On the Polymerization of Methyl Methacrylate by Group 4 Metallocenes

Dimethylzirconocene precatalysts are shown to initiate the polymerization of methyl methacrylate (MMA) when activated by a Lewis acidic methyl abstractor in the absence of any ZnEt2 additive. The order of addition of the various components is crucial to forming a well-defined active species. Conversion of the precatalysts Cp2ZrMe2 (1a), rac-{C2H4(η5-C9H6)2}ZrMe2 (2a), {Me2C(η5-C5H4)(η5-C13H8)}ZrMe2 (3a), {Me2C(η5-C5H4)(η5-C9H6)}ZrMe2 (4a), {Me2C(η5-C5H4)(η5-2-MeC9H5)}ZrMe2 (5a), and (Cp)(Cp*)ZrMe2 (6a) to their cationic methylzirconocene derivatives (2b−6b) followed by addition of methyl methacrylate results in controlled polymerization to poly(methyl methacrylate) with the exception of 3b which is inactive.