Studies on syndiospecific polymerization of styrene catalyzed by CpTiCl2 (OR) /MAO system

Five new alkoxyl substituted half-sandwich complexes CpTiCl2 (OR), R = meth oxylethyl (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 hig h catalytic activity for the syndiospecific polymerization of styrene and w ere more active than CpTiCl3. The different structures of alkoxyl ligands a ffected the activity slightly. When the polymerization was carried in bulk, all the five precursors exhibited high catalytic activity even at low rati o of c(Al)/c(Ti)=300, the s-PS% of the polymer produced by alkoxyl substitu ted complexes was much higher than that of CpTiCl3. The polymerization temp erature of 70 degreesC was more suitable for this kind of complexes. The ex istence of the additional oxygen atom in the alkoxyl ligands stabilized the active species at the higher temperature.