Oxidative hydrogenation of polyanions with gallium, silicon, germanium and tin - functional materials by subtle redox chemistry

通过微妙的氧化还原化学作用，聚阴离子与镓、硅、锗和锡的氧化氢化 - 功能材料

• 批准号: 277832266
• 负责人: Professor Dr. Holger Kohlmann
• 金额: --
• 依托单位: Institut für Anorganische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/277832266?language=en
• 关键词: Oxidative; hydrogenation; polyanions; gallium; silicon

Zintl phases are compounds between an alkaline or alkaline earth metal M with an element E of group 13-16 and usually contain polyanions [Ex-]n with covalent E-E bonds. Hydrogen may react either by oxidizing these polyanions thus increasing their connectivity or by insertion or addition of hydrogen to the polyanions. In a previous project, preliminary rules for the formation of main group element-element and element-hydrogen bonds were established. The hydrogenation of Zintl phases with silicon and germanium zigzag chains (ME with M = Ca, Sr, Ba; E = Si, Ge) by in situ X-ray and neutron powder diffraction, electron microscopy, thermal analysis, solid-state nuclear magnetic resonance spectroscopy, total neutron scattering, quantum-mechanical modelling and Raman spectroscopy revealed new Zintl phase hydrides (MEH4/3, MEH5/3 and MEH6/3) with condensed hydrogen-containing polyanions and intermediates with lower hydrogen content. In the series M(I)-M(II)-M(III), i. e. alkali-alkaline earth-rare earth, the chemical bonding of H atoms shifts from covalent to ionic and metallic. In this project, we will refine this rule-of-thumb for hydrogenation reactions of Zintl phases, enabling us to rationalize existence, thermodynamic stability, chemical bonding, crystal and electronic structure, and hydrogen capacity of hydrogenated Zintl phases. Initially about 45 compounds MxEy with E = Ga, Si, Ge, Sn and M = alkali-alkaline earth-rare earth or a mixture of two of them, featuring various polyanions (zigzag chains, helices, five- and six-membered rings, dumb-bells, 1D ribbons and 3D nets) will be studied by the above mentioned methods. The detailed knowledge of the rules governing the formation of E-E and E-H bonds will enable us to predict further hydrogenation reactions of Zintl phases, i. e. allow for a connectivity tuning in polyanions of Zintl phase hydrides by oxidation with hydrogen. The potential in the preparation of materials for hydrogen storage and low-dimensional materials shall be explored. On one hand, practical aspects of Zintl phases as hydrogen stores will be tested. By volumetric and gravimetric method, thermodynamics, kinetics, reversibility and cycleability for hydrogen storage will be studied for CaSi and further candidates identified in the first part of the project. On the other hand, Zintl phase hydrides will be used as precursors for 1D and 2D materials. Hydrolysis, ammonolysis and methylation reactions may lead to 1D and 2D polymers, which could be interesting intermediates to silicane, germanane, and stannanane or related materials. The controlled oxidation of polyanions by hydrogen, to be developed in this project, has got a great potential for the fine tuning of structural, electronic and magnetic properties of solids. The results of this project are expected to stimulate materials related research with compounds containing polyanions of triels and tetrels, especially gallium, silicon, germanium, tin.

Zintl相是碱金属或碱土金属M与第13-16族元素E之间的化合物，并且通常含有具有共价E-E键的聚阴离子[Ex-]n。氢可以通过氧化这些聚阴离子从而增加它们的连接性或通过将氢插入或添加到聚阴离子中来反应。在以前的一个项目中，建立了主族元素-元素和元素-氢键形成的初步规则。Zintl相硅锗曲折链的氢化（M = Ca，Sr，Ba;通过原位X射线衍射、中子粉末衍射、电子显微镜、热分析、固体核磁共振谱、全中子散射、量子力学模型和拉曼光谱等方法，研究了Zintl（Si，Ge）相的结构，发现了新的Zintl相（MEH 4/3、MEH 5/3和MEH 6/3）与缩合的含氢聚阴离子和具有较低氢含量的中间体。在系列M（I）-M（II）-M（III）中，i. e.碱-碱土-稀土，H原子的化学键从共价键转变为离子键和金属键。在本项目中，我们将完善Zintl相氢化反应的经验法则，使我们能够合理化氢化Zintl相的存在，热力学稳定性，化学键合，晶体和电子结构以及氢容量。首先，将通过上述方法研究大约45个化合物MxEy，其中E = Ga，Si，Ge，Sn和M =碱-碱土-稀土或其中两种的混合物，其具有各种聚阴离子（锯齿链，螺旋，五元环和六元环，哑铃，一维带和三维网）。对E-E键和E-H键形成规律的详细了解将使我们能够预测Zintl相的进一步氢化反应，即：e.允许通过用氢氧化来调节Zintl相聚阴离子的连接性。探索储氢材料和低维材料的制备潜力。一方面，将测试Zintl相作为氢存储器的实际方面。通过体积和重量法，将对CaSi和项目第一部分确定的其他候选材料的储氢热力学、动力学、可逆性和循环性进行研究。另一方面，Zintl相晶体将被用作1D和2D材料的前体。水解、氨解和甲基化反应可以产生一维和二维聚合物，它们可能是硅烷、锗烷和锡烷或相关材料的有趣中间体。本计画所发展的聚阴离子氢氧化反应，在固体结构、电子与磁性的微调上，具有极大的潜力。本计画之研究结果可望促进含三、四元聚阴离子之化合物，特别是镓、硅、锗、锡之相关材料研究。