Spherical aromaticity in icosahedral and tetrahedral gold clusters: insights from 8-, 18- and 20-ce Au135+, W@Au12, and Au20 clusters

Abstract

W@Au₁₂ and Au₂₀ are two prominent bare clusters exhibiting an icosahedral symmetry, with 18- and 20-cluster electrons (ce) and electronic shell configurations of 1S²1P⁶1D¹⁰ and 1S²1P⁶2S²1D¹⁰, respectively. Such species provide prototypical clusters useful for the design of building blocks for functional nanostructures. Here, we explore the magnetic behavior on an equal footing to evaluate aromaticity in such different structures, providing a direct connection to classical aromatics. The long-range magnetic behavior is further analyzed to gain knowledge about the global response outside the cage between icosahedral and tetrahedral species, ascribing W@Au₁₂ and Au₂₀ as spherical aromatic clusters. Our results provide an equal-footing alternative for evaluating aromaticity, providing a direct connection to classical aromatics and revealing certain electron counts that give rise to a shielding cone property, thereby establishing a bridge between organic/inorganic planar and spherical aromatic species towards the unification of the aromaticity concept.