Highly active syndiotactic specific catalyst for the polymerization of styrene are obtained by mixing Cp*TiMe3 with +[B(C6F5)4] - in the mole ratio 1∶1

producing 97.5% syndiotactic PS at an activity of 1.15×106gPS/molTi·h.Treatment of [Cp*TiMe3] with +[B(C6F5)4] - results in the formation of [Cp*TiMe2] +[B(C6F5)4] - complex

which is a good source in solution of the cationic species [Cp*TiMe2] +.Both activity and syndiospecificity of the “cationic” catalyst are no less than the CpTi(OBu)3/MAO and CpTi(OPH)3/MAO catalysts

but are much more active than Cp*TiMe3/MAO as well as Cp*TiCl3 /MAO.The cationic catalyst is a very effective catalyst precursor for the Ziegler-Natta polymerization of styrene to syndiotactic polystyrene at temperatures≥-10℃

while the "cationic"contributes to promoting the polymerization of styrene to atactic polystyrene at temperatures≤-20℃.The molecular weight (Mw of sPS increases with the decrease of the temperature

suggesting that lower temperature contributes to reducing the chain transfer and increasing the life of the active species for chain propagation.The Tm of the sPS polymerized at -10～70℃ is almost constant.The styrene polymerization behaviors were essentially insensitive to the dielectric constant of the polymerization medium.