Polymerization of methyl methacrylate catalyzed by tantalum-diene complexes, Ta(η⁵-C₅R₅)(η⁴-1, 3-butadiene)₂ (R=H and Me), in the presence of cocatalyst AlMe(OC₆H₂-2, 6-(^tBu) ₂-4-Me)₂

Abstract

We demonstrate that half-metallocene diene complexes of tantalum Ta(η⁵-C₅R₅)(η⁴-1, 3-butadiene)₂ [R=Me (6); R=H (7)] were catalyst precursors of the polymerization of MMA. Catalytic activity of these complexes sensitively depends on the choice of precatalyst's architecture as well as the polymerization condition whether an aluminum compounds, AlMe(OAr)₂(Ar=2, 6-di(^tBu)-4-Me-C₆H₂) (14), as a cocatalyst exists or not. When we used 6 as a catalyst precursor for the polymerization of MMA in the presence of 10 equiv. of 14, a syndiotactic polymer was obtained in quantitative yield within 40min. at 0°C.