Isotactic Polymerization of Methyl Methacrylate Using a Prochiral, Zirconium Enolate Initiator

Abstract

There is considerable interest in the use of metallocene or lanthanocene complexes as initiators of polymerization of acrylate-based monomers.1 We and others have demonstrated that C2-symmetric, dialkyl zirconocene initiatorse.g. rac-en(H4Ind)2ZrX2 (1, X = Me)polymerize methyl methacrylate to isotactic poly(methyl methacrylate) (i-PMMA) by an enantiomorphic, site-control mechanism.2 While syndiotactic PMMA can be prepared using sterically encumbered, lanthanocene initiators at low temperatures,1a,c,d,g attempts to use Cs-symmetric, dialkyl zirconocene initiatorsi.e., Me2C(Cp)(Flu)ZrX2 (2, X = Me)for this purpose have been unsuccessful.2b,c