Spectroscopic, kinetic and mechanistic studies of the influence of ligand and substrate concentration on the activation by peroxides of Cu-I-thiolateand other Cu-I complexes

Both free-radical and non-radical routes for peroxide oxidation of Cu-I can be identified for copper complexes obtained by the reduction of Cu-II by t hiols, including glutathione. Copper(I)-thiolate complexes are obtained, ex cept in the presence of e.g. 1,10-phenanthroline, and these undergo ready r eaction with H2O2 and (BuOOH)-Bu-t. EPR spin-trapping studies establish a f ree-radical reaction mechanism (to give (BuO.)-Bu-t) with the latter, and t he formation of HO. from the former occurs only at low concentrations of co pper. Kinetic studies (using UV-vis and EPR spectroscopies), together with NMR analysis, lead to the proposal that Cu-I aggregates react via non-radic al pathways in contrast to monomeric Cu-I.