| abstract |
The synthesis, and use as precatalysts of chiral organozirconium complexes for olefin polymerization are disclosed, having the structure (C 5 R' 4-x R* x ) A (C 5 R" 4-y R"' y ) M Q p , where x and y represent the number of unsubstituted locations on the cyclopentadienyl ring; R', R", R"', and R* represent substituted and unsubstituted alkyl groups having 1-30 carbon atoms and R* is a chiral ligand; A is a fragment containing a Group 13, 14, 15, or 16 element of the Periodic Table; M is a Group 3, 4, or 5 metal of the Periodic Table; and Q is a hydrocarbyl radical, or halogen radical, with 3≦p≦o. Related complexes may be prepared by alkylation of the corresponding dichorides. In the presence of methylalumoxane or triarylborane cocatalysts, these complexes form "cation-like" species which are highly active for olefin polymerization. In combination with a Lewis acid cocatalyst, propylene or other α-olefin polymerization can be effected with very high efficiency and isospecificity. |