Spectrophotometric Studies of the Behaviour of Multidentate Schiff Base Ligands with Copper(II) in Methanol Solution

Abstract

Four formation reaction complexes of polydentate Schiff base ligands derived from condensation of ethylenediamine with salicylaldehyde (L₁) and 2-pyridinecarboxaldehyde (L₂) and of diethylenetriamine with salicylaldehyde (L₃) and 2-hydroxy-1-naphthaldehyde (L₄) as electron donors with copper (II) chloride as an electron acceptor in methanol were studied spectrophotometrically at 301 K. The absorption band wavelengths of the electron donors, the electron acceptor and their complexes were measured and studied. Parameters such as the molar absorptivities, e^AD, of these complexes and the equilibrium constants, K^AD, of their formation reactions obtained from the Benesi-Hildebrand equation were established and discussed. The absorption band energies of the complexes, E, the ionization potentials of the Schiff base ligands, I^D, and the Gibbs energy changes of the above reactions, ΔG, were calculated. Finally, kinetic parameters such as the orders of the reactions, and the rate constants of the forward and reverse reactions, k₁ and k_-1, were determined.


Key Words: UV-Visible,Spectrophotometry,Schiff base ligand,Transition metal complexes,Copper(II) chloride,Methanol,Benesi-Hildebrand


South African Journal of Chemistry Vol.57 2004: 33-36