Highly Active ansa-(Fluorenyl)(amido)titanium-Based Catalysts with Low Load of Methylaluminoxane for Syndiotactic-Specific Living Polymerization of Propylene

摘要

ansa-Dimethylsilylene(fluorenyl)(amido)titanium complexes bearing various electron-donating substituents are synthesized and applied to propylene polymerization by the use of MMAO/2,6-di-tert-butyl-4-methylphenol as a cocatalyst. The complexes containing adamantylamido ligands (1a,b) show unexpectedly high activity (31150 kg of polymer (mol of Ti)(-1) h(-1)) with a low Al:Ti ratio of 20. The catalysts also promote syndiotactic-specific living polymerization to produce propylene-ethylene block copolymers.