On the polymerization of methyl methacrylate by group 4 metallocenes

Dimethylzirconocene precatalysts are shown to initiate the polymerization o f methyl methacrylate (MMA) when activated by a Lewis acidic methyl abstrac tor in the absence of any ZnEt2 additive. The order of addition of the vari ous components is crucial to forming a well-defined active species. Convers ion of the precatalysts Cp2ZrMe2 (1a), rac- [C2H4(eta(5)-C9H6)(2)]ZrMe2 (2a ), {Me2C(eta(5)-C5H4)(eta(5)-C13H8)}-ZrME2 (3a), {Me2C(eta(5)-C5H4)(eta(5)- C9H4)(eta(5)-C9H6)}ZrMe2 (4a), {Me2C(eta(5)-C5H4)(eta(5)-2-MeC9H5)}ZrMe2 (5 a), and (Cp)-(Cp*)ZrMc(2) (6a) to their cationic methylzirconocene derivati ves (2b-6b) followed by addition of methyl methacrylate results in controll ed polymerization to poly(methyl methacrylate) with the exception of 3b whi ch is inactive.