Monatomic zero-valent silicon and germanium complexes (silylones and germylones), stabilised by neutral donating ligands, emerged only recently as a new class of low-valent group 14 element compounds. Featuring four valence electrons in the form of two lone pairs at a single site, silylones and germylones represent a molecular resting state of single Si and Ge atoms, which are typically only observed at high temperature in the gas phase or in interstellar matter. These species are capable of transferring single Si and Ge atoms to unsaturated substrates and acting as building blocks for novel group 14 species. After introducing this type of compound and the examples known to date, this feature article highlights some chelating bis N-heterocyclic carbene (bis(NHC)) and bis N-heterocyclic silylene (bis(NHSi)) supported Si⁰ and Ge⁰ complexes, for which a range of unprecedented reactivity has been discovered. The characteristic behaviour of these silylones and germylones discussed here consists of (i) coordination to Lewis acids, (ii) oxidation with elemental chalcogens, (iii) bond activation of common organic substrates and inert small molecules; and (iv) homocoupling of the Si⁰ and Ge⁰ centres. This wealth of reactivity has opened the door to a series of Si and Ge compounds, which would be otherwise difficult to realise.

中文翻译：

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用可分离的单价硅和锗原子复合物进入新的化学空间

由中性供体配体稳定的单原子零价硅和锗配合物（甲硅烷和锗硅）最近才作为一类新的低价第 14 族元素化合物出现。在单个位点具有两个孤对形式的四个价电子，甲硅烷和锗烯代表单个 Si 和 Ge 原子的分子静止状态，通常仅在高温下在气相或星际物质中观察到。这些物种能够将单个 Si 和 Ge 原子转移到不饱和基材上，并充当新的第 14 族物种的构建单元。在介绍了这种类型的化合物和迄今为止已知的例子之后，这篇专题文章重点介绍了一些螯合双 N-杂环卡宾 (bis(NHC)) 和双 N-杂环亚甲硅烷 (bis(NHSi)) 支持的 Si ⁰和 Ge ⁰配合物，已经发现了一系列前所未有的反应性。此处讨论的这些甲硅烷和胚芽酮的特征行为包括 (i) 与路易斯酸的配位，(ii) 与元素硫属元素的氧化，(iii) 常见有机底物和惰性小分子的键活化；(iv) Si ⁰和Ge ⁰中心的同质耦合。这种丰富的反应性为一系列 Si 和 Ge 化合物打开了大门，否则很难实现。