Aromaticity is one of the most important concepts in chemistry and has been successfully extended to all-metal clusters. However, the study of all-metallic aromatic clusters remains in its early stages, with sigma-aromatic clusters mostly limited to small sizes (<12) that often require external stabilization. In this work, we report the first Ge/Sn-based trimer, ^5–, which can be rationalized as the fusion of three units via a Ge₃ face. Theoretical studies have revealed that two sigma-electrons are delocalized across the entire trimer, with the spherical aromaticity of each unit and the global ?-aromaticity of ^5– further supported by its electron delocalization and magnetic behavior. As a result, this trimer can be viewed as a giant sigma-aromatic counterpart to triatomic H₃⁺ and Li₃⁺. Our findings suggest the potential for synthesizing cluster-of-cluster analogs of discrete all-metallic aromatic species, such as Al₄^2–, and further enhance our understanding of chemical bonding.

It has been recently published open access in Journal of the American Chemical Society:

Ya-Shan Huang, Hong-Lei Xu, Wen-Juan Tian, Zi-Sheng Li, Sílvia Escayola, Miquel Solà, Alvaro Muñoz-Castro, Zhong-Ming Sun*

“5–: A Giant sigma-Aromatic Cluster Analogous to H3+ and Li3+”

J. Am. Chem. Soc., 2025, ASAP

DOI: 10.1021/jacs.4c16401

Girona, March 11th, 2025
For more info: ges.iqcc@udg.edu