Fused-Pentagon C70Cl6 and C70Cl8 Obtained via Chlorination-Promoted Skeletal Transformation of IPR C70

Inorg Chem. 2020 Aug 3;59(15):10400-10403. doi: 10.1021/acs.inorgchem.0c01510. Epub 2020 Jul 10.

Abstract

The isolated-pentagon-rule (IPR) D5h-C70 fullerene is least susceptible to skeletal transformations in comparison with higher fullerenes and even C60. A cage transformation in IPR C70 via a one-step Stone-Wales rearrangement was accomplished by high-temperature (440 °C) ampule chlorination with SbCl5. Subsequent dechlorination at 450 °C, followed by high-performance liquid chromatography separation, allowed the isolation of non-IPR C70Cl6 and C70Cl8. X-ray diffraction study revealed the presence of an unprecedented C70 carbon cage, possessing two pairs of fused pentagons and the chlorination patterns located on one cage hemisphere. A high energetic and thermal stability of both non-IPR chlorides was also confirmed by theoretical calculations of formation energies. Pathways of skeletal transformations of IPR C70 in comparison with those in C60 are discussed.