ABSTRACT

Fullerenes are generally recognized as a series of hollow spherical cages comprising pentagonal and hexagonal rings of trivalent carbon atoms. Most of the stable fullerene isomers previously obtained, such as the C60 buckminsterfullerene (BF) with an icosahedral (Ih) symmetry (Kroto et al. 1985), for instance, have no abutting (fused) pentagon pair that can be energetically unfavorable (Schmalz et al. 1986). e so-called isolated pentagon rule (IPR) has been found to be violated only in limited types of fullerenes such as endohedral metallofullerenes Sc2@C66 and Sc3N@ C68 that were experimentally isolated for the rst time in 2000 (Dunsch and Yang 2007; Stevenson et al. 2000; Wang et al. 2000).