Autoxidation von CuI-Komplexen,VI: Kinetischer Nachweis instabiler Sauerstoffaddukte bei der Oxidation von solvatisiertem Cu+ in Dimethylsulfoxid

Abstract

The interaction between Cu⁺ and O₂ has been studied in DMSO. The experimental rate law is given by  −d[O2]/dt = k_ter [Cu⁺]₂[O₂](1 + k_H[H⁺]) with k_ter = (7.1 ± 0.4)・10³ M^-2s^-1and k_H = 190 ± 12 M^-1 at 25° and l=0.1.The redox-stoichiometry O₂ : Cu⁺ is strictly 1:2 but less than one third of the metal ion was present as ESR active Cu²⁺ in fully reacted aprotic mixtures. Neither H₂O₂ nor O₂^- could be identified in such solutions. Full amounts of Cu²⁺ and H₂O₂ are found in DMSO acidified by H₂SO₄ or HClO₄, however. The results have to be explained by the formation of at least two different unstable dioxygen adducts, one probably being binuclear Cu₂O₂²⁺, and spin coupled Cu²⁺ dimers or polymers with the reaction product of O₂^2- and DMSO as ligand.