We reported the synthesis and characterization of the NHC (N-heterocyclic carbene)-stabilized nickel complex [Ni 2 ( i Pr 2 Im) 4 (COD)] 1 ( i Pr 2 Im = 1,3-di(isopropyl)imidazol-2-ylidene) only recently. 10 This compound is a source of the [Ni( i Pr 2 Im) 2 ] complex fragment in stoichiometric as well as catalytic transformations. We have demonstrated that 1 is an excellent catalyst for the catalytic insertion of diphenyl acetylene into the 2,2'-C−C bond of biphenylene and ...