| abstract |
A process for preparing syndiotactic vinyl aromatic polymers comprising contacting one or more aromatic monomers under polymerization conditions with a catalyst corresponding to the formula: n[Cp m MX n X′p]⁺A⁻ nwherein: nCp is a single η⁵-cyclopentadienyl or η⁵-substituted cyclopentadienyl group; nM is a metal of Group 3, 4, 5, 6, 8, 9, 10 or the Lanthanide Series of the Periodic Table; nX each occurrence is an inert anionic lignd, with the proviso that at least one X is R; nX′ is an inert, neutral, donor ligand; nR is hydrocarbyl, silyl, a combination thereof or a substituted derivative thereof having up to 20 carbon, silicon or carbon and silicon atoms; nm and p are independently 0 or 1; nn is an integer greater than or equal to 1; nthe sum of m and n is equal to the valence of M; and nA⁻ is a noncoordinating, compatible anion of a Bronsted acid salt. |