Valencies of a small fullerene: structures and energetics of C24H2m

Construction of all 352 786 possible addition patterns C24H2m and optimisation with the density-functional-based tight-binding model is used to deduce that the C24 fullerene has an effective valence of 12. The optimal structure of C24H12 has an equatorial ring of 12 sp3 sites and is reachable by a pathway involving cumulative addition to low-energy isomers.