Insight into the Uranyl Oxyfluoride Topologies through the Synthesis

Nov 17, 2016 - 2), with unit cell parameters a = 10.7925(16) Å, b = 10.9183(16) Å, c = 13.231(2) Å, .... index ranges, –17 ≤ h ≤ 18, −18 ≤ k ≤ 18, −22...
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Insight into the Uranyl Oxyfluoride Topologies through the Synthesis, Crystal Structure, and Evidence of a New Oxyfluoride Layer in [(UO2)4F13][Sr3(H2O)8](NO3)·H2O Laurent J. Jouffret,*,† Jean-Michel Hiltbrunner,† Murielle Rivenet,‡ Nicolas Sergent,§,∥ Saïd Obbade,§,∥ Daniel Avignant,† and Marc Dubois† †

Institut de Chimie de Clermont-Ferrand, ICCF−UMR 6296,Campus Universitaire des Cézeaux, 24 avenue Blaise Pascal, 63178 AUBIERE Cedex, France ‡ Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181−UCCS−Unité de Catalyse et Chimie du Solide, F-59000 Lille, France § Univ. Grenoble Alpes, LEPMI, F-38000 Grenoble, France ∥ CNRS, LEPMI, F-38000 Grenoble, France S Supporting Information *

ABSTRACT: A new strontium uranyl oxyfluoride, [(UO2)4F13][Sr3(H2O)8](NO3)·H2O, was synthesized under hydrothermal conditions. The single-crystal X-ray structure was determined. This compound crystallizes in the triclinic space group P1̅ (No. 2), with unit cell parameters a = 10.7925(16) Å, b = 10.9183(16) Å, c = 13.231(2) Å, α = 92.570(8)°, β = 109.147(8)°, γ = 92.778(8)°, V = 1468.1(4) Å3, and Z = 2. The structure is built from uranyl-containing 1 ∞[(UO2 )4 F13] chains of tetrameric units of corner-sharing UO2F5 pentagonal bipyramids. These chains are linked through trimeric strontium units to form strontium−uranyl oxyfluoride layers further assembled by nitrate groups. The interlayer space is occupied by free water molecules. This compound was characterized by spectroscopic methods, especially 19F NMR highlighting the many different fluoride sites. Structural relationships with other uranyl oxyfluorides were investigated through the different F/O ratios, the structural building unit, and the structural arrangement.

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as Ni,26−42 and form crystal structures with a lower variety of dimensionalities than hybrid uranium oxyfluorides. While most of these compounds were discovered nearly half a century ago, our recent successful work on inorganic oxyfluorides has helped in developing an understanding of inorganic actinide fluorides and has shed light on fluorination processes, while also giving insight into the use of UF6 in the nuclear fuel industry.43,44 We report in this paper an example of uranyl oxyfluoride with the divalent cation Sr2+, displaying an unprecedented structural arrangement for inorganic uranyl oxyfluorides. The synthesis, crystal structure, Raman spectroscopy, thermogravimetric analysis (TGA), and solid-state NMR spectroscopy are reported hereafter.

INTRODUCTION Before its isotopic enrichment, uranium is chemically treated to produce uranium hexafluoride. Depending on the source, this uranium is susceptible to contain impurities that can lead to the formation of secondary mixed phases. Any addition of oxygen in the process will lead to the presence of diverse uranium oxyfluoride compounds. However, while uranium-bearing materials have been extensively studied because of their interesting coordination chemistry and diverse physical− chemical properties1−3 very few uranium fluorides and oxyfluorides have been crystallographically characterized and reported in the literature. Most were described after the Manhattan project by Zachariasen,4−8 and few have been investigated since.9−14 Organically templated uranium oxyfluorides have been reported with a wide variety of structures.15−25 A large number of these oxyfluorides adopt either mono or bidimensional structures, while only a few exhibit a three-dimensional (3D) framework. Inorganic uranium oxyfluorides were found only with few monovalent cations, such as K, Rb, and Cs or network-forming metals such © XXXX American Chemical Society

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EXPERIMENTAL SECTION

Synthesis. The title compound was obtained using natural isotopic abundance uranium. Great precautions for working with radioactive Received: July 22, 2016

A

DOI: 10.1021/acs.inorgchem.6b01765 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry materials should be followed, and such work should only take place in appropriate facilities and be conducted by properly trained individuals. UO2(NO3)2·6H2O used in this synthesis was prepared from hydrolysis of UF6 reacted in boiling nitric acid, without further purification. All other chemicals were purchased as reagent grade and were used as received to prepare the aqueous solution. 1.2 g of UO2(NO3)2·6H2O, 0.8 g SrCl2·6H2O (VWR, 99+%), 1 mL of 40% HF (Merck Millipore), and 5 mL of H2O were introduced into a 23 mL Teflon-lined Parr steel autoclave and heated at 200 °C in a Thermo Scientific Heraeus oven for 2 d and then slowly cooled (1 °C/h) to room temperature. The precipitated solid was collected by filtration. The yield of the synthesis was 100% uranium uptake in the solid. Crystal Structure Determination. A crystal of the title compound, of approximate dimensions 0.184 × 0.667 × 1.232 mm, was isolated under an optical microscope and used for the X-ray crystallographic analysis. The selected crystal was mounted on a glass fiber and aligned on a Bruker APEX2 diffractometer equipped with a CCD detector (Bruker AXS APEX2 CCD-4K) and an Oxford Cryostream 700 system to cool the sample to 100 K.45 Intensities were collected using Mo Kα radiation selected by a graphite monochromator. The frames were integrated with the Bruker SAINT software package using a narrow-frame algorithm.46 Data were corrected for absorption effects using the numerical absorption correction from face indices (SADABS).47 The final anisotropic fullmatrix least-squares refinement was performed with SHELX48 on F2 with 370 variables and converged at R1 = 3.11%, for the observed data, and wR2 = 8.12% for all data.48 The largest peak in the final difference electron density was 6.668 e−/Å3, and the largest hole was −3.274 e−/ Å3. This apparent large electron density residue, located close to uranium or strontium atoms, is present in all crystals that were tested and collected. Further spectroscopic characterizations were used to confirm the crystallographic data. Details of the crystallographic data and structure refinement are given in Table 1. Attribution of the cation and anion nature was confirmed by bond valence calculations. Bond valence sum (BVS) values were calculated using the formula vij = exp[(Rij − dij)/b] with Rij = 2.051 and b = 0.519 for U−O49 and Rij = 2.118 for Sr−O, 2.019 for Sr−F, 1.432 for N−O, and b = 0.37.50 Rij = 1.98 and b = 0.4 for U−F.51 The results confirm the atomic assignments, critically for the uranyl oxygen and fluorine atoms, with BVS mean values of, respectively, 1.75 (12) and 0.95 (12). For the water molecule oxygen atoms the BVS mean value is 0.28 (10), and considering O−Hwater bond distances to be in the range of 0.87−0.94 Å, and Rij = 0.907 and b = 0.28 for O−H,52 it results in a BVS close to the theoretical value of 2. Thermal Analyses. TGA and differential thermal analysis (DTA) experiments were performed on a Setaram coupled TGA-DTA 2− 16.18 apparatus equipped with platinum crucibles. Analyses were undertaken in air, with a heating rate of 5 K·min−1. Raman Analyses. Raman spectroscopy was used to detect the nitrate entities and corroborate the presence of uranyl entities. Raman spectra were acquired with a Renishaw InVia spectrometer in microRaman configuration (objective 50×) equipped with a Peltier-cooled CCD detector. The 785 nm excitation line of a LASER diode was used at a power less than 3 mW onto single crystals of the sample to avoid local heating. 19 F and 1H Magic-Angle Spinning Nuclear Magnetic Resonance Spectroscopy. NMR experiments were performed on crushed single crystals with a Bruker Avance spectrometer, with working frequencies of 300.1 and 282.2 MHz for 1H and 19F, respectively. A magic-angle spinning (MAS) probe (Bruker) operating with a 2.5 mm rotor was used. For MAS spectra, a simple sequence was performed with a single π/2 pulse length of 2.0 and 1.9 μs for 1H and 19F, respectively. Recycling times were optimized at 3.0 and 5.0 s for 1H and 19F, respectively. 1H chemical shifts were externally referenced to tetramethylsilane (TMS). 19F chemical shifts were referenced with respect to CFCl3.

Table 1. Crystallographic and Refinement Data chemical formula formula weight temperature wavelength crystal size crystal system space group unit cell dimensions

volume Z density (calculated) absorption coefficient F(000) θ range for data collection index ranges reflections collected independent reflections refinement method function minimized data/restraints/ parameters goodness-of-fit on F2 Δ/σmax final R indices

weighting scheme largest diff. peak and hole

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F13H18NO20Sr3U4 1814.13 g/mol 110(2) K 0.710 73 Å 0.094 × 0.310 × 0.499 triclinic P1̅ a = 10.7882(17) Å b = 10.9194(17) Å c = 13.231(2) Å 1467.8(4) Å3 2 4.105 g/cm3 27.544 mm−1 1568 3.22 to 36.52°

mm

α = 92.565(8)° β = 109.126(8)° γ = 92.764(8)°

−17 ≤ h ≤ 18, −18 ≤ k ≤ 18, −22 ≤ l ≤ 22 236 670 14 296 [R(int) = 0.0705] full-matrix least-squares on F2 ∑w(Fo2 − Fc2)2 14 296/0/443 1.058 3.130 12 657 data; I > 2σ(I) all data

R1 = 0.0311, wR2 = 0.0760 R1 = 0.0397, wR2 = 0.0813 w = 1/[σ2(Fo2) + (0.0443P)2 + 15.4539P] where P = (Fo2 + 2Fc2)/3 6.67 and −3.28 e Å−3

RESULTS AND DISCUSSION Crystal Structure. The asymmetrical unit contains 4 U, 3 Sr, 1 N, 20 O, and 13 F atoms. Each of the four independent U atoms is seven-coordinated by two oxygen and five fluorine atoms in pentagonal bipyramidal environments. The oxygen atoms referred to as uranyl oxygens occupy the apical vertices of the bipyramids, while the fluorines occupy the equatorial positions. The characteristic bond lengths in each U polyhedron are close to those traditionally found for UVIO2F5 pentagonal bipyramids.49 These four uranium polyhedra are connected to each other through fluorine corners to form cyclic tetrameric building blocks (Figure 1), which in turn share

Figure 1. Uranium atom environments and cyclic tetrameric unit (UO2)4F15 in [(UO2)4F13][Sr3(H2O)8](NO3)·1H2O. Atoms are drawn with 50% probability ellipsoids. B

DOI: 10.1021/acs.inorgchem.6b01765 Inorg. Chem. XXXX, XXX, XXX−XXX

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approximately perpendicularly to the [4 0 3] direction, and two adjacent layers are turned upside down and shifted to one another. They are linked by (NO3)− groups that are connected as monodentate and bidentate ligands in the strontium polyhedra, on both sides of each layer. Details of this connection are depicted in Figure 4. This linkage leads to an

alternately F(1)−F(1) and F(9)−F(9) edges along the [1 0−1] direction to form infinite chains ∞1[(UO2 )4 F13] along [−1 1 1]. The three independent Sr atoms are nine-coordinated by fluorine atoms, water molecules, and nitrate groups (Figure 2).

Figure 2. Strontium atom environments (H atoms omitted for clarity. Atoms are drawn with 50% probability ellipsoids).

More accurately, the Sr(1) atom is surrounded by four fluorine atoms, three water molecules, and two oxygen atoms belonging to a bidentate (NO3)− group, in a monocapped square antiprism environment. In this Sr(1) polyhedron the Sr−F distances, ranging from 2.467 to 2.540 Å, are shorter than the Sr−O ones spreading over the 2.586−3.034 Å range. Both Sr(2) and Sr(3) atoms are coordinated by five fluorine atoms, three water molecules, and one oxygen atom from a monodentate nitrate group. These three strontium polyhedra, by sharing triangular faces involving two fluorines and one oxygen, form trimeric structural units, which in turn share alternately F(6)−F(6) and F(13)−F(13) edges along [1−1 0] and [0 1 1] directions, respectively. That generates saw-teeth infinite chains ∞1[Sr3F8(H 2O)8 ], where the oxygen atoms belonging to the nitrate groups complete the Sr coordination polyhedra. Both ∞1[(UO2 )4 F13] and ∞1[Sr3F8(H 2O)8 ] chains alternate along [0 1 0] and are connected to each other by sharing F−F edges to form the ∞2[(UO2 )4 F13][Sr3(H 2O)8 ] layer displayed in Figure 3. The (1 0 1) layers are stacked

Figure 4. Details of the nitrate bridges between the Sr trimeric units. Atoms are drawn with 50% probability ellipsoids.

open framework with one-dimensional (1D) channels running along the [0 1 0] direction and accommodating free water molecules. It is worth noticing that, unlike recent work on uranyl nitrates by Unruh et al.,53 where nitrate groups link readily to the uranium atoms, in our case, the nitrate groups were removed from the coordination of the uranyl ion and substituted by fluorine atoms. Powder X-ray diffraction data on crushed crystals and powder simulation ascertained the purity of the sample used for further analysis.

Figure 3. Overall view of the ∞2[(UO2 )4 F13][Sr3(H 2O)8 ] layer in [(UO2)4F13][Sr3(H2O)8]NO3·1H2O. C

DOI: 10.1021/acs.inorgchem.6b01765 Inorg. Chem. XXXX, XXX, XXX−XXX

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°C (10.7% expt loss/11.9% calcd). Above this temperature, there is a progressive weight loss corresponding to the loss of F atoms. At 1000 °C a mixture of SrUO4 and UO3 has formed, associated with a weight loss of 21.6% close to the theoretical value of 19.8% (Figure 6).

Nuclear Magnetic Resonance Study. Different spinning rates were applied to distinguish between isotropic lines and spinning side bands on 19F MAS spectra; eight isotropic lines (marked with dashed lines in Figure 5a) as well as well-defined

Figure 6. Thermal decomposition of [(UO2)4F13][Sr3(H2O)8](NO3)· 1H2O. The TGA and DTA curves are in red and in blue (dotted line), respectively.

Raman Spectroscopy. The Raman spectrum of a randomly orientated single crystal of the sample is shown in Figure 7. The attributions of the bands, listed in Table 2, were

Figure 5. (a) 19F (various spinning rates) and (b) 1H (30 kHz) MAS NMR spectra. The peaks marked with (°) are spinning sidebands.

corresponding sidebands are found. The chemical shifts are 14.8, 11.1, 6.4, −1.8, −18.4, −57.0, −62.2, and −90.2 ppm. This implies the presence of 4 + 1 groups of 19F nuclei with close environments. Both efficiency of the MAS effect and strong 19F−19F homonuclear dipolar coupling (total linewidth of 600 ppm) mean an ordered neighboring for 19F. The 19F atoms are located in U−Sr layers rather than in the interlayer gap, with no or less effect of spinning for this case. Moreover, motion effect with line narrowing is expected when fluorine nuclei are located in species within the interlayer gap. Such a case is not observed; static spectrum (not shown here) did not exhibit a narrow line in addition to the broad one assigned to overlapping of the eight lines. The interlayer space is indeed composed of water molecules, since no HF molecules are evidenced by 19F NMR. The intense 1H MAS (30 kHz) spectrum is assigned to H2O molecules in the interlayer gap (Figure 5b). Thermal Analyses. TGA and DTA confirm the loss of water molecules and the departure of nitrate groups up to 400

Figure 7. Raman spectrum of a randomly orientated single crystal of the title compound in the 100−1200 cm−1 region.

obtained by simple comparison with the positions and assignments of a zippeite sample K 3 (H 2 O)[(UO 2 ) 4 (SO4)2O3(OH)]54 and a uranyl oxyfluoride [N(C2H5)4]2[(UO2)4(OH2)F10].25 The band at 267 cm−1 could be assigned to the bending mode of UO2+ 2 ion. The two bands at 854 and 863 cm−1 together with the two shoulders at 844 and 849 cm−1 could be attributed to the symmetric stretching mode of UO2+ 2 ion. This could be consistent with the four crystallographically distinct uranium sites in this structure. The single symmetric stretching band of NO−3 ion at 1063 cm−1 is consistent with one crystallographic site. In the study of the zippeite sample, Plasil et al.54 assigned the bands between 100 and 140 cm−1 to U−O−U modes. In our case, the bands in this region could be due to U−F−U modes. Plasil et al. also observed bands between 148 and 222 cm−1, which have been attributed to U−O−sulfate modes. Assuming D

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a long-range order between them. This conclusion holds true with the pentamer U5O22F4, built from a central uranyl hexagonal bipyramid linked to two U2O10F2 dimers through edges.57 The strong tendency to form F−F bridge is confirmed by the examination of 1D structures of uranyl oxyfluoride. The chains present in these compounds are mainly built from UO2F5 entities that share edges to form ∞1[UO2 F3] chains. Up to now this building block has only been observed in organic templated structures.20,22,24 When the chains are obtained with an inorganic cation and/or ammonium, the UO2F5 entities are linked by sharing alternatively corners and edges, seemingly U2O4F8 dimers linked by corners.35−37 With a lower fluorineto-oxygen ratio (F/O = 0.2), the structures are most likely to be constituted of chains of corner-sharing UO5F2 polyhedra, linked by the fluorine atoms. This type of chain is the most common found in systems where oxoanions such as sulfates, selenates or phosphates are present in the coordination of uranium and where the countercation is inorganic or ammonium.58−62 As obtained in this study and in a previous organically templated compound, ∞1[U4O8F13] chains are built from a tetrameric structural unit in which four UO2F5 polyhedra are connected by corner sharing, which are further connected by edge-sharing.24 When an organic template is present, these chains are organized in a purely 1D structure, whereas in the title compound, a pseudo two-dimensional (2D) layered structure is observed. However, Ok et al. have given an example of a pseudo 2D layered structure obtained with N(C2H5)4, where ∞1[(UO2 )3 F9(H 2O)3 ] ribbons are present.25 These chains are composed of tetrameric units built from U2O4F7(H2O) dimers sharing corners with UO2F3(H2O)2 and UO2F5 pentagonal bipyramids. These tetrameric units link to each other through corners to form corrugated chains further linked through edge sharing to form ribbons leading to F/O = 0.91. To describe layered uranyl oxyfluoride topologies, one must start with the uranyl fluoride UO2F2. Its layered structure is based on a tight layer of UO2F6 distorted cubes that share all edges with one another, while all other known layer types are built from pentagonal bipyramids.5 The simplest of those layer types, ∞2[(UO2 )2 F5], is found in (C5H6N)[U2O4F5], where 1 ∞[UO2 F3] chains, as obtained with organic templates, are connected by outer fluorine atoms to their mirror chain.19 In the same manner, tetramers (UO2)4F14, which can be considered as a part of a ∞1[UO2 F3]chain, are the building blocks of (C6H14N2)[(UO2)2F6], connected by two outermost opposite fluorine atoms in a zigzag chain to form the 2 21 In (C4N2H12)2[U2O4F5]4·11H2O, the ∞[(UO2 )2 F6] layer. building block is analogous to the cyclic tetrameric unit found in the title compound, that shares all its outer corner fluorine atoms to form the layer.17 When the uranyl environment is not completely fluorinated (one fluorine atom is replaced by one water molecule), the layer type presents gaps. In M2[(UO2)3F8(H2O)](H2O)3 with M = K or Rb, chains of corner-sharing UO5F2 bipyramids are present. These chains are interlinked by UO2F4(H2O) bipyramids, through fluorine corners to form ∞2[(UO2 )3 F8(H 2O)] layers.32,33 In the 3D ((CH3)4N)[(UO2)2F5] structure obtained with organic templates, orthogonal ∞1[UO2 F3] chains are interconnected by fluorine corners.16,63 Another 3D network was found

Table 2. Positions and Tentative Assignments of the Vibration Bands of a Raman Spectrum of the Title Compound wavenumber/ cm−1

relative intensity (%)

116 135 151 195 233 249 267 367 398 844

15 24 6 10 11 4 12 3 3 31

849 854 863 1063

26 89 100 78

assignment U−F−U modes

U−O−nitrate modes

bending mode ν2(UO2+ 2 ) νas(U−F) νas(U−F) symmetric stretching mode ν1(UO2+ 2 )

νs(NO−3 )

that all things are equal otherwise, the U−O−nitrate modes should be expected approximately in the same range, slightly shifted toward higher wavenumbers. Consequently, the 195, 233, and 249 cm−1 bands could be attributed to U−O−nitrate modes. At last, compared to the uranyl oxyfluoride sample,25 the bands at 367 and 398 cm−1 could be assigned to νas(U−F) and νs(U−F) modes, respectively. Discussion. Uranyl oxyfluoride-bearing compounds display a wide variety of structures, and the investigation of the uranyl environment can help with the understanding of their formation. With only few exceptions, a typical UO 2 F 5 pentagonal bipyramid is at the basis of their U−O−F framework. This is true for the monomers in purely inorganic or NH4+ counter cationic compounds26−31 that display a F/O ratio equal to 2.5. The other zero-dimensional structures can display dimers that present degrees of fluorination varying from F/O = 2 to F/O = 0.2. The fully fluorinated dimer U2O4F8 has been mostly found in inorganic combinations with Ni, Cs, or Rb cations, and only with piperazine in organically templated structures.38−40,17 The unusual U2O4F7(H2O) dimer with a single water molecule substituted for a fluorine is only found with the templating effect of 4,4′-bipyridine in [(UO2)2F8(H2O)2Zn2](4,4′-bpy)2. This surprising dimer is the result of the organic template’s linking to the uranyl oxyfluoride and to Zn polyhedra.23 The uncommon U2O6F6 dimer with two oxygens being substituted for F atoms in opposite equatorial positions of the dimer was found in a single compound bearing the Cs as countercation.34 The dimer U2O8F4 has only been found once in the potassium catena-di-μfluoro−fluorotetraoxodi-μ-sulfato-diuranate hydrate, K2[(UO2F2) (SO4)]H2O, and it is a building block, where the O atoms replace two fluoride atoms in the equatorial plane and are shared with sulfate groups.41 The dimer with the lowest F/O ratio, U2O10F2, has two shared fluorine atoms in the equatorial plane of the uranyl groups and is very common in systems presenting an oxoanion, either chromate or hydrophosphate.55,56 No other arrangement for the oxygen and fluorine atoms has been found, suggesting that the uranyl oxyfluoride dimers will only form with a di-μ-fluoro bridge, regardless of the environment, but with a bias for inorganic systems. All other anionic positions in the equatorial plane of the two uranyl atoms can divided between O and F atoms with E

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in [(UO2)F2(H2O)](H2O)0.571, obtained by the hydrolysis of UO2F2.14 The UO2F2 structure is destroyed by the substitution of water molecules for fluorine, creating nonbridging positions and modifying the uranyl environment from distorded cubes to pentagonal bipyramids. The UO2F4(H2O) bipyramids link through corner involving their four fluorine atoms. The last 3D environment found in the uranyl fluoro peroxide nanocluster, Na6(H2O)[(UO2)24(O2)24F24]Na18(H2O)102,64 is built from hexagonal bipyramids exclusively. This environment is similar to that encountered in U24, one of the nanoclusters reviewed by Qiu et al., but with 24 UO2(O2)2F2 polyhedra in which the usual hydroxyl bridging pair has been replaced by 2 fluorine atoms.65 Up to date, it is the only uranyl fluoro peroxide reported in literature. The main feature in uranyl oxyfluoride topologies is the propensity of the uranyl to adopt the pentagonal bipyramidal environment. The main trend, independently of the dimensionality of uranyl oxyfluoride array, is that the uranyl polyhedra never share a common face but connect through shared F corners or through di-μ-fluoro bridges.

The authors declare no competing financial interest. Further details of the crystal structure of the title compound can be obtained from the ICSD Database by quoting the CSDnumber 431564.

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REFERENCES

(1) Doran, M. B.; Stuart, C. L.; Norquist, A. J.; O’Hare, D. [N2C6H14]2[(UO2)6(H2O)2F2(PO4)2(HPO4)4] 4H2O: A New Microporous Uranium Phosphate Fluoride. Chem. Mater. 2004, 16, 565− 566. (2) Kim, J.-Y.; Norquist, A. J.; O’Hare, D. Variable Dimensionality in the UO2(CH3CO2)2·2H2O/HF/Isonicotinic Acid System: Synthesis and Structures of Zero-, One-, and Two-Dimensional Uranium Isonicotinates. Chem. Mater. 2003, 15, 1970−1975. (3) Chen, W.; Yuan, H.-M.; Wang, J.-Y.; Liu, Z.-Y.; Xu, J.-J.; Yang, M.; Chen, J.-S. Synthesis, Structure, and Photoelectronic Effects of a Uranium−Zinc−Organic Coordination Polymer Containing Infinite Metal Oxide Sheets. J. Am. Chem. Soc. 2003, 125, 9266−9267. (4) Zachariasen, W. Crystal chemical studies of the 5f-series of elements. I. New structure types. Acta Crystallogr. 1948, 1, 265−268. (5) Zachariasen, W. Crystal chemical studies of the 5f-series of elements. III. A study of the disorder in the crystal structure of anhydrous uranyl fluoride. Acta Crystallogr. 1948, 1, 277−281. (6) Zachariasen, W. Crystal chemical studies of the 5f-series of elements. XI. The crystal structure of α-UF5 and of β-UF5. Acta Crystallogr. 1949, 2, 296−298. (7) Zachariasen, W. Crystal chemical studies of the 5f-series of elements. XII. New compounds representing known structure types. Acta Crystallogr. 1949, 2, 388−390. (8) Zachariasen, W. Crystal chemical studies of the 5f-series of elements. XIII. The crystal structure of U2F9 and NaTh2F9. Acta Crystallogr. 1949, 2, 390−393. (9) Otey, M. G.; LeDoux, R. A. U3O5F8A new compound in the UO-F system. J. Inorg. Nucl. Chem. 1967, 29, 2249−2256. (10) Asprey, L. B.; Penneman, R. A. Properties of Uranium (V) in Hydrofluoric Acid Solution; the New Compounds HUF6. 2.5 H2O and HUF6. 1.25 H2O. Inorg. Chem. 1964, 3, 727−729. (11) Paine, R. T.; Ryan, R. R.; Asprey, L. B. Synthesis, characterization, and structure of uranium oxide tetrafluoride. Inorg. Chem. 1975, 14, 1113−1117. (12) Ryan, R. R.; Penneman, R. A.; Asprey, L. B.; Paine, R. T. Singlecrystal X-ray study of β-uranium pentafluoride. The eight coordination of UV. Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1976, B32, 3311−3313. (13) Zadneprovskii, G. M.; Borisov, S. V. Crystal structure of UF4· 2.5 H2O. J. Struct. Chem. 1972, 12, 761−769. (14) Mikhailov, Y. N.; Gorbunova, Y. E.; Stolyarov, I. P.; Moiseev, I. I. A New Modification of Monoaquadifluorouranyl Hydrate. Dokl. Chem. 2001, 380 (4−6), 293−297. (15) Francis, R. J.; Halasyamani, P. S.; Bee, J. S.; O’Hare, D. Variable Dimensionality in the Uranium Fluoride/ 2-Methyl-Piperazine System: Syntheses and Structures of UFO-5, −6, and −7; Zero-, One-, and Two-Dimensional Materials with Unprecedented Topologies. J. Am. Chem. Soc. 1999, 121, 1609−1610. (16) Halasyamani, P. S.; Walker, S. M.; O’Hare, D. The first open framework actinide material (C4N2H12) U2O4F6 (MUF-1). J. Am. Chem. Soc. 1999, 121, 7415−7416. (17) Walker, S. M.; Halasyamani, P. S.; Allen, S.; O’Hare, D. From Molecules to Frameworks: Variable Dimensionality in the UO2(CH3COO)2·2H2O/HF(aq)/Piperazine System. Syntheses, Structures, and Characterization of Zero-Dimensional (C4N2H12)UO2F4· 3H2O, One-Dimensional (C4N2H12)2U2F12·H2O, Two-Dimensional

CONCLUSION We have synthesized a new hydrated strontium uranium oxyfluoride nitrate, [(UO2) 4 F13][Sr 3 (H2O)8 ](NO3 )·H2O, which is obtained as a pure phase under hydrothermal conditions. Its crystal structure may be regarded as built from 2 ∞[(UO2 )4 F13][Sr3(H 2O)8 ] corrugated layers containing unusual cyclic tetrameric [(UO2)4F15] building blocks only found in one oxyfluoride compound, (C4N2H12)2[U2O4F5]4·11H2O, where the presence of bridging fluorine between two opposite uranium bipyramids brings out the folding of the layers. The 3D framework of [(UO2)4F13][Sr3(H2O)8](NO3)·H2O results from the linkage of the ∞2[(UO2 )4 F13][Sr3(H 2O)8 ] layers by (NO3)− groups exclusively coordinated to strontium. That results in 1D channels running along the [010] direction, which accommodates free water molecules. On heating, [(UO2)4F13][Sr3(H2O)8](NO3)·1H2O decomposes by losing water, nitrate, and fluoride, and a mixture of SrUO4 and UO3 is left above 1000 °C. A comparison between the crystal structures of [(UO2)4F13][Sr3(H2O)8](NO3)·H2O and the different uranyl oxyfluoride reported in literature reveals that uranium, in such types of compounds, is almost exclusively found in a pentagonal bipyramidal environment, whatever the structural building unit and the structural arrangement. Depending on the ligand competing with fluoride in the uranium coordination, the uranyl oxyfluoride compounds display a wide range of degrees of fluorination, varying types of linkage by corner- or edgesharing and the dimensionality of the structural arrangement, opening a field of research that needs further investigations. ASSOCIATED CONTENT

* Supporting Information S

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.6b01765. X-ray crystallographic information (CIF)

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ACKNOWLEDGMENTS

UBP-START for the use of the X-ray diffraction facility in Clermont-Ferrand.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: laurent.jouff[email protected]. F

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Inorganic Chemistry (C4N2H12)2(U2O4F5)4·11H2O, and Three-Dimensional (C4N2H12)U2O4F6. J. Am. Chem. Soc. 1999, 121, 10513−10521. (18) Allen, S.; Barlow, S.; Halasyamani, P. S.; Mosselmans, J. F. W.; O’Hare, D.; Walker, S. M.; Walton, R. I. Hydrothermal Synthesis of (C6N2H14)2(UVI2UIVO4F12), a Mixed-Valent One-Dimensional Uranium Oxyfluoride. Inorg. Chem. 2000, 39, 3791−3798. (19) Talley, C. E.; Bean, A. C.; Albrecht-Schmitt, T. E. Hydrothermal Syntheses of Layered Uranium Oxyfluorides: Illustrations of Dimensional Reduction. Inorg. Chem. 2000, 39, 5174−5175. (20) Almond, P. M.; Talley, C. E.; Bean, A. C.; Peper, S. M.; Albrecht-Schmitt, T. E. Hydrothermal Syntheses, Structures, and Fluorescence Spectroscopy of New One-Dimensional Uranium Oxyfluorides Built from Edge-Sharing [UO2F5] Pentagonal Bipyramids. J. Solid State Chem. 2000, 154, 635−641. (21) Cahill, C. L.; Burns, P. C. Building Unit and Topological Evolution in the Hydrothermal DABCO-U-F System. Inorg. Chem. 2001, 40, 1347−1351. (22) Wang, C.-M.; Liao, C.-H.; Lin, H.-M.; Lii, K.-H. [N(CH2CH2NH3)3][U3O2F13]·2H2O: A Novel Organically Templated Mixed-Valent Uranium Oxyfluoride with a Hybrid Network Structure. Inorg. Chem. 2004, 43, 8239−8241. (23) Wang, C.-M.; Liao, C.-H.; Kao, H.-M.; Lii, K.-H. Hydrothermal Synthesis and Characterization of [(UO2)2F8(H2O)2Zn2(4,4‘-bpy)2]· (4,4‘-bpy), a Mixed-Metal Uranyl Aquofluoride with a Pillared Layer Structure. Inorg. Chem. 2005, 44, 6294−6298. (24) Wu, H.; Yang, X.; Li, Y.; Yang, W. Syntheses, structures and luminescent properties of two one-dimensional uranium oxyfluorides. Inorg. Chem. Commun. 2012, 23, 46−49. (25) Ok, K. M.; O’Hare, D. Two- and Three-Dimensional OpenFramework Uranium Arsenates: Synthesis, Structure, and Characterization. J. Solid State Chem. 2007, 180 (2), 446−452. (26) Fawcett, J.; Holloway, J. H.; Laycock, D.; Russell, D. R. Fluoride ion donor properties of UF2O2; preparation and characterization of the adducts UF2O2 nSbF, (n = 2 or 3) and crystal structure of UF2O2 3SbF. J. Chem. Soc., Dalton Trans. 1982, 1355−1360. (27) Brusset, H.; Gillier-Pandraud, H.; Dao, N.-Q. Etude structurale du pentafluoxyuranate d’ammonium. Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1969, B25, 67−73. (28) Mikhailov, Yu.N.; Udovenko, A. A.; Kuznetsov, V. G.; Davidovich, R. L. The crystal structure of K5(UO2)2F9. J. Struct. Chem. 1973, 13 (4), 694−694. (29) Lychev, A. A.; Mashirov, L. G.; Smolin, Yu.I.; Shepelev, Yu.F. Refinement of K3UO2F5 crystal structure. Radiokhimiya 1986, 28, 682−685. (30) Zachariasen, W. Crystal chemical studies of the 5f-series of elements. XX. The crystal structure of tripotassium uranyl fluoride. Acta Crystallogr. 1954, 7, 783−787. (31) Bougon, R.; Fawcett, J.; Holloway, J. H.; Russell, D. R. Interaction between uranium tetrafluoride oxide and antimony pentafluoride ; fluorine-19 nuclear magnetic preparation and characterization of the adducts UF4O nSbF, and catechol in aqueous solution resonance investigations in solution ; (n = 1−3) and crystal structure of UF4O 2SbF. J. Chem. Soc., Dalton Trans. 1979, 1881−1885. (32) Mikhailov, Yu.N.; Ivanov, S. B.; Kuznetsov, V. G.; Davidovich, R. L. X-ray diffraction study of rubidium aquaoctafluorotriuranate trihydrate (Rb2[UO2)3F8(H2O)].3H2O). Koordinatsionnaya Khimiya (Coordination Chemistry (USSR)) 1976, 2, 95−98. (33) Dao, N. Q.; Chourou, S.; Rodier, N.; Bastein, P. Chimie minerale.- Structure cristalline de monoaquo-octafluoro-triuranylate de potassium trihydrate K2((UO2)3F8(H2O))(H2O)3. Comptes Rendus Hebdomadaires des Séances de l’Académie des Sciences, Série C, Sciences Chimiques 1979, 289, 405−408. (34) Mikhailov, Yu.N.; Ivanov, S. B.; Sadikov, G. G. Redetermination of the crystal structure of Cs2((UO2)2F6(H2O)2). Koordinatsionnaya Khimiya (Coordination Chemistry (USSR)) 1979, 5, 1702−1705. (35) Dao, N.-Q.; Chourou, S.; Heckly, J. The crystal structure and some physico-chemical properties of the compound Na3(UO2)2F7· 6H2O. J. Inorg. Nucl. Chem. 1981, 43, 1835−1839.

(36) Mikhailov, Yu.N.; Gorbunova, Yu.E.; Mit’kovskaya, E. V.; Serezhkina, L. B.; Serezhkin, V. N. Crystal structure of Rb[UO2(SO4)F]. Radiokhimiya 2002, 44, 290−292. (37) Ivanov, S. B.; Mikhailov, Yu.N.; Kuznetsov, V. G.; Davidovich, R. L. Crystal structure of Cs2(NH4)[(UO2)2F7]. Koordinatsionnaya Khimiya (Coordination Chemistry (USSR)) 1980, 6, 1746−1750. (38) Ivanov, S. B.; Mikhailov, Yu.N.; Kuznetsov, V. G.; Davidovich, R. L. Crystal structure of Ni3[(UO2)2F7]2 18H2O. Zhurnal Strukturnoi Khimii 1981, 22, 188−191. (39) Dao, N.-Q. Structure cristalline de Cs2UO2F4.H2O. Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1972, B28, 2011−2015. (40) Ivanov, S. B.; Mikhailov, Yu.N.; Davidovich, R. L.; et al. The crystal structure of nickel tetrafluorodooxouranate heptahydrate. Koordinatsionnaya Khimiya (Coordination Chemistry (USSR)) 1982, 8, 1250−1255. (41) Brusset, H.; Dao, N. Q.; Rubinstein-Auban, A. Structure cristalline de Rb2UO2F4.H2O. Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1972, B28, 2617−2619. (42) Alcock, N. W.; Roberts, M. M.; Chakravorti, M. C. Structure of potassium catena-di-μ-fluoro-difluorotetraoxo-di-μ-sulphato-diuranate(VI) hydrate. Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1980, 36, 687−690. (43) Dubois, M.; Dieudonné, B.; Mesbah, A.; Bonnet, P.; El-Ghozzi, M.; Renaudin, G.; Avignant, D. Stabilization of Th3+ ions into mixedvalence thorium fluoride. J. Solid State Chem. 2011, 184, 220. (44) Oudahmane, A.; El-Ghozzi, M.; Jouffret, L.; Avignant, D. Single crystal structures of thallium (I) thorium fluorides and crystal chemistry of monovalent tetravalent cation pentafluorides. J. Solid State Chem. 2015, 232, 73−78. (45) Bruker. APEX2; Bruker AXS Inc: Madison, WI, 2012. (46) Bruker. SAINT; Bruker AXS Inc: Madison, WI, 2012. (47) Bruker. SADABS; Bruker AXS Inc: Madison, WI, 2012. (48) Sheldrick, G. M. Crystal structure refinement with SHELXL. Acta Crystallogr., Sect. C: Struct. Chem. 2015, C71, 3. (49) Burns, P. C.; Ewing, R. C.; Hawthorne, F. C. The crystal chemistry of hexavalent uranium: polyhedron geometries, bondvalence parameters, and polymerization of polyhedra. Can. Mineral. 1997, 35, 1551−1570. (50) Brese, N. E.; O’Keeffe, M. Bond-Valence Parameters for Solids. Acta Crystallogr., Sect. B: Struct. Sci. 1991, B47, 192−197. (51) Zachariasen, W. Bond lengths in oxygen and halogen compounds of d and f elements. J. Less-Common Met. 1978, 62, 1−8. (52) Brown, I. D. Indicated as Private communication to JANA2006 authors: Petricek, V.; Dusek, M.; Palatinus, L., 2014. (53) Unruh, D. K.; Baranay, M.; Baranay, M.; Burns, P. C. Uranium(VI) Tetraoxido Core Coordinated by Bidentate Nitrate. Inorg. Chem. 2010, 49, 6793−6795. (54) Plásǐ l, J.; Buixaderas, E.; Č ejka, J.; Sejkora, J.; Jehlička, J.; Novák, M. , Raman spectroscopic study of the uranyl sulphate mineral zippeite: low wavenumber and U−O stretching regions. Anal. Bioanal. Chem. 2010, 397 (7), 2703−2715. (55) Serezhkin, V. N.; Peresypkina, E. V.; Novikov, S. A.; Virovets, A. V.; Serezhkina, L. B. New fluorochromatouranylates of alkali metals: Synthesis and structure. Russ. J. Inorg. Chem. 2014, 59, 788−797. (56) Ok, K. M.; Baek, J.; Halasyamani, P. S.; O’Hare, D. New Layered Uranium Phosphate Fluorides: Syntheses, Structures, Characterizations, and Ion-Exchange Properties of A(UO2)F(HPO4)· xH2O (A = Cs+, Rb+, K+; x = 0−1). Inorg. Chem. 2006, 45, 10207. (57) Deifel, N. P.; Holman, K. T.; Cahill, C. L. PF6− Hydrolysis as a route to unique uranium phosphate materials. Chem. Commun. 2008, 6037. (58) Serezhkin, V. N.; Soldatkina, M. A. Crystal structure of NH4[UO2SO4F]. Koordinatsionnaya Khimiya (Coordination Chemistry (USSR)) 1985, 11 (1), 103−105. (59) Blatov, V. A.; Serezhkina, L. B.; Serezhkin, V. N.; Trunov, V. K. The Crystal Structure of NH4UO2F(SeO4)H2O. Russ. J. Inorg. Chem. 1989, 34, 91−92. G

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Article

Inorganic Chemistry (60) Mikhailov, Yu.N.; Gorbunova, Yu.E.; Mit’kovskaya, E. V.; Serezhkina, L. B.; Serezhkin, V. N. Crystal Structure of Rb[UO2(SO4)F]. Radiokhimiya 2002, 44, 290−292. (61) Ling, J.; Wu, S.; Simonetti, A.; Shafer, J. T.; Albrecht-Schmitt, T. E.; Chen, F. Does Iodate Incorporate into Layered Uranyl Phosphates Under Hydrothermal Conditions? Inorg. Chem. 2009, 48, 10995− 11001. (62) Serezhkina, L. B.; Vologzhanina, A. V.; Verevkin, A. G.; Serezhkin, V. N. An X-ray Diffraction Study of Rb[UO2(SeO4)F]· H2O. Radiochemistry 2011, 53, 354−357. (63) Ok, K. M.; Doran, M. B.; O’Hare, D. [N(CH3)4][(UO2)2F5]: A new organically templated open-framework uranium oxide fluoride (MUF-2). J. Mater. Chem. 2006, 16, 3366−3368. (64) Zanonato, P. L.; Di Bernardo, P.; Fischer, A.; Grenthe, I. Chemical equilibria in the UO22+-H2O2-F−/OH− systems and possible solution precursors for the formation of [Na6(OH2)8]@[UO2(O2)F]2418‑ and [Na6(OH2)8]@[UO2(O2)OH]2418‑ clusters. Dalton Trans. 2013, 42, 10129−10137. (65) Qiu, J.; Burns, P. C. Clusters of Actinides with Oxide, Peroxide, or Hydroxide Bridges. Chem. Rev. 2013, 113, 1097.

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DOI: 10.1021/acs.inorgchem.6b01765 Inorg. Chem. XXXX, XXX, XXX−XXX