Crystal Structures of Copper(II) Nitrate, Copper(II) Chloride, and Copper(II) Perchlorate Complexes with 2-Formylpyridine Semicarbazone

Compounds dinitrato(2-formylpyridinesemicarbazone)copper (I), dichloro(2-formylpyridinesemicarbazone)copper hemihydrate (II), and bis(2-formylpyridine semicarbazone)copper(2+) perchlorate hydrate (III) are synthesized and their crystal structures are determined. In compounds I-III, the neutral 2-formylpyridinesemicarbazone molecule (L) is tridentately attached to the copper atom via the N,N,O set of donor atoms. In compounds I and II, the Cu: L ratio is equal to 1 : 1, whereas, in III, it is 1 : 2. In complex I, the coordination sphere of the copper atom includes two nitrate ions with different structural functions in addition to the L ligand. The structure is built as a one-dimensional polymer in which the NO3 bidentate group fulfills a bridging function. The coordination polyhedron of the copper(2+) atom can be considered a distorted tetragonal bipyramid (4 + 1 + 1). Compound II has an ionic structure in which the main element is the [CuLCl2-Cu(H2O)LCl]+ dimer. In the dimer, the copper atoms are linked via one of the ¼2-bridging chlorine atoms. The coordination polyhedra of the central atoms of the Cu(H2)LCl and CuLCl2 complex fragments are tetragonal bipyramid and tetragonal pyramid, respectively. In compound III, the copper atom is octahedrally surrounded by two L ligands in the mer configuration.