Synthesis and characterization of organosoluble ruthenium(ii) complexes bearing schiff base ligands: efficient reusable catalyst for the hydrogenation reactions.

ABSTRACT

Six new organosoluble ruthenium(II) complexes bearing dibasic tetradentate Schiff base ligands of the general formula [Ru(CO)(PPh3)(L)] (where L = dibasic tetradentate Schiff base ligands derived by condensing actetoacetanilide/acetoacetotoludide with o-aminophenol/oaminothiophenol/ o-aminobenzoic acid in 12 molar ratio in ethanolic medium) have been synthesized by reacting [RuHCl(CO)(PPh3)3] with the respective Schiff base ligands in 11 molar ratio. The complexes were characterized by physico-chemical and spectroscopic methods. An octahedral structure has been proposed tentatively for all the complexes. These ruthenium(II) complexes possess N2O2/N2S2 metal binding sites and act as a potential catalyst for the hydrogenation reactions. Organosoluble ruthenium(II) complexes have been used as catalysts in the hydrogenation of methoxy benzene and benzaldehyde. From the results it was observed that all the new six complexes proved to be better catalyst in the hydrogenation. All the ruthenium(II) complexes decomposes completely to form ruthenium metal, which in turn forms a active ruthenium hydride in the hydrogenation reaction. The reusability of the ruthenium catalysts have also been evaluated up to six consecutive runs, which does not show much variation in the conversion of the substrate.