Ruthenium(II) Terdentate CNN Complexes. Superlative Catalysts for the Hydrogen Transfer Reduction of Ketones via Reversible Carbonyl Group Insertion into the Ru-H Bond

The novel terdentate CNN complexes [RuX(CNN)(dppb)] (X = Cl, 1; H, 2; dppb = Ph2P(CH2)4PPh2), prepared from 6 (4’-methylphenyl)-2-pyridinemethanamine, are extremely active catalysts for the transfer hydrogenation of ketones (Ru 0.005-0.001 mol % and TOF up to 2.5×106 h-1). When 2 reacts with benzophenone the alkoxide-amine derivatives 3 (X = OCHPh2) is formed via a reversible insertion into the Ru-H bond.