Dinuclear Systems in the Efficient Nickel-Catalyzed Kumada–Tamao–Corriu Cross-Coupling of Aryl Halides

Highly active dinuclear nickel(I) complexes bearing bulky N-heterocyclic carbene ligands have been shown to be involved in the catalytic cycle of the Kumada–Tamao–Corriu cross-coupling reaction of aryl halides. The results of several stoichiometric reactions and kinetics experiments have revealed that monovalent and divalent dinickel species are the active species in the highly efficient, nickel-catalyzed, Kumada coupling reactions of aryl halides.