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).