Article révisé par les pairs
Résumé : In strongly alkaline aqueous solutions of EDTA (Y), the Fe(III)Fe(II) system shows a splitted anodic-cathodic polarisation curve, both parts of which correspond to a reversible monoelectronic transfer. The two related electrode reactions FeIII(OH)-4 + e → FeII(OH)-3 + OH- FeII(OH)2Y4- + OH- → FeIII(OH)3Y4- + e generate unstable intermediates, which are engaged in bulk chemical processes, involving respectively the addition and the abstraction of an EDTA ligand ion. Concordant values for the relevant rate constants have been obtained, for various compositions, using classical polarography, the simple potential step method and double potential step chronocoulometry. A complete quantitative scheme for the reaction mechanism has been derived from the analysis of the results. © 1979.