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

Abstract

The electrochemical reduction of LRu^lll(OH2)^-and LRulll(N2H4R) (where L= ethylenediaminetetraacetate, EDTA; R = Ph or H) has been studied at glassy carbon electrode in a mixture of 0.2 <em>M</em> CH₃COONa and H₂S0₄ <em>(pH </em>2.8) employing cyclic and square wave voltammetry, chronopotentiometry and chronoamperometry methods. The cleavage of N &ndash; N bond in the LRu^III(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 <em>k&rsquo;</em><em>f </em>and <em>k&rsquo;&rsquo;f </em>for the chemical step associated with the two-electron reduction of LRu^lll(N²H⁴R) have been computed from diffusion and catalytic zones, respectively. The standard electron transfer rate constant <em>(k) </em>and the electron transfer coefficient (&alpha;) for the quasi-reversible one-electron reduction of LRu^lll(OH₂)-, have been determined. The diffusion coefficients (D_ox)for the above complexes have also been reported.