On medium effects, added salts, and ion pairs in the acid-catalysed hydrolysis of the trans-azidochlorobis(ethylenediamine)cobalt(III) ion

Abstract

The acid-catalysed replacement of the azido-group of trans-[Co en₂ClN₃]⁺ ion in aqueous solutions of different strong acids has been studied at various temperatures. The results show that the activation energy is the same for all acids studied but the non-exponential terms, and hence the entropies of activation, account entirely for the change in the limiting maximum rate constant from acid to acid. The effect of added salts has been investigated with special reference to solutions in which the substrate is completely protonated. The results show that ion pairing is important. Medium effects, as opposed to ion-pairing effects, have also been investigated. The mechanism of the reactions is discussed.