Activation of single and multiple C–N bonds by Ru(II) catalysts in homogeneous phase

The ruthenium(II) dihydro complexes RuH2(CO)2(PnBu3)2, RuH2(CO)2(PPh3)2, and RuH2(PPh3)4 are able to hydrogenate/hydrogenolyse organic substrates containing single or multiple C-N bonds. The influence of several reaction parameters such as reaction time, temperature, hydrogen pressure and concentration of the catalyst were tested. A benzonitrile conversion of 76.5% was achieved after 24h at 393K. In the same conditions, N-benzylidenaniline is hydrogenated with a 92.1% conversion. Finally the activation parameters and the kinetic constants of these reactions were calculated. New ruthenium hydrido complexes containing a benzonitrile or an imine ligand were identified and spectroscopically characterized. A catalytic cycle was proposed to rationalize the results obtained, on the basis of the new complexes identified.