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Ligand migration in the reaction of titanium complexes with AlMe3.
Autorzy
Rok wydania
2007
Czasopismo
Collection of Czechoslovak Chemical Communications
Numer woluminu
72
Strony
541-559
DOI
10.1135/cccc20070541
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
Five different titanium compounds cis-[Ti(η2-hbo)2(OEt)2]·0.5toluene (1), cis-[TiCl2(η2-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 [Al2(μ2-η2-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).
Słowa kluczowe
Polymerizations, Polymerization catalysts, Titanium complexes, Aluminum complexes, Lewis acids, Ligand migration, Chelates, X-Ray diffraction
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