89Y and 13C NMR Cluster and Carbon Cage Studies of an Yttrium Metallofullerene Family, Y3N@C2n (n = 40−43)

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• 作者：Wujun Fu ; Liaosa Xu ; Hugo Azurmendi ; Jiechao Ge ; Tim Fuhrer ; Tianming Zuo ; Jonathan Reid ; Chunying Shu ; Kim Harich ; Harry C. Dorn
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：August 26, 2009
• 年：2009
• 卷：131
• 期：33
• 页码：11762-11769
• 全文大小：359K
• 年卷期：v.131,no.33(August 26, 2009)
• ISSN：1520-5126

文摘

The members of a new family of yttrium trimetallic nitride-templated (TNT) endohedral metallofullerenes (EMFs), Y₃N@C_2n (n = 40−43), have been synthesized and purified. On the basis of experimental and computational ¹³C NMR studies, we propose cage structures for Y₃N@I_h-C₈₀ (IPR allowed), Y₃N@D_5h-C₈₀ (IPR allowed), Y₃N@C_s-C₈₂ (non-IPR), Y₃N@C_s-C₈₄ (non-IPR), and Y₃N@D₃-C₈₆ (IPR allowed). A significant result is the limited number of isomers found for each carbon cage. For example, there are 24 isolated pentagon rule (IPR) and 51568 non-IPR structures possible for the C₈₄ cage, but only one major isomer of Y₃N@C_s-C₈₄ was found. The current study confirms the unique role of the trimetallic nitride (M₃N)⁶⁺ cluster template in the Krtschmer−Huffman electric-arc process for fullerene cage size and high symmetry isomer selectivity. This study reports the first ⁸⁹Y NMR results for Y₃N@I_h-C_80, Y₃N@C_s(51365)-C₈₄, and Y₃N@D₃(19)-C₈₆, which reveal a progression from isotropic to restricted (Y₃N)⁶⁺ cluster motional processes. Even more surprising is the sensitivity of the ⁸⁹Y NMR chemical shift parameter to subtle changes in the electronic environment at each yttrium nuclide in the (Y₃N)⁶⁺ cluster (more than 200 ppm for these EMFs). This ⁸⁹Y NMR study suggests that ⁸⁹Y NMR will evolve as a powerful tool for cluster motional studies of EMFs.