Efficient mapping of ring currents in fullerenes and other curved carbon networks

Ring-current aromaticity of icosahedral C120 archimedene is probed at the ipsocentric/6-31G* level by direct mapping of the current density induced in its 4-, 6- and 10-sided faces by perpendicular magnetic fields. In contrast to planar phenylene analogues, the 4-faces (and only those faces) support global π ring currents: intense, paratropic (antiaromatic), stronger on the cage interior. The results validate a simple pseudo-π hydrogen-cluster model for curved carbon networks. Its application to [60]- and [70]-fullerenes shows dominant paratropic ring currents in pentagons militating against attribution of global aromaticity. Application to octahedral derivatives C60X12, shows eight 'aromatised' hexagonal rings. To cite this article: P.W. Fowler et al. C.R. Chimie 8(2005). © 2006 Académie des sciences.