Photoelectrochemical oxidation of tris(dimethyldithiocarbamato-S,S′)cobalt(III)

Abstract

The electro-oxidation of tris(dimethyldithiocarbamato-S,S′)cobalt(III), [Co(S₂CNMe₂)₃], at platinum electrodes in acetonitrile solution in the presence of light of wavelengths between 300 and 600 nm gave rise to appreciable photocurrents. These are suggested to arise from an absorption of light by the one-electron oxidation product [Co(S₂CNMe₂)₃]⁺ which is followed by an internal redox reaction which leads to the fragmentation of the cation and the probable formation of [Co(S₂CNMe₂)₂] and oxidised ligand. Kinetic parameters have been obtained for the decomposition of [Co(S₂CNMe₂)₃]⁺ in the presence of light. In the absence of light the cation undergoes a rate-determining dimerisation reaction which is followed by an internal redox reaction which leads to the formation of [Co₂(S₂CNMe₂)₅]⁺; at light intensities of ca. 10 mW cm^–2 both pathways are kinetically significant and the electrode reaction consists of parallel electrodimerisation and photofragmentation pathways.