Spherical Aromaticity inIh Symmetrical Fullerenes: The 2(N+1)2 Rule

Abstract

The maximal spherical aromaticity of an icosahedral fullerene such as C202+ (see picture) can only be achieved with 2(N+1)2 π electrons. There is clear evidence for this rule from the magnetic behavior of the endohedral He complexes on the basis of 3He NMR chemical shifts and it is ascribed to the spherical charge distribution.