Effect of aryloxide ligand in 1-hexene, styrene polymerization catalyzed by nonbridged half-titanocenes of the type, Cp′TiCl2(OAr) (Cp′ = C5Me5, tBuC5H4): Structural analyses for Cp*TiCl2(O-2,6-tBu2C6H3) and Cp*TiCl2(O-2,6-iPr2-4-tBuC6H2)

Various (aryloxo)(pentamethylcyclopentadienyl)titanium(IV) dichloride complexes of the type, Cp*TiCl2(OAr) [Cp* = C5Me5, Ar = 2,6-Me2C6H3 (1), 2,4,6-Me3C6H2 (2), 2,6-iPr2C6H3 (3), 2,6-iPr2-4-tBuC6H2 (4), 2,6-tBu2C6H3 (5), 2,6-tBu2-4-MeC6H2 (6)], have been prepared, and structures for 4 and 5 have been determined by X-ray crystallography. The TiOC (phenyl) bond angles for the Cp* analogues containing the 2,6-diisopropyl-substituted phenoxo ligands (3–4, 173.0–174.6°) were larger than those for other Cp* analogues (155.5–162.3°), suggesting that both Cp* and 2,6-diisopropyl-substituted aryloxo ligand force the unique bond angle leading to more O → Ti π donation into Ti. Effect of aryloxide ligand in 1-hexene polymerization catalyzed by Cp*TiCl2(OAr)—MAO catalysts were explored, and 3–4 exhibited the exceptionally high catalytic activities. Various tert-BuCp analogues of the type, (tBuC5H4)TiCl2(OAr) [Ar = 2,6-Me2C6H3 (7), 2,4,6-Me3C6H2 (8), 2,6-iPr2C6H3 (9), 2,6-iPr2-4-tBuC6H2 (10), 2,6-tBu2C6H3 (11), 2,6-tBu2-4-MeC6H2 (12)], have also been prepared, and explored effect of the aryloxide ligand in syndiospecific styrene polymerization in the presence of MAO cocatalyst. The catalytic activity increased in the order: 10 (activity 2680 kg sPs/mol Ti h) > 7, 9 (1370) > 8 (534) > 11 (258) > 12 (54), strongly suggesting that role of anionic donor ligand was present in this catalysis.

Various half-titanocenes of the type, Cp′TiCl2(OAr) (Cp′ = Cp*, tBuC5H4; Ar = 2,6-Me2C6H3, 2,4,6-Me3C6H2, 2,6-iPr2C6H3, 2,6-iPr2-4-tBuC6H2, 2,6-tBu2C6H3, 2,6-tBu2-4-MeC6H2), were prepared, and structures for Cp*TiCl2(O-2,6-iPr2-4-tBuC6H2) (4), Cp*TiCl2(O-2,6-tBu2C6H3) (5) were determined. Cp*TiCl2(2,6-iPr2C6H3) (3) and 4 possessed unique TiOC bond angles (173.0–174.6°), and exhibited notable catalytic activities for 1-hexene polymerization. The aryloxide ligand affected the activity for syndiospecific styrene polymerization; (tBuC5H4)TiCl2(O-2,6-iPr2-4-tBuC6H2) showed the highest activity. Figure optionsDownload as PowerPoint slide