Uranium dioxide in ionic liquid with a tri-n-butylphosphate-HNO3 complex--dissolution and coordination environment

Uranium dioxide can be dissolved directly in an imidazolium-based ionic liquid (IL) at room temperature with a tri-n-butylphosphate(TBP)-HNO(3) complex. The dissolution process follows pseudo first-order kinetics initially. Raman spectroscopic studies show the dissolved uranyl ions are coordinated with TBP in the IL phase with a molar ratio of (UO(2))(2+) : TBP = 1 : 2. The dissolved uranyl species can be effectively transferred to a supercritical fluid carbon dioxide (sc-CO(2)) phase. No aqueous phase is formed in either the IL dissolution or the supercritical fluid extraction process. Absorption spectra of the extracted uranyl species in the sc-CO(2) phase suggests the presence of a UO(2)(TBP)(2)(NO(3))(2) and HNO(3) adduct probably of the form UO(2)(TBP)(2)(NO(3))(2)·HNO(3). The adduct dissociates in a water-dodecane trap solution during pressure reduction resulting in UO(2)(TBP)(2)(NO(3))(2) collected in the dodecane phase.     

Dissolution of uranium dioxide in supercritical fluid carbon dioxide

Uranium dioxide can be dissolved in supercritical CO2 with a CO2-philic TBP-HNO3 complexant to form a highly soluble UO2(NO3)(2).2TBP complex; this new method of dissolving UO2 that requires no water or organic solvent may have important applications for reprocessing of spent nuclear fuels and for treatment of nuclear wastes.     

The application of novel hydrophobic ionic liquids to the extraction of uranium(VI) from nitric acid medium and a determination of the uranyl complexes formed

Novel ammonium based hydrophobic ionic liquids (ILs) have been synthesised and characterised, and their use in the liquid-liquid extraction of uranium(VI) from an aqueous nitric acid solution using tri-n-butyl phosphate (TBP), studied. On varying the nitric acid concentration, each IL was found to give markedly different results. Relatively hydrophilic ILs showed high uranium(VI) extractability at 0.01 M nitric acid solution which progressively decreased from 0.01 to 2 M HNO(3) and then increased again as the nitric acid concentration was increased to 6 M. An analysis of the mechanisms involved for one such IL, pointed to cationic-exchange being the predominant route at low nitric acid concentrations whilst at high nitric acid concentrations, anionic-exchange predominated. Strongly hydrophobic ILs showed low extractability for nitric acid concentrations below 0.1 M but increasing extractability from 0.1 M to 6 M nitric acid. The predominant mechanism in this case involved the partitioning of a neutral uranyl complex. The uranyl complexes were found to be UO(2)(2+)·(TBP)(3) for the cationic exchange mechanism, UO(2)(NO(3))(2)(TBP)(2) for the neutral mechanism and UO(2)(NO(3))(3)(-)·(TBP) for the anionic exchange mechanism.     

Aqueous coordination chemistry and photochemistry of uranyl(VI) oxalate revisited: a density functional theory study

Using density functional theory (DFT) calculations, we revisited a classical problem of uranyl(VI) oxalate photochemical decomposition. Photoreactivities of uranyl(VI) oxalate complexes are found to correlate largely with ligand-structural arrangements. Importantly, the intramolecular photochemical reaction is inhibited when oxalate is bound to uranium exclusively in chelate binding mode. Previously proposed mechanisms involving a UO(2)(C(2)O(4))(2)(2-) (1:2) complex as the main photoreactive species are thus unlikely to apply, because the two oxalic acids are bound to uranium in a chelating binding mode. Our DFT results suggest that the relevant photoreactive species are UO(2)(C(2)O(4))(3)(4-) (1:3) and (UO(2))(2)(C(2)O(4))(5)(6-) (2:5) complexes binding uranium in an unidentate fashion. These species go through decarboxylation upon excitation to the triplet state, which ensues the release of CO(2) and reduction of U(vi) to U(v). The calculations also suggest an alternative intermolecular pathway at low pH via an electron transfer between the excited state *UO(2)(2+) and hydrogen oxalate (HC(2)O(4)(-)) which eventually leads to the production of CO and OH(-) with no net reduction of U(VI). The calculated results are consistent with previous experimental findings that CO is only detected at low pH while U(IV) is detected only at high pH.     

Studies on metal carbonate equilibria-part 21 Study of the U(VI)H(2)OCO(2)(g) system by thermal lensing spectrophotometry

Equilibria in the U(VI)H(2)OCO(2)(g) system in 0.5M sodium perchlorate medium at 25 degrees have been studied. By using thermal tensing spectrophotometry (TLS) and a very low total concentration of U(V1) (4 x 10(-6)M) information could be obtained on equilibria involving UO(2)(CO(3))(2-)(2) without complications due to formation of the trimer (UO(2))(3)(CO(3))(6-)(6). The experimental data allowed a precise determination of the equilibrium constant log K(3) = 6.35 +/- 0.05 for the reaction UO(2)(CO(3))(2-)(2) + CO(2-)(3) right harpoon over left harpoonright harpoon over left harpoon UO(2)(CO(3))(4-)(3). The interpretation of TLS data is briefly discussed, as well as the potential use of this technique for studies of the speciation of trace elements in natural water systems.     

Uranyl nitrate complex extraction into TBP/dodecane organic solutions: a molecular dynamics study

Liquid-liquid extraction of uranyl is studied by conducting atomistic molecular dynamics simulation using quantum chemistry calibrated force fields via restrained electrostatic potential fitting of atomic forces. The simulations depict the migration of uranyl nitrate complexes from the aqueous-organic interface into the tri-n-butyl phosphate (TBP)/dodecane organic phase, in the form of UO(2)(NO(3))(2)·H(2)O·2TBP and UO(2)(NO(3))(2)·3TBP. The migration process is characterized by the gradual breaking of all the hydrogen bonds between the complex and the water molecules at the interface. Moreover, our simulation results suggest that the experimentally observed complex UO(2)(NO(3))(2)·2TBP is formed after the migration of the aforementioned complexes into the organic phase by means of a reorganization of the nitrate binding mode from mono to bidentate which removes the excess oxygen atoms bound to uranyl.     

Ions generated from uranyl nitrate solutions by electrospray ionization (ESI) and detected with fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometry

Electrospray ionization (ESI) of uranyl nitrate solutions generates a wide variety of positively and negatively charged ions, including complex adducts of uranyl ions with methoxy, hydroxy, and nitrate ligands. In the positive ion mode, ions detected by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry are sensitive to instrumental tuning parameters such as quadrupole operating frequency and trapping time. Positive ions correspond to oligomeric uranyl nitrate species that can be characterized as having a general formula of [(UO(2))(n)(A)(m)(CH(3)OH)(s)](+) or [(UO(2))(n)(O)(A)(m)(CH(3)OH)(s)](+) with n = 1-4, m = 1-7, s = 0 or 1, and A = OH, NO(3), CH(3)O or a combination of these, although the formation of NO(3)-containing species is preferred. In the negative ion mode, complexes of the form [(UO(2))(NO(3))(m)](-) (m = 1-3) are detected, although the formation of the oxo-containing ions [(UO(2))(O)(n)(NO(3))(m)](-) (n = 1-2, m = 1-2) and the hydroxy-containing ions [(UO(2))(OH)(n)(NO(3))(m)](-) (n = 1-2, m = 0-1) are also observed. The extent of coordinative unsaturation of both positive and negative ions can be determined by ligand association/exchange and H/D exchange experiments using D(2)O and CD(3)OD as neutral reaction partners in the gas-phase. Positive ions are of varying stability and reactivity and may fragment extensively upon collision with D(2)O, CD(3)OD and N(2) in sustained off-resonance irradiation/collision-induced dissociation (SORI-CID) experiments. Electron-transfer reactions, presumably occurring during electrospray ionization but also in SORI-CID, can result in reduction of U(VI) to U(V) and perhaps even U(IV).     

The first cyclopentadienyl complex of uranyl

The U(IV) linear pentacyano metallocene [U(C(5)Me(5))(2)(CN)(5)][NEt(4)](3) reacted with 2 molar equivalents of pyridine N-oxide in THF or acetonitrile to give the U(VI) complex [UO(2)(C(5)Me(5))(CN)(3)][NEt(4)](2), the first uranyl species containing the cyclopentadienyl ligand; the crystal structure revealed that the steric effects of the (C(5)Me(5)) ligand force the {UO(2)}2+ ion to deviate from linearity.     

Binary and ternary uranium(VI) humate complexes studied by attenuated total reflection Fourier-transform infrared spectroscopy

The complexation of U(VI) with humic acid (HA) in aqueous solution has been investigated at an ionic strength of 0.1 M (NaCl) in the pH range between pH 2 and 10 at different carbonate concentrations by attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopy. For the first time, the formation of binary and ternary U(VI) humate complexes was directly verified by in situ spectroscopic measurements. The complex formation constants for the binary U(VI) humate complex (UO(2)HA(II)) and for the ternary U(VI) mono hydroxo humate complex (UO(2)(OH)HA(I)) as well as the ternary U(VI) dicarbonato humate complex (UO(2)(CO(3))(2)HA(II)(4-)) determined from the spectroscopic data amount to log β(0.1 M) = 6.70 ± 0.25, log β(0.1 M) = 15.14 ± 0.25 and log β(0.1 M) = 24.47 ± 0.70, respectively, and verify literature data.     

Speciation and coordination chemistry of uranyl(VI)-citrate complexes in aqueous solution

The pH dependence of uranyl(VI) complexation by citric acid was investigated using Raman and attenuated total reflection FTIR spectroscopies and electrospray ionization mass spectrometry. pH-dependent changes in the nu(s)(UO(2)) envelope indicate that three major UO(2)(2+)-citrate complexes with progressively increasing U=O bond lengths are present over a range of pH from 2.0 to 9.5. The first species, which is the predominant form of uranyl(VI) from pH 3.0 to 5.0, contains two UO(2)(2+) groups in spectroscopically equivalent coordination environments and corresponds to the [(UO(2))(2)Cit(2)](2)(-) complex known to exist in this pH range. At pH values >6.5, [(UO(2))(2)Cit(2)](2)(-) undergoes an interconversion to form [(UO(2))(3)Cit(3)](3)(-) and (UO(2))(3)Cit(2). ESI-MS studies on solutions of varying uranyl(VI)/citrate ratios, pH, and solution counteranion were successfully used to confirm complex stoichiometries. Uranyl and citrate concentrations investigated ranged from 0.50 to 50 mM.     

超临界CO2钝化金属铀的理论研究

The present work is devoted to examine the passivation effect of metallic uraniu by supercritical fluid CO2, which is the most significant. The structure and thermodynamic properties of UC, C, UO2 and supercritical fluid CO2 have been calculated, based on which following simultaneous reactions have been examined using chemical equilibrium theory. The results indicate that the △G° for U(α)+CO2(g)UO2(s)+C(Graphite) reaction is -149.8～-632.0 kJ, △G° for 2U(α)+CO2(g)UO2(s)+UC(s) reaction is -725.1～-730.2 kJ, and both △G＜０ and equilibrium closely approach products. It is also well known that the supercritical fluid is quite active in kinetics, and therefore the product compounds UC, C and UO2 would be quite stable. After the calculated molar tatio of UC, C and UO2, the stoichiometric ratio of elements is UC0.65±0.01O1.30±0.01, which would be useful for XPS observation.     

Extraction and coordination studies of the unexplored bifunctional ligand carbamoyl methyl sulfoxide (CMSO) with uranium(VI) and cerium(III) nitrates. Synthesis and structures of [UO2(NO3)2(PhSOCH2CON(i)Bu2)] and [Ce(NO3)3(PhSOCH2CONBu2)2

The bifunctional carbamoyl methyl sulfoxide ligands, PhCH(2)SOCH(2)CONHPh (L1), PhCH(2)SOCH(2)CONHCH(2)Ph (L2), PhSOCH(2)CON(i)Pr(2)(L3), PhSOCH(2)CONBu(2)(L4), PhSOCH(2)CON(i)Bu(2)(L5) and PhSOCH(2)CON(C(8)H(17))(2)(L6) have been synthesized and characterized by spectroscopic methods. The selected coordination chemistry of L1, L3, and L5with [UO(2)(NO(3))(2)] and [Ce(NO(3))(3)] has been evaluated. The structures of the compounds [UO(2)(NO(3))(2)(PhSOCH(2)CON(i)Bu(2))](10) and [Ce(NO(3))(3)(PhSOCH(2)CONBu(2))(2)](12) have been determined by single crystal X-ray diffraction methods. Preliminary extraction studies of ligand L6 with U(VI), Pu(IV) and Am(III) in tracer level showed an appreciable extraction for U(VI) and Pu(IV) in up to 10 M HNO(3) but not for Am(III). Thermal studies on compounds 8 and 10 in air revealed that the ligands can be destroyed completely on incineration. The electron spray mass spectra of compounds 8 and 10 in acetone show that extensive ligand distribution reactions occur in solution to give a mixture of products with ligand to metal ratios of 1: 1 and 2 :1. However, 10 retains its solid state structure in CH(2)Cl(2).     

Chemical equilibria in the binary and ternary uranyl(VI)-hydroxide-peroxide systems

The composition and equilibrium constants of the complexes formed in the binary U(VI)-hydroxide and the ternary U(VI)-hydroxide-peroxide systems have been studied using potentiometric and spectrophotometric data at 25 °C in a 0.100 M tetramethylammonium nitrate medium. The data for the binary U(VI) hydroxide complexes were in good agreement with previous studies. In the ternary system two complexes were identified, [UO(2)(OH)(O(2))](-) and [(UO(2))(2)(OH)(O(2))(2)](-). Under our experimental conditions the former is predominant over a broad p[H(+)] region from 9.5 to 11.5, while the second is found in significant amounts at p[H(+)] < 10.5. The formation of the ternary peroxide complexes results in a strong increase in the molar absorptivity of the test solutions. The absorption spectrum for [(UO(2))(2)(OH)(O(2))(2)](-) was resolved into two components with peaks at 353 and 308 nm with molar absorptivity of 16200 and 20300 M(-1) cm(-1), respectively, suggesting that the electronic transitions are dipole allowed. The molar absorptivity of [(UO(2))(OH)(O(2))](-) at the same wave lengths are significantly lower, but still about one to two orders of magnitude larger than the values for UO(2)(2+)(aq) and the binary uranyl(VI) hydroxide complexes. It is of interest to note that [(UO(2))(OH)(O(2))](-) might be the building block in cluster compounds such as [UO(2)(OH)(O(2))](60)(60-) studied by Burns et al. (P. C. Burns, K. A. Kubatko, G. Sigmon, B. J. Fryer, J. E. Gagnon, M. R. Antonio and L. Soderholm, Angew. Chem. 2005, 117, 2173-2177). Speciation calculations using the known equilibrium constants for the U(vi) hydroxide and peroxide complexes show that the latter are important in alkaline solutions even at very low total concentrations of peroxide, suggesting that they may be involved when the uranium minerals Studtite and meta-Studtite are formed by α-radiolysis of water. Radiolysis will be much larger in repositories for spent nuclear fuel where hydrogen peroxide might contribute both to the corrosion of the fuel and to transport of uranium in a ground water system.     

DFT studies of structure and vibrational frequencies of isotopically substituted diamin uranyl nitrate using relativistic effective core potentials

The infrared and Raman spectra of UO(2)(NH(3))(2)(NO(3))(2) with (14)NH(3)/(15)NH(3) isotopic substitution were measured. The structure was optimized and the vibrational spectrum was calculated by DFT (B3LYP/6-31G(d)) methodology using relativistic effective core potential for U atom. The results for force constant and vibrational frequencies support the experimental assignments and the proposed model, mainly in the far-infrared region, where the metal-ligand bond and lattice vibrations are observed. Based on the theoretical findings and the observed spectra a structure of distorted D(2h) symmetry with the nitrate group acting like bidentate ligands for the UO(2)(NH(3))(2)(NO(3))(2) is proposed.     

Vibrational spectroscopy of anionic nitrate complexes of UO22+ and Eu3+ isolated in the gas phase

Wavelength-selective infrared multiple photon photo-dissociation (IRMPD) was used to generate spectra of anionic nitrate complexes of UO(2)(2+) and Eu(3+) in the mid-infrared region. Similar spectral patterns were observed for both species, including splitting of the antisymmetric O-N-O stretch into high and low frequency components with the magnitude of the splitting consistent with attachment of nitrate to a strong Lewis acid center. The frequencies measured for [UO(2)(NO(3))(3)](-) were within a few cm(-1) of those measured in the condensed phase, the best agreement yet achieved for a comparison of IRMPD with condensed phase absorption spectra. In addition, experimentally-determined values were in good general agreement with those predicted by DFT calculations, especially for the antisymmetric UO(2) stretch. The spectrum from the [UO(2)(NO(3))(3)](-) was compared with that of [Eu(NO(3))(4)](-), which showed that nitrate was bound more strongly to the Eu(3+) metal center, consistent with its higher charge. The spectrum of a unique uranyl-oxo species having an elemental composition [UO(9)N(2)](-) was also acquired, that contained nitrate absorptions suggestive of a [UO(2)(NO(3))(2)(O)](-) structure; the spectrum lacked bands indicative of nitrite and superoxide that would be indicative of an alternative [UO(2)(NO(3))(NO(2))(O(2))](-) structure.     

Solvation of uranyl-CMPO complexes in dry vs. humid forms of the [BMI][PF6] ionic liquid. A molecular dynamics study

The solvation of the [UO(2)(NO(3))(CMPO)](+) and [UO(2)(NO(3))(2)(CMPO)(2)] complexes (CMPO = octyl(phenyl)-N,N-diisobutylmethylcarbamoyl phosphine oxide) is investigated by molecular dynamics in the "dry" and "humid" forms of a room temperature ionic liquid (IL) based on the 1-butyl-3-methylimidazolium (BMI(+)) cation and the hexafluorophosphate (PF(6)(-)) anion. The simulations reveal the importance of the solvent anions in "dry" conditions and of water molecules in the "humid" solvent. For the [UO(2)(NO(3))(CMPO)](+) complex, the monodentate vs. bidentate coordination modes of CMPO are compared, and the first solvation shell of uranyl is completed by 1-3 PF(6)(-) anions in the dry IL and by 2-3 water molecules in the humid IL, leading to a total coordination number close to 5. The energy analysis shows that interactions with the IL stabilize the [UO(2)(NO(3))(bi)(CMPO)(mono)](+) form (with bidentate nitrate and monodentate CMPO) in the dry IL and the [UO(2)(NO(3))(mono)(CMPO)(mono)](+) form (with monodentate nitrate and CMPO) in the humid IL. The extracted compound characterized by EXAFS is thus proposed to be the [UO(2)(NO(3))(mono)(CMPO)(mono)(H(2)O)(3)](+) species. Furthermore we compare the [UO(2)(NO(3))(2)(CMPO)(2)] complex in its associated and dissociated forms ([UO(2)(NO(3))(mono)(CMPO)(mono)](+) + CMPO + NO(3)(-)) and discuss the results in the context of uranyl extraction by CMPO to ionic liquids.     

A theoretical study of the structure of tricarbonatodioxouranate

The results of a study on the ground states of tricarbonato complexes of dioxouranate using multiconfigurational second-order perturbation theory (CASSCF/CASPT2) are presented. The equilibrium geometries of the complexes corresponding to uranium in the formal oxidation states VI and V, [UO(2)(CO(3))(3)](4)(-) and [UO(2)(CO(3))(3)],(5)(-) have been fully optimized in D(3)(h)() symmetry at second-order perturbation theory (MBPT2) level of theory in the presence of an aqueous environment modeled by a reaction field Hamiltonian with a spherical cavity. The uranyl fragment has also been optimized at CASSCF/CASPT2, to obtain an estimate of the MBPT2 error. Finally, the effect of distorting the D(3)(h)() symmetry to C(3) has been investigated. This study shows that only minor geometrical rearrangements occur in the one-electron reduction of [UO(2)(CO(3))(3)](4)(-) to [UO(2)(CO(3))(3)],(5)(-) confirming the reversibility of this reduction.     

Chemical equilibria in the uranyl(vi)-peroxide-carbonate system; identification of precursors for the formation of poly-peroxometallates

The focus of this study is on the identification of precursors in solution that might act as building blocks when solid uranyl(vi) poly-peroxometallate clusters containing peroxide and hydroxide bridges are formed. The precursors could be identified by using carbonate as an auxiliary ligand that prevented the formation of large clusters, such as the ones found in solids of fullerene type. Using data from potentiometric and NMR ((17)O and (13)C) experiments we identified the following complexes and determined their equilibrium constants: (UO(2))(2)(O(2))(CO(3))(4)(6-), UO(2)(O(2))CO(3)(2-), UO(2)(O(2))(CO(3))(2)(4-), (UO(2))(2)(O(2))(CO(3))(2)(2-), (UO(2))(2)(O(2))(2)(CO(3))(2-) and [UO(2)(O(2))(CO(3))](5)(10-). The NMR spectra of the pentamer show that all uranyl and carbonate sites are equivalent, which is only consistent with a ring structure built from uranyl units linked by peroxide bridges with the carbonate coordinated "outside" the ring; this proposed structure is very similar to [UO(2)(O(2))(oxalate)](5)(10-) identified by Burns et al. (J. Am. Chem. Soc., 2009, 131, 16648; Inorg. Chem., 2012, 51, 2403) in K(10)[UO(2)(O(2))(oxalate)](5)·(H(2)O)(13); similar ring structures where oxalate or carbonate has been replaced by hydroxide are important structure elements in solid poly-peroxometallate complexes. The equivalent uranyl sites in (UO(2))(2)(O(2))(2)(CO(3))(2-) suggest that the uranyl-units are linked by the carbonate ion and not by peroxide.     

Uranyl extraction by beta-diketonate ligands to SC-CO2: theoretical studies on the effect of ligand fluorination and on the synergistic effect of TBP

We report theoretical investigations on the effect of H --> F substitution in acetylacetonate ligands in order to understand why fluorination promotes the extraction of uranyl to supercritical CO(2) with a marked synergistic effect of tri-n-butyl phosphate "TBP". The neutral LH and deprotonated L(-) forms of the ligand, and the uranyl complexes UO(2)L(2) and UO(2)L(2)S (S = H(2)O versus trimethyl phosphate "TMP" which mimics TBP) are studied by quantum mechanics (QM) in the gas phase, whereas the ligands LH and their UO(2)L(2) and UO(2)L(2)S complexes are studied by molecular dynamics (MD) in SC-CO(2) solution as well as at a CO(2)-water interface. Several effects are found to favor F ligands over the H ligands. (i) First, intrinsically (in the gas phase), the complexation reaction 2 LH + UO(2)(2+) --> UO(2)L(2) is more exothermic for the F ligands, mainly due to their higher acidity, compared to the H ligands. (ii) The unsaturated UO(2)L(2) complexes with F ligands bind more strongly TMP than H(2)O, thus preferentially leading to the UO(2)L(2)(TMP) complex, more hydrophobic than UO(2)L(2)(H(2)O). (iii) Molecular dynamics simulations of SC-CO(2) solutions show that the F ligands and their UO(2)L(2) and UO(2)L(2)S complexes are better solvated than their H analogues, and that the UO(2)L(2)(TBP) complex with F ligands is the most CO(2)-philic. (iv) Concentrated solutions of UO(2)L(2)(TBP) complexes at the CO(2)-water interface display an equilibrium between adsorbed and extracted species, and the proportion of extracted species is larger with F- than with H- ligands, in agreement with experimental observations. Thus, TBP plays a dual synergistic role: its co-complexation by UO(2)L(2) yields a hydrophobic and CO(2)-philic complex suitable for extraction, whereas TBP in excess at the interface facilitates the migration of the complex to the supercritical phase.     

Precipitation of a dioxouranium(VI) species from a room temperature ionic liquid medium

The novel complex 1-butyl-3-methylimidazolium mu(4)-(O,O,O',O'-ethane-1,2-dioato)-bis[bis(nitrato-O,O)dioxouranate(VI)] (1) has been precipitated from a room-temperature ionic liquid medium containing 1-butyl-3-methylimidazolium nitrate, nitric acid, and acetone. X-ray analysis of complex 1 shows the unit cell contains four [C(4)mim](+) cations and two independent [[UO(2))(NO(3))(2)](2)(mu(4)-C(2)O(4))](2-) moieties, both of which are located about inversion centers. The [C(4)mim](+) cations are arranged such that they produce large channels in which the anions are located. This arrangement of [[(UO(2))(NO(3))(2)](2)(mu(4)-C(2)O(4))](2-) groups is unique to this compound. Crystal data for compound 1: M = 1154.56, monoclinic, space group P2(1)/c, a = 15.452(2) A, b = 20.354(3) A, c = 10.822(4) A, beta = 106.84(2) degrees, U = 3258(1) A(-)(3), Z = 4, mu = 10.023 mm(-1), R(int) = 0.0788.