Buckminsterfullerene 2026-10-20
The ideal carbon cage has Ih molecular point group symmetry. The highest symmetry-protected orbital degeneracy is five; spin degeneracy is counted separately.
Past exam of the chemistry A course of the University of Cambridge 2024 Paper 1 A4 c ii Solution 2026-10-20
The highest expected orbital degeneracy is five. Ideal buckminsterfullerene has Ih molecular point group symmetry. Its irreducible orbital representations include five-dimensional and representations; no single-valued orbital irrep has higher dimension.
This counts distinct spatial molecular orbitals. It does not multiply by electron spin, and it excludes accidental coincidences between unrelated irreps. In a real environment, symmetry lowering can split these degeneracies.[ref]