Hypochlorite Oxidation of a Chromium(III) Schiff Base Complex

Abstract

Abstract Hypochlorite oxidation of the Schiff base complex of chromium(IIl), Cr(salen)(H20)2 has been investigated at pH 9.0 to understand the mechanism of formation of oxochromium(V) species, which has been implicated in the apoptotic cell death brought about by Cr(salen)(H2)O2 . The reaction exhibited a two stage kinetic profile due to the formation of oxochromium( V) species and its subsequent decay. The final product has been unambiguously identified as Chromate. The overall stoichiometry of lfCr(III)]: 1.5[OCl ] has been established for the reaction. The thermodynamic parameters for the formation of oxochromium( V) species are ΔΗ 9.9 ± 1.8 Kcal mol 1 and ΔS 24.5 ± 8.0 e.u. Reaction schemes have been proposed invoking Cr(V) and Cr(IV) dimeric species as possible intermediates. An inner sphere mechanism has been invoked in the formation of oxochromium( V) intermediate.