Cobalt–N-Heterocyclic Carbene Complexes in Catalysis

Cobalt–N-heterocyclic carbene (NHC) complexes have emerged as an attractive class of 3d transition metal catalysts for a broad range of chemical processes, including cross-coupling, hydrogenation, hydrofunctionalization, and cycloaddition reactions. Herein, we present a comprehensive review of catalytic methods utilizing cobalt–NHC complexes with a focus on the catalyst structure, role of the NHC ligand, properties of the catalytic system, mechanism, and synthetic utility. The survey clearly suggests that the recent emergence of well-defined cobalt–NHC catalysts may have a tremendous utility in the design and application of catalytic reactions using more abundant 3d transition metals.