Stereospecific Styrene Polymerization by Methylalumoxane-Activated Ti (IV) N-Trimethylsilylamido Complexes Bearing the N-Biphenyl or N-(6-(2-(Diethylboryl)phenyl)-Pyrid-2-yl) Motif

Cp'TiCl2(N‐(6‐(2‐(diethylboryl)phenyl)pyrid‐2‐yl)SiMe3), [Cp' = C5H5 (3), C5(CH3)5 (4)], and the aminoborane‐free half‐titanocene analogs with the general formula: Cp'TiCl2(N‐(biphenyl‐3‐yl)SiMe3); [Cp' = C5H5 (7), C5(CH3)5 (8)] are synthesized and used in the polymerization of styrene. All the pre‐catalysts are active in styrene polymerization, >90% syndiotactic poly(styrene) (st‐PS) is produced, exceeding that of their ansa‐homologues (C5(CH3)5)TiCl2(6‐(2‐(diethylboryl)phenyl)pyrid‐2‐ylamido)(dimethylsilyl) (9) and (C5(CH3)5)TiCl2(3‐biphen‐3‐ylamido)(dimethylsilyl) (10) both in activity and molecular weight. Pre‐catalyst 8 allows for the synthesis of high‐molecular‐weight st‐PS with activities up to 5000 kgst‐PS molcat−1 h−1. Implications of the 2‐(diethylboryl)phenyl)pyrid‐2‐yl group on polymerization activity and molecular weight are discussed. A series of half‐titanocene analogs is synthesized and used for the synthesis of syndiotactic poly(styrene) (st‐PS). High‐molecular‐weight st‐PS with M¯n values up to 1 400 000 g mol−1 (polydispersity index (PDI) = 1.38) is prepared with activities up to 5000 kgst‐PS molcat−1 h−1.