<b>COPPER(II) COMPLEXES OF <i>o</i>-VANILLIN ACETYLHYDRAZONE (H<sub>2</sub>L) AND THE SINGLE-CRYSTAL X-RAY STRUCTURE OF [{Cu(HL)(H<sub<2</sub>O)(HPZ)}].NO<sub>3</sub></b>

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 (L2-) 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.