Synthesis and characterization of copper(II) complexes with a tridentate schiff base ligand derived from 5-chloro-2-hydroxyacetophenone and salicylhydrazide. X-ray structure of copper(II) (5-chloro-2-hydroxyacetophenone-salicylhydrazide) dimethylformamide

Abstract

Two copper(II) complexes with the Schiff base derived from the condensation of 5-chloro-2- hydroxyacetophenone and salicylhydrazide have been prepared and characterized by means of IR, electronic and EPR spectroscopies and magnetic measurements. For Cu(II) (5-chloro-2-hydroxyacetophenonesalicylhydrazide) dimethylformamide, Cu(5Cl-OHA-SHZ) DMF, obtained by recrystallizing the anhydrous complex Cu(5Cl-OHA-SHZ) from dimethylformamide solution, the crystal structure was also determined. Crystals of Cu(5Cl-OHA-SHZ) DMF are triclinic, space group P 1 , with two molecules in a unit cell of dimensions: a = 8.012(2), b = 8.359(2), c = 13.906(1) Å, α = 88.80(1), β = 88.48(1), γ = 82.01(1)°, and V= 918(1) Å 3. Refinement by full-matrix least-squares gave a final R w = 0.058. In the mononuclear molecule the copper atom is bonded to three ONO donor atoms from the Schiff base ligand and to an oxygen atom from the DMF solvent molecule in a highly distorted square planar geometry. The EPR spectrum of this DMF coordinated complex has been interpreted in terms of the great deviation of the coordination geometry from the idealized square planar one. Cu(5Cl-OHA-SHZ) DMF was found to be a normal paramagnet. Variable temperature magnetic studies on the anhydrous compound suggest a dimeric structure with strong anti-ferromagnetic interactions (2 J = −439 cm −1). The IR spectra are discussed in comparison with that of the free ligand.