Effect of aryloxide ligand in 1-hexene, styrene polymerization catalyzed by nonbridged half-titanocenes of the type, Cp′TiCl 2(OAr) (Cp′ = C 5Me 5, tBuC 5H 4) : Structural analyses for Cp *TiCl 2(O-2,6- tBu 2C 6H 3) and Cp *TiCl 2(O-2,6- iPr 2-4- tBuC 6H 2)

Abstract

Various (aryloxo)(pentamethylcyclopentadienyl)titanium(IV) dichloride complexes of the type, Cp *TiCl 2(OAr) [Cp * = C 5Me 5, Ar = 2,6-Me 2C 6H 3 ( 1), 2,4,6-Me 3C 6H 2 ( 2), 2,6- i Pr 2C 6H 3 ( 3), 2,6- i Pr 2-4- t BuC 6H 2 ( 4), 2,6- t Bu 2C 6H 3 ( 5), 2,6- t Bu 2-4-MeC 6H 2 ( 6)], have been prepared, and structures for 4 and 5 have been determined by X-ray crystallography. The Ti O C (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 *TiCl 2(OAr)—MAO catalysts were explored, and 3– 4 exhibited the exceptionally high catalytic activities. Various tert-BuCp analogues of the type, ( t BuC 5H 4)TiCl 2(OAr) [Ar = 2,6-Me 2C 6H 3 ( 7), 2,4,6-Me 3C 6H 2 ( 8), 2,6- i Pr 2C 6H 3 ( 9), 2,6- i Pr 2-4- t BuC 6H 2 ( 10), 2,6- t Bu 2C 6H 3 ( 11), 2,6- t Bu 2-4-MeC 6H 2 ( 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.