Catalyst for the production of olefin polymers

摘要

A catalyst precursor of the formula: wherein: R1 is a cycloalkadienyl ligand; R2, R3, R4, and R5 are independently hydrogen, a hydrocarbyl group containing 1 to 20 carbon atoms, or a silyl group, and may be connected to R1 through a bridging group comprising at least two Group IVA atoms; with the proviso that one of R3, R4, and R5 is a negative charge stabilizing group selected from the group consisting of Group IVA trialkyl groups, aryl groups, heteroaromatic groups, ethylenically unsaturated hydrocarbon groups, acetylenically unsaturated hydrocarbon groups, ketonic groups, and aromatic organometallic moieties, is provided. When combined with a compound comprising a metal from Groups IIIB to VIII or the Lanthanide series of the Periodic Table of elements and an activating cocatalyst, the catalyst precursor is useful for the polymerization of olefins.