Olefin polymerization and copolymerization with soluble transition-metal complex catalysts

Abstract

Olefin polymerizations catalyzed by Cp'TiCl 2 (O-2,6- 1 Pr 2 C 6 H 8 ) (1-5; Cp' = cyclopentadienyl group), RuCl 2 (ethylene)(pybox) {7; pybox 2,6-bis[(4S)-4-isopropyl-2-oxazolin-2-yl]pyridine), and FeCl 2 (pybox) (8) were investigated in the presence of a cocatalyst. The Cp*TiC 2 (O-2,6- i Pr 2 C 6 H 3 ) (5)-methylaluminoxane (MAO) catalyst exhibited remarkable catalytic activity for both ethylene and 1-hexene polymerizations, and the effect of the substituents on the cyclopentadienyl group was an important factor for the catalytic activity. A high level of 1-hexene incorporation and a lower r E .r H value with 5 than with [Me 2 Si(C 5 Me 4 )(N t Bu)]TiCl 2 (6) were obtained, despite the rather wide bond angle of Cy-Ti-O (120.5°) of 5 compared with the bond angle of Cp-Ti-N of 6 (107.6°). The 7-MAO catalyst exhibited moderate catalytic activity for ethylene homopolymerization and ethylene/1-hexene copolymerization, and the resultant copolymer incorporated 1-hexene. The 8-MAO catalyst also exhibited activity for ethylene polymerization, and an attempted ethylene/1-hexene copolymerization gave linear polyethylene. The efficient polymerization of a norbornene macromonomer bearing a ring-opened poly(norbornene) substituent was accomplished by ring-opening metathesis polymerization with the well-defined MO(CHCMe 2 Ph)(N-2,6- i Pr 2 C 6 H 3 )[OCMe(CF 3 ) 2 ] 2 (10). The key step for the macromonomer synthesis was the exclusive end-capping of the ring-opened poly(norbornene) with p-Me 3 SiOC 6 H 4 CHO, and the use of 10 was effective for this polymerization proceeding with complete conversion.