Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
J Am Chem Soc. 2011 Sep 14;133(36):14151-3. doi: 10.1021/ja203225n. Epub 2011 Aug 22.
Heating a bulk sample of [60]fullerene complexes, (η(5)-C(5)H(5))MC(60)R(5) (M = Fe, Ru, R = Me, Ph), produces small hydrocarbons because of coupling of R and C(5)H(5) via C-C and C-H bond activation. Upon observation by transmission electron microscopy, these complexes, encapsulated in single-walled carbon nanotubes, underwent C-C bond reorganization reactions to form new C-C bond networks, including a structure reminiscent of [70]fullerene. Quantitative comparison of the electron dose required to effect the C-C bond reorganization of fullerenes and organofullerenes in the presence of a single atom of Ru, Fe, or Ln and in the the absence of metal atoms indicated high catalytic activity of Ru and Fe atoms, as opposed to no catalytic activity of Ln. Organic molecules such as hydrocarbons and amides as well as pristine [60]fullerene maintain their structural integrity upon irradiation by ca. 100 times higher electron dose compared to the Ru and Fe organometallics. The results not only represent a rare example of direct observation of a single-metal catalysis but also have implications for the use of single metal atom catalysis in Group 8 metal heterogeneous catalysis.
加热[60]富勒烯配合物（η(5)-C(5)H(5))MC(60)R(5)（M=Fe，Ru，R=Me，Ph）的大块样品，由于 R 和 C(5)H(5)之间通过 C-C 和 C-H 键的激活而发生偶联，会产生小分子烃。通过透射电子显微镜观察，这些封装在单壁碳纳米管中的配合物经历了 C-C 键重排反应，形成了新的 C-C 键网络，包括类似于[70]富勒烯的结构。定量比较了在单原子 Ru、Fe 或 Ln 的存在下以及在没有金属原子的情况下，富勒烯和有机富勒烯的 C-C 键重排所需的电子剂量，结果表明 Ru 和 Fe 原子具有高催化活性，而 Ln 则没有催化活性。与 Ru 和 Fe 有机金属相比，有机分子（如烃和酰胺）以及原始[60]富勒烯在经受约 100 倍更高的电子剂量照射时保持其结构完整性。这些结果不仅代表了对单金属催化的直接观察的罕见实例，而且对在第 8 族金属多相催化中使用单金属原子催化具有重要意义。
