Electron transfer reactions between transition metal complexes in micellar solutions

Abstract

Abstract We report a systematic investigation of the influence of anionic micelles (SDS) on the kinetics of diffusion controlled outer sphere electron transfer reactions between transition metal complexes. — The micelles interact with the reactants through electrostatic repulsion (e. g. IrCl 6 2 ) or attraction which can cause ion association (e. g. Os(dipy) ) as well as through hydrophobic forces (e. g. Fe(phen) 2 (CN) 2 0 ). The rate constants k ET of these reactions range in the order of 10 10 M −1 s −1 in aqueous solution and are decreased by more than four orders of magnitude if these forces superimpose. — By variation of the SDS concentrations and the ionic strengths electrostatic influences were largely eliminated. It was thus possible to establish a hydrophobic barrier in electron transfer reactions between complexes which are solubilized in the hydrophobic core of the micelles and substitution inert complexes in the bulk solution.