Kinetics and mechanism of acid and base hydrolysis of cis-chloro and bromo-(cyclohexylamine)bis-(ethylenediamine) cobalt(III) complexes

Abstract

The kinetics of acid and base hydrolysis of chloro- and bromo-(cyclohexylamine)bis-(ethylenediamine) cobalt(III) complexes have been studied. The rate constants for acid hydrolysis of the chloro and bromo complexes are found to be 3·45 × 10 −5 sec −1 and 15·3 × 10 −5 sec −1, respectively, at 45°C. These are found to be independent of hydrogen ion concentration below pH 3·0 and ionic strength in the range 0·01–0·1 M. The activation parameters, E A and ΔS‡, for the acid hydrolysis reaction of the chloro and bromo complexes are 20·0, 22·8 kcal/mole and −18.4, −·2 eu, respectively. The second order rate constants for base hydrolysis of the chloro and bromo complexes at 0°C and 0·1 M are found to be 2·5 and 8·9 M −1sec −1, respectively.