The synthesis of a series of C1-symmetric metallocene complexes rac-[1-(5,6-dialkoxy-2-methyl- 1-η5-indenyl)-2-(9-η5-fluorenyl)ethane]zirconium dichlorides (alkyl: n-butyl, n-hexyl, n-octyl, n-decyl) is described. These complexes are versatile catalysts in the polymerization of propylene after in situ activation with triisobutylaluminum (TIBA) and Ph3C[B(C6F5)4] in toluene and heptane solution. All catalysts show higher solubility and improved polymerization properties in industrially used hydrocarbon solvents (e.g. heptane). However, the molecular weights and isotacticity values of the resulting polypropylene materials are decreased compared to the ethoxy-bridged analogue rac- [1-(5,6-ethylenedioxy-2-methyl-η5-indenyl)-2-(9-η5-fluorenyl)ethane]zirconium dichloride. A possible explanation is based on enhanced interaction of the active catalyst centers with Al(III) scavenger molecules even at low Al : Zr ratios, leading to reversible chain transfer.
描述了一系列C1对称的金属环戊二烯配合物rac-[1-(5,6-二烷氧基-2-甲基-1-η5-茚基)-2-(9-η5-芴基)乙烷]锆二氯化物(烷基:正丁基、正己基、正辛基、正癸基)的合成。这些配合物在与三异丁基铝(TIBA)和Ph3C[B(C6F5)4]在甲苯和庚烷溶液中原位活化后,可作为聚丙烯的多功能催化剂。所有催化剂在工业中使用的烃溶剂(例如庚烷)中均表现出更高的溶解度和改进的聚合性能。然而,与乙氧基桥联的类似物rac-[1-(5,6-乙二氧基-2-甲基-η5-茚基)-2-(9-η5-芴基)乙烷]锆二氯化物相比,所得聚丙烯材料的分子量和异构度值降低。一个可能的解释是基于活性催化剂中心与Al(III)清除剂分子的增强相互作用,即使在低Al:Zr比例下,也会导致可逆的链转移。