Cationic Ruthenium(Ii)-Nhc Pincer Complexes: Synthesis, Characterisation And Catalytic Activity For Transfer Hydrogenation Of Ketones

Cationic ruthenium pincer complexes, [Ru(CNC)(CO)(PPh3)Cl]X (CNC = 2,6-bis(1-methylimidazol-2-ylidene)-pyridine, X = Cl- [1a], PF6- [1b]), [Ru(CNC)(PPh3)(2)Cl]X (X = Cl- [2a], PF6- [2b]) and [Ru(CNC)(PPh3)(2)(H)]X (X = Cl- [3a], PF6- [3b]) with triphenylphosphine, CO and halides as coligands have been synthesised and characterised by H-1, C-13, P-31 NMR, mass and single-crystal X-ray crystallography. The application of Ru complexes in the transfer hydrogenation of a wide range of ketones with 2-propanol as the hydrogen source is explored. The in situ transformations observed during the synthesis help understand and suggest a plausible mechanism via the hydride complex 3b. All complexes appear to be efficient catalyst precursors for transfer hydrogenation of ketones.