Ferrous and Cobaltous Chlorides Bearing 2,8-Bis(imino)quinolines: Highly Active Catalysts for Ethylene Polymerization at High Temperature
摘要:
A series of 2,8-bis(1-aryliminoethyl)quinolines [2,8-(2,6-R-2(1)-4-(RC6H2N)-C-2=CCH3)(2)C9H5N (L), R-1 = Me, Et, or i-Pr, R-2 = H or Me] is synthesized and used in the reaction with ferrous or cobaltous chlorides. The corresponding complexes LMCl2 are limitedly formed with ligands containing ortho-methyl groups of the imino phenyl rings (R = H, M = Fe (Fe1), M = Co (Co1); R = Me, M = Fe (Fe2), M = Co (Co2). The X-ray diffraction study reveals a distorted pyramidal geometry of Co1 around the cobalt atom. These complexes, activated with methylaluminoxane (MAO), show unique properties toward ethylene polymerization: no activity observed at low temperature, but high activity achieved at temperatures higher than 80 degrees C (up to 7.61 x 10(6) g.mol(-1).h(-1) at 100 degrees C). Moreover, the polyethylenes obtained are high molecular weight with narrow molecular distribution. This is the first example of iron and cobalt procatalysts with high activity for ethylene polymerization at high temperature.