Icosahedral symmetry carbon cage molecules

Graphite, when vaporized by laser irradiation, produces a very stable cluster of 60 carbon atoms which, it has been suggested, takes the uniquely elegant form of one of the archimedian semiregular polyhedra—the truncated icosahedron 1,2 . In considering the possibility of other structures of especial stability, we are led by a sequence of fairly general arguments to consider a relatively restricted family of high-symmetry cage structures, which correspond to novel convex polyhedra of icosahedral symmetry. Considering each of the smaller (computationally accessable) species in the family we predict here that C 20 is unstable; C 80 and C 140 have moderate resonance energies but are open shell; and C 60 , C 180 and C 240 are closed shell especially stable forms. The latter two are possible stable carbon cages not yet experimentally characterized.