Reactions of cobalt(I) complexes with ammonium and sulphonium ions and organic halides

Abstract

Kinetic measurements are reported for the dealkylation reactions of ammonium and sulphonium compounds and organic halides with cobalt(I) complexes of a series of tetradentate Schiff's bases. The reaction was followed by polarography and cyclic voltammetry. The kinetics conformed to a second order rate law and pseudo-first order plots were obtained in the presence of an excess of substrate. The plot of E_½ values vs. log k″ for the reaction with PhBr and EtBr and [Me₂SC₆H₄Me]⁺ shows a linear free energy relationship suggesting a simple S_N2 displacement reaction and confirming that the nucleophilicity of cobalt(I) species is influenced by the nature of the chelating ligands.