Synthesis, crystal structure and spectroscopic studies of copper complexes with tridentate Schiff base ligand

Four Cu(II) complexes [CuLX], where X = NO₃ (1), Br (2), Cl (3), ClO₄ (4) and L = benzoylacetonacetohydrazid tridentate Schiff base, HL, have been synthesized and characterized by elemental analysis, FT-IR, UV-Vis spectroscopy. The structure of compound 1, has been determined by single-crystal X-ray diffraction analysis. The structure of 1 is a mononuclear species, the coordination geometry around the copper(II) ion is four coordinated square planar, L acts as a tridentate ligand which forms one five-membered and one six-membered chelate rings with the Cu(II) metal center, and the fourth position at the Cu ion is occupied by the NO₃ anion. The nitrate ions play role in the H bonding network. In fact the amide NH groups act as H donor towards the nitrate oxygen. The formation of the copper complexes in solution was monitored by a UV/Vis titration experiment. The results revealed that the complexes were of the composition (ligand/metal) 1:1 in solution.