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10026-10-5Relevant articles and documents
Prins, G.,Cordfunke, E. H. P.
, p. 109 - 112 (1982)
The Exceptional Diversity of Homoleptic Uranium–Methyl Complexes
Autschbach, Jochen,Baker, Tessa M.,Brennessel, William W.,Neidig, Michael L.,Sears, Jeffrey D.,Sergentu, Dumitru-Claudiu
, p. 13586 - 13590 (2020)
Homoleptic σ-bonded uranium–alkyl complexes have been a synthetic target since the Manhattan Project. The current study describes the synthesis and characterization of several unprecedented uranium–methyl complexes. Amongst these complexes, the first example of a homoleptic uranium–alkyl dimer, [Li(THF)4]2[U2(CH3)10], as well as a seven-coordinate uranium–methyl monomer, {Li(OEt2)Li(OEt2)2UMe7Li}n were both crystallographically identified. The diversity of complexes reported herein provides critical insight into the structural diversity, electronic structure and bonding in uranium–alkyl chemistry.
Isolation of the large {actinide}38 poly-oxo cluster with uranium
Falaise, Clément,Volkringer, Christophe,Vigier, Jean-Fran?ois,Beaurain, Arnaud,Roussel, Pascal,Rabu, Pierre,Loiseau, Thierry
, p. 15678 - 15681 (2013)
By controlling the water content, a new poly-oxo-metalate species containing 38 uranium centers has been solvothermally synthesized in the presence of benzoic acid in tetrahydrofuran (THF). The {U38} motif contains a distorted UO2 core of fluorite type, stabilized by benzoate and THF molecules. This compound is analogous to the {Pu38} motif and was characterized by X-ray photoelectron spectroscopy and magnetic analyses.
Facile syntheses of pure uranium halides: UCl4, UBr4 and UI4
Rudel, Stefan S.,Kraus, Florian
, p. 5835 - 5842 (2017)
Herein we describe convenient lab scale syntheses of several uranium(iv) halides of high purity by reaction of AlX3 (X = Cl, Br and I) with UO2, which is readily available by reduction of uranyl salts like UO2(NO3/su
Crystal structures of 2,2′:6′,2″-terpyridine uranyl chlorides molecular assemblies and their luminescence signatures
Lhoste, Jér?me,Henry, Natacha,Loiseau, Thierry,Guyot, Yannick,Abraham, Francis
, p. 321 - 327 (2013)
A series of three compounds bearing uranyl cations and 2,2′:6′, 2″-terpyridine (terpy) has been hydrothermally synthesized from uranium tetrachloride aqueous solution. An oxidation process into the hexavalent state has been observed for uranium in these synthesis conditions, together with the crystallization of different phases, which have been characterized by single-crystal X-ray diffraction analysis. The tetrachloridodioxidouranate terpyridinium salts UO2Cl4·H 2terpy·H2O (1) and UO2Cl 4·(H2terpy)2·2Cl (2) consist of the molecular assemblies of tetrachloro-uranyl anions ([UO2Cl 4]2-, square plane bipyramidal environment), isolated to each other via the doubly protonated H2terpy molecules. The latter chelate either water (1) or chlorine anions (2). The addition of organic base such as pyridine favored the crystallization of the complex, UO 2Cl2(terpy) (3), with the neutral terpy moiety coordinating one uranyl center via the nitrogen atoms of the pyridyl rings. It resulted in one uranyl center bonded to three nitrogen and two terminal chlorine anions, located in a distorted equatorial plane and two terminal perpendicular uranyl oxygens in apical position of a pentagonal bipyramid ([UO 2Cl2N3]). Different π-π interactions between the pyridyl rings of neighboring terpy molecules also occur for these complexes. Fluorescence spectroscopy of these different complexes has been measured at room temperature and 77 K showing the various local environments of the emitting centers.
Sigurdson, Elin R.,Wilkinson, Geoffrey
, (1977)
How to explain the difficulties in the coffinite synthesis from the study of uranothorite?
Costin,Mesbah,Clavier,Dacheux,Poinssot,Szenknect,Ravaux
, p. 11117 - 11126 (2011)
The preparation of Th1-xUxSiO4 uranothorite solid solutions was successfully undertaken under hydrothermal conditions (T = 250 °C). From XRD and EDS characterization, the formation of a complete solid solution between x = 0 (thorite) and x = 0.8 was evidenced. Nevertheless, additional (Th,U)O2 dioxide and amorphous silica were systematically observed for the highest uranium mole loadings. The influence of kinetics parameters was then studied to avoid the formation of such side products. The variation of the synthesis duration allowed us to point out the initial formation of oxide phases then their evolution to a silicate phase through a dissolution/precipitation process close to that already described as coffinitization. Also, the uranium mole loading initially considered was found to significantly influence the kinetics of reaction, as this latter strongly slows down for x > 0.3. Under these conditions, the difficulties frequently reported in the literature for the synthesis of pure USiO4 coffinite were assigned to a kinetic hindering associated with the coffinitization reaction.
Homoleptic Aryl Complexes of Uranium (IV)
Wolford, Nikki J.,Sergentu, Dumitru-Claudiu,Brennessel, William W.,Autschbach, Jochen,Neidig, Michael L.
, p. 10266 - 10270 (2019)
The synthesis and characterization of sterically unencumbered homoleptic organouranium aryl complexes containing U?C σ-bonds has been of interest to the chemical community for over 70 years. Reported herein are the first structurally characterized, steric
Formation of a sol of mixed U(IV) ? U(VI) hydroxide in aqueous solutions with pH 1.5-4
Gogolev,Shilov,Peretrukhin,Yusov,Fedoseev
, p. 349 - 353 (2008)
Addition of a Cs2UCI6 sample to solutions with pH 1.5 - 4, saturated with argon and containing 1 × 10-4-0.1 MUO 2(CIO4)2' results in the appearance of U(V), so that U(IV), U(V), and U(VI) occur in an equilibrium. However, after a certain induction period, black colloidal particles containing U(IV) polymer start to form. With an increase in pH from 1.5 to 4 or in temperature, the induction period becomes shorter. Under anaerobic conditions, the colloidal solution is stable for more than a month. Centrifugation at 8000 rpm (5500g) allows separation of the colloidal particles from the liquid phase. The colloid slowly dissolves in mineral acids saturated with argon or in a K2CO 3 solution, whereas precipitates of individual freshly prepared U(IV) and U(VI) hydroxides dissolve rapidly. Short UV irradia-of a UO 2(ClO4)2 solution saturated with argon and containing ethanol (pH 2.5) results in the appearance of U(V) which then disproportionates, and U(IV) forms with U(VI) a black colloid similar to that arising on mixing U(IV) and U(VI) solutions.
Samsonow, A.
, p. 96 - 96 (1911)
Syntheses, structures, and magnetic and optical properties of the compounds [Hg3Te2][UCl6] and [Hg4As2][UCl6]
Bugaris, Daniel E.,Ibers, James A.
, p. 3189 - 3193 (2008)
Two new quaternary salts, [Hg3Te2][UCl6] and [Hg4As2][UCl6], have been synthesized and their structures determined by single-crystal X-ray diffraction analysis. [Hg3Te2][UCl6] is the product of a reaction involving UCl4, HgCl2, and HgTe at 873 K. The compound crystallizes in space group P21/c of the monoclinic system. [Hg4As2][UCl6] results from the reaction of U, Hg2Cl2, and As at 788 K. It crystallizes in space group Pbca of the orthorhombic system. [Hg3Te2][UCl6] has a two-dimensional framework of ∞2 [Hg3 Te22 +] layers, whereas [Hg4As2][UCl6] has a three-dimensional framework of ∞2 [Hg3 As2] layers interconnected by Hg atoms linearly bonded to As atoms. Both framework structures contain discrete [UCl6]2- anions between the layers. [Hg3Te2][UCl6] exhibits temperature-independent paramagnetism. The optical absorption spectra of these compounds display f-f transitions.
Three-dimensional MOF-type architectures with tetravalent uranium hexanuclear motifs (U6O8)
Falaise, Clement,Volkringer, Christophe,Vigier, Jean-Francois,Henry, Natacha,Beaurain, Arnaud,Loiseau, Thierry
, p. 5324 - 5331 (2013)
Four metal-organic frameworks (MOF) with tetravalent uranium have been solvothermally synthesized by treating UCl4 with rigid dicarboxylate linkers in N,N-dimethylfomamide (DMF). The use of the ditopic ligands 4,4′-biphenyldicarboxylate (1), 2,6-naphthalenedicarboxylate (2), terephthalate (3), and fumarate (4) resulted in the formation of three-dimensional networks based on the hexanuclear uranium-centered motif [U6O4(OH)4(H2O)6]. This motif corresponds to an octahedral configuration of uranium nodes and is also known for thorium in crystalline solids. The atomic arrangement of this specific building unit with organic linkers is similar to that found in the zirconium-based porous compounds of the UiO-66/67 series. The structure of [U6O4(OH)4(H2O)6(L) 6]·X (L=dicarboxylate ligand; X=DMF) shows the inorganic hexamers connected in a face-centered cubic manner through the ditopic linkers to build up a three-dimensional framework that delimits octahedral (from 5.4A for 4 up to 14.0A for 1) and tetrahedral cavities. The four compounds have been characterized by using single-crystal X-ray diffraction analysis (or powder diffraction analysis for 4). The tetravalent state of uranium has been examined by using XPS and solid-state UV/Vis analyses. The measurement of the Brunauer-Emmett-Teller surface area indicated very low values (Langmuir 2 g-1 for 1, 2 g-1 for 2-4) and showed that the structures are quite unstable upon removal of the encapsulated DMF solvent. Copyright
Novel peroxo complexes of uranium containing organic ligands
Westland,Tarafder
, p. 3992 - 3995 (1981)
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Electrochemical behaviour of uranium (IV) in DMF at vitreous carbon
Afonso,Gomes,Carvalho,Alves,Wastin,Gon?alves
, p. 7318 - 7323 (2009)
The electrochemical behaviour of UCl4 (0.01 mol L-1 up to 0.05 mol L-1) in 0.1 mol L-1 TBAPF6/DMF solution at vitreous carbon was studied, at room temperature, by cyclic voltammetry and potentiostatic
A U(V) chalcogenide: Synthesis, structure, and characterization of K 2Cu3US5
Gray, Danielle L.,Backus, Lisa A.,Von Nidda, Hans-Albrecht Krug,Skanthakumar,Loidl, Alois,Soderholm,Ibers, James A.
, p. 6992 - 6996 (2007)
The compound K2Cu3US5 was obtained by the reaction of K2S, UCl4, CuCl, and S at 973 K. K 2Cu3US5 crystallizes in a new structure type in space group Cmcm of the orthorhombic system in a cell of dimensions a = 3.9374(6) A, b = 13.813(2) A, c = 17.500(3) A, and V = 951.8(2) A3 at 153 K. The structure comprises ∞2[UCu3S52-] slabs separated by K+ cations. The slabs are built from CuS4 tetrahedra and US6 octahedra. Their connectivity differs from other known octahedral/tetrahedral packing patterns. In the temperature range 130-300 K the compound exhibits Curie-Weiss magnetic behavior with μeff = 2.45(8) μB. This result together with both the bond distances and bond valence calculations and the absence of a Cu2+ ESR signal support the formulation of the above compound as K+ 2Cu+3U5+S2-5.
ELECTRON DIFFRACTION BY URANIUM TETRACHLORIDE
Ezhov, Yu. S.,Komarov, S. A.,Mikulinskaya, N. M.
, p. 692 - 694 (1988)
Vapor electron diffraction has been applied to the molecular structure of uranium tetrachloride.The molecule is a distorted tetrahedron (symmetry group C2v) having internuclear distances rg in angstroem r(UCl1) = 2.475(15), r(UCl2) = 2.558(18), r(Cl1-Cl2) = 3.612(6), r(Cl1Cl1') = 3.312(12), r(Cl2Cl2') = 4.178(12).The Cli and Cli' lie in the same plane.The vibrational frequencies have been calculated.
