A Highly Active Catalyst Composed of ansa-Fluorenylamidodimethyltitanium Derivative for Propene Polymerization

Me₂Si(C₂₉H₃₆)(N ^t Bu)TiMe₂ (4; C₂₉H₃₆, octamethyloctahydrodibenzofluorenyl) was synthesized and characterized by elemental analysis, ¹H NMR and single crystal X-ray analysis. The complex was applied for propene polymerization using dried modified methylaluminoxane (dMMAO) as a cocatalyst at 0 °C by a semi-batch method. The catalytic system showed the activity of 11,400 kg-polymer mol-Ti⁻¹ h⁻¹, which was too high to control the polymerization. Batch-wise polymerizations were then conducted by changing the amount of propene in feed. The polymerizations proceeded quantitatively, and the number-average molecular weight increased linearly against the polymer yield with keeping the number of polymer chains constant although the polydispersity indices were broader than that expected in a living polymerization. The results of postpolymerization indicated the smooth chain transfer after the monomer consumption.