Collect. Czech. Chem. Commun. 2007, 72, 541-559

Ligand Migration in the Reaction of Titanium Complexes with AlMe3

Michał J. Kobyłkaa, Lucjan B. Jerzykiewicza, Jasson T. Pattonb, Szymon Przybylaka, Józef Utkoa and Piotr Sobotaa,*

a Faculty of Chemistry, University of Wrocław, 14 F. Joliot-Curie, 50-383 Wrocław, Poland
b The Dow Chemical Company, Catalysis Laboratory, Midland, Michigan 48674, USA


Five different titanium compounds cis-[Ti(η2-hbo)2(OEt)2]·0.5toluene (1), cis-[TiCl22-thp)2] (2), [TiCl2(edbp)2] (3), [Ti2(μ-OMe)2(edbp)2(Me)2] (6), [Ti2(μ-OMe)2(edbp)2(OMe)2] (7) (Hhbo = 2-(2-hydroxyfenyl)benzoxazole, Hthp = tetrahydropyran-2-methanol, H2edbp = 2,2'-ethylidenebis(4,6-di-tert-butylphenol)), have been prepared and tested in combination with MAO as catalysts for propene polymerization and ethene and oct-1-ene copolymerization with the aim of gaining insight into the structure of the active species. Investigation of the 1/AlMe3 or 2/AlMe3 systems resulted in isolation of [Al(η2-hbo)2(Me)] (4) and [Al222-thp)2(Me)4] (5) in high yields. This indicates that the trimethylaluminum contained in MAO abstracts ligands from 1 or 2, affecting thus the catalytic performance of the 1,2/MAO catalysts. In contrast, compound 3 reacted with MAO affording methylated product 6. Accordingly, the 3/MAO catalyst differed from the above ones, furnishing at 70 °C e.g., narrow molecular weight polypropylene (Mn = 454 000; Mw/Mn = 2.49; Tm = 158.2 °C).

Keywords: Polymerizations; Polymerization catalysts; Titanium complexes; Aluminum complexes; Lewis acids; Ligand migration; Chelates; X-Ray diffraction.

References: 34 live references.