Phosphuranylite and autunite minerals are the primary classes of phosphorus containing minerals, as phosphorus bearing uranium minerals make up nearly a quarter of all identified uranium minerals. (2016) most recent review of hexavalent uranium compounds, autunite, phosphuranylite, and uranophane are significant minerals classes with 40 proposed autunite minerals, 16 phosphuranylite, and 10 uranophane minerals. For example, uranium containing minerals present a few prominent sheet anion topologies that can be observed both in minerals and synthetic compounds. Nature often gives a good indication of what chemical compounds can be made synthetically. For these reasons, it is advantageous to further expand our understanding of uranium coordination chemistry, specifically in extended structures, as this can give us insights in understanding intermediate phases in the nuclear waste cycle, identifying potential structures useful in nuclear waste processing or storage, and possible pathways within the environment for the migration of U 6+ and other actinides. Nuclear power has been well-established for several decades and, nonetheless, studies continue to develop a deeper understanding of the nuclear fuel cycle, including exploring improved methods of both long-term and short-term waste storage ( zur Loye et al., 2018), and continuing to investigate the processes of radionuclide leaching into surrounding ecosystems. Optical measurements were performed on 1 and 2 and the UV-vis and fluorescence spectra show features characteristic of the UO 2 2 + uranyl group. Ion exchange experiments were performed on 1 and 2 and demonstrate the ability of these structures to exchange approximately half of the parent alkali cation with a target alkali cation in an aqueous concentrated salt solution. First principles calculations were used to explore why a pure oxide structure is obtained for the Cs containing phase ( 1) and in contrast an oxyfluoride phase for the Rb containing phase ( 2). The location of the fluorine in structures 2- 4 is discussed using bond valence sums. Cs 11 ( 1) and Rb 11 ( 2) contain uranyl phosphate layers exhibiting a new sheet topology that can be related to that of β-U 3O 8, while Cs 4.4K 0.6 ( 3) and Rb 4.4K 0.6 ( 4) contain layers of a known isomer of the prominent phosphuranylite topology. Single crystals of four new layered uranyl phosphates, including three oxyfluoride-phosphates, were synthesized by molten flux methods using alkali chloride melts, and their structures were determined by single-crystal X-ray diffraction.
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