Murphy Gabriel L, Kegler Philip, Klinkenberg Martina, Wang Shuao, Alekseev Evgeny V
Institute of Energy and Climate Research, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X) and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China.
Dalton Trans. 2020 Nov 17;49(44):15843-15853. doi: 10.1039/d0dt03367g.
Herein the first examples of alkali earth uranyl molybdates synthesised using extreme conditions of high temperature and high pressure (HT/HP) methods, namely K2[UO2(Mo2O7)2], K2[(UO2)2(Mo(vi)4Mo(iv)(OH)2)O16], K3[(UO2)6(OH)2(MoO4)6(MoO3OH)] and K5[(UO2)10MoO5O11OH]·H2O, are described and characterised. K2[UO2(Mo2O7)2] forms a monoclinic 2D layered structure in space group P21/c that consists of interlinking Mo2O7 dimers that link isolated UO22+ moieties forming [UO2(Mo2O7)2]2- layers which are separated by K+ cations. K2[(UO2)2(Mo(vi)4Mo(iv)(OH)2)O16] forms a disordered triclinic 3D framework structure in space group P1[combining macron]. The structure consists of isolated UO22+ moieties connected in a layered configuration via Mo(vi)O6 polyhedra of which the layers are bridged by Mo(iv)O6 polyhedra that are partially positionally disordered by charge balancing K+ and bridging Mo4+ cations. K3[(UO2)6(OH)2(MoO4)6(MoO3OH)] adopts a disordered orthorhombic 3D framework structure in space group Pbcm consisting of small channels and large cavities built upon corner sharing MoO4 and UO22+ moieties that respectively encapsulate ordered and disordered K+ cations. K5[(UO2)10MoO5O11OH]·H2O forms a triclinic 3D framework structure in space group P1[combining macron] consisting of interlinking UO6, UO7 and MoO5 polyhedra which utilise cation-cation interactions between UO22+ moieties to create infinite channels parallel to the [001] direction which contain partially disordered K+ cations and H2O molecules. A combination of single crystal X-ray diffraction, bond valence sums calculations and scanning electron microscopy with energy dispersive X-ray spectroscopic measurements was used to characterise all obtained samples in this investigation. The structures uncovered in this investigation are discussed systematically in detail with other members of the broader A+-U-Mo-O system from the literature where the relationship between the degree of pressure applied and U/Mo ratio used during synthesis on the ability to obtain high dimensional structures via condensation and oligomerization of polyhedra is identified and discussed in detail.
本文描述并表征了使用高温高压（HT/HP）方法合成的碱土铀酰钼酸盐的首批实例，即K2[UO2(Mo2O7)2]、K2[(UO2)2(Mo(Ⅵ)4Mo(Ⅳ)(OH)2)O16]、K3[(UO2)6(OH)2(MoO4)6(MoO3OH)]和K5[(UO2)10MoO5O11OH]·H2O。K2[UO2(Mo2O7)2]在空间群P21/c中形成单斜二维层状结构，该结构由相互连接的Mo2O7二聚体组成，这些二聚体连接孤立的UO22+部分，形成[UO2(Mo2O7)2]2-层，这些层被K+阳离子分隔。K2[(UO2)2(Mo(Ⅵ)4Mo(Ⅳ)(OH)2)O16]在空间群P1[上加一横]中形成无序三斜三维骨架结构。该结构由孤立的UO22+部分组成，这些部分通过Mo(Ⅵ)O6多面体以层状构型连接，其中层由Mo(Ⅳ)O6多面体桥接，Mo(Ⅳ)O6多面体因电荷平衡K+和桥接Mo4+阳离子而部分位置无序。K3[(UO2)6(OH)2(MoO4)6(MoO3OH)]在空间群Pbcm中采用无序正交三维骨架结构，由基于角共享MoO4和UO22+部分构建的小通道和大空腔组成，这些部分分别封装有序和无序的K+阳离子。K5[(UO2)10MoO5O11OH]·H2O在空间群P1[上加一横]中形成三斜三维骨架结构，由相互连接的UO6、UO7和MoO5多面体组成，这些多面体利用UO22+部分之间的阳离子-阳离子相互作用，创建平行于[001]方向的无限通道，通道中包含部分无序的K+阳离子和H2O分子。在本研究中，使用单晶X射线衍射、键价和计算以及扫描电子显微镜与能量色散X射线光谱测量相结合的方法对所有获得的样品进行了表征。本文详细系统地讨论了本研究中发现的结构与文献中更广泛的A+-U-Mo-O系统的其他成员之间的关系，其中确定并详细讨论了合成过程中施加的压力程度和使用的U/Mo比与通过多面体的缩合和低聚获得高维结构的能力之间的关系。
