Collect. Czech. Chem. Commun. 2008, 73, 616-626

Kinetics and Mechanism of Zn(II) Ion Electroreduction in the Presence of Vetranal

Jolanta Nieszporek*, Dorota Gugała-Fekner, Dorota Sieńko, Jadwiga Saba and Krzysztof Nieszporek

Faculty of Chemistry, M. Curie-Skłodowska University, M. Curie-Skłodowska University Sq. 3, 20-031 Lublin, Poland


The two-step reduction of Zn(II) ions at a dropping mercury electrode in 1 M NaClO4 with addition of vetranal was examined using dc polarography, cyclic voltammetry and impedance measurements. Small changes of reversible potential of half-wave, Er1/2, values indicate that the Zn(II)-vetranal complexes formed in the solution are very unstable. A stepwise character of electron transfer in the Zn(II) ion reduction was established. The catalytic activity of vetranal is stronger in the first step of electron transfer than in the second one. The linear dependence of the true rate constant for the forward reaction, ktf, of Zn(II) electroreduction versus relative surface excess, Γ′, of vetranal at a given potential in the reaction plane, Φr, was interpreted in terms of a "bridging model".

Keywords: Catalytic activity; Zinc(II) electroreduction; Vetranal; Rate constants; Mercury electrode.

References: 30 live references.