Effect of solvent on the kinetics of oxidation of trans-[CoNH3(en)2NCS]2+ by IO –4: a quantitative approach

Abstract

The effect of solvent on the rate constants and activation parameters for the oxidation of trans-[CoNH₃(en)₂NCS]²⁺ by IO^–₄ in aqueous mixtures of methanol tert-butyl alcohol and acetonitrile have been analysed into initial and transition-state contributions. From kinetic measurements, solubilities of the complex salt and enthalpies of solution, the thermodynamic transfer functions Δ_trsG^⊖, Δ_trsH^⊖, Δ_trsS^⊖ corresponding to the transfer of reactants and activated complex from water to aqueous–organic mixtures were evaluated. From the results of a multiple linear correlation, it is concluded that the kinetics are controlled by the acidity and basicity parameters and the excess Gibbs free energy of the mixture, respectively.