Abstract
A new series of copper(II) complexes resulted from the reaction of CuCl
2
·2H
2
O or Cu(ClO
4
)
2
·6H
2
O and 1-benzotriazol-1-yl-1-[(p-X-phenyl)hydrazono]-propan-2-one, X = H (HL
1
), Cl (HL
2
), Br (HL
3
), OCH
3
(HL
4
) and CH
3
(HL
5
) have been synthesized and characterized by different spectral, magnetic measurements and elemental analysis. IR spectral data indicate that: (i) the free ligands exist in the hydrazo-ketone rather than azo-enol form in the solid state. Furthermore, the hydrazo-NH exists as hydrogen bonded to the keto-oxygen either as intra- or as intermolecular hydrogen bond. (ii) All ligands are neutral bidentate, coordinated to the copper(II) via hydrazone-nitrogen and the keto-oxygen atoms, and (iii) the ionic nature of
and coordinated and/or non-coordinated solvent molecules (H
2
O or EtOH) with the possibility of hydrogen bonding with either the oxo-anions and/or triazole-nitrogen. The magnetic and spectral (UV/Vis and ESR) data indicate that these complexes have square planar, trigonal bipyramidal octahedral and tetrahedral structures. The nature of metal-ligand bonding is determined from the different electronic and ESR spectral parameters. The extent of distortion from ideal symmetry is also estimated and related to the electronic effects of the p-substituents, the nature of the ligand and counter ions.