Oxidation electron stoichiometry, diffusion coefficients and formal potentials of two di-nickel-bis(salen) complexes

Two di-nickel complexes based on bis(salen) ligands are investigated by electrochemical and NMR techniques with respect to determination of their diffusion coefficients D and the number n of electrons involved in oxidation in organic electrolytes and at a Pt electrode. It is shown that in both cases the oxidation involves two electrons despite the appearance of the cyclic voltammograms which can not easily be distinguished from those of a one-electron process. The difference of the formal potentials of the two electron transfer processes is determined by simulation of the experimental cyclic voltammograms, and found to be below 60 mV.