Spectrophotometric studies of the formation of charge transfer complex of iron(III) with N,N′-bis(2-pyridylmethylidene)-1,2-diiminoethane di-Schiff base ligand in methanol

Abstract

The complex formation reaction between N,N′-bis(2-pyridylmethylidene)-1,2-diiminoethane (BPIE) di-Schiff base ligand as an electron donor and iron(III) chloride as an electron acceptor have been studied spectrophometrically in methanol at 28°C. The values of equilibrium constants, K and molar absorptivities, ε were obtained from the Benesi–Hildebrand, Scott and Foster–Hammick–Wardley equations. The results indicate the formation of 1 : 1 charge transfer complex. The absorption band energy of the complex, E CT, the ionization potential of the BPIE Schiff base ligand, I D, and the Gibbs energy changes of the above reaction, ΔG 0, were calculated. Finally, the kinetics of the complex formation reaction were studied and was found to be second-order in each reactant. The values of the rate constants of the forward and reverse reactions k 1 and k −1 were determined.