Olefin Polymerization by (Cyclopentadienyl)(aryloxy)titanium(IV) Complexes−Cocatalyst Systems

Abstract

Various titanium(IV) complexes of the type Cp‘Ti(OAr)Cl2 (Cp‘ = cyclopentadienyl; OAr = aryloxy) could be prepared in high yields from Cp‘TiCl3. Cp*Ti(O-2,6-iPr2C6H3)Me2 (Cp* = C5Me5) could also be prepared from Cp*TiMe3 with 2,6-iPr2C6H3OH in high yield (77%). These complexes showed notable catalytic activities for ethylene polymerization with MAO or AliBu3−Ph3CB(C6F5)4: Cp*Ti(O-2,6-iPr2C6H3)X2 [X = Cl (2b), Me (8b), CF3SO3 (9b)] showed the highest activities among these complexes. The effects of substituents on both cyclopentadienyl (pentamethylcyclopentadienyl) and aryloxy (2,6-diisopropylphenoxy) groups are important for the remarkable activity. The crystallographic analyses of CpTi(O-2,6-iPr2C6H3)Cl2 (1b), Cp*Ti(O-2,6-iPr2C6H3)Cl2 (2b), and (1,3-tBu2C5H3)Ti(O-2,6-iPr2C6H3)Cl2 (6b) could be performed, and the bond angle of Ti−O−C (phenyl group) for 2b (173.0°) was found to be significantly different from those for other complexes (162.3−163.1°), although no significant differences are observed for ot...