Head-to-Tail and Back-to-Back Dimerization of an Open-Cage Fullerene Derivative through π–π Interaction-Based Self-Assembly

Open-cage fullerene derivative 2, C59(O)4(NAr)2 (Ar = p-tBuC6H4), was prepared from 1, C60(O)4(OH)2(NAr)2, through processes involving decarbonylation and elimination of the two hydroxyl groups. The phenyl groups in compound 2 act as chelating ligands for the fullerene cage and induce partial dimerization of 2 in solution. The single crystal X-ray structure of 2 shows strong intradimer π–π interactions and also weaker interdimer CH−π and π–π interactions.