Hydrogenation of α,β-unsaturated carbonyl compounds catalyzed by ruthenium(ii) complexes

Abstract

Four new ruthenium(II) complexes containing 8-methyl-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-4(N)-substituted thiosemicarbazones (HL^1–4) were synthesized. Characterization of the compounds was done by using spectral techniques such as IR, UV-Vis, NMR and mass spectrometry analyses, which confirmed their stoichiometric formation. The structure of the complexes was confirmed by X-ray crystallography where the ligands coordinated as N,S bidentate monoanionic donors. Based on the above data, an octahedral structure has been confirmed for the complexes. Ruthenium complexes were tested for their catalytic efficiency in hydrogenation of rigid alkenes, where the CO and CC groups of alkenes were reduced in the presence of NaBH₄ as a hydrogen source and these hydrogenated products were confirmed by ¹H, ¹³C, GC–MS and CD spectral analyses. The reusability and morphological change of the catalyst were analysed by powder XRD and SEM images.