Synthesis and structure of new copper(II) coordination compounds with 8-quinoline aldehyde semicarbazones and thiosemicarbazones

Abstract

Copper(II) salts were reacted with various quinoline aldehyde chalcogensemicarbazones to yield compounds formulated as Cu(HL)X2 · nH2O (I: HL = quinoline aldehyde thiosemicarbazone (HL1), X = ClO4, n = 2; II: HL = quinoline aldehyde 4-C2H5-thiosemicarbazone (HL1a), X = NO3, n = 0; III: HL = quinoline aldehyde semicarbazone (HL2), X = ClO4, n = 3 and IV: HL = quinoline aldehyde 4-Ph-semicarbazone (HL2a), X = NO3, n = 1). Regardless of the reagent ratio, the products were compounds having the metal: ligand ratio of 1: 1, where the organic ligand was coordinated tridentate in a molecular form. Single-crystal X-ray diffraction showed that, depending on the chalcogen atom in the organic ligand (S or O), the substituent in the 4th position (at the terminal nitrogen atom), and the specifics of the acido ligand, complexes I–IV had appreciably differing molecular structure organizations. The structures of I and III are formed by a 1D charged coordination polymer, ClO4− anions, and water molecules and may be described by the formula [Cu(HL)(H2O)(ClO4)]n(ClO4)n · nH2O. Copper(II) coordination polyhedra in I and II are (4 + 2) and (4 + 1 + 1) tetragonal bipyramids, respectively. In II and IV, the structures are monomeric and can be described as [Cu(HL1a)(NO3)2] with the metal coordination polyhedron shaped as a (4 + 1) tetragonal pyramid in II and as [Cu(HL2a)(H2O)(NO3)](NO3) with the metal coordination polyhedron shaped as a (3 + 2) trigonal bipyramid in IV. The structure of II is built of molecular complexes, each comprising, apart from ligand HL1a, two monodentate coordinated NO3− groups. The oxygen atom of one anion together with the NNS donor atom set of ligand HL1a form the base, and the oxygen atom of the other anion is in the apex of the coordination polyhedron. In IV, the structure is ionic and built of NO3− anions and [Cu(HL2a)(H2O)(NO3)]+ complex cations, where a cationic coordination polyhedron has a trigonal-bipyramidal configuration with organic ligand HL2a positioned along the long edge. The bipyramidal base is made up by the oxygen atoms of the coordinated water molecule and monodentate nitrato group and the nitrogen atom N2 of the azomethyne group.