Soluble Chlorofullerenes C₆₀Cl_2,4,6,8,10. Synthesis, Purification, Compositional Analysis, Stability, and Experimental/Theoretical Structure Elucidation, Including the X-ray Structure of <i>C</i>₁-C₆₀Cl₁₀

The efficacy of various analytical techniques for the characterization of products of C60 chlorination reactions were evaluated by (i) using samples of C60Cl6 of known purity and (ii) repeating a number of literature syntheses reported to yield pure C60Cln compounds. The techniques were NMR, UV−vis, IR, and Raman spectroscopy, FAB, MALDI, LDI, ESI, and APCI mass spectrometry, HPLC, TGA, elemental analysis, and single-crystal X-ray diffraction. Most of these techniques are shown to give ambiguous or erroneous results, calling into question the composition and/or purity of nearly all C60Cln compounds reported to date. The optimum analytical method for chlorofullerenes was found to be a combination of HPLC and either MALDI or APCI mass spectrometry. For the first time, the chlorination of C60 by ICl, ICl3, and Cl2 was studied in detail using dynamic HPLC analysis and APCI mass spectrometry. Suitable conditions were found for the preparation of the new chlorofullerenes 1,7-C60Cl2, 1,9-C60Cl2, 1,6,9,18-C60Cl4, and 1,2,7,10,14,24,25,28,29,31-C60Cl10. The latter compound was also studied by 13C NMR spectroscopy and X-ray diffraction, which led to the unambiguous determination of its asymmetric addition pattern. The unusual structure of C60Cl10 was compared with other possible isomers using DFT-predicted relative energies. These results, along with additional experimental data and an analysis of the DFT-predicted frontier orbitals of likely intermediates, were used to rationalize the formation of the new compound C60Cl10 from C60Cl6 and excess ICl without the rearrangement of any C−Cl bonds. For the first time, the stability of C60Cln compounds under a variety of conditions was studied in detail, leading to the discovery that they are, in general, very light-sensitive in solution. The X-ray structure of C60Cl6 was also redetermined with higher precision.本研究通过两种方式评估了各类分析技术用于C60氯化反应产物表征的效能：其一为使用已知纯度的C60Cl6样品，其二为重复多篇文献中报道的可生成纯C60Cln类化合物的合成方法。所评估的分析技术包括核磁共振波谱法（NMR）、紫外-可见分光光度法（UV−vis）、红外光谱法（IR）、拉曼光谱法（Raman）、快原子轰击质谱法（FAB）、基质辅助激光解吸电离质谱法（MALDI）、激光解吸电离质谱法（LDI）、电喷雾电离质谱法（ESI）、大气压化学电离质谱法（APCI）、高效液相色谱法（HPLC）、热重分析法（TGA）、元素分析法以及单晶X射线衍射法。研究表明，其中多数技术会得到模糊不清或错误的结果，这使得截至目前报道的几乎所有C60Cln类化合物的组成和/或纯度受到质疑。本研究发现，氯化富勒烯的最优分析方法为高效液相色谱法（HPLC）与基质辅助激光解吸电离质谱法（MALDI）或大气压化学电离质谱法（APCI）的联用方案。本研究首次利用动态高效液相色谱分析与大气压化学电离质谱法（APCI），对一氯化碘（ICl）、三氯化碘（ICl3）及氯气（Cl2）与C60的氯化反应进行了详细研究。本研究找到了制备新型氯化富勒烯1,7-C60Cl2、1,9-C60Cl2、1,6,9,18-C60Cl4以及1,2,7,10,14,24,25,28,29,31-C60Cl10的适宜反应条件。研究人员还通过碳-13核磁共振波谱法（13C NMR）与X射线衍射法，对最后一种化合物进行了表征，明确确定了其不对称加成模式。研究人员基于密度泛函理论（DFT）预测的相对能量，将C60Cl10的特殊结构与其他可能的异构体进行了对比。结合额外的实验数据以及对密度泛函理论（DFT）预测的可能中间体前线轨道的分析，本研究合理阐释了C60Cl6与过量一氯化碘（ICl）无需发生碳-氯键重排即可生成新型化合物C60Cl10的反应机制。本研究首次详细探究了C60Cln类化合物在多种条件下的稳定性，发现这类化合物在溶液中普遍对光照极为敏感。研究人员还以更高的精度重新测定了C60Cl6的X射线晶体结构。