Langer Eike M, Walter Olaf, Colle Jean-Yves, Bosbach Dirk, Alekseev Evgeny V
Institute of Energy and Climate Research (IEK-6), Forschungszentrum Jülich GmbH , D-52428, Jülich, Germany.
European Commission, DG Joint Research Centre, Directorate G - Nuclear Safety and Security , Postfach 2340, D-76125, Karlsruhe, Germany.
Inorg Chem. 2018 Feb 5;57(3):1604-1613. doi: 10.1021/acs.inorgchem.7b02961. Epub 2018 Jan 22.
A study of neptunium (Np) chemistry in the complex oxo-selenium system has been performed. Hereby, two sets of precipitation experiments were conducted, investigating the influence of the initial oxidation state of selenium using SeO and HSeO with Np in alkali nitrate solution, keeping the ratio of Np/Se constant. Surprising results were observed. Five novel neptunium and selenium bearing compounds have been obtained by slow evaporation from aqueous solution. The novel Np phase K[Np(SeO)(HSeO)]·(HO) (1) crystallizes in green-colored, plate-shaped crystals and was obtained by adding SeO and ANO to a Np stock solution. Single-crystal X-ray diffraction reveals one-dimensional chain structures composed of square antiprismatic NpO polyhedra linked via four trigonal pyramidal SeO and HSeO units. Raman spectral analysis supports the presence of both selenite and hydroselenite due to the presence of corresponding modes within the spectra. The addition of selenic acid to a Np stock solution resulted in the precipitation of elongated rose prisms of K[(NpO)(SeO)(HO)]·(HO) (2), Rb[(NpO)(SeO)(HO)]·(HO) (3) and K[(NpO)(SeO)(HO)]·(HO) (4) as well as light red plates of Cs[(NpO)(SeO)] (5). To our knowledge, this is the first report of Np selenates. All four structures show two-dimensional layered structures with alkali cations acting as charge balancing counter cations. Hereby the layers of compounds 2 and 3 are found to be orientational geometric isomers. Distinctly different phenomena are made responsible for the phase formation within these systems. The kinetically driven process of Np disproportionation led to the formation of the Np selenites in the Se-based system, whereas the oxidation of Np by reduction of nitrate in acidic conditions is responsible for the formation of the Np selenates in the Se system. The influence of air oxygen is also discussed for the latter reaction.
对复杂的氧代硒体系中的镎（Np）化学性质进行了一项研究。在此，进行了两组沉淀实验，在碱金属硝酸盐溶液中使用SeO和HSeO研究硒的初始氧化态对镎的影响，保持Np/Se的比例恒定。观察到了令人惊讶的结果。通过从水溶液中缓慢蒸发获得了五种新型的含镎和硒的化合物。新型的Np相K[Np(SeO)(HSeO)]·(HO) (1)以绿色板状晶体形式结晶，是通过向Np储备溶液中加入SeO和ANO得到的。单晶X射线衍射揭示了由方形反棱柱形NpO多面体通过四个三角锥状SeO和HSeO单元连接而成的一维链状结构。拉曼光谱分析由于光谱中存在相应的模式，支持亚硒酸盐和亚硒酸氢盐的存在。向Np储备溶液中加入硒酸导致K[(NpO)(SeO)(HO)]·(HO) (2)、Rb[(NpO)(SeO)(HO)]·(HO) (3)和K[(NpO)(SeO)(HO)]·(HO) (4)的细长玫瑰色棱柱沉淀以及Cs[(NpO)(SeO)] (5)的浅红色片状沉淀。据我们所知，这是关于镎硒酸盐的首次报道。所有四种结构都显示出二维层状结构，其中碱金属阳离子作为电荷平衡的抗衡阳离子。在此，发现化合物2和3的层是取向几何异构体。这些体系中不同的现象导致了相的形成。镎歧化的动力学驱动过程导致了基于硒的体系中镎亚硒酸盐的形成，而在酸性条件下通过硝酸盐还原对镎的氧化导致了硒体系中镎硒酸盐的形成。对于后一个反应，还讨论了空气氧气的影响。
