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• 作者：Tianming Zuo ; Marilyn M. Olmstead ; Christine M. Beavers ; Alan L. Balch ; Guangbin Wang ; Gordon T. Yee ; Chunying Shu ; Liaosa Xu ; Bevan Elliott ; Luis Echegoyen ; James C. Duchamp ; Harry C. Dorn
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：June 16, 2008
• 年：2008
• 卷：47
• 期：12
• 页码：5234 - 5244
• 全文大小：6225K
• 年卷期：v.47,no.12(June 16, 2008)
• ISSN：1520-510X

文摘

We report an efficient method for the preparation and purification of the I_h and the D_5h isomers of Tm₃N@C₈₀. Following preparation in a Krätschmer−Huffman electric-arc generator, the Tm₃N@C₈₀ isomers were obtained by a chemical separation process followed by a one-stage isomer selective chromatographic high-performance liquid chromatography (HPLC) separation (pyrenyl, 5PYE column). The HPLC chromatographic retention behavior on a pentabromobenzyl (5PBB) column suggests a charge transfer of ~6 electrons; [M₃N]⁶⁺@C₈₀⁶⁻ and the chromatographic retention mechanisms of the I_h and the D_5h isomers of Tm₃N@C₈₀ on both 5PBB and 5PYE columns are discussed. Single-crystal X-ray diffraction data demonstrate that the Tm₃N cluster has a planar structure but represents a tight fit for trapping the Tm₃N cluster inside the I_h- and the D_5h-C₈₀ cages. Specifically, the Tm atoms punch out the cage carbon atoms adjacent to them. The “punched out” effect can be demonstrated by cage radii and pyramidal angles at cage carbon atoms near the Tm atoms. The magnetic susceptibility (χT) for Tm₃N@ I_h-C₈₀ was found to exhibit Curie−Weiss behavior with C = 23.4 emu·K/mol, which is consistent with the calculated value for three uncoupled Tm³⁺ ions by considering the spin and orbital contributions with no quenching of the orbital angular momentum (L = 5, S = 1, and J = 6; C_calcd = 23.3 emu·K/mol). The electrochemical measurements demonstrate that both the I_h and the D_5h isomers of Tm₃N@C₈₀ have a large electrochemical gap.