Synthesis and Structural Characterization of Nickel(II) Complexes with Imino-N-heterocyclic Carbene Heteroditopic Ligands

Two different heteroditopic bis­(aryl)-substituted imino-N-heterocyclic carbene ligands were coordinated to nickel using new copper carbene dimers as transmetalating agents. The oxidative addition of an imidazolium salt precursor with Ni­(COD)2 led to the unexpected bis­(carbene)­NiCl2 complex, presumably through a putative nickel hydride intermediate. All new complexes were isolated in good yield and were structurally characterized. The size of the iminic carbon substituent was found to have a profound impact on the bond angles and bond lengths about the metal center. All nickel complexes were tested for ethylene polymerization activity at standard temperature and pressure and were found to be inactive.