Structure, stability, and NMR properties of lower fullerenes C38-C50 and azafullerene C44N6

A systematic survey of the complete set of isomers of fullerenes C-38, C-40, C-42, C-44, C-46, C-48, C-50 and azafullerene C44N6 is reported. All isomeric structures were optimized using first-principle density functional theory at the B3LYP/6-31G* level. The isomeric structures with the lowest energies are C-38:17, C-40:38, C-42:45, C-44:75, C-44:89, C-46:109, C-48:171, and C-50:270. The ground-state structure of the azafullerene C44N6 in the framework Of C-50:270 has D-3 symmetry. The C-13 NMR chemical shifts and nucleus-independent chemical shifts (NICS) for the stable isomers of each fullerene are presented.