Synthesis, structure, and theoretical study of trifluoromethyl derivatives of C84(23) fullerene

Trifluoromethylation of a higher fullerene mixture with CF3I was performed in ampoules at 550 °C. HPLC separation followed by crystal growth and X-ray diffraction study resulted in the structure elucidation of nine CF3 derivatives of D2d-C84 (isomer 23). The molecular structures of C84(23)(CF3)4, C84(23)(CF3)8, C84(23)(CF3)10, C84(23)(CF3)12, two isomers of C84(23)(CF3)14, two isomers of C84(23)(CF3)16, and C84(23)(CF3)18 were discussed in terms of their addition patterns and the relative formation energies. Extensive theoretical DFT calculations were performed to identify the most stable molecular structures. It was found that the addition of CF3 groups to the C84(23) fullerene is governed by two main rules: no additions in positions of triple hexagon junctions and predominantly para additions in C6(CF3)2 hexagons on the fullerene cage. The only exception with an isolated CF3 group in C84(23)(CF3)12 is discussed in more detail.