From Rare Gas Atoms to Fullerenes: Spherical Aromaticity Studied From the Point of View of Atomic Structure Theory

Abstract

The characteristic features of molecules like polyhedra and fullerenes, which follow the 2(N+1)(2) rule of spherical aromaticity, can be related to energetically stable closed-shell configurations of (pseudo-)atoms. This unifying view relies on a thought experiment, which produces a polyhedron in a two-step process and which can, in turn, relate the electronic configuration of any spherical polyhedron to the one of a corresponding closed-shell atom. In the first step, the electronic ground-state configuration is identified. In the second step, a group theoretical analysis can be carried out; this relates the spherically symmetric atomic orbitals to the molecular orbitals classified according to the irreducible representations of the point group of the polyhedron under consideration. This procedure explains and justifies the pseudo-l classification of molecular orbitals, which is the basis of the 2(N+1)(2) rule. For the transition from the electronic configuration of the rare gas Eka-Rn (Uuo) to the icosahedral fullerene C(20) (2+), we show how a change in the ground-state configuration leads to the phenomenologically found 2(N+1)(2) rule for spherically aromatic fullerenes.

On the Aromaticity of the Planar Hydrogen-Bonded (HF)3 Trimer

“…[11][12][13] Spherical aromatic molecules consist of approximately spherical (e.g., icosahedral) molecules fulfilling a 2(N + 1) 2 rule for the number of valence electrons. [14][15][16][17][18] These are the magic numbers of electrons for closed-shell model systems with an indefinitely thin spherically symmetric shell potential. Simpler three-dimensional cage-shaped molecules are found to possess 3D aromaticity.…”

High‐Electron‐Density C6H6 Units: Stable Ten‐π‐Electron Benzene Complexes

“…The planar two-dimensional aromatic systems and the three-dimensional 1 A 1g complex all have negative NICS values, whereas the three-dimensional 3 E 2u complex has a highly positive one. Further, according to the 2(n+1) 2 rule of three-dimensional aromaticity, [12,13] ten p electrons are unfavourable. To build a molecular wire from ten-p-electron benzene molecules, a means to align several benzene molecules along the C 6 axis is required.…”

Computational Termochemistry Study of the C80 Isomers and Their Endo Lanthanum Complexes by Applying Homodesmotic and Isodesmic Reactions

“…This additional stability has been attributed to a type of spherical aromaticity in C 60 [37], from which we can conclude that a similar effect occurs in C 80 , in spite of the symmetry or changes in symmetry that are evident in the different cages. …”