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 Co-II complexes in the oligomerization of ethylene to alpha-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 C-4-C-14 alpha-olefins. In situ EPR experiments showed the occurrence of a spin state changeover with the formation of low-spin Co-II 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.
Electronic influence of the thienyl sulfur atom on the oligomerization of the ethylene by cobalt, pyridine catalysis / C. Bianchini; D. Gatteschi; G. Giambastiani; I.G. Rios; A. Ienco; F. Laschi; C. Mealli; A. Meli; L. Sorace; A. Toti; F. Vizza. - In: ORGANOMETALLICS. - ISSN 0276-7333. - STAMPA. - 26:(2007), pp. 726-739. [10.1021/om0609665]
Electronic influence of the thienyl sulfur atom on the oligomerization of the ethylene by cobalt, pyridine catalysis
BIANCHINI, CLAUDIO;GATTESCHI, DANTE;G. Giambastiani;SORACE, LORENZO;
2007
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 Co-II complexes in the oligomerization of ethylene to alpha-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 C-4-C-14 alpha-olefins. In situ EPR experiments showed the occurrence of a spin state changeover with the formation of low-spin Co-II 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.File | Dimensione | Formato | |
---|---|---|---|
ORGANOMET2007_(LS1).pdf
Accesso chiuso
Tipologia:
Versione finale referata (Postprint, Accepted manuscript)
Licenza:
Tutti i diritti riservati
Dimensione
519.63 kB
Formato
Adobe PDF
|
519.63 kB | Adobe PDF | Richiedi una copia |
I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.