Cationic ruthenium pincer complexes, [Ru(CNC)(CO)(PPh 3 )Cl]X (CNC = 2,6-bis) with triphenylphosphine, CO and halides as coligands have been synthesised and characterised by 1 H, 13 C, 31 P 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.

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The application of cationic Ru(II)‐CNC pincer complexes [Ru(CNC)(CO)(PPh3)Cl]PF6 (1), [Ru(CNC)(PPh3)2Cl]PF6 (2), [Ru(CNC)(η2:η2‐COD)Cl]PF6 (4), and [Ru(CNC)(DMSO)2Cl]PF6 (5) in acceptorless dehydrogenation of alcohols is reported under conventional “oil‐bath” and microwave heating conditions. The effect of different ancillary ligands (CO, PPh3, COD, and DMSO) have been demonstrated during catalysis. Complexes with more π‐acid ligands CO and COD perform better compared with those with PPh3 and DMSO ligands. A plausible mechanism is proposed based on NMR and mass investigation during the catalysis. The catalytic performance matches with the order of trans effect among the four ancillary ligands studied in these complexes. Further, a significant reduction in reaction time, as well as reaction temperature, was observed for catalytic reactions under the microwave‐assisted reaction compared with the oil‐bath heating reaction.

Reductive amination has been widely used for manufacturing carbon-nitrogen-containing building blocks. Despite its versatility, the requirements for a chemical reductant or harmful hydrogen gas have limited its further utilization in...