Kinetics and mechanisms of the reaction between thioacetamide and lead(II), cadmium(II), and cobalt(II) ions in acetate buffered solution

Abstract

The interaction between thioacetamide and lead(II), cadium(II), and cobalt(II) ions in acetate buffered solution leads to acetonitrile and metal sulphide. A mechanism is suggested which involves the rate-determining decomposition of the deprotonated form of 1:1 metal–thioacetamide complexes. The mechanism accounts for the rate dependence on thioacetamide hydrogen ion, and metal ion concentration. The influence of the nature of the metal ions on the reaction rate, characterised by the sequence Pb > Cd > Co, is discussed in the light of the hard–soft acid–base principle. The difference in mechanism between the hydrogen ion and metal ion catalysed reaction of thioacetamide is also rationalised.