Electrooxidation of Alcohols Catalyzed by Amino Alcohol Ligated Ruthenium Complexes

Ruthenium transfer hydrogenation catalysts physisorbed onto edge-plane graphite electrodes are active electrocatalysts for the oxidation of alcohols. Electrooxidation of CH3OH (1.23 M) in a buffered aqueous solution at pH 11.5 with [(η6-p-cymene)(η2-N,O-(1R,2S)-cis-1- amino-2-indanol)]RuIICl (2) on edge-plane graphite exhibits an onset current at 560 mV vs NHE. Koutecky-Levich analysis at 750 mV reveals a four-electron oxidation of methanol with a rate of 1.35 M-1 s -1. Mechanistic investigations by 1H NMR, cyclic voltammetry, and desorption electrospray ionization mass spectrometry indicate that the electroxidation of methanol to generate formate is mediated by surface-supported Ru-oxo complexes. © 2013 American Chemical Society.