Synthesis, characterization, and investigation of catalytic properties of RuII complexes with Schiff bases based on 2-hydroxybenzaldehyde and 5-bromo-2-hydroxybenzaldehyde

Abstract

Pursuing our recent interest concerning the catalytic activity of half-sandwich Ru-II complexes containing Schiff base ligands (L-1 and L-2), in this study new Schiff bases and their half-sandwich Ru-II complexes were prepared. The structures of these compounds were confirmed by a variety of spectral and physical methods such as microanalysis, FT-IR, electronic spectra, proton and carbon NMR, TGA and mass spectra. The catalytic activities of the Ru-II complexes toward the transfer hydrogenation of ketones to their corresponding alcohols were investigated using i-PrOH as a hydrogen source and solvent. The complexes showed high catalytic activities at catalyst concentrations of 0.01 mmol and were able to carry out transfer hydrogenation (TH) to a wide range of ketones in the presence of KOH. In general, Schiff bases recognition, the coordination chemistry, and the ketone substrates were found to influence the catalytic performance of these complexes.