Synthesis and spectroscopic and structural studies of ruthenium carbonyl derivatives of N-salicylidene-2-hydroxyaniline Schiff base

The mononuclear ruthenium tricarbonyl derivative mer-[Ru(CO)3(sha)], 1, was synthesized from the reaction of [Ru3(CO)12] with N-salicylidene-2-hydroxyaniline (shaH2) Schiff base. The corresponding reactions of the ruthenium cluster with shaH2 in the presence of a secondary ligand L, L = 2-aminobenzimidazole, thiourea, pyridine, and triphenylphosphine, resulted in formation of the dicarbonyl derivatives [Ru(CO)2(sha)(L)], 2–5. The two carbonyl groups in these complexes were attached to the metal in a cis arrangement. In case of bipyridine (bpy) as a secondary ligand the [Ru(CO)2(shaH)(bpy)], 6, where the two CO moieties in a trans position. All the complexes were characterized by elemental analysis, mass, infrared and 1H nuclear magnetic resonance spectra. The ultraviolet–vis spectra of the complexes showed broad visible bands due to metal-to-ligand charge transfer. The stereochemistry and theoretical optimization of the three-dimensional geometry of the ligand and the complexes were determined.