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CHEMICAL AND STRUCTURAL STUDIES OF SUBSTITUTED TRAN SITION METAL CARBONYL COMPLEXES by Gillian Wendy Harris A Thesis Submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, for the Degree of Doctor of Philosophy. November 1984 ABSTRACT Catalytic routes were employed to prepare isonitrlie (RNC) and phosphine (PR^) substituted derivatives of monomeric and dimeric transition metal carbonyl complexes, representative new derivatives being characterized by single crystal X-ray crystallography. Isonitrile derivatives of (n-Arene)Cr(C0J3 and (n-^CgHg)- Mn(cu)g were aynt'.nai*. rt by catalysed substitution reactions, catalyses being [ ( ' 'Oj.y., and/or PdD. The structures of two of the new derivatives, (,1”c6:iijcc >Me)Cr(C0>2f'MBu*), and (n-CgHg)l4n(C0)g(CNBu^), were determined • : ’’ lography, and stereochemical information obtained used in explaining anomalous 1R spectra of these complexes. X-ray crystallography was employed to establish the substitution .geometry of the di-isonitrile derivative of iron pentacarbonyl, FetCOj^iCNNe)^. The molecular structure was unable to account for anomalies in the IR spectrum. A chemical and structural study was undertaken of isonitrile and phosphine derivatives of Reg(CO)^^. The use of PdO to catalyse ths reaction between Re2(CO)10 and RNC enabled the facile syntheses of the isonitrile derivatives R B g C C O j ^ ^ C N R ^ (n = 1-4). These new derivatives were fully characterized by IR, NMR and mass spectroscopy. X-ray crystallography established the structures of a aeries of representative compounds, Rag(CO}g{CNBut}, Re2 (CO)e(CNC6H3He2-2,6)2 , Re2 (C0 )7(CNMe)3 and R»g(CO)^(GMCgHgMe.-Z,0)^ The struct- "‘in of two analogous manganese carbonyl isonitrile derivative i,(C0)g(CNBut )2 and Mn2(ro)6(CNC6H3Me2-2,6)d , were also investigated by X-ray crystallography. Differences observed in the IR and NMR spectra of the di-isonitrile derivatives of rhenium and manganese carbonyl could be explained in terms of the observed molecular structures. The stereochemistry of the mono- to tetra-isonitrile substituted derivaGivra are discussed in terms of electronic and stieric factors. Attempts were made to extrsnd the Pd-catalysed carbonyl substitution reaction of Re2(C0)1Q to phosphine ligands. Although the catalysed reaction with PR^ is much less facile than with RNC, this route was successfully employed in the synthesis of mono- and di-substituted phosphine derivatives, Re2(CO)10 ^(PRg)^ (n = 1 ,2 ). The X-ray crystal structure of dlax[Re.(CO)»(PMe^Ph)^3 was determined. A correlation was established between IR spectral data and substitution geometry for M ^ f C O g d J ^ { M = Re,Mn) complexes. This study demonstrated the synthetic utility of transition metal-catalysed routes to substituted metal carbonyl derivatives. X-ray crystallography was shown to be a powerful tool in the rationalization, in terms of structure, of certain observed properties of these complexes. DECLARATION I hereby declare that the work presented in this thesis was carried out exclusively by myself under the supervision of Professor J.C.A Borayens and Dr. N.J. Coville. This thesis has neven been submitted for a degree in any other university. G.W. Harris 1 November 1984 ■ACKNOWLEDGEMENTS I should like to express my sincere thanks to the following . Professor J.C.A. Boeyens and Dr. N.J. Coville, my supervisors, for their guidance and enthusiasm. Professor w.J. Kruger, for edvice o . crystallographic problems in Professor Boeyens' aussnce. Mr. J. Albain, for the collection of the X-ray data. Mr. D.C. Levendis, for assistance with computing problems. Dr. M.O. Albers, for helpful advice on certain synthetic aspects, and for running the FTIR spectra. Dr. P.R. Boshoff, for running the mass spectra. Professor I.S. Butler, and Mr. P.D. Harvey, of McGill University, Montreal, for communicating the results of their Raman studies on the Re2(CO)^0_n(CNR)n (n = 1-4) complexes prepared as part of this work. Mrs. A. Maritz, for typing this thesis. Mrs. M. Crabb and Mrs. R. Hillier, for the labelling of the ORTEP diagrams. Finally, I wish to acknowledge the financial support from the University of the Witwatersrand, and the South African Council for Scientific and Industrial Research. In addition, I should like to express my gratitude to Mr. M.I.J. ManeeE, of Birbeck College, University of London, for use of the EMPMDS program. , Drs. D.S. Moss, R.A. Palmer and B.J. Howlin, of Birkbeck College, University of London, for advice on crystullographic and computing problems. and Professor. T.L. Blundell, of Birkbeck College, for the use of the College Computing facilities. PREFACE It is not fvr nothing that the scholar invented the Ph.D. thesis as his principal contribution to literary form. The Ph.3. thesis is the perfect image of his world. It 5a work done for the sake of doing work - perfectly conscientious, perfectly laborious, perfectly irresponsible. - Archibald MacLeish (The Irresponsibles) TABLE OF CONTENTS ACKNOWLEDGEMENTS LIST OP TABLES LIST OF FIGURES LIST OF ABBREVIATIONS AND SYMBOLS I- Introduction II Catalytic Synthesis and characterization of Isonitrile Derivatives of (n-Ai'ene)Cr(CO)^ 2.1 Int ‘Auction 2.2 Result 2.2.1 Reaction of (rnA/‘-ine)Cr(C0)3 complexes with iscnitriles 2.2.2 Reaction of (n^CgHgi-OgMe)Cr(CO)3 with 2,S-MSgCgHgNC, iu the presence of Iron Dimer Catalysts 2.2.3 Formation of by-products of the type Cr(CO). (CNCJLMe -2,6) (n « 3,4) o-n o o 2 - n in the reaction of (n-CgHgCOgMe)- Cr(C0)3 with 2,6-Me2C6H3NC 2.3 Spectroscopic properties of (n§Arene)Cr(CO)2~ (CNR> complexes 2.3.1 Infra Red 2.3.2 Proton Nuclear Magnetic Resonance 2.3.3 Mass Spectrum of {ij-C-H-COpMe)- 6 5 Cr(C0)_(CNBuT) Experimental 2.4.1 The catalysed synthesis of L>'“ 'gHgX)- Cr(C0).(CNR)] ( X = H,C<,C0„ ■ ,As\ R = Bu , 2,6-Me2C6H3 ) 2.4.2 Reaction of {irCgHgCOgMejCrfCOjg with 2,6-MeaC6H3NC, with catalyst [CpFe(L)2] ICp = CgHg, CgH4C02Me, CgMeg; L = CO; Cp = CgHg, L = 2,6-MSgCgHgNC) and co­ catalyst PdO 2.4.3 Preparation of [(C5HdC02Me)Fe(C0)2]2 2.4.4 Reaction of [(OgH COgMe)Fe(CO)2]2 with S u N C (1:1 Ratio) Reaction 01 [(C5H4C02Me)Fc(C0)g ]2 with S u N C (1:3 Ratio) i'ir III The Modification of (n^.H-CO Me)Cr<C0)3 by 3.1 Introduction > 3.2 The Structure of (n^C-H-COgMe)Cr(CO)^ Ligand geometry Confornation 20 ■ Cr-C bond lengths 23 Ring C-C bond lengths 23 :VV Planrity of Ring 23 i Cr-C-0 bond angles 24 Packing considerations 24 The structural effect of substitution of CO by Ligand L 3.3.1 Ligand geometry Conformation Influence of electronic nature of L on Cr-C bond lengths Ring C-C bond lengths Planarity of Ring Cr-C-C and Cr-C-R bond angles ■ i Packing, and Steric Factors X-ray Crystallograpl >: Studies of (n-CgHg- CO?Me}Cr(CO)2L complexes 3. 1 OC-Cr-CO and OC-Cr-L angles Conformation; An exception Trends in Cr-C bond lengths Ring C-C bond lengths Ring planarity and bending of CO^Me Cr-C-0 ar nd angles (L = OR) Conform.. ligand L 3.5 Conclusion The Crystal and Molecular Structure of (n-CgHgCOgMe)- Cr(C0)2(CNBut ) 4.1 Introduction - ix - ion of the Structure of (n-CgHgCOgMe)- Cr(CO) CNBu*} 4.2.1 OC-Cr-CO and OC-Cr-CN angles Conformation Cr-C bond lengths ,Ring C-C bond lengths Ring planarity and bending of COgME group 41 Cr-C-CO and Cr-C-N bond angles 42 Conformation of the CNBu*" ligand 42 Structural Features of (n-C^HgCOgMe)- , Cr(CO) 4.3.1 Staggered Conformation Position of ^BuNC vis-S-vis CO^Me 4.3.3 Bending of the *BuNC ligand 4.3.4 Intra- and Inter-molecular Interactions Experimental ; 4.4.1 Data collection 4.4.2 Structure Solution and Refinement I Catalytic Synthesis and Characterisation of Isonitrile 1 Derivatives of (n-C-H-)Mn(CO)3 Introduction Results and Di6C'.,"3ion 5.2.1 PdO-cata1' ■ "d reaction of (n -CgHg)- Mn(C0)3 . '•i Isonitriles 5.2.2 Characterization of (n-CgHg)Mn(CO)^ (CNR) produi-v.s (a) Infra hiJ (b) Proton Nuclear Magnetic Resonance (ci Mass spectrum of h^CgHg)- Mn(CO)-(CNBut ) Experimental - preparation of (n-CgN )Mn(U0)a- (CNR), R = Bu , C6H5CH2 , C6Hi V C6N3Me2-2,6, Me) Modification of (nSC5H5 >Mn(C0>3 by Ligands L 54 Introduction 54 j The Structure v.' (frCgHg)Mn(CO)g Ligand geometry and conformation Conformation Mn-C-ring and Mn-CO bond lengths Ring planarity and C-C bond lengths Mn-C-0 bond angles Packing considerations X-ray Crystallogrophxc Studies of (i-C-H,)- Mn(CO) 2L complexes OC-Mn-CO and OC-Mn-L angles Molecular Conformation Mn-C-ring and Mn-CO bond lengths 6.3.4 Ring C-C bond lengths 6.3.5 Mn-C-0 bond angles 6.3.6 Packinp — t Steric Factors 6.4 Conclusion The Crystal and _ .jr Structure c/ (n"C^Hg)Mn- (C0)2(CNBut) 7.1 Introduction 7.2 Discussion of the S'ructure of (n^CgHg)Mn- (oofgfCN*/; 7.2.1 OC-Mn-CO and OC-Mn-CN angles 7.2.2 Molecular Conformation 7.2.3 Mn-C bond lengths 7.2.4 Ring planarity and C-C bond lengths 7.2.5 M-C-0 and M-C-h iir.nd angles 7.2.6 Conformation c.
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