title: Electrocatalytic Alcohol Oxidation with Ruthenium Transfer Hydrogenation Catalysts.
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-1are 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, Fc0/+) 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 Fc0/+. By cyclic voltammetry, fast turnover frequencies of 3.2 and 4.8 s-1for 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%.
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Kate M
authors.initials: KM
authors.lastname: Waldie
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Kristen R
authors.initials: KR
authors.lastname: Flajslik
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Elizabeth
authors.identifier: 0000-0003-1481-266X
authors.initials: E
authors.lastname: McLoughlin
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Christopher E D
authors.initials: CE
authors.lastname: Chidsey
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Waymouth