Anionic Chemistry of Noble Gases: Formation of Mg鈥揘G (NG = Xe, Kr, Ar) Compounds under Pressure

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• 作者：Mao-sheng Miao ; Xiao-li Wang ; Jakoah Brgoch ; Frank Spera ; Matthew G. Jackson ; Georg Kresse ; Hai-qing Lin
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：November 11, 2015
• 年：2015
• 卷：137
• 期：44
• 页码：14122-14128
• 全文大小：399K
• ISSN：1520-5126

文摘

While often considered to be chemically inert, the reactivity of noble gas elements at elevated pressures is an important aspect of fundamental chemistry. The discovery of Xe oxidation transformed the doctrinal boundary of chemistry by showing that a complete electron shell is not inert to reaction. However, the reductive propensity, i.e., gaining electrons and forming anions, has not been proposed or examined for noble gas elements. In this work, we demonstrate, using first-principles electronic structure calculations coupled to an efficient structure prediction method, that Xe, Kr, and Ar can form thermodynamically stable compounds with Mg at high pressure (鈮?25, 鈮?50, and 鈮?50 GPa, respectively). The resulting compounds are metallic and the noble gas atoms are negatively charged, suggesting that chemical species with a completely filled shell can gain electrons, filling their outermost shell(s). Moreover, this work indicates that Mg₂NG (NG = Xe, Kr, Ar) are high-pressure electrides with some of the electrons localized at interstitial sites enclosed by the surrounding atoms. Previous predictions showed that such electrides only form in Mg and its compounds at very high pressures (>500 GPa). These calculations also demonstrate strong chemical interactions between the Xe 5d orbitals and the quantized interstitial quasiatom (ISQ) orbitals, including the strong chemical bonding and electron transfer, revealing the chemical nature of the ISQ.