Synthesis and spectroscopic studies of copper(II) complexes with 1-benzotriazol-1-yl-1-[(p-X-phenyl)hydrazono] propan-2-one

Abstract

A new series of copper(II) complexes resulted from the reaction of CuCl₂·2H₂O or Cu(ClO₄)₂·6H₂O and 1-benzotriazol-1-yl-1-[(p-X-phenyl)hydrazono]-propan-2-one, X = H (HL¹), Cl (HL²), Br (HL³), OCH₃ (HL⁴) and CH₃ (HL⁵) 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 (H₂O 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.

Keywords:

• Benzotriazole derivatives
• Copper(II)
• Complexes
• Spectra

Acknowledgement

This work was supported by Kuwait University through research grant #SC04/03 and general facility projects grants #GS01/01 and GS03/01.