Effect of Terminal Aryloxo Ligands in Ethylene Polymerization Using Titanatranes of the Type, [Ti(OAr){(O-2,4-R2C6H2)-6-CH2}3N]: Synthesis and Structural Analysis of the Heterobimetallic Complexes of Titanatranes with AlMe3

Abstract

Effects of aryloxo terminal ligands and AlMe3 in ethylene polymerization using a series of Ti(OAr)[{(O-2,4-R2C6H2)-6-CH2}3N] [R = Me (1), tBu (2); Ar = 2,6-Me2C6H3 (a), 2,6-iPr2C6H3 (b), 2,6-Ph2C6H3 (c), 2,6-F2C6H3 (d), C6F5 (e)] (1a–1e, 2d,2e) in the presence of methylaluminoxane (MAO) have been explored. Reactions of 1b,1d,1e, which showed an increase in the activity upon addition of a small amount of AlMe3, with 1.0 equiv of AlMe3 afforded heterobimetallic Ti–Al complexes, TiMe(O-2,6-iPr2C6H3)[(O-2,4-Me2C6H2-6-CH2)(μ2-O-2,4-Me2C6H2-6-CH2)(Me2Al-μ2-O-2,4-Me2C6H2-6-CH2)N] (3b) and [TiMe{(O-2,4-Me2C6H2-6-CH2)2(μ2-O-2,4-Me2C6H2-6-CH2)N}][Me2Al(μ2-OAr)] [Ar = 2,6-F2C6H3 (3d), C6F5 (3e)], in moderate yields, and their structures were determined by X-ray crystallography. In contrast, the similar reaction of 1a (which showed a decrease in the activity upon addition of AlMe3) yielded [Al(μ2-O-2,6-C6H3)Me2]2 and TiMe[{(O-2,4-Me2C6H2)-6-CH2}3N] as isolated forms: [Al(μ2-OC6F5)Me2]2 was isolated from the mixture i...