Stereo‐ and Regioselectivity of Chiral, Alkyl‐substituted ansa‐Zirconocene Catalysts in Methylalumoxane‐activated Propene Polymerization

Up to 94% yields of isotactic pentads are achieved in the polymerization of propene with the ansa-zirconocene catalysts 1. It emerges that bulky substituents are decisive for the stereoselectivity, while α-substituents are decisive for the regioselectivity. Moreover, α-substituents favor the synthesis of long chains (Mw up to 9190). R1  tBu, iPr; R2  H. Me; μ-X  Me2CCMe2, Me2Si.