Synthesis of Chain‐End Functionalized Polyolefins with a Bis(phenoxy imine) Titanium Catalyst

Polyethylenes and highly syndiotactic poly(propylene)s possessing chain end hydroxyl groups were synthesized by living polymerizations using L 2 TiCl 2 [ 1 , L: C 6 F 5 NCH(2OC 6 H 3 3 t Bu)]/MAO and functionalized α ‐olefins, H 2 CCH(CH 2 ) n Y [ 2 ; YOAlMe 2 , n  = 4 ( 2a ); YOSiMe 3 , n  = 9 ( 2b )]. Because the primary insertion of 2 to a cationic species L 2 Ti + Me ( 3 ) derived from 1 /MAO is much faster than the successive secondary insertion of 2 , addition of an equimolar amount of 2 to 3 resulted in the quantitative formation of L 2 Ti + CH 2 CH(Me)(CH 2 ) n Y [ 4 ; YOAlMe 2 , n  = 4 ( 4a ); YOSiMe 3 , n  = 9 ( 4b )]. These cationic species 4 served as functionalized initiators for the living polymerization of both ethylene and propylene and afforded polyolefins having extremely narrow molecular weight distributions and a hydroxyl group at the initiating chain end. The terminating chain end of the syndiotactic poly(propylene)s was also functionalized by adding an excess amount of 2b as a chain end capping agent to the living L 2 Ti–polymeryl species. Due to much slower insertion of the second molecule of 2b relative to the first one, the obtained polymers were end capped quantitatively by a single molecule of 2b . Telechelic syndiotactic poly(propylene)s were successfully synthesized through a living polymerization initiated by 4b and an end capping using 2b .