are trans to each other. It i s suggested that the complex 9 i s the k i n e t i c a l l y favoured isomer i n the carbonyla-ti o n reaction, and i t rearranges to the more thermodynamically stable isomer 10 v i a CO d i s s o c i a t i o n upon removal of the excess CO. Both 9 and 10 are unstable i n sol u t i o n at room temperature as they rearrange to the planar iridium(I) carbonyl complex, Ir(C0)-[N(SiMe 2CH 2PPh 2) 2], and methyldiphenylphosphine. Once again, the 51 formation of a carbon-phosphorus bond i s observed i n this r e a c t i o n . 3.2 Suggestions f o r Future Work Studies to characterize the complexes observed i n the thermolysis reaction as well as experiments to trap the proposed intermediate Ir(=CH 2) (PHPh 2)[N(SiMe 2CH 2PPh 2) 2] i n the hydrogenation reaction should be pursued. The preparation of the complex Ir(CH 3)(PHR)[N(SiMe 2CH 2PPh 2) 2] would be of p a r t i c u l a r i n t e r e s t , since this complex, upon i t s photolysis or thermo-l y s i s , might lead to the corresponding phosphinidene complex v i a loss of methane. 52 CHAPTER 4 EXPERIMENTAL 4.1 General Information A l l manipulations were performed under pr e - p u r i f i e d nitrogen i n a Vacuum Atmospheres HE-533-2 glove box equipped with a MO-40-2H p u r i f i c a t i o n system, or in standard Schlenk-type glassware. Iridium t r i c h l o r i d e hydrate was obtained on loan from Johnson-Matthey and used d i r e c t l y i n the synthesis of [Ir( n 2-C 8H l t t) 2C°-] 2 « 6 6 The complexes Ir(T1 2-C 8H 1 1 +) [N(SiMe 2CH 2PPh 2) 2 ] , and Ir(R)(I) [N(SiMe 2CH 2PPh 2) 2] 52 56 (R = Me, Ph, CH2Ph) were prepared by published procedures. ' L i P P h 2 and L i P ( m - t o l ) ^ were prepared by the dropwise addition of n-butyllithium i n hexane (1.6M, Ald r i c h ) to a hexane sol u t i o n of PHPh 2 and PH(m-tol) 2, r e s p e c t i v e l y . After several washings with hexane, the resultant lemon-yellow powders were used d i r e c t l y i n the preparation of Ir(CH 3)(PPh 2)-[N(SiMe 2CH 2PPh 2) 2] and Ir(CH 3) {P(m-tol) 2} [N(SiMe 2CH 2PPh 2) 2] • Toluene, hexane and d i e t h y l ether were dried and deoxygenated by d i s t i l l a t i o n from sodium benzophenone k e t y l under argon. Tetrahydrofuran (THF) was pre-dried by r e f l u x i n g over CaH 2 and then d i s t i l l e d from sodium benzophenone k e t y l under argon. H 2 was p u r i f i e d by passing i t through a column of molecular sieves and MnO. 1 3CH 3I (99.7 atom % 1 3 C ) , CD 3I (98 atom % D) and 1 3C0 (90 atom % 1 3C) were obtained from MSD. D 2 (99.8 atom % D) was obtained from Matheson. A l l these reagents were used as obtained. Deuterated benzene 53 (CgDg; 99.6 atom % D), purchased from MSD, was dried over activated 4 A molecular sieves, vacuum transferred and degassed by freeze-pump-thawing several times before being used. Melting points were determined on a Mel-Temp apparatus i n sealed c a p i l l a r i e s under nitrogen and are uncorrected. Carbon, hydrogen and nitrogen analyses were performed by Mr. P. Borda of this department. *-H NMR spectra were recorded on a Bruker WH-400 spectrometer i n C 6D 6 and were referenced to C 6D 5H at 7.15 ppm. 3 1P{ 1H} NMR spectra were run at 121.4 MHz on a Varian XL-300 or 109.1 MHz on a Nicolet HXS-270. A l l 3 1P chemical s h i f t s were referenced to external P(0Me)3 set at 141.00 ppm r e l a t i v e to 85% H 3 P 0 V 1 3C{ 1H} and 2R{lE} NMR spectra were run at 75 MHz and 40 MHz, respectively, on a Varian XL-300, and were referenced to . solvent peaks ( 1 3C: C 6D 6 at 128.0 ppm; 2H: CH 3C 6H 5 at 2.1 ppm). A l l chemical s h i f t s (*H, 2H, 1 3C and 3 1 P ) are reported i n ppm with the coupling constants expressed i n Hz. Infrared spectra were recorded on a Pye-Unicam SP-1100 spectrophotometer on solu t i o n samples. A l l inf r a r e d absorptions are given i n cm-*. UV-Vis spectra i n hexane were recorded on a Perkin Elmer 5523A UV/VIS spectrophotometer. 4.2 Synthesis 4.2.1 Ir(CH 3)(PR2)[N(SiMe2CH 2PPh2)2J A sol u t i o n of LiPR 2 (R = Ph, m-tol) i n THF (5 mL) was added dropwise with s t i r r i n g to a so l u t i o n of Ir(CH 3)(I)[N(SiMe 2CH 2PPh2) 2] i n toluene (10 mL) at room temperature. The I n i t i a l l y deep green solution immediately 54 turned dark purple i n colour. A f t e r s t i r r i n g for an hour, the solu t i o n was f i l t e r e d through C e l i t e i n order to remove L i l . The solvent was removed in vacuo and the resultant powder r e c r y s t a l l i z e d from toluene/hexane at -30°C which yielded purple c r y s t a l s of Ir(CH 3)(PR 2) [N(SiMe 2CH 2PPh 2) 2] • 4.2.1a Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2] 2a Ir(CH 3)(I)[N(SiMe 2CH 2PPh 2) 2] (0.24 g, 0.28 mmol); L i P P h 2 (0.05 g, 0.31 mmol). Anal. Calcd. for I r C ^ H ^ N P 3 S i 2 : C, 56.07; H, 5.36; N, 1.52. Found: C, 55.80; H, 5.35; N, 1.40. m.p. 123±2°C (decomp.). 3 1P{ 1H} NMR (C 6D 6, 121.4 MHz): PPh 2, 105.65 ( t , 2 J = 34.8); CH 2PPh 2, 10.28 (d). r , r Y i e l d : 0.18 g (70%). 4.2.1b lr(CH 3){P(m-tol) 2}[N(SiMe 2CH 2PPh 2) 2] 2b Ir(CH 3)(I)[N(SiMe 2CH 2PPh 2) 2] (0.22 g, 0.25 mmol); L i P ( m - t o l ) 2 (0.05 g, 0.26 mmol). Anal. Calcd. for I r C ^ H ^ N P 3 S i 2 : C, 56.94; H, 5.63; N, 1.48. Found: C, 56.70; H, 5.62; N, 1.42. m.p. 118±2°C (decomp.). 3 1P{ 1H} NMR (C 6D 6, 109.3 MHz): P(m-tol) 2, 117.84 ( t , 2 J = 34.7); CH 2PPh 2, 15.48 r , r (d). Y i e l d : 0.18 g (75%). 4.2.2 Ir(PCH^h 2)[N(SiMe2CH 2PPh2)2] 3 Method 1. A C 6D 6 s o l u t i o n (5 mL) of Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2] (0.10 g, 0.11 mmol), sealed under N 2, was exposed to a 275-W sunlamp for 24 hours. The o r i g i n a l deep purple s o l u t i o n turned orange-yellow as the photolysis proceeded. The solvent was removed in vacuo. The addition of hexane to the resultant o i l yielded yellow c r y s t a l s . Anal. Calcd. for I r C l t 3 H i t 9 N P 3 S i 2 : C, 56.07; H, 5.36; N, 1.52. Found: C, 55.80; H, 5.35; N, 1.40. 3 1P{ XH} NMR (C 6D 6, 121.4 MHz): CH 2PPh 2, 25.30 (d, 2 J = 22.8); 55 PCH 3Ph 2, -1.79 ( t ) . Method 2. A solution of PCH 3Ph 2 (0.01 g, 0.05 mmol) in toluene (2 mL) was added dropwise to a toluene sol u t i o n (5 mL) of Ir( r^-C^H^)-53 [N(SiMe 2CH 2PPh 2) 2] (0.05 g, 0.06 mmol). After s t i r r i n g for 0.5 hour, the solvent was removed in vacuo. Yellow c r y s t a l s were obtained upon c r y s t a l l i z a t i o n from hexane. Y i e l d : 0.04 g (76%). Method 3. A fr e s h l y prepared ether solution (2 mL) of C H 2 N 2 ^ was added dropwise to a toluene sol u t i o n (5 mL) of Ir(PHPh 2)-62 [N(SiMe 2CH 2PPh 2) 2] (0.03 g, 0.04 mmol) at room temperature. Af t e r s t i r r i n g for 0.5 hour, the solvent was removed i n Vacuo. R e c r y s t a l l i z a t i o n of the resultant powder from hexane yielded yellow c r y s t a l s . Y i e l d : 0.02 g (68%). c i s I—I 4.2.3 Ir(CH 3)(PCH3Ph2)(I)[N(SiMe 2CH2PPh2)2l A Method 1. This preparation Involved the vacuum transfer of an excess (at least f i v e fold) of degassed CH 3I at -10°C to a toluene sol u t i o n (10 mL) of Ir(CH 3)(PPh 2)[N(SIMe 2CH 2PPh 2) 2] (0.25 g, 0.27 mmol). The sol u t i o n was allowed to warm to room temperature, during which time the o r i g i n a l purple colour changed to l i g h t yellow. After s t i r r i n g for 0.5 hour, the solvent was removed in vacuo. R e c r y s t a l l i z a t i o n of the resultant powder from toluene yielded yellow c r y s t a l s . Y i e l d : 0.21 g (75%). Anal. Calcd. for IrC^H 5 2NP 3SI 2I«^- C 7H 8: C, 50.59; H, 5.01; N, 1.29. Found: C, 50.40; H, 5.08; N, 1.20. m.p. 190±2°C (decomp.). 3 1P{ 1H> NMR (C 6D 6, 121.4 MHz): CH 2PPh 2, -17.67 (d, 2 J = 18.6); PCH 3Ph 2, -36.60 ( t ) . 56 Method 2. To a solution of Ir(PCH 3Ph 2)[NSiMe 2CH 2PPh 2) 2] (0.05 g, 0.05 mmol) i n toluene (5 mL), excess (at least f i v e fold) degassed C H 3 I at -10°C was vacuum transferred. The solu t i o n was s t i r r e d for 0.5 hour and the solvent removed in vacuo to give a yellow o i l . The addition of toluene/hexane resulted i n yellow c r y s t a l s . Y i e l d : 0.04 g (65%). trans I I 4.2.4 Ir(CH 3)(PCH3Ph2)(I)[N(SiMe2CH 2PPh2)2l A toluene solution (1 mL) of PCH 3Ph 2 (0.01 g, 0.05 mmol) was added dropwise to a toluene solution (5 mL) of Ir(CH 3)(I)[N(SiMe 2CH 2PPh 2) 2] (0.04 g, 0.05 mmol) at room temperature. The o r i g i n a l green colour changed immediately to l i g h t yellow. The solvent was removed in vacuo. R e c r y s t a l l i z a t i o n of the resultant powder from toluene yielded yellow c r y s t a l s . Y i e l d : 0.^4 g (70%). Anal. Calcd. for IrCi t HH 5 2NP 3 S i 2 I C 7H 8: C, 50.59; H, 5.01; N, 1.29. Found: C, 50.68; H, 5.42; N, 1.17. 4.2.5 Ir(H)2(PHPh2)[N(SiMe 2CH2PPh 2)2] 5 Method 1. A solu t i o n of Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2] (0.10 g, 0.11 mmol) i n toluene (10 mL) was s t i r r e d under one atm of H 2 for 24 hours at room temperature. Within minutes, the purple solution turned l i g h t yellow. The solvent was removed in Vacuo, and the resultant pale yellow powder was r e c r y s t a l l i z e d from toluene/hexane. Colourless c r y s t a l s were obtained. Y i e l d : 0.09 g (85%). Anal. Calcd. for I r C ^ H ^ N P 3 S i 2: C, 55.49; H, 5.43; N, 1.54. Found: C, 55.83; H, 5.46; N, 1.49. m.p. 173±2°C (decomp.). 3 1P( 1H> NMR (C 6D 6, 109.3 MHz): CH 2PPh 2, 10.70 (d, 2 J p p = 15.8); PHPh2, -23.72 ( t ) . IR (CH 2C1 2, cm" 1): v i r _ H = 2220 ( s , b r ) . 57 Method 2. A toluene solution (2 mL) of PHPh 2 (0.02 g, 0.13 mmol) was added dropwise to a Ir(H) 2[N(SiMe 2CH 2PPh2) 2] 6 1 (0-09 g, 0.14 mmol) sol u t i o n i n toluene (10 mL). The reaction mixture was s t i r r e d for 0.5 hour. After removing the solvent in vacuo, the resultant brown powder was r e c r y s t a l l i z e d from hexane at -30°C. Y i e l d : 0.08 g (63%). 4.2.6 Ir(CH 3)(H)(PHPh 2)[N(SiMe2CH 2PPh 2) 2] 6 A solution of Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2] (0.10 g, 0.11 mmol) i n toluene (10 mL) was s t i r r e d under one atm of H 2 for 5 min at room temperature. Upon solvent removal, the yellow powder was r e c r y s t a l l i z e d from toluene/hexane. An a n a l y t i c a l l y pure sample of this product was not obtained since i t was always contaminated with the major dihydride complex 5 • 3 1P{ 1H) NMR (C 6D 6, 109.3 MHz): CH 2PPh 2, 13.48 (d, 2 J = 15.3); r , r PHPh2, -33.90 ( t ) . IR (CH 2C1 2, cm - 1): v i r _ R = 2242 (m). 4.2.7 Deuteration Studies The reactions to generate the complexes Ir(D) 2(PDPh 2)-[N(SiMe 2CH 2PPh 2) 2], 7, and Ir(CH 2D)(D)(PHPh 2)[N(SiMe 2CH 2PPh 2) 2], 8, were ca r r i e d out exactly as described above for the dihydride complex 5 and the methyl hydride complex 6 using D 2 (Matheson, 99.8% enriched). 4.2.8 /ac-Ir(H 2)(PHPh 2[N(SiMe 2<ra 2PPh 2) 2] A d 6-benzene sol u t i o n (1 mL) of Ir(PHPh 2)[N(SiMe 2CH 2PPh 2) 2] (0.03 g, 0.04 mmol) was exposed to one atm of H 2 for 5 min at room temperature. The o r i g i n a l yellow coloured s o l u t i o n immediately turned c o l o u r l e s s . The 58 product was characterized by 1H and 3 1P NMR spectroscopy. 3 1p{ 1H} NMR (C 6D 6, 121.4 MHz): CH 2PPh 2, 5.72 (m); PHPh2, 0.07 (m). 4.2.9 Ir(CH 3)(C0)(PPh2)[N(SiMe 2CH2PPh2)2l 9 and 10 A sol u t i o n of Ir(CH 3)(PPh 2)[N(SiMe 2CH 2PPh 2) 2] (0.03 g, 0.03 mmol) i n CgDg (1 mL) was sealed under one atm of CO. The purple s o l u t i o n turned yellow immediately. 3 1P{ 1H} NMR (C 6D 6, 109.3 MHz): CH 2PPh 2, -22.30 (d, 2 J p p = 26.0); PPh 2, -61.73 ( t ) . IR (C 6D 6, cm" 1): v C Q = 2009 ( s ) . l 3C{ lH) NMR (C 6D 6, 75 MHz): 13C0, 173.2 (dt, 2 J C H 2 p p h 2 > 13 c - 9.1, 1 3 q = 51.8). As the excess CO was pumped off from the yellow carbonyl s o l u t i o n , the complex isomerized to complex 10. 3 1P( 1H> NMR (C 6D 6, 121.4 MHz): CH 2PPh 2, 25.88 ( s ) ; PPh 2, -5.51 ( s ) . IR (C 6D 6, cm - 1): v = 1944 ( s ) . 1 3C( 1H} NMR (C 6D 6, 75 MHz): 1 3C0, 177.5 (dt, 2 J C H ^^ i 3 q = 11.5, 2 j P P h 2 , 1 3 c = 6 5 6 - 8 ) ' Both isomers were very unstable i n solu t i o n , as they s t a r t converting within minutes to the previously reported complex Ir(CO)-52 [N(SiMe 2CH 2PPh 2) 2] and free PCH 3Ph 2; therefore, i t was not possible to obtain t h e i r elemental analyses. 4.3 Table 1 XH NMR sp e c t r a l data Complex S i ( C H 3 ) 2 PCH 2Si P ( C 6 H 5 ) 2 Other Ir(CH 3)(PPh2)[N(SiMe2CH 2PPh2)2] -0.13(s) 0.68(s) 1.82(dt,J =4.6, , aPP 2 J =12.0) gem 2.36(dt,J =4.8) app 7.10(m,para/meta) 7.85(m,ortho) IrCH 3 0.72(q, 3J p > H=4.0) t Ir(CH 3)(P(m-tol) 2>[N(SiMe 2CH 2PPh 2) 2] -0.13(s) 0.70(s) 1.75(dt,J =4.6, app 2 J =13.3) gem 2.36(dt,J =4.7) app 7.ll(m,para/meta) 7.90(m,ortho) IrCH 3 0.75(q, 3J p ) H=4.0) t P(C 6H\CH 3) 2^2.10(s) Ir(PCH 3Ph 2)tN(SiMeCH 2PPh 2) 2] 0.18(s) 1.87(t,J =5.3) app 6.88(m,para/meta) 7.65(m,ortho) PCH 3Ph 2 1.37(d, 2J p H=6.7) c i s f — i I r(CH 3)(PCH 3Ph 2)(I)-tN(SiMe 2CH 2PPh 2) 2] j 0.52(s) 0.75(s) 2.24(dt,J =6.6, ' a P P 2 J =14.7) gem 2.50(dt,J =6.3) app 7.07(m,para/meta) 7.38(m,ortho) 8.50(m,ortho) ' IrCH 3 0.80(q, 3J p j R=5.3) t PCH 3Ph 2 1.58(d, 2J =10.6) trans r-- i Ir(CH 3)(PCh 3Ph 2)(I)-[N(SiMe 2CH 2PPh 2) 2] 0.46(s) 0.75(s) 1.58(dt,J =6.6, 'app 2 J =13.3) gem 2.03(dt,J =6.3) app 7.33(m, para/meta) 7.80(m,ortho) 8.06(m,ortho) IrCH 3 1.43(dt, % CH 3Ph 2,H = 2 0 ' 0 )  3 jCH2PPh 2,H = 6 * 0 ) PCH 3Ph ? 1.92(d, 2 J D „ = 6.7) — ^ F y n. Table 1 (contd) Complex S i ( C H 3 ) 2 PCH 2Si P ( C 6 H 5 ) 2 Other mer^Ir(E)2(PHPh2)[N(SlMe2CH2PPh2)2] 0.23(B) 0.67(B) 1.74(dt,J =5.2, ' aPP 2 J =13.0) gem 1.91(dt,J =5.2) app 7.04(m,para/meta) 7.43(m,ortho) 8.32(m,ortho) PHPh 2 5.84(dt, 1J =334.7, 3JP,H= 9 ' 7 ) IrH(trans to PHPh2) -9.75(dtd, 2J p H p h 2 > H=140.4, , ^ C H . P P h , ^ 1 8 - 2 ' 2 jH,H = 5- 0 ) IrH(trans to N) -19.17(qd, 2 J p H-15.1, 2 j H > 5 ' 2 ) Ir(CH 3)(H)(PHPh 2)[N(SlMe 2CH 2PPh 2) 2] 0.12(B) 0.63(B) ~1.9 (obscured) 2.08(dt,J =4.6, ' aPP 2 J =~13.0 gem ~7.0(m,para/meta) 8.72(m,ortho) IrCH 3 0 . 3 0 ( d t , 3 j C H ^ p h 2 > H = 7 . 2 , 3 jPHPh 2,H = 3' 6 ) PHPh 2 5.76(dt, 1J = 334.7, r ,n 3 JP.H = 8' 4> IrH ^-9.06(dt, 2J p H p h 2 ) H=150.0, 2 jCH 2PPh* fH- 1 0- 1 ) fae-Ir(H) 2(PHPh 2)[N(SiMe 2CH 2PPh 2) 2] 0.58(s) 0.83(s) . 1.68(m) 1.99(m) 6.90(m,para/meta) 7.43(m,ortho) PHPh 9 6.17(dt, 1J D =346.7, 3 jp,H= 6- 7> IrH -10.43(m) Ir(PHPh 2)[N(SiMe 2CH 2PPh 2) 2] 0.29(s) l,9 6 ( t , J =4.7) app 7.03(m,para/meta) 7.78(m,ortho) PHPho 5.95(dt, 1J T, =346.7, 3 jP,H = 1 1' 3> Table 1 (contd) Complex S i ( C H 3 ) 2 PCH2S1 P ( C 6 H 5 ) 2 Other c i s 1 1 Ir(CH 3)(CO)(PPh 2)[N(SiMe 2CH 2PPh 2) 2] - 0.03(s) 0.81(B) 1.86(dt,J =6.6,' app 2 J =13.3) gem 2.73(dt,J =6.7) app 7.01(m,para/meta) 7.38(m,ortho) 7.80(m,ortho) IrCH 3 0 . 9 6 ( q , 3 J p H = 5 . 3 ) + trans 1 i Ir(CH3)(C0)(PPh 2)tN(SiMe 2CH 2PPh 2)2] 0.34(B) 0.67(s) 2.13(dt,J =6.3, , aPP 2 J =13.3) gem 2.44(dt,J =7.3) app 7.04(m,para/meta) 7.51(m,ortho) 8.ll(m,ortho) IrCH 3 0 . 5 6 ( t , 3 J p H=5.3) 0 h t The IrCF[ 3 resonance In these complexes i s observed to be a four l i n e pattern and i s indicated as "q"; however, a se l e c t i v e phosphorus decoupling experiment done on the complex Ir(CH 3)PPh 2[N(SIMe 2CH 2PPh 2) 2] shows the methyl-resonance to be a t r i p l e t of doublets (see p.21 ). Even though the 3 1P decoupling experiments were not performed on the rest of the complexes, i t i s assumed that the four l i n e patterns In these complexes are t r i p l e t of doublets 62 CHAPTER 5 REFERENCES 1. Alyea, E.C.; Meek, D.W. "C a t a l y t i c Aspects of Metal Phosphine  Complexes", American Chemical Society, Washington, D.C; 1982. 2. Collman, J.P.; Hegedus, L.S.; Norton, J.R.; Finke, R.G. "P r i n c i p l e s  and Applications of Organotransition Metal Chemistry", University Science Books: M i l l V alley, CA; 1987, p. 73. 3. Bohle, D.S.; Jones, T.C.; Rickard, C.E.F.; Roper, W.R. J . Chem. S o c , Chem. Commun. 1984, 865. 4. a) Barrow, M.J.; Sim, G.A., J. Chem. S o c , Dalton Trans. 1975, 291. b) Peters, K.; Weber, D. Cryst, Struct. Commun. 1981, 10, 1259. c) Hutchins, L.D.; Duesler, E.N.; Paine, R.T. Organometallies J . ; 1982, 1254. 5. a) Ebsworth, E.A.V.; Gould, R.O.; McManus, N.T.; Pilki n g t o n , N. Rankin, D.W.H. J . Chem. S o c , Dalton Trans. 1984, 2561. b) Ebsworth, E.A.V.; McManus, N.T.; Rankin, D.W.H.; Whitelock, J.D., Angew. Chem. Int. Ed. Engl. 1981, 20 , 801. 6. Hutchins, L.D.; Paine, R.T.; Campana, C.F. J. Am. Chem. Soc. 1980, 102, 4521. 7. Day, V.W.; Tavanaiepour, I; Abdel-Meguid, S.S.; Kirner, J.F.; Goh, L.Y.; Muetterties, E.L. Inorg. Chem. 1982,21 , 657. 63 8. Rocklage, S.M.; Schrock, R.R.; C h u r c h i l l , M.R.; Wasserman, H.J. Organometallies 1982,1 , 1332. 9. Baker, R.T.; Krusic, P.J.; T u l i p , T.H.; Calabrese, J . C ; Wreford, S.S. J . Am. Chem. Soc. 1983, 105 , 6763. 10. Domaille, P.J.; Foxman, B.M.;•McNesse, T.J.; Wreford, S.S. J . Am.  Chem. Soc. 1980, 102, 4114. 11. Jones, R.A.; Lasch, J . C ; Norman, N.C; Whittlesey, B.R.; Wright, T.C J . Am. Chem. Soc. 1983,105 , 6184. 12. Baker, R.T.; Whitney, J.F.; Wreford, S.S. Organometallics 1983, 2 , 1049. 13. Hutchins, L.D.; Duesler, E.N.; Paine, R.T. Organometallics 1984, 3, 399. 14. Gross, E.; Jorg, K.; F i e d e r l i n g , K.; Go t t l e i n , A.; Malisch, W.; Boese, R. Angew. Chem., Int. Ed. Engl. 1984, 23 , 738. 15. Burger, H.; Neese, H.J. Inorg. Nucl. Chem. L e t t . 1970, 6 , 299. 16. a) Malisch, W.; Alsmann, R. Angew. Chem., Int. Ed. Engl. 1976,15 , 769. b) Buhro, W.E.; Chisholm, M.H.; F o l t i n g , K.; Huffman, J.C. J . Am.  Chem. Soc. 1987, 109, 905. 17. Malish, W.; Maisch, R.; Colquhoun, I.J.; MacFarlane, W. J . Organomet.  Chem. 1981, 220 , CI. 18. Karsch, H.H.; Reisacher, H-U.; Huber, B.; Mu'ller, C ; Malish, W.; Jorg, K. Angew. Chem. Int. Ed. Engl. 1986, 25 , 455. 19. Buhro, W.E.; Georgiou, S.; Hutchinson, J.P.; Gladysz, J.A. J . Am.  Chem. Soc. 1985,107 , 3346. 64 20. Dobbie, R.C.; Hopkinson, M.J.; Whittaker, D. J . Chem. S o c , Dalton  Trans. 1972, 1030. 21. Bennett, D.W. ; Parry, R.W. J. Am. Chem. S o c 1979J01, 755. 22. Schaefer, H. Z. Anorg. A l l g . Chem. 1980,467 , 105. 23. Weber, L.; Reizig, K.; Boese, R. Chem. Ber. 1985,118 , 1193. 24. Bohle, D.S.; Jones, T.C.; RIckard, C.E.F.; Roper, W.R. Organometalllcs 1986, 5, 1612. 25. Schaefer, H. Z. Anorg. A l l g . Chem. 1979, 459, 157. 26. Ebsworth, E.A.V.; McManus, N.T.; Rankin, D.W.H. J . Chem. S o c , Dalton  Trans. 1984, 2573. 27. Ebsworth, E.A.V.; McManus, N.T.; Pilkington, N.J.; Rankin, D.W.H. J .  Chem. S o c , Chem. Commun. 1983, 484. 28. Ebsworth, E.A.V.; Mayo, R. Angew. Chem., Int. Ed. Engl. 1985, 24, 68. 29. Hayter, R.G. Prep. Inorg. React. 1965, 2, 211. 30. Dobbie, R.C.; Mason, P.R. J. Chem. S o c , Dalton Trans. 1973, 86 1124. 31. Cullen, W.R.; Hayter, R.G. J. Am. Chem. S o c 1964, 86, 1030. 32. Jorg, K.; Malish, W.; Reich, W.; Meyer, A.; Schubert, U. Angew.  Chem., Int. Ed. Engl 1986, 25, 92. 33. Roddick, D.M.; Santarsiero, B.D., Bercaw, J.E. J . Am. Chem. Soc. 1985, 107 , 4670. 34. a) Fagan, P.J.; Manriquez, J.M.; Marks, T.J.; Day, V.W.; Vollmer, S.H.; Day, C.S. J . Am. Chem. Soc. 1980, 102, 5393. 65 b) Cramer, R.E.; Maynard, R.B.; Paw, J.C.; G i l j e , J.W. Organometalllcs 1982, 1 , 869. 35. a) Shulman, P.M.; Burkhardt, E.D.; Lundquist, E.G.; P i l a t o , R.S.; Geoffroy, G.L. Organometalllcs 1987, 6 , 101. b) Rosenberg, S.; Mahoney, W.S.; Hayes, J.M.; Geoffroy, G.L.; Rheingold, A.L. Organometalllcs 1986, 5, 1065. 36. Yu, Y.; G a l l u c c i , J . ; Wojcicki, A. J. Am. Chem. Soc. 1983, 105, 4826. 37. Jones, R.A.; Wright, T.L.; Atwood, J.L.; Hunter, W.E. Organometalllcs 1983, 2, 470. 38. Hayter, R.G. J. Am. Chem. Soc. 1964, 86, 823. 39. a) Gelmini, L.; Matassa, L.C.; Stephan, D.W., Inorg. Chem., 1985, 24, 2585. b) Finke, R.G.; Gaughan, G.; Pierpont, C ; Cass, M.E. J . Am. Chem.  Soc. 1981, 103, 1394. c) Cotton, F.A. Acc. Chem. Res. 1978, 11, 225. d) Kubiak, CP.; Eisenberg, R. J. Am. Chem. Soc. 1977, 99, 6129. 40. Collman, J.P.; Rothrock, R.K.; Finke, R.G.; Moore, E.J.; Rose-Munch, F. J . Am. Chem. Soc. 1982, 21 , 146. 41. Fischer, E.O.; Maasbol, A. Angew. Chem., Int. Ed. Engl. 1964, 3, 580. 42. Dehnicke, K.; Strahle, J . Angew. Chem., Int. Ed. Engl. 1981, 20, . 413. 66 43. Huttner, G.; Evertz, K. Acc. Chem. Res. 1986, 19, 406. 44. Huttner, G.; Muller, H.D.; Frank, A.; Lorenz, H. Angew. Chem. 1975, 87 , 714. 45. Fryzuk, M.D.; MacNeil, P.A. J . Am. Chem. Soc. 1981, 103 , 3592. 46. Datta, S.; Fischer, M.B.; Wreford, S.S., J . Organomet. Chem., 1980, 188 , 353. 47. P a r s h a l l , G.W.; Schrock, R.R. Chem. Rev. 1976, 76 , 243. 48. Lappert, M.F.; Power, P.P.; Sanger, A.R.; Srivastava, R.C "Metal and  Metalloid Amides", Horwood-Wiley, Chichester-New York, 1980. 49. Fryzuk, M.D.; MacNeil, P.A. Organometallics 1982, 1 , 918. 50. Fryzuk, M.D.; MacNeil, P.A. Organometallics 1982, 1 , 1540. 51. Fryzuk, M.D.; William, H.D. Organometallics 1983, 2, 162. 52. Fryzuk, M.D.; MacNeil, P.A.; Rett i g , S.J. Organometallics 1986, 5, 2469. 53. Fryzuk, M.D.; MacNeil, P.A.; Rettig, S.J. J. Am. Chem. S o c 1987, 109, i n press. 54. a) Collman, J.P.; Hegedus, L.S. " P r i n c i p l e s and Applications of  Organotransition Metal Chemistry", University Science Books: M i l l V a lley, CA; 1980, pp. 205, 320. b) i b i d , p. 185. 55. Siedle, A.R.; Newmark, R.A.; Pignolet, L.H. Organometallics 1984, 3, 855. 56. Fryzuk, M.D.; MacNeil, P.A.; McManus, N.T. Organometallics 1987, 6, 882. 67 57. Brookes, P.R.; Shaw, B.L. J. Chem. Soc. A. 1967, 1079. 58. Moore, D.S.; Robinson, S.D. Inorg. Chim. Acta. 1981, 53, L171. 59. Fryzuk, M.D.; MacNeil, P.A.; B a l l , R.G. J. Am. Chem. Soc. 1986, 108, 6414. 60. Fryzuk, M.D.; MacNeil, P.A. Organometalllcs 1983, 2, 682. 61. To our knowledge, this i s the f i r s t example of an intramolecular proton transfer from a hydrocarbyl ligand to a phosphido donor. 62. The complex Ir(PHPh 2)[N(SiMe 2CH 2PPh2) 2] w a s synthesized by addition of one equivalent of PHPh 2 to the toluene solution of Ir( n ^ C g H ^ ) -[N(SiMe 2CH 2PPh 2) 2]-63. Fryzuk, M.D.; MacNeil, P.A.; Rettig, S.J. J. Am. Chem. Soc. 1985, 107, 6708. 64. Clark, G.R.; Roper, G.R.; Wright, A.H. J. Organomet. Chem. 1984, 273, C17. 65. a) Todd, L.J.; Wilkinson, J.R. J. Organomet. Chem. 1974, 80, C31. b) Hartshorn, A.J.; Lappert, M.F.; Turner, K. J . Chem. S o c , Dalton  Trans. 1978, 348. 66. Van der Ent, A.; Onderlinden, A.L. Inorg. Synth. 1973, 14, 93. 67. I s s l e i b , K.; Tzschach, A. Chem. Ber. 1959, 92 , 1118. 68. Halpern, J . Disc. Faraday Soc. 1968, 46, 7. 69. Brothers, P.J. Prog. Inorg. Chem. 1981, 28, 1. 70. Black, T.H. Aldrlchlmica Acta 1983, 16, 3. 68 APPENDIX Below, i s a comprehensive l i s t of t r a n s i t i o n metal phosphide complexes reported i n the l i t e r a t u r e along with the 3 1P{ 1H} chemical s h i f t values and the assigned stereochemistry (wherever available) of the phosphide ligands. An as t e r i s k denotes c r y s t a l l o g r a p h i c a l l y characterized complexes. Table 2 T r a n s i t i o n metal phosphide complexes reported i n the l i t e r a t u r e Compound 3 1P{ 1H> chemical s h i f t (ppm) of the phosphide ligand Phosphide ligand geometry Reference T i ( P R 2 1 ) ( N R 2 2 ) 3 R 1=Et,SiMe 3 R2=Me,Et [Li(DME) n][M(PCy 2) 4] n=l, M=Ti,V,Re n=2, M=Nb Cp 2M(PR 2) 2 M R a. Zr Et b. Zr Cy c Zr Ph d. Hf Et e. Hf Cy f. Hf Ph at 25°C: a-f, 100-160 (s) at -126°C: e, P A = 270.2 (d) P B = -15.3 (d) planar and bridging planar and pyramidal 15 12 69 Appendix (contd) Compound 3 1 P ( 1 H ) chemical s h i f t Phosphide ligand Reference (ppm) of the phosphide geometry ligand [Li(DME)][M(PCy 2) 5] M=Zr Hf * planar and bridging 9 Cp*HfCl 2{P(CMe 3) 2} 209.9 (s) planar 33 Cp*HfCl{P(CMe 3) 2} 2 261.3 (s) planar 33 Cp*HfCl(R){P(CMe 3) 2} R=CH2CMe3 CH2Ph Ph 213.6 (s) 222.2 (s) 216.2 (s) planar 33 Cp*Hf(Me) 2{P(CMe 3) 2} 202.5 planar 33 Ta(H)(PPh 2) 2(dmpe) 2 * — 10 Cp(CO) 3M(PCl 2) M=Cr Mo W 421 (s) 394 (s) 362 (s) pyramidal 16a MeNCH2CH2N(Me)P-MoCp(CO) 2 * — planar 6 70 Appendix (contd) Compound 3 1P{ 1H) chemical s h i f t (ppm) of the phosphide ligand Phosphide ligand geometry Reference Cp(CO) 3M(PPh 2) pyramidal 17 M=Mo — W -63.3(d, 1J p w=52.0 Hz) Cp(CO) 2(PMe 3)M(PPh 2) pyramidal 17 M=Mo -31.9 (s) W -55.9 ( d , ^ =62.9 Hz) Mo(PCy2)i» * — planar 9 1,2-M 2(P(t-Bu) 2)NMe 2)i + — 16b M=Mo * pyramidal W * planar Cp(CO)2M(P(R)(CH=PR)} planar 18 R=2,4,6-t-Bu 3C 6H 2 M=Mo * W 303.4 ( d , 2 J =55 Hz) EP 246.7 (dd, ZJ =64 Hz, , PP ^ = 6 3 8 Hz) Cp(C0) 2W(PR 2) planar 32 R=i-Pr 401.9 (d, 1J w p=591 Hz) t-Bu * 373.4 (d, 1J w p=552 Hz) 71 Appendix (contd) Compound 3 1P{ 1H} chemical s h i f t (ppm) of the phosphide ligand Phosphide ligand geometry Mn 2{P(CH3) 2}2(C0)9 Cp(NO)(PPh 3)Re(PPh 2) * (Tl 5-C 5H 5)(CO) 2Fe-{P(CF 3) 2> [MeNCH2CH2N)(Me)P-Fe(CO), t] +PF 6-Cp(CO) 2Fe{P(SiMe 3) 2} Cp (CO) 2Fe(PR 1R 2) R1=R2=Ph * SiMe 3 CMe3 R1=CMe3, R 2=SiMe 3 M(PRPh)(Cl)(CO) 2-( P P h 3 ) 2 -265(dd, 3J p F e C H=2.0 Hz, 3 jPSiCH= 4' 0 H z> M R Ru H Os H Os Ph Os I Os OMe pyramidal pyramidal pyramidal pyramidal pyramidal 72 Appendix (contd) Compound 3 1P{ 1H> chemical s h i f t (ppm) of the phosphide ligand Phosphide ligand geometry Reference 0s(PHPh)(PH 2Ph)(Cl)- — pyramidal 24 (CO)(PPh 3) 2 R h ( P F 2 ) ( C O ) ( X ) 2 ( P E t 3 ) 2 pyramidal 26 X=Br 388.0(dd, XJ =1153 Hz, rr I l jPRh= 2 7 H Z> 395.4(dd, 1J p F=1155 Hz, l jPRh= 2 5 H Z> Rh(PFCl)(CO)(Cl) 2- 369.8 pyramidal 26 ( P E t 3 ) 2 (ABMXY pattern, l J = rr 1195^Hz, 1 J p R h - 2 6 Hz, 2J p p=3 Hz) I r ( P F 2 ) ( C O ) ( X ) 2 ( P E t 3 ) 2 pyramidal 5b X=C1 * 364.8(dd, X J =1105 Hz, rr Br 2J p p=9.2 Hz) 363.3(dd, X J =1108 Hz, IT J? I 2J p p=8.6 Hz) 364.8(dd, X J =1112 Hz, rr 2J p p=8.3 Hz) 73 Appendix (contd) Compound ' 3 1P{ 1H> chemical s h i f t (ppm) of the phosphide ligand Phosphide ligand geometry Reference Ir(PF 2)(CO)(X)(H)-( P E t 3 ) 2 X=Br I 380.0(dd, \ j -1105 Hz, 2J p p=26.4 Hz) 367.7(dd, 1 J p F = l l l l Hz, 2J p p=25.9 Hz) pyramidal 5b I r ( P F 2 ) ( C O ) ( X ) ( C l ) -( P E t 3 ) 2 X=Br I 362.1(dd, X J =1111 Hz, 2J p p=8.6 Hz) 359.5(dd, X J _ =1117 Hz, Ft 2J p p=7.5 Hz) pyramidal 5b I r ( P C l 2 ) ( C O ) ( C l ) 2 -( P E t 3 ) 2 * 304.0(d, 2J p p=34.0 Hz) pyramidal 5a Ir(PH 2)(CO)(X)(H)-( P E t 3 ) 2 X=C1 Br -217.9(d, 1 J =172.4 Hz) rn -219.3(d, 1J p R=172.8 Hz) pyramidal 28 I r ( P a H 2 ) ( P b H 2 ) ( C O ) -( H ) ( P E t 3 ) 2 P a,-218.2(d, l j p R = 176 Hz) P b,-239.4(d, lJpR= 164 Hz pyramidal pyramidal 28 74 Appendix (contd) Compound 3 1P{ 1H> chemical s h i f t (ppm) of the phosphide ligand Phosphide ligand geometry Reference Cp(R)Ni{P(SiMe 3) 2} pyramidal 25 R=PPh3 -269(dd, 3 J p s i c H = 3.8 Hz, 3 J p N i C H = <0.3 Hz) CO -236.5(dd, 3 J p S i C H = 4 ' 4 3 jPNiCH= 2.4 Hz) 

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