The position of the sulfur atom in the thienyl group of 6-(thienyl)-2-(imino)pyridine ligands strongly affects the catalytic activity of the corresponding tetrahedral high-spin dihalide CoII complexes in the oligomerization of ethylene to R-olefins upon activation with methylaluminoxane (MAO). Complexes with the sulfur atom in the 3-position of the thienyl ring catalyze the selective conversion of ethylene to 1-butene, while catalysts containing thien-2-yl groups give C4-C14 R-olefins. In situ EPR experiments showed the occurrence of a spin state changeover with the formation of low-spin CoII species upon activation of the catalyst precursors by MAO. DFT calculations suggest that only thien-2-yl rings allow for the coordination of the sulfur atom to the cobalt center in the MAO-activated systems.

Claudio, B., Dante, G., Giuliano, G., Itzel Guerrero, R., Andrea, I., Laschi, F., et al. (2007). Electronic Influence of the Thienyl Sulfur Atom on the Oligomerization of Ethylene by Cobalt(II) 6-(Thienyl)-2-(imino)pyridine Catalysis. ORGANOMETALLICS, 26, 726-739 [10.1021/om0609665].

Electronic Influence of the Thienyl Sulfur Atom on the Oligomerization of Ethylene by Cobalt(II) 6-(Thienyl)-2-(imino)pyridine Catalysis

LASCHI, FRANCO;
2007-01-01

Abstract

The position of the sulfur atom in the thienyl group of 6-(thienyl)-2-(imino)pyridine ligands strongly affects the catalytic activity of the corresponding tetrahedral high-spin dihalide CoII complexes in the oligomerization of ethylene to R-olefins upon activation with methylaluminoxane (MAO). Complexes with the sulfur atom in the 3-position of the thienyl ring catalyze the selective conversion of ethylene to 1-butene, while catalysts containing thien-2-yl groups give C4-C14 R-olefins. In situ EPR experiments showed the occurrence of a spin state changeover with the formation of low-spin CoII species upon activation of the catalyst precursors by MAO. DFT calculations suggest that only thien-2-yl rings allow for the coordination of the sulfur atom to the cobalt center in the MAO-activated systems.
Claudio, B., Dante, G., Giuliano, G., Itzel Guerrero, R., Andrea, I., Laschi, F., et al. (2007). Electronic Influence of the Thienyl Sulfur Atom on the Oligomerization of Ethylene by Cobalt(II) 6-(Thienyl)-2-(imino)pyridine Catalysis. ORGANOMETALLICS, 26, 726-739 [10.1021/om0609665].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/22931
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