Copper(II) complexes of o-vanillin acetylhydrazone (H2L) and the single-crystal X-ray structure of [(Cu(HL)(H2O)(HPZ))]•NO3

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 center dot) and dideprotonated (L2-) states. Monoanionic complexes [(Cu(HL)(H2O}2]center dot 2BF(4) and [(Cu(HL)(Hpz)(H2O}]center dot NO3 have been isolated. After neutralization the complex [{Cu(L)}(2)].5/2H(2)O 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)}]center dot NO3 was also determined. This crystal is orthorombic with the space group I-222, a = 13.417(3), b = 22.662(6), c = 22.518(5) angstrom, alpha=beta=gamma= 90 degrees 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.