The role of organometallic copper(III) complexes in homogeneous catalysis

Organometallic Cu-III species have been invoked in many copper-catalyzed reactions, but until recently, experimental evidences were lacking. The advent of new spectroscopic techniques and the characterization of simple and stable catalyst models have been key to gain clear mechanistic insights into these important reactions. In this perspective, we will discuss these discoveries and the corresponding mechanistic proposals that derive from important reactions such as nucleophilic organocuprate chemistry for C-C bond formation, C-heteroatom cross-coupling reactions (Ullmann condensation reactions and halide-exchange processes) and direct C-H bond functionalizations catalyzed by copper.