2-Benzoxazolyl-6-(1-(arylimino)ethyl)pyridyl cobalt (II) chlorides: A temperature switch catalyst in oligomerization and polymerization of ethylene

Rong Gao, Kefeng Wang, Yan Li, Fosong Wang, Wen-Hua Sun, Carl Redshaw, Manfred Bochmann

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Abstract

A series of cobalt (II) complexes ligated by 2-(2-benzoxazolyl)-6-(1-(arylimino)ethyl)pyridines was synthesized and characterized by FT-IR spectroscopic and elemental analysis. The molecular structures of Co1 (Ar=2,6-Me2C6H3), Co2 (Ar=2,6-Et2C6H3) and Co7 (Ar=2,6-Br2C6H3) were determined by single-crystal X-ray diffraction. Compounds Co1 and Co2 display a distorted trigonal-bipyramidal geometry, whereas complex Co7 is a distorted square-pyramid. Upon activation with methylaluminoxane (MAO), all cobalt complexes showed reactivity towards ethylene. There was however an unexpected temperature dependence; whereas, at room temperature oligomerization was observed, giving 1-alkenes with high selectivities, at elevated temperatures polyethylene was produced. This unusual catalytic behavior of the new complexes was investigated in detail under various reaction parameters.
Original languageEnglish
Pages (from-to)166-171
Number of pages6
JournalJournal of Molecular Catalysis A: Chemical
Volume309
Issue number1-2
DOIs
Publication statusPublished - Jun 2009

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