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

A series of new binuclear neutral κ 2 -N, O-chelated Ni (II) complexes (H 2 C) n [ (2, 6-R 2 -4-yl-C 6 H 2) -N═C (H) - (3, 5-I 2 -2-O-C 6 H 2) -κ 2 - N, O Ni (CH 3) (pyridine) 2 ] (R = i Pr, 3, 5- (CF 3) 2 C 6 H 3; 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 × 10 5 TO h −1, high molecular weight polymer is obtained (M w 9. 2 × 10 5 g mol −1; M n 2. 8 × 10 5 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 T m 112 to 136 °C. Polymerization in aqueous emulsion affords polyethylene dispersions.