Synthesis of C62N Containing a Heptagon

Chemical synthesis of nonclassical fullerenes is one of the remaining challenges in fullerene science. Until our recent report on the synthesis of C64N, C65N, and C75N, there had been only limited examples such as conversion of C60 into C62. In this Letter, we showcase the synthesis of C62N from C60 through three steps. The crystal structure indicates that the C62N fullerene possesses an N-containing heptagon, i.e., 2,7-dihydro-1H-azepine, on its sphere. The major axis reaches 8.735(5) Å, which is larger than that of C60 by 23%. The reactivity and electronic properties of C62N fullerene are also discussed.