Abstract
The kinetics of the solvolysis of the ions [Co(NH3)5Cl]2+ and [Co(CN)5Cl]3- have been investigated in a range of water-rich mixtures of water with n-PrOH at various temperatures. The variation of the enthalpies and entropies of activation with solvent composition show extrema in composition ranges where the physical properties of the mixtures, influenced by changes in solvent structure, also show extrema. From the application of a free energy cycle to the process of the initial state going to the transition state, it is concluded for the solvolyses of both complexes that the species of Co(III) in the transition state is more stable in water + n-PrOH mixtures than the ionic complexes of Co(III) in the initial state. The results are compared with those for the solvolysis of these and related complexes in mixtures of water with other alcohols.