Structure Determination of Tetranitromethane, C(NO2)4, in the Solid and Gaseous Phases

本文拟对四硝基甲烷（C(NO2)4， TNM）的固相和气相结构进行研究。TNM不仅是一种三元物质，它是有机硝基材料的母体分子，因此具有重要的意义。早期的研究对其结构给出了部分不确定的结果。在固态中存在不同的相，但由于分子动力学和/或无序性的原因，结构尚未得到解决。早期的振动光谱结果指向固体高温相（高于-98°C）的动力学行为。在气相中，两次气体电子衍射的尝试只提供了实验散射强度的部分描述。用量子化学计算的S4对称结构对实验结果的简单描述是不令人满意的。我们希望通过应用不同的结晶技术来规避早期的实验问题，以便获得x射线衍射晶体，从而在固态中获得可分解的结构，并通过新的电子衍射实验和分子复杂动态描述的分析来探索实验气相。合适样品的制备将在慕尼黑进行，结构化学实验将在比勒费尔德的核心设施GED@BI（气体电子衍射和小分子结构中心）进行。这些结果有望为TNM的反应性和行为提供更深入的理解，并可以为理解高硝化化合物的结构、反应性和化学行为及其相互关系提供模型。

We propose to study the structure of tetranitromethane (C(NO2)4, TNM) in the solid state and the gas phase. TNM is not only a ternary substance, it is the parent molecule for organic nitro materials and thus of fundamental interest. Earlier studies have given partly inconclusive results concerning its structure. In the solid state different phases exist, but the structures have not been solved probably due to molecular dynamics and/or disorder. Earlier vibrational spectroscopy results point to dynamics behaviour in the solid high temperature phase (above -98°C).In the gas phase, two attempts of gas electron diffraction have provided only a partial description of the experimental scattering intensities. A simple description of the experimental results by a quantum-chemically calculated structure of S4 symmetry is not satisfying. We want to circumvent the earlier experimental problem by applying different crystallization techniques in order to gain crystals for X-ray diffraction that lead to resolvable structures in the solid state and to explore the experimental gas phase by new electron diffraction experiments and analysis with a sophisticated dynamic description of the molecules. The preparation of suitable samples will be performed in Munich, the structural chemistry experiments will be carried out in the core facility GED@BI (Centre of Gas Electron Diffraction and Small Molecule Structures) in Bielefeld. The results promise to provide a deeper under¬standing for the reactivity and behaviour of TNM and can be model the understanding of the structure, reactivity and chemical behaviour and their mutual relationships of highly nitrated compounds.