Synthesis and characterization of some lanthanoid complexes of salicylaldehyde salicyloyl hydrazone

Abstract

Some lanthanoid complexes of the types, [Ln(ssh)(H2O)n].H2O and [Ln′(Hssh)(X)(H2O)3].H2O, where Ln = Y, La, Nd, Gd, Tb and Dy; Ln′= Pr/Sm for X = NO3/Cl and H3ssh = salicylaldehyde salicyloyl hydrazone, have been synthesized and characterized by elemental analyses, molar conductance, magnetic susceptibility, infrared, electronic and 1H NMR spectral data. Selected complexes have also been studied on the basis of their solid state electrical conductivity, band gap, and powder X-ray diffraction data. The complexes, except those of the Pr and Sm, are polymeric in nature showing high decomposition points. Dehydration study indicates the presence of water molecules both in the lattice and coordination sphere of the complex metal ions. IR and 1H NMR spectral data suggest trinegative tetradentate and dinegative tridentate coordination of H3ssh in the complexes. The chloro and nitrato groups are found to coordinate to the metal ion as monodentate and bidentate-chelating species respectively. Solid state electrical conductivity data at various frequencies show semi-conducting nature of the complexes. Optical band gap studies show the complex [Gd(ssh)(H2O)3].H2O to be a direct band gap semi-conducting material with a band gap of 2.64 eV. Powder X-ray diffraction patterns show orthorhombic structure for most of the complexes. Various polyhedral geometries such as distorted octahedron, pentagonal bipyramid and distorted square antiprism are tentatively proposed for the complexes.