Theoretical evidence for the major isomers of fullerene C84 based on 13C NMR chemical shifts

Geometry optimizations for three isomers of fullerene C84, 21, 22 and 23, have been performed by density functional theory (DFT) at the B3LYP/6-31G* level of theory. 13C NMR chemical shifts were evaluated by the GIAO method employing 6-31G* and 6-311G** basis sets. Isomers 22 and 23 are predicted to have essentially equal energies and isomer 21 to be 16 kcal mol−1 less stable. The calculated 13C NMR chemical shifts of isomers 22 and 23 agree nicely with experimental data while the results of isomer 21 show large differences, indicating that isomer 22 is the experimentally observed D2 isomer.