Selective Electrocatalytic Oxidation of a Re–Methyl Complex to Methanol by a Surface-Bound RuII Polypyridyl Catalyst
† Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
‡ The Scripps Energy and Materials Center, Department of Chemistry, The Scripps Research Institute, Jupiter, Florida 33458, United States
J. Am. Chem. Soc., Article ASAP
DOI: 10.1021/ja507979c
Publication Date (Web): October 17, 2014
Copyright © 2014 American Chemical Society
Abstract
The complex [Ru(Mebimpy)(4,4′-((HO)2OPCH2)2bpy)(OH2)]2+ surface bound to tin-doped indium oxide mesoporous nanoparticle film electrodes (nanoITO-RuII(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-RuIV(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 rhenium–methyl bond of MTO with a detectable intermediate.
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