Highly Active Binuclear Neutral Nickel(II) Catalysts Affording High Molecular Weight Polyethylene

A series of new binuclear neutral κ2-N,O-chelated Ni(II) complexes [(H2C)n{[(2,6-R2-4-yl-C6H2)-N═C(H)-(3,5-I2-2-O-C6H2)-κ2-N,O]Ni(CH3)(pyridine)}2] (R = iPr, 3,5-(CF3)2C6H3; n = 0, 1) are reported. The complexes are single-component catalyst precursors for ethylene polymerization. Catalyst activities exceed those of mononuclear analogues studied substantially. With 3.4 × 105 TO h−1, high molecular weight polymer is obtained (Mw 9.2 × 105 g mol−1; Mn 2.8 × 105 g mol−1). Semicrystalline polyethylene with a low degree of branching is formed (2 to 12 branches/1000 carbon atoms; prepared at 30 to 70 °C polymerization temperature), with Tm 112 to 136 °C. Polymerization in aqueous emulsion affords polyethylene dispersions.