Low oxidation state ruthenium chemistry.VI. Stoichiometric and catalytic oxidation by molecular oxygen of primary amines bound to dichlorobis(triphenylphosphine)ruthenium(II)

Under a strict nitrogen atmosphere Ru(PPh3)3Cl2 reacts with primary amines to give the complexes, Ru(PPh3)2(RNH2)2Cl2 [R = H (I), CH3(CH2)4 (II), C6H5CH2 (III), p-CH3OC6H4 (IV)]. Chelating ligands such as 5-methyl-1,2-phenylenediamine, ethylenediamine, benzoylhydroxylamine and benzoylhydrazine give the complexes Ru(PPH3)2(chel)Cl2, (V) - (VIII). Compounds (I) - (V) react with molecular oxygen at room temperature to give different products depending on the nature of R, while compounds (VI) - (VIII) are stable with respect to oxidation by O2. Compound (III) acts as a catalyst in the oxidation of benzylamine to benzonitrile with molecular oxygen at 80 °C. The reaction of (III) with molecular oxygen has been followed by ESR spectroscopy, and the intermediate formation of paramagnetic ruthenium-(III) species has been detected.