| Abstract
| - Styrene polymerizations with a series of nonbridged half-titanocenes of the type Cp‘TiCl2(L)[L = O-2,6-iPr2C6H3, Cp‘ = Cp (1), 1,3-Me2C5H3 (2), 1,2,4-Me3C5H2 (3), C5Me5 (Cp*, 4); Cp‘ = Cp*, L =OPh (5), O-4-MeC6H4 (6), O-2,6-Me2C6H3 (7), O-2,6-tBu2C6H3 (8); Cp‘ = 1,3-Me2C5H3, L = NMeCy (9, Cy= cyclohexyl), N(2,6-Me2C6H3)(SiMe3) (10); L = Cl, Cp‘ = Cp (1‘), 1,3-Me2C5H3 (2‘), 1,2,4-Me3C5H2 (3‘),C5Me5 (Cp*, 4‘)] have been explored in the presence of MAO cocatalyst under various conditions. Thecatalytic activities for syndiospecific styrene polymerization with a series of half-titanocenes containingan aryloxo ligand, Cp‘TiCl2(O-2,6-iPr2C6H3), were higher than those with the trichloro analogues, Cp‘TiCl3,and the activity with a series of Cp* analogues (4, 4‘, 5−8) and 1,3-Me2C5H3 analogues (2, 2‘, 9, 10) werehighly dependent upon the anionic donor ligand used. (tBuC5H4)TiCl2(O-2,6-iPr2C6H3) (11) exhibited arelatively high catalytic activity for syndiospecific styrene polymerization at 25 °C when both[PhMe2NH]B(C6F5)4 and a mixture of AliBu3/Al(n-C8H17)3 were used as the cocatalyst, and the activitywith a series of (1,3-Me2C5H3)TiCl2(OAr) depended on the aryloxide ligand used. The role of the anionicdonor ligand, like the aryloxide ligand, toward both the catalytic activity and the Mw values of polystyrenehas thus been observed irrespective of the kind of cocatalyst employed.
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