Metal exchange reactions between divalent metal ions and their dithiocarbamate complexes in dimethyl sulfoxide: a kinetic and mechanistic study

Abstract

The kinetics and mechanism of metal exchange between Ni^II, Cu^II, Zn^II, Cd^II, Pb^II and Hg^II and their dithiocarbamate complexes have been studied in dimethyl sulfoxide. Two pathways for ligand transfer are observed. The first involves dissociation of dithiocarbamate from the metal complex followed by substitution at the metal ion, while the second involves direct electrophilic attack by the metal ion on the dithiocarbamate complex. The relative importance of the pathways depends on the stability of the complex and the substitution lability and electrophilic character of the metal ion. The stability of the dithiocarbamate complexes in dimethyl sulfoxide is in the order Hg > Cu > Ni > Pb ≈ Cd > Zn.