Effect of Metal on the Stereospecificity of 2-Arylindene Catalysts for Elastomeric Polypropylene
作者:Michael D. Bruce、Geoffrey W. Coates、Elisabeth Hauptman、Robert M. Waymouth、Joseph W. Ziller
DOI:10.1021/ja971895r
日期:1997.11.1
hafnium-based catalysts yield polypropylenes that are significantly less isotactic than the corresponding zirconium compounds, although molecular weights and productivities were similar for hafnium and zirconium derivatives. The X-ray crystal studies of these catalysts show nearly identical structures for corresponding zirconium and hafnium compounds. Variable temperature NMR of the metallocene dibenzyl
丙烯与双(2-苯基茚基)二氯化锆和双(2-[3,5-双三氟甲基)茚基]二氯化锆聚合生成弹性聚丙烯。这些聚合物的弹性性能已被解释为立体嵌段微结构。通过 13 C NMR 对微观结构的分析表明,全同立构五单元组含量 [mmmm] 范围为 6% 至 74%。研究铪衍生物以探究过渡金属对聚合行为的影响。尽管铪和锆衍生物的分子量和生产率相似,但铪基催化剂产生的聚丙烯的全同立构规整度明显低于相应的锆化合物。这些催化剂的 X 射线晶体研究表明,相应的锆和铪化合物具有几乎相同的结构。茂金属二苄基类似物的变温 NMR 表现出与茚基配体的旋转一致的行为,其中茚基的旋转...