Aquation of penta-ammine(dimethyl sulphoxide)cobalt(III) perchlorate in ethanol–water–perchlorate media
Abstract
Rates of aquation of penta-ammine(dimethyl sulphoxide)cobalt(III) perchlorate have been measured in a variety of ethanol–water–perchlorate-ion media. The pseudo-first-order rate constant for aquation is independent of the perchloric acid concentration, ionic strength, and nature of the cation but is dependent on perchlorate-ion concentration and on the ethanol : water ratio. The average enthalpy and entropy of activation are 25.4 ± 0.3 kcal mol–1 and 1.9 ± 1.0 cal K–1 mol–1, respectively. There is little evidence of solvent assistance for the leaving and entering groups in the transition state.