LAUSR

A series of allyl ansa-lanthanidocenes, [{Me2C(C5H4)(Flu)}Nd(1,3-C3H3(SiMe3)2)2]K (Flu = 9-fluorenyl; 1-Nd-K(allyl)) and {R2C(C5H4)(R′R′Flu)}Ln(1,3-C3H3(SiMe3)2)(THF)x (R = Me, R′ = 2,7-tBu2, Ln = Y (2-Y), Sc (2-Sc), x = 0; Ln = La (2-La), Pr (2-Pr), Nd (2-Nd), Sm (2-Sm), x = 1; R = Me, R′ = oct = octamethyloctahydrodibenzo, Ln = Nd, x = 1 (3-Nd); R = Ph, R′ = H, Ln = Nd, x = 1 (4-Nd); R = Me, R′ = 3,6-tBu2, Ln = Nd, x = 1 (5-Nd)), were prepared in good yields and characterized by NMR spectroscopy (for diamagnetic complexes 2-Sc, 2-Y, and 2-La) and by single-crystal X-ray diffraction (1-Nd-K(allyl), 2-La, 2-Pr, 2-Nd, 2-Sm, and 4-Nd). Those complexes, especially 1-Nd-K(allyl), 2-Nd, 4-Nd, 2-La, and 2-Sm, act as single-component catalyst precursors for polymerization of styrene (in bulk or in aliphatic hydrocarbon solutions, (nBu)2Mg as scavenger, Tpolym = 60–140 °C), affording highly syndiotactic polystyrene (sPS) ([r]5 = 63–88%; Tm up to 260 °C). High productivities (up to 4560 kg(sPS) mol(Ln)−1 h–1) were...