PREPARATION AND CHARACTERIZATION OF COMPLEXES OF THE ANTITUMOR COPPER(II) 2-FORMYLPYRIDINE THIOSEMICARBAZONE (HL) SYSTEM AND THE SINGLE-CRYSTAL X-RAY STRUCTURES OF [(CU(HL)(CF3CO2))2][CF3CO2]2 AND [CU(HL)(H2O)(CLO4)2] 2H2O

The complexes [{Cu(HL)X}2]X2.nH2O (HL = 2-formylpyridine thiosemicarbazone, X = CF3CO2, F or I, n = O; X = Br, n = 2) and [Cu(HL)(H2O)X2].nH2O (X = ClO4, n = 2; X = NO3, n = O) have been prepared from the reaction of [{CuL(MeCO2)}2] with the appropriate acid, HX. Also prepared were the deprotonated ligand complexes [(CuLX)2].nH2O from the reaction of NaL with the appropriate copper(II) salt (X = F, n = 5.5; X = 1/2SO4, n = 3) or by the reaction of [{CuL(MeCO2)}2] with the appropriate sodium salt, NaX (X = N3, n = 1; X = CN, n = 2). The complexes have been characterized by a variety of physicochemical techniques and the crystal and molecular structures of [{Cu(HL)(CF3CO2)}2][CF3CO2]2 and [Cu(HL)(H2O)(ClO4)2].2H2O determined by single-crystal X-ray diffraction studies. Crystals of [{Cu(HL)(CF3CO2)}2][CF3CO2]2 are triclinic, space group P1BAR, with a = 9.6015(7), b = 10.837(1), c = 8.811(2) angstrom, alpha = 100.71(1), beta = 117.06(1), gamma = 80.877(7)-degrees, and Z = 1. The complex cation is a centrosymmetric dimer, the monomeric units being bridged by two CF3CO2- anions. The copper atoms have a distorted square-pyramidal co-ordination geometry with three donor atoms (NNS) coming from HL and the fourth donor (an oxygen) from the bridging anion. The fifth position is occupied by a less strongly bound oxygen from the second bridging anion. Crystals of [Cu(HL)(H2O)(ClO4)2].2H2O are monoclinic, space group P2(1)/c, with a = 12.9615(5), b = 9.7638(4), c = 14.9964(8) angstrom, beta = 111.580(4)-degrees, and Z = 4. The complex is monomeric with a distorted tetragonal co-ordination around the copper atom. The four in-plane donor atoms are provided by HL (NNS) and an oxygen from a co-ordinated water molecule. Two weakly bound ClO4- ions occupy the fifth and sixth positions. In both complexes hydrogen-bonding schemes appear to be important in stabilizing them in the solid state. The differences in the bonding parameters for the Cu(HL)2+ and CuL+ systems are discussed and related to the fact that the S --> Cu(II) ligand-to-metal charge-transfer absorption (at ca. 400 nm) is always observed at higher energies for the HL complexes.