The interaction of carbon-centered radicals with copper(I) and copper(II) complexes*

Although alkylcopper(I) reagents are widespread, compounds containing alkyl ligands on Cu^II or Cu^III are much less common. Such complexes, however, are generated as transient species when carbon-center radicals add to Cu^I or Cu^II complexes, respectively, and appear to be involved in several copper-catalyzed organic transformations. A few organocopper(II) and organocopper(III) complexes were found sufficiently robust to allow isolation and full characterization. This article reviews the reactivity of carbon-centered radicals with Cu^I and Cu^II ions, both in aqueous and non-aqueous environments, with focus on the importance of the resulting organocopper species on atom transfer radical polymerization and on copper-catalyzed radical termination.