Synthesis and characterization of novel oxime-imine ligands and their heteronuclear ruthenium(III) complexes

Vicinal carbonyl oxime (HL1) and oxime-imine (H2L2) ligands and their mononuclear Ru(III) and Cu(II), heterodinuclear Ru(III)-Mn(II), Ru(III)-Ni(II), Ru(III)-Cu(II), and heterotrinuclear Ru(III)-Cu(II)-Ru(III) chelates were synthesized and characterized by elemental analysis, molar conductivity, IR, ESR, ICP-OES, magnetic moment measurements, and thermal analyses studies. The free ligands were also characterized by H-1 NMR spectra. The carbonyl-oxime ligand coordinates through the oxygen of =N-OH to form a six-membered chelate ring. The quadridentate tetraaza ligand (H2L2) obtained by condensing of the bidentate ligand 1-p-diphenylmethane-2-hydroxyimino-2-(1-naphthylamino)-1-ethanone (HL1) with 1,2-phenylenediamine coordinates with Ru(III) through its nitrogen donors in the equatorial position with the loss of one of the oxime protons and concomitant formation of an intramolecular hydrogen bond. Stoichiometric and spectral results of the metal complexes indicated that the metal: ligand ratios in the mononuclear complexes of the ligand (HL1) were found to be 1: 2, while these ratios were 1: 1 in the mononuclear complexes of the ligand (H2L2). The metal: ligand ratios of the dinuclear complexes were found to be 2: 1, and this ratio was 3: 2 in the trinuclear complex.