SEARCH Articles Figures Tables VI provides a comparison of the catalytic activities of various zir-conocenes and one hafnocene measured under the same conditions, along with the product molecular weight, isotacticity, and melting point. The bisin-denyl compounds show high activity, but the activities of the hafnocene and the mixed cyclopentadienyl compounds are significantly lower. The ligand in the bridge is also influencial. Replacement of the methyl group with a phenyl increases the activity, whereas replacement with benzyl [Publishers Imprint]