Arene Ruthenium Complexes as Versatile Catalysts in Water in both Transfer Hydrogenation of Ketones and Oxidation of Alcohols. Selective Deuterium Labeling of rac-1-Phenylethanol

The preparation of three series of arene Ru(II) half-sandwich compounds with the functional ligand 4,4′-dimethoxy-2,2′-bipyridine (dmobpy) is described. The new cationic derivatives have the general formula [(η6-arene)RuCl(κ2-N,N-dmobpy)]X (arene = benzene, X = Cl– ([1]Cl), BF4– ([1][BF4]), TsO– ([1]TsO), PF6– ([1][PF6]); arene = p-cymene (p-cym), X = Cl– ([2]Cl), BF4– ([2][BF4]), TsO– ([2]TsO), PF6– ([2][PF6]); arene = 2-phenoxy-1-ethanol (phoxet), X = Cl– ([3]Cl), BF4– ([3][BF4]), TsO– ([3]TsO), PF6– ([3][PF6])). The structures of [1]Cl, [1]TsO, [2]TsO, [2][BF4], and [2][PF6] were determined by X-ray crystallography. All of the complexes except the PF6– salts were water-soluble, and they behaved as active catalysts in two different processes: the transfer hydrogenation of water-soluble and -insoluble ketones to the corresponding alcohols, using HCOONa as the hydrogen source at pH 4, and the oxidation of rac-1-phenylethanol to acetophenone with tBuOOH at pH 7, both in aqueous solution. For the transfer h...