Fullerene Isomerism: Isolation of <i>C</i> _{2 <i>v</i>} ,-C ₇₈ and <i>D</i> ₃ -C ₇₈

<jats:p> Early reports on the formation of the higher fullerenes C <jats:sub>76</jats:sub> , C <jats:sub>78</jats:sub> , C <jats:sub>84</jats:sub> , C <jats:sub>90</jats:sub> , and C <jats:sub>94</jats:sub> by resistive heating of graphite stimulated theoretical calculations of possible cage structures for these all-carbon molecules. Among the five fullerene structures with isolated pentagons found for C <jats:sub>78</jats:sub> , a closed-shell <jats:italic>D</jats:italic> <jats:sub> 3 <jats:italic>h</jats:italic> </jats:sub> -isomer was predicted to form preferentially. Two distinct C <jats:sub>78</jats:sub> -isomers were formed in a ratio of ∼5:1 and could be separated by high-performance liquid chromatography. The carbon-13 nuclear magnetic resonance (NMR) spectrum of the major isomer is uniquely consistent with a <jats:italic>C</jats:italic> <jats:sub> 2 <jats:italic>v</jats:italic> </jats:sub> -structure. The NMR data also support a chiral <jats:italic>D</jats:italic> <jats:sub>3</jats:sub> -structure for the minor isomer. The isolation of specifically these two isomers of C <jats:sub>78</jats:sub> provides insight into the stability of higher fullerene structures and into the mechanism for fullerene formation in general. </jats:p>