Importance

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Abstract

Provided is a metallocene catalyst component for use if preparing isotactic polyolefins, which component has the general formula (I): R' (CpR.sup.1 R.sup.2 R.sup.3)(Cp'R'n) MQ.sup.2 wherein Cp is a substituted cyclopentadienyl ring; Cp' is substituted or unsubstituted fluorenyl ring; R' is a structural bridge imparting stereorigidity to the component; R.sup.1 is a substituent on the cyclopentadienyl ring which is distal to the bridge, which distal substituent comprises a bulky group of the formula XR.sup.*.sub.3 in which X is chosen from Group IVA, and each R.sup.* is the same or different and chosen from hydrogen or hydrocarbyl of from 1 to 20 carbon atoms, R.sup.2 is substituent on the cyclopentadienyl ring which is proximal to the bridge and positioned non-vincinal to the distal substituent, and is of the formula YR.sup.#.sub.3, in which Y is chosen from Group IVA, and each R.sup.# is the same or different and chosen from hydrogen or hydrocarbyl of 1 to 7 carbon atoms, R.sup.3 is a substituent on the cyclopentadienyl ring which is proximal to the bridge and is a hydrogen atom or is of the formula ZR.sup.$.sub.3, in which Z is chosen from Group IVA, and each R.sup.$ is the same or different and chosen from hydrogen or hydrocarbyl of 1 to 7 carbon atoms, each R' is the same or different and is hydrocarbyl having 1 to 20 carbon atoms in which 0.ltoreq.n.ltoreq.8; M is a Group IVB transition metal or vanadium; and each Q is hydrocarbyl having 1 to 20 carbon atoms or is a halogen.

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First Claim