The electrocatalytic oxidation of methanol by a ruthenium(V) oxo complex

cis-[Ruv(L)(Cl)(O)]2+(L = N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)ethylenediamine) is an active catalyst for the electro-oxidation of methanol in solution. The second order rate constants for the reaction between cis-[Ruv(L)(Cl)(O)]2+and CH3OH, CH3OD and CD3OH evaluated by rotating disc voltammetry are (6.6 ± 0.6) × 102, (5.5 ± 0.6) × 102and (6.6 ± 0.5) × 10dm3mol-1s-1, respectively. The large kinetic isotope effect for CH3OH (kH/kD= 10) indicates the importance of α-CH bond cleavage in the transition state. A chemically modified electrode prepared by immobilization of the ruthenium complex inside a Nafion film on the pyrolytic graphite electrode surface is capable of catalyzing the electro-oxidation of methanol. Reduction and/or oxidation of the complex inside Nafion would lead to the irreversible conversion of the catalyst to a new species which is catalytically inactive.