Syndiospecific Propylene Polymerization Using <i>C</i><sub>1</sub>-Symmetric <i>a</i><i>nsa</i>-Metallocene Catalysts: Substituent and Bridge Effects
作者:Fernando J. Gómez、Robert M. Waymouth
DOI:10.1021/ma011910j
日期:2002.4.1
A series of syndiospecific C1-symmetric ansa-metallocenes ([Me2X(Cp)(2-R1-3-R2-Ind)]ZrCl2, X = C, Si; R1 = H, Me; R2 = Me, Et, CH2SiMe3) have been synthesized, and their catalytic behavior in the polymerization of propylene has been studied. Upon activation with MAO, these carbon- or silicon-bridged cyclopentadienyl/indenyl systems afford polypropylene with various degrees of syndiotacticity ([rrrr]
一系列间同立构的Ç 1 -对称柄-metallocenes([我2 X(CP)(2-R 1 -3-R 2 -Ind)]的ZrCl 2,X = C,硅; R 1 = H中,Me; R 2 = Me,Et,CH 2 SiMe 3)已经合成,并且已经研究了它们在丙烯聚合中的催化行为。通过MAO活化后,这些碳桥或硅桥联的环戊二烯基/茚基体系可提供具有不同间同规整度的聚丙烯([ rrrr] = 28-66%),取决于取代基的大小,取代方式和桥连部分。硅桥连系统产生的PP样品具有较高的分子量,较低的间同立构规整度和相对于碳桥连类似物的可比生产率。实验五单元组分布的统计模型表明,位点差向异构化是两组中立体误差的主要原因,而硅桥联系统可能暗示位点立体特异性降低。