Hyperdistorted Tungsten Allyl Complexes and Their Stereoselective Deprotonation to Form Dihapto-Coordinated Dienes

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• 作者：Daniel P. Harrison ; Adam C. Nichols-Nielander ; Victor E. Zottig ; Laura Strausberg ; Rebecca J. Salomon ; Carl O. Trindle ; Michal Sabat ; T. Brent Gunnoe ; Diana A. Iovan ; William H. Myers ; W. Dean Harman
• 刊名：Organometallics
• 出版年：2011
• 出版时间：May 9, 2011
• 年：2011
• 卷：30
• 期：9
• 页码：2587-2597
• 全文大小：1185K
• 年卷期：v.30,no.9(May 9, 2011)
• ISSN：1520-6041

文摘

Several 蟺-allyl complexes of {TpW(NO)(PMe₃)} are investigated as possible sources of 畏²-diene complexes. In order to prepare the diene complex as a single diastereomer, the allyl complex must undergo deprotonation stereoselectively. Allyl complexes of this tungsten system are highly distorted, with the difference between the W鈭扖 bond lengths for the two allyl termini being as much as 0.69 脜. DFT calculations and several crystal structures are presented that collectively suggest that one terminus, C1, distal to the PMe₃ group, tends toward an sp² carbocation. Consistent with this interpretation, deprotonation preferentially occurs at a carbon adjacent to this allyl terminus for six-membered rings. However, in the presence of base the five-membered cyclic analogue [TpW(NO)(PMe₃)(C₅H₇)]⁺ fails to form either isomer of the corresponding 畏²-diene complex.