1994 Volume 51 Issue 10 Pages 637-646
Recent developments of olefin polymerization catalysts based on group III and IV metal complexes are described. Me2Si-bridged Cp rings with sterically bulky substituents were used as ligands for organolanthanide complexes and their reactivities to olefins were examined. As for the divalent Sm, racemic type complex Me2Si (2-Me3Si-4-t-Bu-C5H2) 2Sm (THF) 2 gave higher molecular weight polyethylene than Cp2Sm (THF) 2, and also showed catalytic activity to α-olefins, giving isotactic poly (α-olefin) s. A meso type Sm (II) complex with high activity for ethylene polymerization afforded relatively low molecular weight polyethylene. A C1 symmetric trivalent Sm complex Me2Si [2, 4- (Me3Si) 2C5H2] [3, 4- (Me3Si) 2C5H2] SmCH (SiMe3) 2 showed high activity for ethylene polymerization, but the same kinds of racemic and meso type complexes did not show it at all. The structures of the active complexes were revealed by the X-ray method. Atrivalent hydride complex [Me2Si (2-Me3Si-4-t-BuMe2Si-C5H2) 2H] 2 showed high activity for a-olefins, giving isotactic poly (1-pentene) and poly (1-hexene) in high yield. Furthermore, the complex catalyzed cyclopolymerization of 1, 5-hexadiene affording high molecular weight poly (methylene-1, 3-cyclopentane).
