THE ELECTROCHEMICAL REDUCTION-MECHANISM OF [N,N'-1,2-PHENYLENEBIS(SALICYLIDENEIMINATO)]COBALT(II)

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(I)L]-, 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.