Divergent Reactivity of a Dinuclear (NHC)Nickel(I) Catalyst versus Nickel(0) Enables Chemoselective Trifluoromethylselenolation

We herein showcase the ability of NHC‐coordinated dinuclear Ni I –Ni I complexes to override fundamental reactivity limits of mononuclear (NHC)Ni 0 catalysts in cross‐couplings. This is demonstrated with the development of a chemoselective trifluoromethylselenolation of aryl iodides catalyzed by a Ni I dimer. A novel SeCF 3 ‐bridged Ni I dimer was isolated and shown to selectively react with Ar−I bonds. Our computational and experimental reactivity data suggest dinuclear Ni I catalysis to be operative. The corresponding Ni 0 species, on the other hand, suffers from preferred reaction with the product, ArSeCF 3 , over productive cross‐coupling and is hence inactive.