文献类型：期刊文献

英文题名：Ethylene and propylene polymerization by the new substituted bridged (cyclopentadienyl)(fluorenyl) zirconocenes

作者：Yang, Xiaoxia[1]; Zhang, Yong[1]; Huang, Jiling[1]

机构：[1]E China Univ Sci & Technol, Organomet Chem Lab, Shanghai 200237, Peoples R China

年份：2006

卷号：20

期号：2

起止页码：130

外文期刊名：APPLIED ORGANOMETALLIC CHEMISTRY

收录：;EI(收录号：2006069680018);WOS:【SCI-EXPANDED(收录号:WOS:000234901600005)】；

语种：英文

外文关键词：ethylene polymerization; propylene polymerization; zirconocene; bridge

摘要：Eight Cs-symmetric complexes, R1R2C(Cp)(Flu)MCl2 [R-1 = R-2 = CH3CH2CH2, M = Zr (1), Hf (2); R-1 = R-2 = p-CH3OC6H4, M = Zr (3), Hf (4); R, = p-(BUC6H4)-B-t, R-2 = Ph, M = Zr (5), Hf (6); R-1 = R-2 = p-(BUC6H4)-B-t, M = Zr (7); R-1 = R-2 = PhCH2, M = Zr (8)] have been synthesized and characterized. Zirconocenes all showed the same high catalytic activities in ethylene polymerization as complex Ph2C(Cp)(Flu)ZrCl2 (9). However, in the propylene polymerization, the catalytic activities decreased in the order 5 approximate to 9 > 7 > 8. Introduction of Bu-t decreased the activities, probably due to the bulk steric hindrance. The polypropylene produced by 5 and 7 with Bu-t substituent showed a higher molecular weight (M eta) than that produced by 9. The C-13 NMR spectrum revealed the polymers from 7 and 8 to have shorter average syndiotactic block length than polymer produced by 9. It was noted that [mm] stereodefect of polypropylene by 8 could not be observed from 13C NMR, which showed that the benzyl on bridge carbon 8 prevented chain epimerization and enatiofacial misinsertion in polymerization. Copyright (c) 2005 John Wiley & Sons, Ltd.