Higher fullerenes with more than 70 carbon atoms are present in fullerene soot in very small amounts. This makes their investigation and even identification challenging tasks. However, high-temperature chlorination allows the isolation of higher fullerene chlorides in the crystalline state and their subsequent study by single crystal X-ray diffraction.

Sergey Troyanov and colleagues, Moscow State University, Russia, confirmed the presence of a relatively unstable isomer of C₉₀, D_5h-C₉₀, in the fullerene soot produced from undoped graphite rods for the first time. They used VCl₄ to chlorinate the fullerenes at 350 °C over a period of weeks.

The team determined the structure of the resulting C₉₀Cl₁₂ (in co-crystals with C₉₀Cl₁₀) using synchrotron radiation. The results revealed a nanotubular cage with twelve Cl atoms, six on each end of the cage (pictured). Earlier, D_5h-C₉₀ had been isolated only from the soot produced with Sm₂O₃-doped graphite rods.

• Unstable Isomer of C₉₀ Fullerene Isolated as Chloro Derivatives, C₉₀(1)Cl_10/12,
  Norbert S. Chilingarov, Sergey I. Troyanov,
  Chem. Asian J. 2016.
  DOI: 10.1002/asia.201600713