Anorganische Chemie - Beckhaus

Tetrabenzo[a,c,g,i]titanium(III) and -(IV) Complexes: Syntheses, Reactions and catalytic Application

Kai Schröder, Detlev Haase, Wolfgang Saak, Rüdiger Beckhaus *, Winfried P. Kretschmer, Arne Lützen
Organometallics
2008, 27(8), 1859-1868.

Abstract

Reacting tetrabenzo[a,c,g,i]fluorenyllithium {TbfLi(THF)4 (1)} with TiCl3(THF)3 (2) leads to the formation of the η5-tetrabenzo[a,c,g,i]fluorenyltitanium(III) derivative TbfTiCl2(THF) (3), which can be conveyed to the titanium(IV)complex TbfTiCl3 (4) by oxidative chlorination with CCl4. Subsequent reaction with various lithium phenoxides gives a series of titanium complexes of the type TbfTiCl2(OAr) (Ar = 4-tBuC6H4 (5), 2,6-Me2C6H3 (6), 2,4,6-Me3C6H2 (7), 2,6-iPrC6H3 (8), 2,6-Ph2C6H3 (9)). Furthermore, 3 was reacted with radicals or radical-generating peroxides to form the complexes TbfTiCl2TEMPO (10) and TbfTiCl2OtBu (11). All compounds were characterized by IR, MS, and NMR measurements and X-ray crystallography. Finally, compounds 6, 8, 9, and 10 were subjected to ethylene polymerization experiments using d-MAO. The activities increase in the following order [kG(PE)mol(Ti)−1 h−1 bar−1]: 6 (320) < 8 (320) < 10 (760) < 9 (1000).

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