Pentalene substituted metallocene complexes for olefin polymerization

Pentalene bridged zirconocene/methylaluminoxane catalysts are described as useful for the polymerization of ethene, propene, and co-polymerizations with norbornene. They show a high thermostability up to polymerization temperatures of 105 °C. Polyethylenes with molecular masses of 4 million g/mol are obtained at 30 °C and 500,000 g/mol at more than 90 °C. The molecular mass distribution varies between 2 and 15 because of the steric isomers of the pentalene ligand. Some of the complexes are active for the polymerization of propene. Similar to ansa cyclopentadienyl–fluorenyl complexes, the tacticity of the produced polypropylenes can be changed from syndiotactic to isotactic by substitution of the cyclopentadienyl ring.