SINGLE-SITE POLYMERIZATION OF ETHYLENE AND 1-OLEFINS INITIATED BY RARE-EARTH-METAL COMPLEXES

Ethylene polymerization was explored by using the racemic SiMe(2)(2-Si Me(3)-4-tBuC(5)H(2))(2)Sm(THF)(2) complex (1), meso type (2)Si(Me(2)Si OSiMe(2))(3-tBuC(5)H(2))(2)Sm(THF)(2) complex (2), and C-1-symmetric , 4-(SiMe(3))(2)C5H2][3,4-(SiMe(3))(2)C5H2]Sm(THF)2 complex (3) in the a bsence of methylaluminoxane. As a result, the mese isomer exhibits hig hest initiating activity, but the number-average molecular weight is r elatively low ((M) over bar(n) = 50000). In contrast to these complexe s, the C-1-symmetric complex provides the highest molecular weight of polyethylene, (M) over bar(n) > 1000000, with relatively narrow molecu lar weight distribution ((M) over bar(w)/(M) over bar(n) = 1.60). Only the racemic complex exhibits good activity for the polymerization of propylene, 1-pentene and 1-hexene.