Preparation of half-titanocenes of thiophene-fused trimethylcyclopentadienyl ligands and their ethylene copolymerization reactivity
作者:Eun Seok Park、Ji Hae Park、Hoseop Yun、Bun Yeoul Lee
DOI:10.1016/j.jorganchem.2011.03.014
日期:2011.6
Methylthiophene-fused or dimethylthiophene-fused trimethylcyclopentadienyltitanium trichloride complexes, (eta(5)-Me4RC7S) TiCl3 (R = Me or H), are prepared, from which a chloride ligand is replaced with 2,6-diisopropylphenoxy, di(tert-butyl) ketimide, or tri(tert-butyl) phosphinimide ligand to yield (eta(5)-Me4RC7S)TiXCl2 (11, R Me, X iPr(2)C(6)H(3)O-; 12, R = H, X = iPr(2)C(6)H(3)O-; 13, R Me, X tBu(2)C N-; 14, R = H, X = tBu(2)C N-; 15, R Me, X = tBu(3)P Ne; 16, R = H, X = tBu(3)P Ne). The molecular structures of 11, 14, and 16 are confirmed by X-ray crystallography. The Cp(centroid)-Ti-N angles of 11, 14, and 16 (119.83 degrees, 111.98 degrees, and 125.34 degrees, respectively) are significantly larger than the corresponding angle observed for the related thiophene-fused and tetrahydroquinaldine-linked cyclopentadienyl complex (1), [(eta(5)-(Me4C7S)-(2-MeC9H9N-kN)] TiMe2 (106.6 degrees). The phenoxy complexes 11 and 12 shownegligible activity, while the ketimido and phosphinimido complexes 13-16 exhibit good activities (5-20 x 10(6) g/molTi h) for ethylene/1-octene copolymerization. The ketimido-complexes 13 and 14 are able to incorporate a high amount of 1-octene (15-16 mol%), while the phosphinimido-complexes 15 and 16 are not as capable (8 mol % 1-octene) under the identical polymerization conditions. The catalytic performance of 13-16 is inferior to 1 in terms of activity and comonomer incorporation. (C) 2011 Elsevier B.V. All rights reserved.