Chemistry Of Binuclear And Cluster Complexes Of Ruthenium, Cobalt And Nickel

The work described in this thesis is mainly focused on the synthesis, characterization and chemical reactivity of dinuclear and trinuclear phosphine substituted carbonyl complexes of Ru, Co and Ni. The thesis can be broadly classified into three sections. The first section comprising chapters 2 and 3, deals with the chemistry of dinuclear and trinuclear ruthenium complexes with dppm, bis(diphenylphosphino)methane, bridging ligands. The reaction mixture RuCl{dollar}\sb3{dollar}/dppm/NaBH{dollar}\sb4{dollar}/CO yielded mainly trans- (RuCl{dollar}\sb2{dollar}(dppm){dollar}\sb2{dollar}). However, when silver acetate was added to the reaction mixture prior to the reduction with NaBH{dollar}\sb4{dollar}, a high yield synthesis of (Ru{dollar}\sb2{dollar}({dollar}\mu{dollar}-CO)(CO){dollar}\sb4{dollar}({dollar}\mu{dollar}-dppm){dollar}\sb2{dollar}) was achieved. In addition, (RuH(CO)(dppm){dollar}\sb2{dollar}) {dollar}\sp+{dollar} and the electron rich cluster (Ru{dollar}\sb3{dollar}(CO){dollar}\sb6{dollar}({dollar}\mu{dollar}-dppm){dollar}\sb3{dollar}) were also isolated. Reactions of (Ru{dollar}\sb2{dollar}({dollar}\mu{dollar}-CO)(CO){dollar}\sb4{dollar}({dollar}\mu{dollar}-dppm){dollar}\sb2{dollar}) with alkynes produced several new products.;The second section (chapter 4) deals with the synthesis and characterization of di and tetranuclear cobalt complexes with dmpm, bis(dimethylphosphino)methane, ligands. The dinuclear complex (Co{dollar}\sb2{dollar}(CO){dollar}\sb4{dollar}(dmpm){dollar}\sb2{dollar}) was found to exist in two isomeric forms, one with two bridging carbonyl ligands, and the other with only terminal carbonyl ligands. The dynamics of the fluxional processes and thermodynamics of the equilibrium between isomeric forms were investigated.;Chapters 5-7 discuss the synthesis and characterization of mononuclear, dinuclear and trinuclear nickel complexes formed from the Ni(II)/dppm, Ni(II)/dppm/NaBH{dollar}\sb4{dollar}/CO, and Ni(II)/dmpm/NaBH{dollar}\sb3{dollar}CN/CO reaction systems. The structure of five coordinate (NiCl{dollar}\sb2{dollar}({dollar}\eta\sp1{dollar}-dppm)({dollar}\eta\sp2{dollar}-dppm)) was established by X-ray crystallography and represents the first structurally characterized example of a chelating dppm complex of nickel. The reaction of (Ni{dollar}\sb2{dollar}({dollar}\mu{dollar}-CO)(CO){dollar}\sb2{dollar}({dollar}\mu{dollar}-dppm){dollar}\sb2{dollar}) with (NiCl{dollar}\sb2{dollar}(dppm){dollar}\sb2{dollar}) gave a remarkable dinuclear complex (Ni{dollar}\sb2{dollar}({dollar}\mu{dollar}-CO)Cl{dollar}\sb2{dollar}({dollar}\mu{dollar}-dppm){dollar}\sb2{dollar}) in which, as shown by X-ray diffraction studies, the two phosphorus donors have trans sterochemistry at one nickel atom and cis stereochemistry at the other. The fluxionality, chemical bonding and magnetic properties of this unusual complex are discussed.;From the reaction mixture of Ni(II)/dmpm/CO/NaBH{dollar}\sb3{dollar}CN, two complexes were isolated and their structures were fully established by X-ray crystal structure analysis. The dinuclear (Ni{dollar}\sb2{dollar}(CN){dollar}\sb4{dollar}({dollar}\mu{dollar}-dmpm){dollar}\sb2{dollar}), whose formation involves the cleavage of the B-C bond of BH{dollar}\sb3{dollar}CN{dollar}\sp-{dollar}, is analogous to known Pd and Pt complexes of the type trans, trans- (M{dollar}\sb2{dollar}(CN){dollar}\sb4{dollar}({dollar}\mu{dollar}-dppm){dollar}\sb2{dollar}). The second product was a novel trinuclear complex cation (Ni{dollar}\sb3{dollar}({dollar}\mu{dollar}-CO)({dollar}\mu{dollar}-dmpm){dollar}\sb4{dollar}) {dollar}\sp{lcub}2+{rcub}{dollar}. (Abstract shortened by UMI.