ELECTROCATALYTIC OXIDATION OF METHANOL BY THE [Ru3O(OAc)(6)(py)(2)(CH3OH)](3+) CLUSTER: IMPROVING THE METAL-LIGAND ELECTRON TRANSFER BY ACCESSING THE HIGHER OXIDATION STATES OF A MULTICENTERED SYSTEM

摘要

The [Ru3O(Ac)(6)(py)(2)(CH3OH)](+) cluster provides an effective electrocatalytic species for the oxidation of methanol under mild conditions. This complex exhibits characteristic electrochemical waves at -1.02, 0.15 and 1.18 V, associated with the Ru-3(III,II,II)/Ru-3(III,III,II)/Ru-3(III,III,III)/Ru-3(IV,III,III) successive redox couples, respectively. Above 1.7 V, formation of two Ru-IV centers enhances the 2-electron oxidation of the methanol ligand yielding formaldehyde, in agreement with the theoretical evolution of the HOMO levels as a function of the oxidation states. This work illustrates an important strategy to improve the efficiency of the oxidation catalysis, by using a multicentered redox catalyst and accessing its multiple higher oxidation states.