Synthesis and catalytic activity of neutral salicylaldiminato nickel(II) complexes bearing a single N-heterocyclic carbene ligand

Neutral salicylaldiminato Ni(II) complexes bearing a single N-heterocyclic carbene (NHC) ligand [3,5-tBu2-2-(O)C6H2CHdouble bond; length as m-dashNAr]Ni(C{RNCHCHNiPr})Ph [Ar = 2,6-iPr2C6H3, R = Bn (1); Ar = 2,6-iPr2C6H3, R = iPr (2)], have been synthesized via a one-pot procedure in high yield. The X-ray structure analysis reveals that both of 1 and 2 adopt distorted square-planar coordination geometry and NHC carbon (Ccarbene) is trans to the ketimine nitrogen. Preliminary study indicates that complex 1 is inert toward the insertion of ethylene, however, it can catalyze the dimerization of ethylene in the presence of modified methylaluminoxane (MMAO) with a moderate activity of 3.05 × 104 g(mol Ni)−1 h −1 atm−1 in a highly selective fashion.