Five new alkoxyl substituted half sandwich complexes CpTiCl 2(OR), R=methoxylethyl(1), methoxylpropyl(2), methoxylisopropyl(3), o methoxylphenyl(4), tetrahydrofurfuryl(5), were synthesized, characterized and tested as catalyst precursors for the syndiospecific polymerization of styrene. When activated with methylaluminoxane(MAO), the new precursors 1-5 exhibited high catalytic activity for the syndiospecific polymerization of styrene and were more active than CpTiCl 3. The different structures of alkoxyl ligands affected the activity slightly. When the polymerization was carried in bulk, all the five precursors exhibited high catalytic activity even at low ratio of c (Al)/ c (Ti)=300, the s PS% of the polymer produced by alkoxyl substituted complexes was much higher than that of CpTiCl 3. The polymerization temperature of 70 ℃ was more suitable for this kind of complexes. The existence of the additional oxygen atom in the alkoxyl ligands stabilized the active species at the higher temperature.
