Bis(Pyrazolyl)Pyridine Late Transition Metal Complexes as Single-Site Catalysts for Ethylene Polymerization to Highly Linear Polyethylene

摘要

The synthesis, characterization of the halide complexes LMX_n (M = Co (1), Fe (2); X = Cl; n = 2); (M = Ni (3), X = Br, n = 2) bearing 2,6-bis(3,5-dime-thylpyrazol-1-ylmefhyl)pyridine ligand (L) and ethylene polymerization behaviour of these complexes are described. Complexes 1-3 display reasonable activity for ethylene polymerization on treatment with activated methylaluminoxane (MAO), produce single-site catalysts that polymerized ethylene to highly linear polyethylene (PE). Molecular weights (M_w) of the polymers produced are in the range (0.7-1.4) X 10~6 g mol~(-1) with relatively narrow molecular weight distribution (2.1-2.8).