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Electrocatalytic Alcohol Oxidation with Ruthenium Transfer Hydrogenation Catalysts.
Title Electrocatalytic Alcohol Oxidation with Ruthenium Transfer Hydrogenation Catalysts.
Authors Waldie, K.M.; Flajslik, K.R.; McLoughlin, E.; Chidsey, C.E.D.; Waymouth, R.M.
Journal J Am Chem Soc
DOI 10.1021/jacs.6b09705
Abstract

Octahedral ruthenium complexes [RuX(CNN)(dppb)] (1, X = Cl; 2, X = H; CNN = 2-aminomethyl-6-tolylpyridine, dppb = 1,4-bis(diphenylphosphino)butane) are highly active for the transfer hydrogenation of ketones with isopropanol under ambient conditions. Turnover frequencies of 0.88 and 0.89 s(-1) are achieved at 25 °C using 0.1 mol % of 1 or 2, respectively, in the presence of 20 equiv of potassium t-butoxide relative to catalyst. Electrochemical studies reveal that the Ru-hydride 2 is oxidized at low potential (-0.80 V versus ferrocene/ferrocenium, Fc(0/+)) via a chemically irreversible process with concomitant formation of dihydrogen. Complexes 1 and 2 are active for the electrooxidation of isopropanol in the presence of strong base (potassium t-butoxide) with an onset potential near -1 V versus Fc(0/+). By cyclic voltammetry, fast turnover frequencies of 3.2 and 4.8 s(-1) for isopropanol oxidation are achieved with 1 and 2, respectively. Controlled potential electrolysis studies confirm that the product of isopropanol electrooxidation is acetone, generated with a Faradaic efficiency of 94 ± 5%.