摘要 : Ligand effects on the catalytic activity [and norbornene (NBE) incorporation] for both ethylene polymerization and ethylene/NBE copolymerization using half-titanocenes (titanium half-sandwich complexes) containing ketimide ligand ... 展开 Ligand effects on the catalytic activity [and norbornene (NBE) incorporation] for both ethylene polymerization and ethylene/NBE copolymerization using half-titanocenes (titanium half-sandwich complexes) containing ketimide ligand of type Cp'TiCl2[N=C(R-1)R-2] [Cp' = Cp (1), (CMe5)-Me-5 (Cp*, 2); R-1,R-2 -' Bu,' Bu (a),' Bu,Ph (b), Ph,Ph (c)]-methylaluminoxane (MAO)catalyst systems have been investigated. CpTiCl2[N=C(' Bu)Ph] (1b) CpTiCl2(N=CPh2) (1c), and Cp*TiCl2(N=CPh2) (2c) were prepared and identified; the structure of Cp*TiCl2(N=CPh2) (2c) was determined by X-ray crystallography. The catalytic activity for ethylene polymerization increased in the order: 1a > 1b > 1c, suggesting that an electronic nature of the ketimide ligand affects the activity. However, molecular weight distributions for resultant (co)polymers prepared by 1b,c and by 2c-MAO catalyst systems were bi- or mufti-modal, suggesting that the ketimide substituent plays a key role in order for these (co)polymerizations to proceed with single catalytically-active species. CpTiCl2(N=C ' Bu-2) (la) exhibited both remarkable catalytic activity and efficient NBE incorporation for ethylene/NBE copolymerization. (C) 2007 Elsevier B.V. All rights reserved. 收起