The effect of the oxidation state of molybdenum complexes on the catalytic transformation of terminal alkynes: Cyclotrimerization vs. polymerization
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- 作者：Izabela Czelu?niak ; Paulina Koci?cka ; Teresa Szyma¨½ska-Buzar
- 关键词：Molybdenum catalysts ; Alkynes ; Alkynols ; Cyclotrimerization ; Polymerization ; NMR
- 刊名：Journal of Organometallic Chemistry
- 出版年：2012
- 出版时间：1 October, 2012
- 年：2012
- 卷：716
- 期：Complete
- 页码：70-78
- 全文大小：544 K
文摘
Reactions of monosubstituted alkynes (PhC¡ÔCH, tBuC¡ÔCH, nBuC¡ÔCH, HOCH2C¡ÔCH, HO(CH3)2CC¡ÔCH) in the presence of molybdenum(0) and molybdenum(II) carbonyl complexes (Mo(CO)6/hv, [Mo(CO)4(pip)2] (pip = piperidine), [Mo(CO)4(pip)2]/SnCl4, [Rpip]2[{(¦Ì-Cl)Mo(¦Ì-Cl)(SnCl3)(CO)3}2] (R = C3H5, H)) lead to the formation of cyclotrimerization and polymerization products, which were characterized by chromatography (GC-MS, GPC) and by 1H and 13C NMR spectroscopy. The effect of the oxidation state of the molybdenum catalyst on the transformation of the terminal alkynes was observed: cyclotrimerization vs. polymerization. Only molybdenum(II) complexes lead to the formation of polyenic polymers. Moreover, reaction of prop-2-yn-1-ol initiated by [Mo(CO)4(pip)2] in dichloromethane leads to the formation of oligomers containing the vinylidene unit. Mechanistic NMR studies show that ¦Ç2-alkyne complex formation is the principal feature of all transformations of alkynes catalyzed by molybdenum complexes.