Solvent-free Sc₃N@C₈₀-I_h and Its Precursor Cocrystal with Toluene

Abstract

Solvent-free Sc₃N@C₈₀-I_h was prepared for the first time in high quality microcrystalline form via thermal decomposition of its toluene cocrystal. The production route and structural studies of both materials are presented. The structures were determined by x-ray powder diffraction, and confirmed by cohesion energy calculations. The solvent-free endohedral fullerene forms face centered cubic crystals with lattice parameter a = 15.611 Å and the molecules are orientationally disordered. This is a new member of the high-symmetry isostructural expansion series of fullerenes. The parent cocrystals precipitated from toluene possess 1:1 stoichiometry; their structure is orthorhombic of Cmcm space-group. At room temperature the toluene molecules are located in large cavities in a severely disordered way. A symmetry lowering phase transition is observed on cooling indicating the dynamic nature of the disorder. The decomposition, assisted by toluene diffusion at elevated temperatures, is also analyzed in detail.

Keywords::

• Sc₃N@C₈₀
• endohedral fullerene
• cocrystal
• thermal decomposition
• X-ray powder diffraction
• energy calculation
• supramolecular interaction

Acknowledgments

Gábor Bortel and Éva Kováts acknowledge the support of the Bolyai János Scholarship of the Hungarian Academy of Sciences. The authors are grateful to Gyula Faigel and Gábor Oszlányi for the useful discussions.

Additional information

Funding

This work was supported by OTKA, the Hungarian Research Fund, grant number NK105691.