M2@C79N (M = Y, Tb): Isolation and Characterization of Stable Endohedral Metallofullerenes Exhibiting M−M Bonding Interactions inside Aza[80]fullerene Cages

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• 作者：Tianming Zuo ; Liaosa Xu ; Christine M. Beavers ; Marilyn M. Olmstead ; Wujun Fu ; T. Daniel Crawford ; Alan L. Balch ; Harry C. Dorn
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：October 1, 2008
• 年：2008
• 卷：130
• 期：39
• 页码：12992-12997
• 全文大小：312K
• 年卷期：v.130,no.39(October 1, 2008)
• ISSN：1520-5126

文摘

Y₂@C₇₉N and Tb₂@C₇₉N have been prepared by conducting the Krätschmer−Huffman electric-arc process under 20 Torr of N₂ and 280 Torr of He with metal oxide-doped graphite rods. These new heterofullerenes were separated from the resulting mixture of empty cage fullerenes and endohedral fullerenes by chemical separation and a two-stage chromatographic process. Crystallographic data for Tb₂@C₇₉N·Ni(OEP)·2C₆H₆ demonstrate the presence of an 80-atom cage with idealized I_h symmetry and two, widely separated Tb atoms inside with a Tb−Tb separation of 3.9020(10) Å for the major terbium sites. The EPR spectrum of the odd-electron Y₂@C₇₉N indicates that the spin density largely resides on the two equivalent yttrium ions. Computational studies on Y₂@C₇₉N suggest that the nitrogen atom resides at a 665 ring junction in the equator on the fullerene cage and that the unpaired electron is localized in a bonding orbital between the two yttrium ions of this stable radical. Thus, the Tb−Tb bond length of the single-electron bond is an exceedingly long metal−metal bond.