SYNTHESIS AND CHARACTERIZATION OF SOME 4-COORDINATE AND 5-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)]CENTER-DOT-H2O COMPLEXES

Copper(II) complexes of general formula, [Cu(NNS)(H2O)(x)X]. nH(2)O (N NS- = 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 cha racterized by a variety of physico-chemical techniques. Magnetic and s pectroscopic evidence support a square-planar structure for the [Cu(NN S)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 bee n 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 b y a unidentate acetate and water ligand, respectively. The sulphate-co mplex is also five-coordinate with the thiosemicarbazone coordinated a s a neutral NNS ligand and the fourth and fifth coordination sites are occupied by a water molecule and a unidentate sulphate ligand, respec tively. (C) 1998 Elsevier Science Ltd. All rights reserved.