近日，德国萨尔兰大学David Scheschkewitz团队研究了五硅杂环戊二烯：一种处于共振与平衡边界的休克尔芳香性化合物。相关论文于2026年2月5日发表在《科学》杂志上。

芳香环体系（如广泛存在的π配体环戊二烯基阴离子C₅H₅^-）遵循著名的休克尔规则，具有4n+2个π电子构成的环状离域体系。自1981年稳定硅-硅π键出现以来，全硅芳香化合物的研究一直是追求目标，但迄今仅有三元环丙烯类似物（Si₃R₃⁺，R为硅基）通过实验实现。

研究组报道了一种稳定的全硅环戊二烯基阴离子（Si₅R₅^-，R为芳基），该结构基本呈平面构型且明确具有芳香性，尽管实验与计算数据表明其在非平面异构体间存在超快平衡。当与三甲基氯锡烷反应时，Si₅R₅^-会重构Si₅核心骨架形成三环异构体，这证实了锂阳离子对其稳定性的关键作用。全硅环戊二烯基阴离子有望发展出堪比碳基环戊二烯基阴离子的丰富化学性质，其结构灵活性对传统上明确区分"共振"与"平衡"的范式提出了新的思考。

附：英文原文

Title: Pentasilacyclopentadienide: A Hückel aromatic species at the border of resonance and equilibrium

Author: Ankur, Bernd Morgenstern, David Scheschkewitz

Issue&Volume: 2026-02-05

Abstract: Aromatic rings such as the ubiquitous π-ligand cyclopentadienide (C5H5) adhere to the famous Hückel rule with their 4n+2 π cyclically delocalized electrons. Since the advent of stable Si–Si π-bonds in 1981, all-silicon aromatics have been targeted, yet only a three-membered cyclopropenium analog (Si3R3+; R, silyl) has been experimentally realized. We report a stable persilacyclopentadienide (Si5R5; R, aryl), which is essentially planar and decidedly aromatic, although experimental and computational data suggest an ultrarapid equilibrium between nonplanar isomers. With trimethylchlorostannane, Si5R5 rearranges the Si5 core to a tricyclic isomer confirming the pivotal role of the lithium cation for stability. The persilacyclopentadienide promises a rich chemistry akin to carbon-based cyclopentadienides. Its structural flexibility questions the paradigm of a clear-cut distinction between resonance and equilibrium.

DOI: aed1802

Source: https://www.science.org/doi/10.1126/science.aed1802