Li Haijian, Kegler Philip, Bosbach Dirk, Alekseev Evgeny V
Institute of Energy and Climate Research (IEK-6) , Forschungszentrum Jülich GmbH , 52428 Jülich , Germany.
Institut für Kristallographie , RWTH Aachen University , 52066 Aachen , Germany.
Inorg Chem. 2018 Apr 16;57(8):4745-4756. doi: 10.1021/acs.inorgchem.8b00466. Epub 2018 Apr 2.
Four novel uranyl silicates and germanates with framework structures, KNa(UO)(SiO)·3HO, KNa(UO)(GeO)·3HO, HO(UO)(HGeO)·2HO, and Na(UO)GeO, have been synthesized by means of the hydrothermal method. The structures of the title compounds were refined by single-crystal X-ray diffraction and characterized by Raman spectroscopy. We used the method of secondary building units (SBUs) for a crystal chemical analysis of the 3D framework and their topologies. The framework of the KNa(UO)(TO)·3HO (T = Si, Ge) series exhibits large 14-membered rings and smaller 8-membered rings which are built upon [UT] pentamers. The internal size of the largest pores is approximately 12.39 × 3.33 Å. HO(UO)(HGeO)·2HO is based on 10-membered rings with intermediate sized pores. They are built upon [UGe] tetramers with 7-fold-coordinated U. The internal dimension of the pores in HO(UO)(HGeO)·2HO is smaller compared to the KNa(UO)(TO)·3HO (T = Si, Ge) series with ∼5.91 × 5.33 Å. Its topology is similar to several uranium germanate synthetic phases and silicate minerals, especially α- and β-uranophane which are constructed from similar building units. A novel 3D framework type of Na(UO)GeO with 8-membered rings demonstrates the smallest free volume in the family of porous uranium germanates. It crystallizes in tetragonal symmetry and is built upon corner sharing of [UGe] pentamers. The size of the channels is ∼6.76 × 4.27 Å. The vibrational bands in Raman spectra were associated with pyro-(SiO) and -(GeO) groups, with the Ge-OH bond and with HO cations, confirming the results of the X-ray crystallographic structural characterization. We systemized existing uranyl silicates and germanates based on their building units and chemical composition. We found a simple structural dependence between synthetic conditions and chemical composition.
通过水热法合成了四种具有骨架结构的新型铀酰硅酸盐和锗酸盐，分别为KNa(UO₂)(SiO₄)·3H₂O、KNa(UO₂)(GeO₄)·3H₂O、H₂O(UO₂)(H₂GeO₄)·2H₂O和Na(UO₂)GeO₃。通过单晶X射线衍射对标题化合物的结构进行了精修，并通过拉曼光谱进行了表征。我们使用二级结构单元（SBU）方法对三维骨架及其拓扑结构进行晶体化学分析。KNa(UO₂)(TO₄)·3H₂O（T = Si，Ge）系列的骨架呈现出大的14元环和较小的8元环，这些环基于[UT]五聚体构建。最大孔的内部尺寸约为12.39×3.33 Å。H₂O(UO₂)(H₂GeO₄)·2H₂O基于具有中等尺寸孔的10元环。它们基于具有七配位U的[UGe]四聚体构建。与KNa(UO₂)(TO₄)·3H₂O（T = Si，Ge）系列相比，H₂O(UO₂)(H₂GeO₄)·2H₂O中孔的内部尺寸较小，约为5.91×5.33 Å。其拓扑结构与几种铀锗酸盐合成相和硅酸盐矿物相似，特别是由相似构建单元构成的α-和β-硅钙铀矿。具有8元环的新型三维骨架类型Na(UO₂)GeO₃在多孔铀锗酸盐家族中显示出最小的自由体积。它以四方对称结晶，基于[UGe]五聚体的角共享构建。通道尺寸约为6.76×4.27 Å。拉曼光谱中的振动带与焦（SiO₄）和（GeO₄）基团、Ge-OH键以及H₂O阳离子相关，证实了X射线晶体结构表征的结果。我们根据其构建单元和化学成分对现有的铀酰硅酸盐和锗酸盐进行了系统化。我们发现了合成条件与化学成分之间简单的结构依赖性。
