ELECTROCHEMICALLY CONTROLLED DISSOCIATION OF DIOXYGEN FROM A MU-PEROXO COBALT(III) DIMER

The electrochemistry of the mu-peroxo dimer of a cobalt Schiff-base complex, [{CoIII(salen)(dmso)}2O2] [salen = N,N'-ethylenebis(salicylideneiminate), dmso = dimethyl sulfoxide], has been studied in solution in dmso. Controlled-potential oxidative electrolysis of the dimer is a two-electron process and resulted in its dissociation, with release of dioxygen to the solution and formation of [Co(III)(salen) (dmso)2]+. Reduction of the cobalt(III) complex produced the corresponding cobalt(II) complex. The various redox and co-ordination states of the process were characterised by spectroelectrochemistry. The results provide conclusive evidence that electrochemical oxidation can be used as a mechanism for release of O2 from a dioxygen-containing complex.