Extremely active α-olefin polymerization and copolymerization with ethylene catalyzed by a dMAO-activated zirconium(iv) dichloro complex having an [OSSO]-type ligand

Abstract

The ability of a zirconium(IV) dichloro complex (6b) incorporating an [OSSO]-type ligand 5 with dMAO as an activator for the polymerization of 1-hexene and 4-methyl-1-pentene (4-MP) is described. In the polymerization of 1-hexene, the combination of the 6b/dMAO catalyst system efficiently provided poly(1-hexene)s with completely isotactic [mmmm] pentad more than 95% and relatively large molecular weight (M_w = 40 000–150 000 g mol⁻¹). The corresponding activity was recorded with quite high values up to 18 100 g mmol(6b)⁻¹ h⁻¹, which increased significantly compared with those of the related non-Cp complexes. The polymerization of 4-MP using the 6b/dMAO system at different temperatures also gave perfect isotactic poly(4-MP)s ([mmmm] > 95%) with moderate molecular weights (M_w = 7000–21 300 g mol⁻¹), relatively narrow polydispersities (M_w/M_n = 1.5–1.7), and activities of 1220–1690 g mmol(6b)⁻¹ h⁻¹. This catalyst system was also found to promote ethylene copolymerization with different amounts of 1-hexene at 25 °C under atmospheric pressure producing random ethylene/1-hexene copolymers (M_w = 10 100–17 300 g mol⁻¹, M_w/M_n = 1.8–1.9, 1-hexene contents = 37.3–66.7 mol%) with fairly high activity up to 2700 g mmol(6b)⁻¹ h⁻¹.