MECHANISM OF OXIDATION OF IRON(II) CHELATES BY HEXAVALENT CHROMIUM AND HEPTAVALENT MANGANESE IN AQUEOUS SULFURIC-ACID AND MICELLAR MEDIA - A KINETIC APPROACH

Oxidation of the Fe-II chelates [FeL] (L = phen or bipy) by Cr-VI and Mn-VII in H2SO4 medium was found to proceed through the formation of a bimetallic insertion complex which decomposes in the slow step, follo wed by electron transfer from [FeL] to the oxidant. The reactions are catalysed by both anionic and non-ionic micelles [SDS and triton-x (Tx ), respectively]. A mechanism is suggested involving electrostatic sta bilization of the cationic forms of the Fe-II chelates by anionic SDS and the partial anionic character of polyoxyethylene moiety of Tx, res pectively. The marginal catalysis of cationic micelles (CTAB) is attri buted to co-anion-micellar interactions.