| 摘要 |
Metallocene catalyst components having bis-fluorenyl ligands of a staggered conformation and processes for the isotactic propagation of a polymer chain from ethylenically unsaturated monomers. The catalyst components comprise bridged bis-fluorenyl metallocenes characterized by the following formula: X(F1Ya)(F1'Zb)MeQn (1) wherein, F1 and F1' are fluorenyl groups which are interconnected by a structural bridge X to impart stereorigidity to the metallocene ligand, Me is a Group 3, 4, or 5 transition metal each Y is the same or different and is a hydrocarbyl or heterohydrocarbyl substituent at a distal position on the fluorenyl group, each Z is the same or different and is a hydrocarbyl or heterohydrocarbyl substituent at a distal position on the other fluorenyl group F1', and a and b are each independently 1 or 2. The relative locations of Y and Z on their respective fluorenyl groups are such that each is in a staggered position relative to a plane of symmetry through the ligand structure which contains the structural bridge. The substituent groups Y and Z are on opposed sides of this plane of symmetry to provide a staggered conformation to the ligand. One of the substituents Y and Z may take a form of a heterohydrocarbyl group with the other a hydrocarbyl group. Z may be a hydrocarbyl group and Y a heterohydrocarbyl group, specifically an alkyl and alkoxy group such as an oxymethyl group, or an amino group such as a dimethylamino group. Y and Z may be the same.
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