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Abstract

A process for preparing polyolefins having a monomer length of up to C10, which comprises first contacting: (1) a metallocene catalyst component for the preparation of a polyolefin which comprises an isotactic polyolefin or syndiotactic/isotactic block polyolefin having a monomer length of up to C.sub.10, the component having the general formula: R'(CpR.sub.1 R.sub.2 R.sub.3)(Cp'R.sub.1 'R.sub.2 ')MQ.sub.2 wherein Cp is a cyclopentadienyl ring substituted with at least one substituent of R.sub.1 R.sub.2 and/or R.sub.3 ; Cp' is a substituted fluorenyl ring with substituents R.sub.1 ' and R.sub.2 '; R' is a structural bridge imparting stereorigidity to the component; R.sub.1 is a substituent on the cyclopentadienyl ring which is distal to the bridge; R.sub.2 is a substituent on the cyclopentadienyl ring which is proximal to the bridge and positioned either non-vicinal or vicinal to the distal substituent; R.sub.3 is a substituent on the cyclopentadienyl ring which is proximal to the bridge; R.sub.1 ' and R.sub.2 ' are each independently substituent groups on the fluorenyl ring; M is a Group IVB transition metal or vanadium; and each Q is hydrocarbyl, and (2) an aluminum- or boron-containing co-catalyst capable of activating the catalyst component. Second, contacting the activated catalyst with at least one olefin in a reaction zone under polymerization conditions to form an isotactic polyolefin or a syndiotactic/isotactic block polyolefin.

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