Inner-sphere oxidation of a ternary dipicolinatochromium(III) complex involving a malonic acid co-ligand

Abstract

The oxidation of a ternary complex of chromium(III), [Cr III (DPA)(Mal)(H 2 O) 2 ] -, involving dipicolinic acid (DPA) as primary ligand and malonic acid (Mal) as co-ligand, was investigated in aqueous acidic medium. The periodate oxidation kinetics of [Cr III (DPA)(Mal)(H 2-O) 2 ]to give Cr(VI) under pseudo-first-order conditions were studied at various pH, ionic strength and temperature values. The kinetic equation was found to be as follows: Rate ¼ IO À 4 (SDS) had no effect. The thermodynamic activation parameters were estimated, and the oxidation is proposed to proceed via an inner-sphere mechanism involving the coordination of IO 4 to Cr(III).Electronic supplementary material The online version of this article (