Synthesis, characterisation, and aquation kinetics of [N-(o-carboxyphenyl)iminodiacetato](glycinato)chromate(III) complex ion in acidic media

Abstract

The potassium salt of the [N-(o-carboxyphenyl)iminodiacetato](glycinato)chromate(III) complex has been synthesised and characterised. In acidic media, the complex has been shown to aquate to diaqua[N-(o-carboxyphenyl)iminodiacetato]chromium(III) and protonated glycine as the ultimate products. The rates of aquation of the complex in aqueous perchloric acid media are reported as a function of acid concentration and temperature. The variation of the observed pseudo-first-order rate constants with acid concentration suggests the operation of two concurrent paths with k_obs.=k₀+k_H[H⁺], where k₀ and k_H are the appropriate rate constants for uncatalysed and acid-catalysed pathways respectively. The production of a metastable bidentate glycinato-O,O′ ligand configuration in the aquation process is proposed to explain the reactivity of the chromate(III) complex.