COPPER(II) COMPLEXES OF o-VANILLIN ACETYLHYDRAZONE (H2L) AND THE SINGLE-CRYSTAL X-RAY STRUCTURE OF [{Cu(HL)(HO)(HPZ)}].NO3

Abstract

A hydrazonic ligand, o-vanillin acetylhydrazone (H₂L) has been prepared and used as chelating agent towards copper(II) ion. The ligand acts like a tridentate ligand in the monodeprotonated (HL^-) and dideprotonated (L^2-) states. Monoanionic complexes [{Cu(HL)(H₂O)}₂]•2BF₄ and [{Cu(HL)(Hpz)(H₂O)}]•NO₃ have been isolated. After neutralization the complex [{Cu(L)}₂].5/2H₂O is obtained. These complexes have been characterized by a range of physicochemical and spectroscopic studies. The X-ray crystal structure of the mononuclear complex [{Cu(HL)(Hpz)(H₂O)}]•NO₃ was also determined. This crystal is orthorombic with the space group I222, a = 13.417(3), b = 22.662(6), c = 22.518(5) Å, α = β = γ = 90° and Z = 8. The copper ion has a square-pyramidal geometry with the basal donors atoms from the tridentate ligand (ONO) and the pyrazole (N), the apical position being occupied by a coordinated water molecule weakly linked to the copper(II) center. The binuclear complexes exhibit interesting magnetic properties.

KEY WORDS: Copper(II) complexes, Tridentate ligand, o-Vanillin acetylhydrazone, X-Ray crystal structure


Bull. Chem. Soc. Ethiop. 2006, 20(1), 35-43.