A New Class of Zirconocene Catalysts for the Syndiospecific Polymerization of Propylene and Its Modification for Varying Polypropylene from Isotactic to Syndiotactic
作者:Timothy A. Herzog、Deanna L. Zubris、John E. Bercaw
DOI:10.1021/ja962413z
日期:1996.1.1
metallocene catalysts led us to the ligand system of the Csub 3} symmetric zirconocene 2, seemingly closely related to that of 1. A likely explanation for the behavior of these catalysts is that site epimerization by `chain swinging` may complete with insertion of propylene at lower propylene concentrations and higher temperatures, thus lowering syndiospecificity (Scheme 1). For catalyst 5b, insertions