Activation of Bis(pyrrolylaldiminato) and (Salicylaldiminato)(pyrrolylaldiminato) Titanium Polymerization Catalysts with Methylalumoxane

Konstantin P. Bryliakov, Evgenii A. Kravtsov, Lewis Broomfield, Evgenii P. Talsi, Manfred Bochmann

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

Cationic intermediates formed upon activation of an olefin polymerization catalyst based on bis[N-phenylpyrrolylaldiminato]titanium(IV) dichloride (L2TiCl2, I) and [N-(3-tert-butylsalicylidene)-2,3,4,5,6-pentafluoroanilinato-N‘-phenylpyrrolylaldiminato]titanium(IV) dichloride (L‘LTiCl2, II) with methylalumoxane (MAO) have been identified. Outer-sphere ion pairs of the type [L2TiMe(S)]+[MeMAO]- and [L‘LTiMe(S)]+[MeMAO]- capable of ethene polymerization have been characterized by 1H and 13C NMR spectroscopy. Unlike methyl metallocenium cations, the barrier of the first ethene insertion into the Ti-Me bonds of these species is not significantly higher than that of subsequent insertions. Surprisingly, whereas homoligated catalyst precursors L2TiCl2 in the presence of MAO are prone to ligand transfer to aluminum, under the same conditions the heteroligated system L‘LTiCl2/MAO proved resistant to ligand scrambling.
Original languageEnglish
Pages (from-to)288-293
Number of pages6
JournalOrganometallics
Volume26
Issue number2
DOIs
Publication statusPublished - 2007

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