Hydrothermal Synthesis of (C6N2H14)2(UVI2UIVO4F12), a Mixed-Valent One-Dimensional Uranium Oxyfluorid

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• 作者：Simon Allen ; Stephen Barlow ; P. Shiv Halasyamani ; J. Frederick W. Mosselmans ; Dermot O'Hare ; Susan M. Walker ; and Richard I. Walton
• 刊名：Inorganic Chemistry
• 出版年：2000
• 出版时间：August 21, 2000
• 年：2000
• 卷：39
• 期：17
• 页码：3791 - 3798
• 全文大小：136K
• 年卷期：v.39,no.17(August 21, 2000)
• ISSN：1520-510X

文摘

A new hybrid organic-inorganic mixed-valent uranium oxyfluoride, (C₆N₂H₁₄)₂(U₃O₄F₁₂), UFO-17, has beensynthesized under hydrothermal conditions using uranium dioxide as the uranium source, hydrofluoric acid asmineralizer, and 1,4-diazabicyclo[2.2.2]octane as template. The single-crystal X-ray structure was determined.Crystals of UFO-17 belonged to the orthorhombic space group Cmcm (no. 63), with a = 14.2660(15) Å, b =24.5130(10) Å, c = 7.201(2) Å, and Z = 4. The structure reveals parallel uranium-containing chains of twotypes: one type is composed of edge-sharing UO₂F₅ units; the other has a backbone of edge-sharing UF₈ units,each sharing an edge with a pendant UO₂F₅ unit. Bond-valence calculations suggest the UF₈ groups contain U^IV,while the UO₂F₅ groups contain U^VI. EXAFS data give results consistent with the single-crystal X-ray structuredetermination, while comparison of the uranium L_III-edge XANES of UFO-17 with that of related U^IV and U^VIcompounds supports the oxidation-state assignment. Variable-temperature magnetic susceptibility measurementson UFO-17 and a range of related hybrid organic-inorganic uranium(IV) and uranium(VI) fluorides andoxyfluorides further support the formulation of UFO-17 as a mixed-valent U^IV/U^VI compound.