Effect of Cyclopentadienyl and Anionic Ancillary Ligand in Syndiospecific Styrene Polymerization Catalyzed by Nonbridged Half-Titanocenes Containing Aryloxo, Amide, and Anilide Ligands: Cocatalyst Systems

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. The catalytic activities for syndiospecific styrene polymerization with a series of half-titanocenes containing an 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) were highly dependent upon the anionic donor ligand used. (tBuC5H4)TiCl2(O-2,6-iPr2C6H3) (11) exhibited a relatively high catalytic activity for syndiospecific styrene polymerization at 25 °C when both [...