Peculiar All-Metal [sigma]-Aromaticity of the [Au2Sb16]4- Anion in the Solid State

• Published in: Angewandte Chemie 2016-12, Vol.128 (49), p.15570
• Main Authors: Popov, Ivan A, Pan, Fu-Xing, You, Xue-Rui, Li, Lei-Jiao, Matito, Eduard, Liu, Chao, Zhai, Hua-Jin, Sun, Zhong-Ming, Boldyrev, Alexander I
• Format: Article
• Language: ger
• Subjects: Chemistry
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201609497

Gas-phase clusters are deemed to be σ-aromatic when they satisfy the 4n+2 rule of aromaticity for delocalized σelectrons and fulfill other requirements known for aromatic systems. While the range of nvalues was shown to be quite broad when applied to short-lived clusters found in molecular-beam experiments, stability of all-metal cluster-like fragments isolated in condensed phase was previously shown to be mainly ascribed to two electrons (n=0). In this work, the applicability of this concept is extended towards solid-state compounds by demonstrating a unique example of a storable compound, which was isolated as a stable [K([2.2.2]crypt)]+ salt, featuring a [Au2Sb16]4- cluster core possessing two all-metal aromatic AuSb4 fragments with six delocalized σelectrons each (n=1). This discovery pushes the boundaries of the original idea of Kekulé and firmly establishes the usefulness of the σ-aromaticity concept as a general idea for both small clusters and solid-state compounds.