Structural and mechanistic studies of co-ordination compounds. Part VIII. Preparation, aquation, and base hydrolysis of some trans-monosubstituted tetra-aminecobalt(III) cations

Abstract

The preparation and characterization of trans-[Co(NH₃)₄CNBr]⁺, trans-[Co(cyclam)CNBr]⁺, and trans-[Co(NH₃)₄N₃Cl]⁺ cations and an improved preparation of trans-[Co(cyclam)N₃Cl]⁺ cation are described. The aqation and base hydrolysis of these complex cations have been studied over a range of temperature. The thermodynamic and kinetic data are discussed, as before, in terms of the nephelauxetic effect of the amine ligands on the central cobalt(III) ion. Kinetic evidence is produced to support a dissociative mechanism for the base hydrolysis of octahedral cobalt(III)–amine complexes.