Endohedral complexes of C58 cage with H2 and CO

Ab initio Hartree–Fock (HF) calculations were carried out to determine the structures and energies of the endohedral complexes of C58 cage with H2 or CO. It was demonstrated that the formation of these complexes is endothermic with destabilization energies of 3.3 kcal/mol for H2 and 18.6 kcal/mol for CO. Furthermore, the H2 and CO molecules have different orientations in the C58 cage, namely, the orientation of the molecular axis of the former is normal to the face of the 7-member ring, while that of the latter is parallel to that face. In addition, the H–H bond of the H2 molecule is shortened inside the cage, whereas the length of the C–O bond remains unchanged.