Copper(II) coordination compounds with 8-quinolinaldehyde semicarbazone: Synthesis and structure

A series of compounds of the general formula Cu(HL)X2 • nH2O (compound I, X = ClO4, n = 3; compound II, X = NO3, n = 2; compound III, X = Cl, n = 0.5; compound IV, X = 1/2SO4, n = 0) is isolated by the reactions of the copper(II) salts with quinolinaldehyde semicarbazone (HL). Regardless of the reactant ratio, only the compounds with a metal to ligand mole ratio of 1: 1 are formed, where the organic reactant is coordinated in the molecular form. The X-ray diffraction analyses of the [Cu(HL)(NO3)(H2O)](NO3) • H2O (II) and [Cu(HL)Cl2] • 0.5H2O(III) compounds show their substantially different organizations of the molecular structures depending on the specifics of the acido ligand. An ionic structure with one NO 3 - anion incorporated into the inner coordination sphere of the metal as a bidentate chelate ligand is observed in compound II. Molecular tetragonal pyramidal complexes associated into a dimer due to the bridging function of one coordinated Cl- anion are formed in structure III. The coordination polyhedron of the copper atom in structures II and III is an asymmetrically extended tetragonal bipyramid. The CuClCu angle equal to 90° and the distance between two planes in compound III equal to 2.978 Å determine the insignificant antiferromagnetic interaction in this compound (g = 2.1, J = -2.5 cm-1). © 2009 Pleiades Publishing, Ltd.