THE ELECTROCATALYTIC OXIDATION OF METHANOL BY A RUTHENIUM(V) OXO COMPLEX

cis-[Ru(V)(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-[Ru(V)(L)(Cl)(O)]2+ and CH3OH, CH3OD and CD3OH evaluated by rotating disc voltammetry are (6.6 +/- 0.6) x 10(2), (5.5 +/- 0.6) x 10(2) and (6.6 +/- 0.5) x 10 dm3 mol-1 s-1, respectively. The large kinetic isotope effect for CH3OH (k(H)/k(D) = 10) indicates the importance of alpha-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.