Endohedral Group-14 Clusters Au@X12 (X = Ge, Sn, Pb) and Their Anions: A First-Principles Study

Group-14 (Ge, Sn, Pb) clusters have attracted a lot of attention not only because of their unique structural models but also the outstanding building blocks as cluster-assembled materials. In this paper, we have systematically investigated the structure, chemical stability, electronic property, spherical aromaticity, and bonding of neutral Au@X12 (X = Ge, Sn, Pb) clusters and their anions using density-functional theory (DFT) calculations. It is found that the Au@Ge12 cluster displays bicapped pentagonal prism geometry, whereas Au@X12 (X = Sn, Pb) possess the perfect icosahedral geometry. Analysis of binding energy reveals that the species exhibit high chemical stabilities, especially for closed-shell anionic clusters, which con-tain 60 valence electrons. The hybridization between cage and Au enhances the chemical stability of clus-ters, while the enhanced stability can be explained by spherical aromaticity, confirmed by largely negative NICS values, of which eight p electrons satisfy 2(N + 1)2 counting rule, forming 2S22P6 set. The AdNDP analysis reveals that the delocalized chemical bonding is responsible for structural stabiliza-tion of clusters, e.g., eight delocalized 4c-2e r-bonds on inner shell and five delocalized 4c-2e r-bonds on outer shell. To summarize, the calculated results will provide further understanding for the design of novel building blocks as cluster-assembled nanomaterials.(c) 2023 Elsevier B.V. All rights reserved.