Selective Electrocatalytic Oxidation of a Re-Methyl Complex to Methanol by a Surface-Bound RuII Polypyridyl Catalyst

The complex [Ru(Mebimpy)(4,4'-((HO)(2)OPCH2)(2)bpy)(OH2)](2+) surface bound to tin-doped indium oxide mesoporous nanoparticle film electrodes (nanoITO-Ru-II(OH2)(2+)) is an electrocatalyst for the selective oxidation of methylrhenium trioxide (MTO) to methanol in acidic aqueous solution. Oxidative activation of the catalyst to nanoITO-Ru-IV(OH)(3+) induces oxidation of MTO. The reaction is first order in MTO with rate saturation observed at [MTO] > 12 mM with a limiting rate constant of k = 25 s(1). Methanol is formed selectively in 87% Faradaic yield in controlled potential electrolyses at 1.3 V vs NHE. At higher potentials, oxidation of MTO by nanoITO-RuV(O)(3+) leads to multiple electrolysis products. The results of an electrochemical kinetics study point to a mechanism in which surface oxidation to nanoITO-RuIV(OH)(3+) is followed by direct insertion into the rheniummethyl bond of MTO with a detectable intermediate.