Physical Chemistry Chemical Physics
Royal Society of Chemistry
NSF, Division of Chemistry (CHE) 1664379
NSF, Division of Chemistry (CHE)
The most characteristic feature of planar π-aromatics is the ability to sustain a long-range shielding cone under a magnetic field oriented in a specific direction. In this article, we showed that similar magnetic responses can be found in σ-aromatic and spherical aromatic systems. For [Au13]5+, long-range characteristics of the induced magnetic field in the bare icosahedral core are revealed, which are also found in the ligand protected [Au25(SH)18]− model, proving its spherical aromatic properties, also supported by the AdNDP analysis. Such properties are given by the 8-ve of the structural core satisfying the Hirsch 2(N + 1)2 rule, which is also found in the isoelectronic [M@Au12]4+ core, a part of the [MAu24(SR)18]2− (M = Pd, Pt) cluster. This contrasts with the [M@Au12]6+ core in [MAu24(SR)18]0 (M = Pd, Pt), representing 6-ve superatoms, which exhibit characteristics of planar σ-aromatics. Our results support the spherical aromatic character of stable superatoms, whereas the 6-ve intermediate electron counts satisfy the 4N + 2 rule (applicable for both π- and σ-aromatics), showing the reversable and controlled interplay between 3D spherical and 2D σ-aromatic clusters.
Fedik, Nikita, et al. “Aromatic Character of [Au13]5+ and [MAu12]4+/6+ (M = Pd, Pt) Cores in Ligand Protected Gold Nanoclusters – Interplay between Spherical and Planar σ-Aromatics.” Physical Chemistry Chemical Physics, vol. 21, no. 45, The Royal Society of Chemistry, 2019, pp. 25215–19, doi:10.1039/C9CP04477A.