Ansa-metallocene polymerization catalysts: Effects of the bridges on the catalytic activities

Ansa-metallocene complexes have been extensively studied as the precatalysts for olefin polymerization. The bridges have important effects on the activities of the catalysts and polymer properties such as molecular weight and tacticity, mainly by altering the framework of the catalysts. Here, we review the effects of the structures of ansa-metallocene complexes on the catalytic activities, especially the effects of the bridges on the catalytic activities.