Octahedral cobalt(III) complexes in dipolar aprotic solvents. V. The substitution of chloride and thiocyanate into the cis-chlorodimethylformamidebisethylenediaminecobalt(III) ion in anhydrous NN-dimethylformamide

Abstract

The kinetics and mechanism of the substitution of chloride ion and thiocyanate ion into the cis-chlorodimethylformamidebisethylenediaminecobalt(111) ion, cis-[CoCl(DMF) en₂]²⁺, have been studied in ,NN-dimethylformamide (DMF). The chloride entry shows mixed kinetics which are accounted for by two paths, a slow ion pair dissociation, and a fast bimolecular attack of chloride on an ion pair. The steric course of the reaction, which is chloride dependent, shows that the ion pair dissociative mechanism is more important at low chloride concentrations. The thiocyanate entry shows similar characteristics. Thiocyanate enters faster than chloride in the bimolecular path, but in the ion pair dissociative path, which is significant at lower anion concentration, both chloride and thiocyanate enter at the same rate.