Kinetic Study of Electron Transfer Reaction Between Fe(Iii)-Schiff Base Complex and L-Cysteine Hydrochloride

Mohammed Aoudia, Suad Ibrahim Al-Shihi and Salama B. Salama

Department of Chemistry, College of Science, P.O. Box 36 Al-Khod (Sultanate of Oman)

A Schiff base ligand and its iron complex were synthesised and characterized by 1H and 13C NMR, infrared and UV-visible spectra. Kinetic studies were carried out to investigate the reduction of Fe(III)-Schiff base complex by L-cysteine hydrochloride. Kinetic data were best fitted with a sum of three exponential equation. The two first rate constants (k1 ~ 70 s-1 and k2 ~ 10 s-1) were found to be independent of the reactant concentrations. These two rates were explained by an inner-sphere mechanism in which water ligand molecules are exchanged with cysteine-HCl molecules. The third rate constant (k3) was shown to be first-order concentration dependent with respect to both cysteine-HCl and Fe(III)-Schiff base complex and was associated to the oxidation reaction of cysteine-HCl by the iron complex.

Kinetic study; Fe(III) Schiff base complex; L-cysteine HCl