title: Synthesis and structures of cycloalkylidene-bridged cyclopentadienyl metallocene catalysts: effects of the bridges of ansa-metallocene complexes on the catalytic activity for ethylene polymerization.
abstract: A series of cycloalkylidene-bridged cyclopentadienyl metallocene complexes, [(CH(2))(n)C(C(5)H(4))(2)MCl(2)] (M = Ti, n = 4 (4), 5 (5), 6 (6); M = Zr, n = 4 (7), 5 (8), 6 (9); M = Hf, n = 4 (10), 5 (11), 6 (12)), have been synthesized and applied to ethylene polymerization after activation with methyl aluminoxane (MAO). The cycloalkylidene-bridged titanocene catalysts exhibit much higher activities than the corresponding zirconocene and hafnocene analogues, and have the highest activities at higher temperatures. In comparison, the silacyclopentylidene-bridged metallocene complexes [(CH(2))(4)Si(C(5)H(4))(2)MCl(2)] (M = Ti (13), Zr (14)) and isopropylene-bridged metallocene complexes [Me(2)C(C(5)H(4))(2)MCl(2)] (M = Ti (15), Zr (16)) have also been synthesized and applied to ethylene polymerization. In both cases, the titanocene complexes show much higher activities than the corresponding zirconocene analogues, especially at a lower temperature. The molecular structures of complexes 4-9 have been determined by X-ray diffraction. The structure-activity relationships, especially the effects of the bridges of ansa-metallocene complexes, are discussed.
authors.affiliation: The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin 300071, P. R. China. bqwang@nankai.edu.cn
authors.forename: Baiquan
authors.initials: B
authors.lastname: Wang
authors.forename: Bin
authors.initials: B
authors.lastname: Mu
authors.forename: Xiaobin
authors.initials: X
authors.lastname: Deng
authors.forename: Huiling
authors.initials: H
authors.lastname: Cui
authors.forename: Shansheng
authors.initials: S
authors.lastname: Xu
authors.forename: Xiuzhong
authors.initials: X
authors.lastname: Zhou
authors.forename: Fenglou
authors.initials: F
authors.lastname: Zou
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Ling
authors.initials: L
authors.lastname: Yang
authors.forename: Yufei
authors.initials: Y
authors.lastname: Li
authors.forename: Youliang
authors.initials: Y
authors.lastname: Hu