Synthesis and characterization of Ru(II) complexes with polyfunctional amides and their application in catalytic oxidative coupling of amines

Abstract

The synthesis and characterization of some new mononuclear Ru(II) complexes of the type [(Ru(L)2(DMSO)2] and [(Ru(L)2] (L = O,O-donor bidentate or N,O,O-donor tridentate or O,O,O-donor tridentate amide ligands) is described. These metal complexes were characterized by Elemental analysis (EA), IR, 1H NMR, and mass spectral data and their structures have been proposed. Next, these complexes were investigated as catalysts in the oxidative coupling of amines by tert-butyl hydroperoxide (TBHP) oxidant to produce selectively the corresponding imines in high yields in CH3CN. The influence of various reaction parameters such as selection of oxidant and solvent during the benzyl amine oxidative coupling was systematically monitored to optimize the catalytic conditions. The utility of optimized reaction conditions was further extended to investigate the amine substrate scope. Based on the experimental results and previous reports, a plausible mechanism was also deduced for the selective synthesis of imines.