Synthesis and characterization of some four- and five-coordinate copper(II) complexes of 6-methyl-2-formylpyridinethiosemicarbazone (HNNS) and the X-ray crystal structures of the [Cn(NNS)(CH3COO)(H2O)] and [Cu(HNNS)(H2O)(SO4)]•H2O complexes

Copper(II) complexes of general formula, [Cu(NNS)(H2O)(x)X]. nH(2)O (NNS- = uninegatively charged tridentate thiosemicarbazone ligand formed from 6-methyl-2-formylpyridine; X = NCS-, CH3COO-, N-3(-); x = 0,1; n = 0.5, 1) and [Cu(HNNS)(H2O)(SO4)]. H2O have been synthesized and characterized by a variety of physico-chemical techniques. Magnetic and spectroscopic evidence support a square-planar structure for the [Cu(NNS)X] (X = NCS-, N-3(-)) complexes and a five-coordinate structure for the [Cu(HNNS)(H2O)(SO4)]. H2O complex. The crystal structures of the [Cu(NNS)(CH3COO)(H2O)] and [Cu(HNNS)(H2O)(SO4)]. H2O complexes have been determined by X-ray diffraction. The acetato complex has a distorted square-pyramidal geometry with the thiosemicarbazone ligand acting as a uninegatively charged tridentate NNS chelating agent and the fourth and fifth coordination positions of the copper(II) ion are occupied by a unidentate acetate and water ligand, respectively. The sulphate-complex is also five-coordinate with the thiosemicarbazone coordinated as a neutral NNS ligand and the fourth and fifth coordination sites are occupied by a water molecule and a unidentate sulphate ligand, respectively. (C) 1998 Elsevier Science Ltd. All rights reserved.