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10026-10-5Relevant academic research and scientific papers
Comments on reactions of oxide derivatives of uranium with hexachloropropene to give UCl4
Patel, Dipti,Wooles, Ashley J.,Hashem, Emtithal,Omorodion, Harrison,Baker, Robert J.,Liddle, Stephen T.
, p. 7559 - 7562 (2015)
We report that U3O8, UO2(NO3)2·6H2O, and UO2Cl2 react with hexachloropropene (HCP) to give UCl4 in 60, 100, and 92% yields, respectively, and report a protocol to recycle the HCP. This renders the preparation of UCl4 more accessible and sustainable. 2,5-Dichlorohexachlorofulvene has been identified as a significant by-product from these reactions.
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.
Synthesis and structure of (Ph4P)2MCl6 (M = Ti, Zr, Hf, Th, U, Np, Pu)
Minasian, Stefan G.,Boland, Kevin S.,Feller, Russell K.,Gaunt, Andrew J.,Kozimor, Stosh A.,May, Iain,Reilly, Sean D.,Scott, Brian L.,Shuh, David K.
, p. 5728 - 5736 (2012)
High-purity syntheses are reported for a series of first, second, and third row transition metal and actinide hexahalide compounds with equivalent, noncoordinating countercations: (Ph4P)2TiF6 (1) and (Ph4P)2MCl6 (M = Ti, Zr, Hf, Th, U, Np, Pu; 2-8). While a reaction between MCl4 (M = Zr, Hf, U) and 2 equiv of Ph4PCl provided 3, 4, and 6, syntheses for 1, 2, 5, 7, and 8 required multistep procedures. For example, a cation exchange reaction with Ph4PCl and (NH4)2TiF6 produced 1, which was used in a subsequent anion exchange reaction with Me3SiCl to synthesize 2. For 5, 7, and 8, synthetic routes starting with aqueous actinide precursors were developed that circumvented any need for anhydrous Th, Np, or Pu starting materials. The solid-state geometries, bond distances and angles for isolated ThCl62-, NpCl6 2-, and PuCl62- anions with noncoordinating counter cations were determined for the first time in the X-ray crystal structures of 5, 7, and 8. Solution phase and solid-state diffuse reflectance spectra were also used to characterize 7 and 8. Transition metal MCl 62- anions showed the anticipated increase in M-Cl bond distances when changing from M = Ti to Zr, and then a decrease from Zr to Hf. The M-Cl bond distances also decreased from M = Th to U, Np, and Pu. Ionic radii can be used to predict average M-Cl bond distances with reasonable accuracy, which supports a principally ionic model of bonding for each of the (Ph 4P)2MCl6 complexes.
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.
Coffinite, USiO4, Is Abundant in Nature: So Why Is It so Difficult to Synthesize?
Mesbah, Adel,Szenknect, Stephanie,Clavier, Nicolas,Lozano-Rodriguez, Janeth,Poinssot, Christophe,Den Auwer, Christophe,Ewing, Rodney C.,Dacheux, Nicolas
, p. 6687 - 6696 (2015)
Coffinite, USiO4, is the second most abundant U4+ mineral on Earth, and its formation by the alteration of the UO2 in spent nuclear fuel in a geologic repository may control the release of radionuclides to the environment. Despite its abundance in nature, the synthesis and characterization of coffinite have eluded researchers for decades. On the basis of the recent synthesis of USiO4, we can now define the experimental conditions under which coffinite is most efficiently formed. Optimal formation conditions are defined for four parameters: pH, T, heating time, and U/Si molar ratio. The adjustment of pH between 10 and 12 leads probably to the formation of a uranium(IV) hydroxo-silicate complex that acts as a precursor of uranium(IV) silicate colloids and then of coffinite. Moreover, in this pH range, the largest yield of coffinite formation (as compared with those of the two competing byproduct phases, nanometer-scale UO2 and amorphous SiO2) is obtained for 250°C, 7 days, and 100% excess silica. (Figure Presented).
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
Convenient synthesis, structure, and reactivity of (C5Me5)U(CH2C6H5)3 : A simple strategy for the preparation of monopentamethylcyclopentadienyl uranium(IV) complexes
Kiplinger, Jaqueline L.,Morris, David E.,Scott, Brian L.,Burns, Carol J.
, p. 5978 - 5982 (2002)
A high-yield one-pot synthesis of (C5Me5)U(CH2C6H5)3 has been developed and applied to the synthesis of a new organouranium complex possessing a (pentamethylcyclopentadienyl)bis(cyclopentadienyl) ligand framework, (C5Me5)(C5H5)2U(CH2 C6H5). Both complexes have been structurally characterized. We also report herein an improved and safer synthesis for the popular uranium starting material UCU.
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.
[UCl4(HCN)4]-a hydrogen cyanide complex of uranium tetrachloride
Rudel,Pietzonka,Hoelzel,Kraus
, p. 1241 - 1244 (2018)
The reaction of uranium tetrachloride with anhydrous liquid hydrogen cyanide yields a turquoise microcrystalline powder of tetrachloridotetraformonitrileuranium(iv), [UCl4(HCN)4]. We determined the crystal structure of this compound by powder neutron diffraction. The compound was further characterized by IR spectroscopy and thermogravimetric analysis as well as by magnetic measurements. The paramagnetic compound crystallizes in the tetragonal space group type I4. To the best of our knowledge this compound represents the first structurally elucidated uranium(iv) complex with HCN as a ligand.
Synthesis, structure, and characterization of uranium(IV) phenyl phosphonate, U(O3PC6H5)2, and uranium(IV) pyro phosphate, UP2O7
Cabeza, Aurelio,Aranda, Miguel A. G.,Cantero, Fernando M.,Lozano, Diego,Martinez-Lara, Maria,Bruque, Sebastian
, p. 181 - 189 (1996)
Two tetravalent uranium compounds have been characterized. The structure of a new uranium(IV) phosphonate, U(O3PC6H5)2, has been solved from laboratory X-ray powder diffraction data by using ab initio methodology. U(O3PC6H5)2 crystallizes in the space group C2/m with a = 9.4559(7) A, b = 5.6769(5) A, c = 14.9687(12) A, β= 96.539(5) A, V = 798.3(1) A3, Z = 2. The reliability factors were RWP = 8.0%, RP = 6.04%, and RF = 3.0%. The structure is lamellar, and the framework of the U(O3P)2 layers is similar to that of the α-Zr(HPO4)2·H2O-type structure, although the symmetry of the phosphonate group is higher than that of the phosphate groups in α-Zr(HPO4)2·H2O and the phosphonate group in Zr(O3PC6H5)2. The phenyl groups are located in the interlamellar space, being inclined 10° to the c-axis. The phenyl rings are tilted out 53° from the ac plane, and they are disordered. We have also characterized this compound by UV-VIS-IR spectroscopies and thermal analysis. The thermal decomposition product is uranium(IV) pyro phosphate. This compound was identified through its X-ray powder diffraction pattern. UP2O7 crystallizes in the Pa3 space group (a = 8.6311(2) A, V = 642.99(4) A3, Z = 4). The structure belongs to the cubic ZrP2O7-type structure. The reliability factors were RWP = 11.7%, RP = 8.6%, and RF = 10.4%. Disorder has been found in the oxygen that bridges the pyrophosphate groups, leading to an angular P-O-P arrangement. The VIS-near-IR adsorption spectra revealed the uranium(IV) presence and the oxygen environment.
