Kinetics and Mechanism of Electroreduction of Palladium(II) Bisethylenediamine Complexes on a Dropping Mercury Electrode

Kinetics of electroreduction of complexes Pd(en)²⁺ ₂(2 × 10^–5M) on a dropping mercury electrode is studied in solutions with various concentrations of ethylenediamine and supporting electrolytes (NaF, NaClO₄) at pH 4.5–11 and different instantaneous current recording times. Diffusion coefficients for reducing complexes and kinetic parameters of the slow electrochemical stage are determined. The concentration of supporting electrolytes is found to affect the half-wave potential, which points to an inner-sphere mechanism of electrochemical stage at supporting electrolyte concentrations of 0.005 to 0.03 M and to a predominantly outer-sphere mechanism at higher concentrations.