Assembling Au4 Tetrahedra to 2D and 3D Superatomic Crystals Based on Superatomic-Network Model

Thiolate-protected gold nanodusters (denoted as Au-m(SR)(n) or AunLm) have received extensive attention both experimentally and theoretically. Understanding the growth mode of the Au-4 unit in Au-m(SR)(n) is of great significance for experimental synthesis and the search for new gold clusters. In this work, we first build six clusters of Au-7(AuCl2)(3), Au-12(AuC17)(4), Au-16(AuCl2)(6), Au-22(AuCl2)(6), and Au-30(AuCl2)(6) with the Au-4 unit as the basic building blocks. Density functional theory (DFT) calculations show that these newly designed clusters have high structural and electronic stabilities. Based on chemical bonding analysis, the electronic structures of these dusters follow the superatom network (SAN) model. Inspired by the duster structures, we further predicted an Au-4 two-dimensional (2D) monolayer and a three-dimensional (3D) crystal using graphene and diamond as templates, respectively. The computational results demonstrate that the two structures have high dynamic, thermal, and mechanical stabilities, and both structures exhibit metallic properties according to the band structures calculated at the HSE06 level. The chemical bonding analysis by the solid-state natural density partitioning (SSAdNDP) method indicates that they are superatomic crystals assembled by two electron Au-4(-) superatoms. With this construction strategy, the new bonding pattern and properties of AunLm are studied and the structure types of gold are enriched.

Automated summary

Researchers have designed new structures of gold nanoclusters using the Au-4 unit, showing high stability and following the superatom network model. They also predicted 2D monolayer and 3D crystal structures of Au-4 based on these clusters, demonstrating metallic properties.