Chen Pengfei, Chen Jiaxin, Zhao Yue, Ma Jing, Xie Jin, Zhu Congqing, Lin Zhenyang, Zhu Qin
State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong 999077, China.
J Am Chem Soc. 2025 Jun 18;147(24):21153-21161. doi: 10.1021/jacs.5c06541. Epub 2025 Jun 4.
Aromaticity, a fundamental concept for understanding molecular stability, has long been established in organic chemistry. However, isolating examples of all-metal aromaticity has remained a rare achievement, despite its initial proposal in an Al cluster two decades ago. In this study, we successfully isolated and characterized the first all-metal aluminum cluster with a trigonal prismatic geometry. X-ray crystallography reveals that each rectangular face of the Al trigonal prism is capped by a Pd atom, which is further stabilized by six chelating monoanionic ligands and two counter potassium ions. The Pd-capped Al trigonal prismatic cluster features three 3c-2e σ bonds in each of the top and bottom Al layers, and a unique 6c-2e π-π interacting bond connecting the two Al faces. Quantum chemical calculations provide strong evidence for aromaticity in the Pd-capped Al trigonal prism. This discovery not only extends the concept of aromaticity to polyhedral aluminum clusters but also opens new avenues for the synthesis and exploration of novel all-metal aromatic systems.
芳香性是理解分子稳定性的一个基本概念，在有机化学中早已确立。然而，尽管全金属芳香性在二十年前就已在一个铝簇中首次被提出，但分离出全金属芳香性的实例仍然是一项罕见的成就。在这项研究中，我们成功地分离并表征了首个具有三角棱柱几何形状的全金属铝簇。X射线晶体学表明，铝三角棱柱的每个矩形面都被一个钯原子覆盖，该钯原子通过六个螯合单阴离子配体和两个抗衡钾离子进一步稳定。钯覆盖的铝三角棱柱簇在顶部和底部的每个铝层中都具有三个3c-2e σ键，以及一个连接两个铝面的独特的6c-2e π-π相互作用键。量子化学计算为钯覆盖的铝三角棱柱中的芳香性提供了有力证据。这一发现不仅将芳香性的概念扩展到多面体铝簇，也为新型全金属芳香体系的合成与探索开辟了新途径。
