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Synthesis and Structures of Cycloalkylidene‐Bridged Cyclopentadienyl Metallocene Catalysts: Effects of the Bridges of Ansa‐Metallocene Complexes on the Catalytic Activity for Ethylene Polymerization
Author(s) -
Wang Baiquan,
Mu Bin,
Deng Xiaobin,
Cui Huiling,
Xu Shansheng,
Zhou Xiuzhong,
Zou Fenglou,
Li Yang,
Yang Ling,
Li Yufei,
Hu Youliang
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400750
Subject(s) - metallocene , cyclopentadienyl complex , ethylene , polymerization , post metallocene catalyst , polymer chemistry , catalysis , chemistry , materials science , organic chemistry , polymer
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.