On the Importance of Halogen-Halogen Interactions in the Solid State of Fullerene Halides: A Combined Theoretical and Crystallographic Study

In this manuscript, we combined DFT (Density Functional Theory) calculations (BP86-D3/def2-TZVP level of theory) and a search in the CSD (Cambridge Structural Database) to analyze the role of halogen-halogen interactions in the crystal structure of fullerene halides. We have used a theoretical model of a halogenated C-60 and evaluated the formation of halogen-halogen complexes between F, Cl, Br and I derivatives. In addition, we also carried out AIM (Atoms in Molecules) and NBO (Natural Bonding Orbital) analyses to further describe and characterize the interactions described herein. Finally, we have carried out a search in the CSD and found several X-ray structures where these interactions are present and important in governing the crystal packing of the fullerene halides, thus giving reliability to the results derived from the calculations.