KINETICS AND MECHANISM OF THE HOMOGENEOUS REACTION BETWEEN SOME MANGANESE(III) SCHIFF-BASE COMPLEXES AND HYDROGEN-PEROXIDE IN AQUEOUS AND SODIUM DODECYL-SULFATE SOLUTIONS

The kinetics of the reaction between H2O2 and some Schiff base complexes of Mn-III have been investigated in both aqueous and micellar sodium dodecyl sulphate (SDS) solution. The reaction rate is first order in both H2O2 and [complex], and inversely proportional to [H+]. The second-order rate constant increases in the sequence [Mn(salophen)(OAc)] > [Mn(salen)(OH2)]ClO4 > [Mn(salen)(OAc)]H2O, where salen = N,N'-bis(salicylidene)ethylenediamine and salophen = N,N'-bis(salicylidene)-o-phenylenediamine. At SDS concentrations below the critical micellar concentration, there is almost no effect on the rate of reaction whereas at higher concentrations the reaction rate increases slightly. A mechanism involving Mn-III and a peroxo intermediate is proposed.