Cyclic voltammetric and impedance spectrometric investigations on addition/elimination reactions of Lewis bases accompanying the electrode reactions of a nickel chelate complex with a structural resemblance to the coenzyme F430

Planar nickel chelate complexes bearing a structural resemblance to the coenzyme F430 have attracted growing interest over the last few years. The present paper describes the electrochemical behavior of such a complex in the presence of Lewis bases. The paper demonstrates that, despite the intricate coupling of charge transfer and base addition/elimination kinetics, most of the thermodynamic and kinetic constants involved in the complex reaction scheme can be determined under favorable experimental conditions by subjecting a large number of experimental cyclic voltammograms (CVs) obtained for different scan rates and base concentrations to a non-linear data-fitting procedure. Some of the thermodynamic and kinetic constants could also be measured by other electrochemical techniques such as impedance spectrometry. The good agreement of the results obtained by the two methods confirms the reliability of the CV fitting technique. (C) 1997 Elsevier Science S.A.