Disodium uranium(IV) fluoride

Cousson, A.; Tabuteau, A.; Pagès, M.; Gasperin, M.

doi:10.1107/s0567740879005872

Cited by 20 publications

(12 citation statements)

References 2 publications

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“…Simple molecular fluorides such as these are uncommon, as only eight of over 50 ternary (M x U y F z ) and quaternary (M w M′ x U y F z ) uranium(IV) structures (M, M′ = NH 4 + , group 1–13 metal ions, Ge 4+ , Sn 2+/4+ , Pb 2+/4+ , Sb 3+/5+ ) currently in the Inorganic Crystal Structure Database (ICSD) feature such distinct uranium environments. The remaining structures all feature corner-, edge-, or face-sharing structures and one- to three-dimensional topologies, most of which are held together by μ 2 bridging fluorides. ,,− One important exception is UF 6 , which sublimes at relatively mild temperature alongside homologue UCl 6 , due to weak van der Waals interactions between discrete octahedral molecules. , …”

Section: Introductionmentioning

confidence: 99%

Electronic, Magnetic, and Theoretical Characterization of (NH₄)₄UF₈, a Simple Molecular Uranium(IV) Fluoride

et al. 2018

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The simple system of tetraammonium octafluorouranate is employed to derive a fundamental understanding of the uranium–fluorine interaction. The structure is composed of isolated molecules, enabling a detailed examination of the U4+ (f 2) ion. Characterization of single-crystals by X-ray diffraction, absorption spectroscopy, and magnetic analysis up to 45 T is combined with extensive theoretical treatment by CASSCF. The influence of different active spaces and representations of the structure is examined in the context of the experimental evidence. The Interacting Quantum Atoms method (IQA) is used to examine the nature of the U–F bond, concluding that there is a non-negligible degree of covalent character (9% of the total bond energy) in [UF8]4−. For the structural and theoretical reasons discussed herein, it is proposed that the structure of (NH4)4UF8 may be appropriately employed as a benchmark compound for future theoretical characterization of U(IV).

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Section: Introductionmentioning

confidence: 99%

Electronic, Magnetic, and Theoretical Characterization of (NH₄)₄UF₈, a Simple Molecular Uranium(IV) Fluoride

et al. 2018

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“…23 The single-crystal synthesis of several U(IV) fluorides has also been reported using UF 4 and a LiCl−ZnCl 2 eutectic flux under argon in a monel alloy reactor. 24,25 Furthermore, the flux growth of many reduced uranium chalcogenides using a variety of fluxes including BaS, BaBr 2 /KBr, and CsCl, in sealed tubes, has been reported. 26−32 However, the flux synthesis of uranium(IV) oxides presents several further challenges.…”

Section: ■ Introductionmentioning

confidence: 99%

Flux Synthesis, Structure, Properties, and Theoretical Magnetic Study of Uranium(IV)-Containing A₂USi₆O₁₅ (A = K, Rb) with an Intriguing Green-to-Purple, Crystal-to-Crystal Structural Transition in the K Analogue

et al. 2015

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The flux growth of uranium(IV) oxides presents several challenges, and to the best of our knowledge, only one example has ever been reported. We succeeded in growing two new reduced uranium silicates A2USi6O15 (A = K, Rb) under flux growth conditions in sealed copper tubes. The compounds crystallize in a new structure type with space group C2/c and lattice parameters a = 24.2554(8) Å, b = 7.0916(2) Å, c = 17.0588(6) Å, β = 97.0860(6) ° (K) and a = 24.3902(8) Å, b = 7.1650(2) Å, c = 17.2715(6) Å, β = 96.8600(6) ° (Rb). A2USi6O15 (A = K, Rb) are isocompositional to a previously reported Cs2USi6O15, and the two structures are compared. K2USi6O15 undergoes an interesting crystal-to-crystal structural phase transition at T ≈ 225 K to a triclinic structure, which is accompanied by an intense color change. The magnetic properties of A2USi6O15 (A = K, Rb, Cs) are reported and differ from the magnetism observed in other U(4+) compounds. Calculations are performed on the (UO6)(-8) clusters of K2USi6O15 to study the cause of these unique magnetic properties.

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“…Uranium fluorides are an important group of materials that are fundamental for uranium separation processes, are potential materials for use in long-term nuclear waste storage, and can play a role in the development of new classes of fuel rod assemblies. − Not surprisingly, the binary uranium fluorides, such as UF 4 and UF 6 , have been extensively investigated and are currently being used in a variety of nuclear processes. − In addition, over 20 ternary inorganic uranium fluorides (other than minerals), such as alkali uranium fluorides and some transition metal uranium fluorides (Na 2 UF 6 , Na 3 UF 7 , K 3 UF 7 , CsU 2 F 9 , AuU 2 F 11 ) have been synthesized, and their structures were reported in the literature. − Surprisingly, only a handful of quaternary uranium-containing fluorides, such as CaLi 2 UF 8 , have been reported. , Typically the U 4+ cations in these structures are found in large coordination environments of UF x ( x = 7, 8, 9) polyhedra that lead to the formation of complex structure types. Remarkably, the total number of transition metal-containing uranium fluorides is very small, considering the importance of uranium as an element.…”

Section: Introductionmentioning

confidence: 99%

Application of a Mild Hydrothermal Approach Containing an in Situ Reduction Step to the Growth of Single Crystals of the Quaternary U(IV)-Containing Fluorides Na₄MU₆F₃₀ (M = Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) Crystal Growth, Structures, and Magnetic Properties

et al. 2014

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A family of rare U(IV)-containing quaternary fluorides, Na4MU6F30 (M = Mn(2+), Co(2+), Ni(2+), Cu(2+), and Zn(2+)), was synthesized in single crystal form via a mild hydrothermal technique utilizing an in situ U(VI) to U(IV) reduction step. The modified hydrothermal route is described, and the conditions to obtain single crystals in high yield are detailed. The crystal structures were determined by single crystal X-ray diffraction. The isostructural fluorides crystallize in a new structure type in the trigonal space group P3̅c1. They exhibit a complex three-dimensional crystal structure consisting of corner- and edge-shared UF9 and MF6 polyhedra. The main building block, a U6F30(6-) group, is arranged to create two distinct hexagonal channels, inside which MF6 octahedra and Na(+) cations are located. The copper-containing member of the series, Na4CuU6F30, is unusual in that the Cu(2+) cation exhibits a rare symmetrical coordination environment consisting of six identical Cu-F bond distances, indicating the lack of the expected Jahn-Teller distortion. Magnetic susceptibility measurements of Na4ZnU6F30 yielded an effective magnetic moment of 3.42 μB for the U(4+) (f(2)) cation in the structure. Measurements of the other members containing magnetic transition-metal cations in addition to U(4+), Na4MU6F30 (M = Mn(2+), Co(2+), Ni(2+), and Cu(2+)) yielded total effective magnetic moments of 10.2, 9.84, 8.87, and 8.52 μB for the Mn-, Co-, Ni-, and Cu-containing materials, respectively. No evidence for long-range magnetic ordering was found down to 2 K. Measurements of the magnetization as a function of applied magnetic field at 2 K for Na4MnU6F30 confirmed that the U(4+) magnetic cation exhibits a nonmagnetic singlet ground state at low temperature. Thermal stability measurements and UV-vis diffuse reflectance spectroscopy are also reported.

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Disodium uranium(IV) fluoride

Cited by 20 publications

References 2 publications

Electronic, Magnetic, and Theoretical Characterization of (NH₄)₄UF₈, a Simple Molecular Uranium(IV) Fluoride

Electronic, Magnetic, and Theoretical Characterization of (NH₄)₄UF₈, a Simple Molecular Uranium(IV) Fluoride

Flux Synthesis, Structure, Properties, and Theoretical Magnetic Study of Uranium(IV)-Containing A₂USi₆O₁₅ (A = K, Rb) with an Intriguing Green-to-Purple, Crystal-to-Crystal Structural Transition in the K Analogue

Application of a Mild Hydrothermal Approach Containing an in Situ Reduction Step to the Growth of Single Crystals of the Quaternary U(IV)-Containing Fluorides Na₄MU₆F₃₀ (M = Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) Crystal Growth, Structures, and Magnetic Properties

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Disodium uranium(IV) fluoride

Cited by 20 publications

References 2 publications

Electronic, Magnetic, and Theoretical Characterization of (NH4)4UF8, a Simple Molecular Uranium(IV) Fluoride

Electronic, Magnetic, and Theoretical Characterization of (NH4)4UF8, a Simple Molecular Uranium(IV) Fluoride

Flux Synthesis, Structure, Properties, and Theoretical Magnetic Study of Uranium(IV)-Containing A2USi6O15 (A = K, Rb) with an Intriguing Green-to-Purple, Crystal-to-Crystal Structural Transition in the K Analogue

Application of a Mild Hydrothermal Approach Containing an in Situ Reduction Step to the Growth of Single Crystals of the Quaternary U(IV)-Containing Fluorides Na4MU6F30 (M = Mn2+, Co2+, Ni2+, Cu2+, and Zn2+) Crystal Growth, Structures, and Magnetic Properties

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Electronic, Magnetic, and Theoretical Characterization of (NH₄)₄UF₈, a Simple Molecular Uranium(IV) Fluoride

Electronic, Magnetic, and Theoretical Characterization of (NH₄)₄UF₈, a Simple Molecular Uranium(IV) Fluoride

Flux Synthesis, Structure, Properties, and Theoretical Magnetic Study of Uranium(IV)-Containing A₂USi₆O₁₅ (A = K, Rb) with an Intriguing Green-to-Purple, Crystal-to-Crystal Structural Transition in the K Analogue

Application of a Mild Hydrothermal Approach Containing an in Situ Reduction Step to the Growth of Single Crystals of the Quaternary U(IV)-Containing Fluorides Na₄MU₆F₃₀ (M = Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) Crystal Growth, Structures, and Magnetic Properties