The electrochemical reduction mechanism of [N,N′-1,2-phenylenebis(salicylideneiminato)]cobalt(II)

Abstract

The electrochemical reduction mechanism of [CoL][L =N,N′-1,2-phenylenebis(salicylideneiminate)] has been investigated in dimethylformamide by means of cyclic voltammetry and controlled-potential electrolysis. The cobalt(II) complex shows three successive one-electron reduction processes. The first electron uptake is metal-centred yielding [Co^IL]^–, whereas the second and third electron transfers are both ligand based, corresponding to the reduction of one imine double bond. This leads to the formation of a new cobalt complex [Co^I(HL^–)]^2– which has the Co^II–Co^I redox couple located at a potential ca. 600 mV negative of the potential of the same redox couple of the original [CoL] complex. Decay reactions of some reduction intermediates have been kinetically characterised and the corresponding rate constants have been determined.