Deuterium isotope effect in octahedral substitutions. Part III. Liberation of chloride ions from some cis-chloro(amine)bis(ethylenediamine)cobalt(III) cations in neutral, acidic, and basic solutions

Abstract

The rates of release of co-ordinated chlorine from various cis-chloro(amine)bis(ethylenediamine)cobalt(III) cations in neutral, acidic, and basic deuterium oxide solutions are reported and compared with corresponding data for protium oxide solutions. The results are discussed in terms of the solvation of complex cations, the degree of bond-fission in the transition state, hyperconjugation, intramolecular electron-transfer, ligand deuteriation, and specific hydrogen-bonding. Where the complex contains a unidentate ambident ligand with the idle nucleophilic site suitably spaced for the formation of a chelate ring of low strain with cobalt, the observed deuterium isotope effect on solvolysis conforms to an initial rate-determining internal attack.