Half‒Sandwich (η6‒p‒Cymene) Ruthenium(II) complexes bearing 5‒Amino‒1‒Methyl‒3‒Phenylpyrazole Schiff base ligands: Synthesis, structure and catalytic transfer hydrogenation of ketones

Abstract

New (η6‒p‒cymene) ruthenium(II) complexes containing Schiff base ligands of the general composition [RuCl(η6‒p‒cymene)(L1‒3)] have been synthesized. The complexes were characterized by analytical and spectral (FT‒IR, UV–Vis, 1H NMR and 13C NMR) methods. The molecular structure of the representative complex [RuCl(η6‒p‒cymene)(L3)] 6 was determined by single crystal X−ray diffraction studies, revealing a pseudo-octahedral piano stool geometry around ruthenium(II) ion. Further, one of the complexes 6 was screened for their efficiency as a catalyst in the transfer hydrogenation of various ketones to alcohols in the presence of KOH and 2‒propanol showed an excellent conversion up to 99%. Under the optimized conditions, the influence of base, reaction temperature and substrate scope was also reported.