Synthesis and structural analysis of phenoxy-substituted half-titanocenes with different anionic ligands, Cp*TiX(Y)(O-2,6-iPr2C6H3): Effect of anionic ligands (X,Y) in ethylene/styrene copolymerization

Synthesis and structural analysis of various phenoxy modified half-titanocenes with different anionic ligands of the type, Cp*TiX(Y)(O-2,6-iPr2C6H3) [X = Y = pyr (2, pyr = C4H4N), pz (3, C3H3N2), OPh (4); X = Cl, Y = OCH(CF3)2 (5)] have been explored. Ethylene/styrene copolymerization by 2, 5, and Cp*TiCl2(O-2,6-iPr2C6H3) (1) in the presence of [PhN(H)Me2][B(C6F5)4] and Al(i-Bu)3/Al(n-octyl)3 afforded poly(ethylene-co-styrene)s as the sole product even at 55 and 70 °C, whereas the pyrazolato analogue (3) showed the negligible activity and 4 afforded a mixture of copolymer and syndiotactic polystyrene: 5 showed the better catalyst performance in terms of activity, suggesting that the anionic ligand (X,Y) plays a role in this catalysis.

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► Syntheses of new phenoxy modified half-titanocenes with various anionic ligands.
► Notable effects of anionic ligands and cocatalysts in Ti catalyzed ethylene/styrene copolymerization.
► Exclusive syntheses of ethylene/styrene copolymers with high styrene content at 70 °C.
► Best catalyst performance attained by Cp*TiCl[OCH(CF3)2](O-2,6-iPr2C6H3).