Electron transfer at tetrahedral cobalt(II). Part V: kinetics of permanganate ion reduction

The kinetics and mechanism of the reduction of MnO4- by CoW12O4O6- in aqueous HC1O4 were studied. The reaction follows the rate law:-d[MnOinf4sup- ]/d t = 5 Ka k[H+][MnOinf4sup- ][CoW12O4O6-] with Ka = 2.99 × 10-3mol-1 dm3 and k = 2.00 ± 0.02 × 103dm6mol-2s-1 at 25°C. Close agreement between kobs and kcalc on the basis of Marcus theory suggest an outersphere mechanism operates. Alkali metal ions catalyse the reaction in the order K+ > Na+ > Li+ and this result has been rationalized