THE OXIDATION OF URANIUM(IV) BY POLYVALENT METAL-IONS - A LINEAR FREE-ENERGY CORRELATION

The validity of application of a linear correlation to the kinetics of oxidation of uranium(IV) by multicharged metal ions in aqueous perchl orate media ha, been examined. The plot of DELTAG(double dagger) versu s DELTAG-degrees for most of these redox reactions was fairly linear w ith a slope slightly smaller than that required by the Marcus theory. This behaviour suggests that at least some of these reactions proceed via outer-sphere mechanism. \ The variation in the structure of reacta nts in the rate-determining step, in particular quadrivalent uranium f rom the hydrated U4+ to the oxytype oxidation states UO+2 or UO22+, wa s found to play a very important role in the reaction kinetics. Reacti on mechanisms consistent with the empirical rate laws and the kinetic parameters were discussed.