Isolable Tetragold(0) Clusters with Polarity‐Tunable exo‐Au−Au Bond via Intramolecular σ‐Aromatization

Abstract

Intramolecular π‐aromatization is a trait of many organic compounds that enhances the stability of their structures and polarizes related C‒C π bonds. In contrast, rare study is focused on this phenomenon in metal clusters. Many existing homometallic clusters exhibit aromaticity, often characterized by nonpolar metal‐metal bonds and a high degree of symmetry. However, synthesizing low‐symmetric homometallic clusters with high‐polar metal‐metal bonds is challenging due to their limited thermodynamic stability. Herein, we report a facile strategy for the synthesis of [Au(μ2‐ER2)]3‒AuPMe3 (E = Ge, Sn; R2 = 1,1,4,4‐tetrakis(trimethylsilyl)butane‐1,4‐diyl) clusters and reveal a novel stabilization mode, intramolecular σ‐aromatization. Our electronic structure analyses show that these low‐symmetric clusters possess a ten‐electron σ‐aromatic system, which is achieved via intramolecular σ‐aromatization. Moreover, the strength of σ‐aromaticity gives rise to a polarity‐tunable exo‐Au‒Au bond.