Ligational, potentiometric and floatation studies on Cu(II) complexes of hydrazones derived from p and o-vanillin condensed with diketo hydrazide

Abstract

Copper (II) complexes of both 2-(2-(4-hydroxy-3-methoxybenzylidene) hydrazinyl)-2-oxo-N-phenylacetamide (H2L1) and 2-(2-(2-hydroxy-3-methoxybenzylidene) hydrazinyl)-2-oxo-N-phenylacetamide (H2L2) have been prepared and investigated by analytical, magnetic and spectroscopic techniques. IR spectra displayed that (H2L1) behaves as mono-negative tridentate or mono-negative tetradentate in both of [Cu(HL1)Cl]·(2H2O) and [Cu2(HL1)Cl3(H2O)](1.5H2O), respectively. But (H2L2) behaves as neutral bidentate or bi-negative pentadentate in both of [Cu(H2L2)2Cl2]·(2H2O) and [Cu2(L2)Cl2(H2O)]·(2H2O), respectively. 1H NMR spectra showed the replaceable hydrogens of the prepared ligands. The magnetic moment values helped to investigate the geometry of the complexes. Thermogravimetric studies gave a general pattern for the main stages of the thermal decomposition with kinetic data to evaluate thermodynamic parameters ΔH* and ΔG* for each step of degradation to compare between stability of those complexes. Also pH-metric measurements were used to evaluate the proton–ligand formation constants and the stability constants of metal complexes at 298°K. Floatation procedure was carried out to investigate the optimum conditions for Cu(II) separation by ligand molecules.