Computational Design of C2-Symmetric Metallocene-Based Catalysts for the Synthesis of High Molecular Weight Polymers from Ethylene/Propylene Copolymerization

Indenyl-based C-2-symmetric metallocenes have been used extensively as catalysts for the synthesis of high molecular weight polymers from ethylene or propylene homopolymerization. However, the same catalysts afford only low molecular weight polymers in ethylene/propylene copolymerization. We have in a recent study shown [Wang et al. Organometallics 2008, 27, 2861] that the poor performance of fluorenyl-based C-1-symmetric zirconocenes in ethylene/propylene polymerization is a result of electronic effects. In the present computational study, we demonstrate how it is possible by substitutions in the 2- and 4-positions of the indenyl ligands to design catalysts that afford high molecular weight polymers from ethylene/propylene copolymerization.