Half-sandwich ruthenium(II) complexes with water-soluble Schiff base ligands: Synthesis and catalytic activity in transfer hydrogenation of carbonyl compounds

New ionic Schiff-base ligands have been synthesized by condensation of (3-formyl-4-hydroxybenzyl) triphenylphosphonium and 3-(3-formyl-4-hydroxybenzyl)-1-methyl-1H-imidazol-3-ium chloride and hexafluorophosphate salts with N,N-dimethylethylenediamine. Treatment of the dimeric derivative [{RuCl(mu-Cl)(eta(6)-p-cymene)}2] with two equivalents of these ligands allowed the preparation of novel mononuclear water-soluble Ru(II) complexes, which proved to be catalytically active in the transfer hydrogenation of ketones and aldehydes under aqueous conditions. (C) 2016 Elsevier B.V. All rights reserved.