Structural and electronic insights into Au2C20− cluster: A superhalogen with dual aromaticity

• Published in: Chemical physics letters 2025-02, Vol.860, p.141814, Article 141814
• Main Authors: Lu, Sheng-Jie, Cao, Guo-Jin, Gao, Zhao-Ou, Sun, Zhong-Xin
• Format: Article
• Language: English
• Subjects: Aromaticity; Bonding properties; DFT and ab initio calculations; Geometrical structures; Gold carbides
• ISSN: 0009-2614
• DOI: 10.1016/j.cplett.2024.141814

Au2C20− displays an extraordinary and unprecedented planar 22-membered cyclic structure, distinguished by its exceptional stability, superhalogen properties, and a remarkable manifestation of both σ and π double aromaticity. This unique structural arrangement not only bolsters its electronic stability but also plays a pivotal role in conferring upon it a pronounced chemical inertness. [Display omitted] •Au2C20− displays a planar 22-membered cyclic structure.•Au2C20− shows σ and π double aromaticity.•Au2C20− is a superhalogen anion. This study delves into the exploration of the geometrical and electronic characteristics of the Au2C20− anion and its neutral counterpart using DFT and ab initio calculations. We found that the lowest-energy isomers of Au2C20− anion and Au2C20 neutral exhibit striking differences in their planar cyclic structures. Notably, an in-depth analysis of electron localization and adaptive natural density partitioning provides the presence of both σ and π double aromaticity, along with significant electron delocalization. Furthermore, The C − C bonds exhibit a more pronounced covalent character compared to the Au − C bonds, thereby contributing to the superhalogen properties of Au2C20− anion.