Electrometric studies on the reduction of Ru(III)-EDTA and its hydrazinium complexes

The electrochemical reduction of LRu111(OH2)- and LRu111(N2H4R) (where L = ethylenediaminetetraacetate, EDTA; R=Ph or H) has been studied at glassy carbon electrode in a mixture of 0.2 M CH3COONa and H2SO4 (pH 2.8) employing cyclic and square wave voltammetry, chronopotentiometry and chronoamperometry methods. The cleavage of N-N bond in the LRu111(N2H4R) two complexes has been observed at very low potentials caused by the transfer of two electrons from the electrode to the bound hydrazine through metal. The rate constants kf' and kf'' for the chemical step associated with the two-electron reduction of LRu111(N2H4R) have been computed from diffusion and catalytic zones, respectively. The standard electron transfer rate constant (ks0) and the electron transfer coefficient (α) for the quasi-reversible one-electron reduction of LRu111(OH2)-, have been determined. The diffusion coefficients (Dox) for the above complexes have also been reported. (author)