A new set of chiral alkoxy substituted half-sandwich titanium complexes of Cp'TiCl2(OR*) (Cp' = Cp, CH3CH(CH3)Cp, CH3OCH2CH2Cp, CH3OCH2CH(CH3)Cp; R* = menthyl, fenchyl) were synthesized, characterized and tested as catalyst precursors for the syndiospecific polymerization of styrene. The structure of complex 8 was confirmed by X-ray crystallography. When chiral alkoxy groups took the place of chlorine atom, it was found that the intramolecular coordination of the oxygen on Cp ring to the titanium disappeared in the solid state. Under the same conditions, complexes 1-4 showed higher activity, and complexes 5-8 showed lower activity than CpTiCl3. The catalytic activity increased in the order 8 < 7 < 6 < 5 < CpTiCl3 < 4 < 3 < 2 < 1. The highest activity was 7.37 x 10(7) g s-PS/(mol Ti mol S h) for complex 1/methylaluminoxane (MAO) at a molar ratio of Al/Ti = 2000. Kinetic measurements of the polymerization were carried out at different temperature for complex 1. The effects of variation on temperature, Al/Ti ratio for catalytic activity and syndiotactic polystyrene (s-PS)% were also studied. (C) 2003 Elsevier B.V. All rights reserved.