Arteaga Ana, Arino Trevor, Moore Guy C, Bustos Jenna L, Horton Matthew K, Persson Kristin A, Li Jun, Stickle William F, Kohlgruber Tsuyoshi A, Surbella Robert G, Nyman May
Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA.
Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99354, USA.
Chemistry. 2024 May 14;30(27):e202301687. doi: 10.1002/chem.202301687. Epub 2024 Apr 3.
Spectator ions have known and emerging roles in aqueous metal-cation chemistry, respectively directing solubility, speciation, and reactivity. Here, we isolate and structurally characterize the last two metastable members of the alkali uranyl triperoxide series, the Rb and Cs salts (Cs-U and Rb-U). We document their rapid solution polymerization via small-angle X-ray scattering, which is compared to the more stable Li, Na and K analogues. To understand the role of the alkalis, we also quantify alkali-hydroxide promoted peroxide deprotonation and decomposition, which generally exhibits increasing reactivity with increasing alkali size. Cs-U, the most unstable of the uranyl triperoxide monomers, undergoes ambient direct air capture of CO in the solid-state, converting to Cs[UO(CO)], evidenced by single-crystal X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. We have attempted to benchmark the evolution of Cs-U to uranyl tricarbonate, which involves a transient, unstable hygroscopic solid that contains predominantly pentavalent uranium, quantified by X-ray photoelectron spectroscopy. Powder X-ray diffraction suggests this intermediate state contains a hydrous derivative of CsUO, where the parent phase has been computationally predicted, but not yet synthesized.
旁观离子在水基金属阳离子化学中分别具有已知和新出现的作用，它们分别决定着溶解度、物种形成和反应活性。在此，我们分离并对碱金属双氧铀系列的最后两个亚稳成员铷盐和铯盐（Cs-U和Rb-U）进行了结构表征。我们通过小角X射线散射记录了它们在溶液中的快速聚合过程，并将其与更稳定的锂、钠和钾类似物进行了比较。为了理解碱金属的作用，我们还对碱金属氢氧化物促进的过氧化物去质子化和分解进行了量化，其反应活性通常随着碱金属离子尺寸的增大而增强。Cs-U是双氧铀单体中最不稳定的，在固态下能在空气中直接捕获CO，转化为Cs[UO(CO)]，单晶X射线衍射、透射电子显微镜和拉曼光谱证实了这一点。我们试图对Cs-U向三碳酸双氧铀的演化进行基准测试，这涉及一种瞬态、不稳定的吸湿性固体，主要含有五价铀，通过X射线光电子能谱进行了量化。粉末X射线衍射表明，这种中间状态包含CsUO的一种含水衍生物，其母体相已通过计算预测，但尚未合成。
