Ruthenium(II) terdentate CNN complexes: Superlative catalysts for the hydrogen-transfer reduction of ketones by reversible insertion of a carbonyl group into the Ru-H bond

(Chemical Equation Presented) Very low loading and short reaction times are characteristic features of the quantitative reduction of different ketones using 2-propanol and terdentate [RuX(CNN)-(dppb)] (X = H, Cl (see structure); dppb = Ph2P(CH2)4PPh2) complexes prepared from 6-(4′-methylphenyl)-2-pyridyl-methylamine. The reduction apparently takes place by reversible insertion of the substrate into the Ru-H bond, thus leading to a RuII alkoxide. © 2005 Wiley-VCH Verlag GmbH & Co. KGaA.