Kinetics of the base hydrolysis and aquation of some trans-halogenoaminebis(dimethylglyoximato)-cobalt(III) complexes

Abstract

The kinetics of the base hydrolysis of some trans-halogenoaminebis(dimethylglyoximato)-cobalt(III) complexes (amine-pyridine or γ-picoline; halogen-chloride or bromide ion), have been studied at 30°C and 0.1 M ionic strength at 8<pH<13. The kinetic data were found to obey the following rate equation: k_obs=(k_a+k_bK[OH⁻]+k_cK[OH⁻]²)(1+K[OH⁻])⁻¹. The rate constants and activation parameters for the aquation of these complexes have also been determined at 0.1 M ionic strength. The bromo complexes are found to undergo hydrolysis at a lower rate than the chloro complexes. The results have been interpreted in terms of a dissociative interchange mechanism for hydrolysis.