Au₂Si₂₀: a honeycomb-shaped structure with short Au−Au single bond at the centre coordinated by twelve Si₅ pentagons and reinforced by strong Au−Si interactions and aromaticity

Abstract

Investigating the structures and properties of large-sized silicon clusters doped with multiple Au atoms can provide valuable microscopic information for gold-catalyzed high-quality Si nanowire and Au−Si alloying reactions, and also for the production of cluster-assembled functional materials. In this work, a quantum chemical investigation on the structural and electronic properties of double Au atoms doped Si₂₀ cluster using density functional theory calculations was performed. The lowest-lying isomers of $\text{A}{\text{u}}_{\text{2}}{\text{Si}}_{20}^{-/0/+}$ (The meaning of the acronym: $\text{A}{\text{u}}_{\text{2}}{\text{Si}}_{20}^{-/0/+}$ refers to Au₂Si₂₀ cluster with a negative charge, neutral state, and a positive charge, respectively.) were found to all adopt a C_2h symmetric Au₂-endohedral honeycomb-shaped structure consisting of twelve Si₅ pentagons. Interestingly, in the anionic, neutral, and cationic Au₂Si₂₀, twelve Si₅ pentagons can be stabilised by two Au atoms. The two Au atoms in $\text{A}{\text{u}}_{\text{2}}{\text{Si}}_{20}^{-/0/+}$ tend to occupy high coordinate sites and exhibit strong aurophilic interactions. In addition, the Au−Si bonds show both covalent and ionic bonding characters. Moreover, $\text{A}{\text{u}}_{\text{2}}{\text{Si}}_{20}^{-}$, Au₂Si₂₀, and $\text{A}{\text{u}}_{\text{2}}{\text{Si}}_{20}^{+}$ are all aromatic.

GRAPHICAL ABSTRACT

KEYWORDS:

• Silicon clusters
• transition-metals
• geometrical structures
• bonding properties
• aromaticity

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Natural Science Foundation of Shandong Province, China (grant number ZR2018BB040), Open Funds of Beijing National Laboratory for Molecular Sciences (grant number BNLMS201804 and Z191100007219009), and Research Start-up Funds (Doctoral Science Foundation) of Heze University (grant number XY18BS02).