Oligomerization and Polymerization of Ethylene Initiated by a Novel Ni(II)-Based Acetyliminopyridine Complexes as Single-Site Catalysts

Novel Ni(II)-based acetyliminopyridine complexes 1b, 2b, 3b (1–3b), which are synthesized from ligands 1a, 2a, 3a (1-3a) and [NiCl2(DME)], are suitable precursors for the catalysts that are necessary for ethylene oligomerization and polymerization reactions, activated by methylaluminoxane (MAO). The MAO-treated 1–3b presents an active catalytic center, which may oligomerize and polymerize ethylene to produce linear α-olefins and polyethylene, respectively. The molecular weight distributions of oligomers that are obtained are in good agreement with the Schulz-Flory rules for oligomers>C4. The activity of 3b-MAO complex is 6.3 × 107 g/(molNi-h) at 50 °C. The activities and molecular weight distributions of oligomers show significant reliance on the structures of catalyst precursors.