Kinetics of the oxidation of water by silver(II) ions complexed with 2,2′-bipyridine in aqueous nitrate media

Abstract

The kinetics of the oxidative decay of silver(II) ions complexed by 2,2′-bipyridine (bipy) when present in aqueous acidic media have been investigated. The reaction is found to be second order in [Ag^II] and zero order in [H⁺] with an inverse dependence on [Ag^I]. From a detailed consideration of the experimental data, including the overall enthalpy and entropy of activation, it is concluded that Ag^III is not involved as an intermediate and that the essential redox step consists of the interaction of two molecules of [Ag(bipy)(OH)]⁺ formed in the hydrolysis of [Ag(bipy)]²⁺(aq), which has been found to be the active bipy complex of Ag^II involved in the oxidation of substrate ligands added to aqueous solutions.