Electrochemical studies of dinuclear molybdenum(V) complexes with EDTA in aprotic solvents

Abstract

The electrochemical behaviour of the dinuclear complexes [Mo 2O 4- n S n (edta)] 2− ( n = 0–2) was investigated in various aprotic solvents, acetonitrile (CH 3CN), dimethyl sulphoxide (DMSO), N,N-di-methylformamide (DMF) and N,N-dimethylacetamide (DMA). These complexes undergo quasi-reversible one-electron reduction and quasi-reversible one-electron oxidation in CH 3CN. This behaviour is quite different from that in aqueous media. The formal potentials for the reduction of these complexes, as well as the formal potentials for the oxidation of these complexes, shift in the positive direction with an increase in the number of bridging sulphides. The electrochemical behaviour of these complexes in DMF and DMA is similar to that in CH 3CN. The only exception is the oxidation processes of [Mo 2O 4edta)] 2−. in which an irreversible and nearly two-electron transfer occurs in DMF or DMA. The complexes of [Mo 2O 4− n S n edta)] 2− ( n = 0–2) also undergo quasi-reversible one-electron reduction in DMSO. However, anomalies were observed for the oxidation process in this solvent.