Poly[di­ammonium [di­aqua­(μ7-benzene-1,2,3,4,5,6-hexa­carboxyl­ato)tetra­oxido­diuranium(VI)]]

Cantos, P.M.; Cahill, C.L.

doi:10.1107/S1600536814006047

metal-organic compounds

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ISSN: 2056-9890

Volume 70| Part 4| April 2014| Pages m142-m143

doi:10.1107/S1600536814006047

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Poly[diammonium [diaqua(μ₇-benzene-1,2,3,4,5,6-hexacarboxylato)tetraoxidodiuranium(VI)]]

Paula M. Cantos ^a and Christopher L. Cahill ^a ^*

^aDepartment of Chemistry, The George Washington University, 725 21st St NW, Washington, DC 20052, USA
^*Correspondence e-mail: cahill@gwu.edu

(Received 17 December 2013; accepted 18 March 2014; online 22 March 2014)

Uranyl-carboxylate hybrid materials dominate the catalog of uranyl compounds owing in part to the affinity between COO⁻ functional groups and UO₂²⁺. Polycarboxylate organic ligands may present a degree of steric hindrance and could thus influence the resulting uranyl topology. Single crystals of the title compound, {(NH₄)₂[(UO₂)₂(C₁₂O₁₂)(H₂O)₂]}_n, were synthesized hydrothermally as a result of reacting uranyl nitrate with benzene-1,2,3,4,5,6-hexacarboxylic acid (mellitic acid). The structure is comprised of a single unique monomeric uranyl cation adopting a pentagonal bipyramidal geometry. The uranyl coordination sphere is composed of four O atoms originating from one half of a fully deprotonated mellitic acid ligand and a single water molecule. The observed axial U—O bonds display an average distance of 1.765 (8) Å, whereas equatorial O atoms are found at an average distance of 2.40 (5) Å. All uranium–oxygen bond lengths are in good agreement with literature values. Furthermore, the coordination between the uranyl pentagonal bipyramids and the mellitic acid anion constructs a three-dimensional anionic framework which is charge-balanced with ammonium cations. Additional stabilization of the structure is provided by O—H⋯O and N—H⋯O hydrogen bonding interactions between the components.

CCDC reference: 992448

Related literature

Experimental

Crystal data

(NH₄)₂[(UO₂)₂(C₁₂O₁₂)(H₂O)₂]
M_r = 948.29
Monoclinic, P 2₁ /c
a = 8.0083 (4) Å
b = 10.2948 (6) Å
c = 11.7481 (6) Å
β = 99.733 (1)°
V = 954.62 (9) Å³
Z = 2
Mo Kα radiation
μ = 17.05 mm⁻¹
T = 100 K
0.4 × 0.3 × 0.2 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1999 ) T_min = 0.467, T_max = 0.746
18160 measured reflections
2912 independent reflections
2398 reflections with I > 2σ(I)
R_int = 0.036

Refinement

R[F² > 2σ(F²)] = 0.017
wR(F²) = 0.035
S = 1.04
2698 reflections
178 parameters
All H-atom parameters refined
Δρ_max = 1.02 e Å⁻³
Δρ_min = −0.98 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O9—H6⋯O4ⁱ	0.74 (5)	2.02 (5)	2.700 (3)	152 (5)
O9—H5⋯O6ⁱⁱ	0.91 (6)	1.88 (5)	2.744 (3)	158 (4)
O9—H5⋯O7	0.91 (6)	2.38 (5)	2.884 (3)	115 (4)
N1—H3⋯O2ⁱⁱⁱ	0.81 (5)	2.12 (5)	2.908 (4)	165 (5)
N1—H1⋯O5^iv	0.85 (4)	2.36 (4)	2.990 (4)	131 (3)
N1—H1⋯O6^v	0.85 (4)	2.29 (4)	2.905 (4)	130 (3)
N1—H4⋯O7	0.94 (5)	1.94 (5)	2.851 (4)	162 (5)
Symmetry codes: (i) $[x, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[x+1, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (iii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) -x+1, -y+1, -z; (v) x+1, y, z.

Data collection: APEX2 (Bruker, 2008 ); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CrystalMaker (CrystalMaker, 2009 ) and ORTEP-3 (Burnett & Johnson 1996 ); software used to prepare material for publication: WinGX (Farrugia, 2012 ).

Supporting information

CCDC reference: 992448

Crystal structure: contains datablocks I, publication_text. DOI: 10.1107/S1600536814006047/gg2133sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536814006047/gg2133Isup2.hkl

checkCIF report

Comment top

The portfolio of uranyl hybrid materials displays diverse architectures, which may be attributed to the modification of synthetic parameters, especially varying the organic ligand. The literature provides prior studies focused on the reaction of the uranyl cation with a series of related organic ligands, typically decorated with carboxylate functional groups, in order to observe an influence on overall topology. The position of carboxylic acids on an aromatic ligand, such as those on mellitic acid, allows one to investigate the steric influence of multiple functional groups on the local and the global architecture of a UO₂²⁺ hybrid material. Indeed, other f-block homo- and heterometallic mellitic acid compounds have been reported in the literature. Li et al., (2006); Tang et al., (2008); Taylor et al., (2008); Chui et al., (2001); Han et al., (2012); Mihalcea et al., (2012); Volkringer et al., (2012).

The title coordination polymer was synthesized hydrothermally and contains a pentagonal monomer (U1) of the uranyl mellitic hybrid material contains typical U=O axial bond distances to O1 and O2 (1.760 (2) and 1.771 (2) Å, respectively) Burns (2005). Three mellitic acid molecules bind to U1: O3 and O8 bond in a monodentate fashion, while O4 and O5 participate in a pseudo-bidentate mode. An oxygen atom (O9) from a water molecule completes the local coordination sphere of U1 yielding a distance of 2.452 (2) Å. The rotation of carboxylate functional groups are a direct consequence of sterics within (NH₄)₂[(UO₂)₂(C₁₂O₁₂)(H₂O)₂]. The proximity of adjacent carboxylate groups O5—C6—O6 and O4—C1—O3 located on the benzene ring prompts a rotation of these functional groups (yielding torsion angles of 50.62° and 67.27°, respectively), thus connecting both to U1 while O4—C1—O3 further bonds to U1ⁱ. Similarly, O8ⁱⁱ—C5ⁱⁱ—O7ⁱⁱ bonds to U1ⁱⁱ and extends the formation of channels along the [100] direction as seen in Figure 2.

Related literature top

The background literature for uranyl aromatic, carboxylate coordination polymers is extensive: Go et al. (2007); Andrews & Cahill (2012); Frisch & Cahill (2006); Rowland & Cahill (2010); Couston et al. (1995); Severance et al. (2011); Mihalcea et al. (2012); Thuery (2009); Leciejewicz et al. (1995). For related uranyl mellitic complexes, see: Volkringer et al. (2012). For f-block homo- and heterometallic mellitic acid compounds, see: Li et al. (2006); Tang et al. (2008); Taylor et al. (2008); Chui et al. (2001); Han et al. (2012); Mihalcea et al. (2012); Volkringer et al. (2012). For typical U=O bond lengths, see: Burns (2005). Scheme - The scheme should show the correct repeating unit in brackets, i.e. either the asymmetric unit or (better) one mellitic acid anion, two uranyl units (with water molecules) and two ammonium cations. When doing so, the carboxylate groups should be shown with delocalised bonds. Furthermore, all O atoms of the ligand should have bonds outside the bracket; this is also true for all O atoms (except water and uranyl) of the pentagonal bipyramid.

Experimental top

Caution! Whereas the uranium oxynitrate hexahydrate, (UO₂)(NO₃)₂·H₂O, used in this investigation contains depleted uranium, standard precautions for handling radioactive substances should be followed. Uranium nitrate was recrystallized from a mixture of uranyl nitrate and uranyl oxide dissolved in concentrated nitric acid. Powder X-ray diffraction confirmed the formation of uranium oxinitrate hexahydrate. (PDF-#27–0936). Mellitic acid was commercially available and used without any further purification. Uranium oxynitrate hexahydrate (0.146 g, 0.29 mmol), mellitic acid (0.050 g, 0.14 mmol), and deionized water (1.5 ml, 83.2 mmol) were placed into a 23 ml Teflon-lined Parr bomb. Concentrated ammonium hydroxide was used to adjust the pH (pHi = 4.38). The vessel was sealed and heated statically at 150°C for three days. Yellow prismatic crystals were obtained. Phase purity was confirmed via powder X-ray diffraction data patterns. Calculated and observed elemental analysis results (Galbraith Laboratories, Knoxville, Tennessee, USA) of 1 agreed, confirming the contents of the material [observed (calculated): C 1.47% (1.51%), H < 0.5% (0.10%), N < 0.5% (0.25%)].

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CrystalMaker (CrystalMaker, 2009) and ORTEP-3 (Burnett & Johnson 1996); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures top

	Fig. 1. The ORTEP representation of an asymmetric unit of (NH₄)₂[(UO₂)₂(C₁₂O₁₂)(H₂O)₂]. The ellipsoids are shown at the 50% level and the hydrogen atoms have been removed for clarity. [Symmetry codes: (i) x,-y + 3/2,z - 1/2; (ii) x,-y + 3/2,z + 1/2; (iii) -x,-y + 1,-z + 1; (iv) -x + 1,y + 1/2,-z + 1/2; and (v) -x + 1,y - 1/2,-z + 1/2].
	Fig. 2. Polyhedral representation of the channels down the [100] in 1. Yellow polyhedra represent uranium atoms; and red spheres, oxygen atoms. Hydrogen atoms and charge balancing NH₄ molecules have been removed for clarity.

Poly[diammonium [diaqua(µ₇-benzene-1,2,3,4,5,6-hexacarboxylato)tetraoxidodiuranium(VI)]] top

Crystal data top

(NH₄)₂[(UO₂)₂(C₁₂O₁₂)(H₂O)₂]	F(000) = 852
M_r = 948.29	D_x = 3.299 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 18686 reflections
a = 8.0083 (4) Å	θ = 7.0–60.6°
b = 10.2948 (6) Å	µ = 17.05 mm⁻¹
c = 11.7481 (6) Å	T = 100 K
β = 99.733 (1)°	Rods, yellow
V = 954.62 (9) Å³	0.4 × 0.3 × 0.2 mm
Z = 2

Data collection top

Bruker APEXII CCD diffractometer	2912 independent reflections
Radiation source: fine-focus sealed tube	2398 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.036
ω scans	θ_max = 30.5°, θ_min = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1999)	h = −11→8
T_min = 0.467, T_max = 0.746	k = −14→14
18160 measured reflections	l = −16→16

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.017	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.035	All H-atom parameters refined
S = 1.04	w = 1/[σ²(F_o²) + (0.0125P)² + 1.2966P] where P = (F_o² + 2F_c²)/3
2698 reflections	(Δ/σ)_max = 0.001
178 parameters	Δρ_max = 1.02 e Å⁻³
0 restraints	Δρ_min = −0.98 e Å⁻³

Crystal data top

(NH₄)₂[(UO₂)₂(C₁₂O₁₂)(H₂O)₂]	V = 954.62 (9) Å³
M_r = 948.29	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 8.0083 (4) Å	µ = 17.05 mm⁻¹
b = 10.2948 (6) Å	T = 100 K
c = 11.7481 (6) Å	0.4 × 0.3 × 0.2 mm
β = 99.733 (1)°

Data collection top

Bruker APEXII CCD diffractometer	2912 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1999)	2398 reflections with I > 2σ(I)
T_min = 0.467, T_max = 0.746	R_int = 0.036
18160 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.017	0 restraints
wR(F²) = 0.035	All H-atom parameters refined
S = 1.04	Δρ_max = 1.02 e Å⁻³
2698 reflections	Δρ_min = −0.98 e Å⁻³
178 parameters

Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > 2σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
U1	0.412520 (13)	0.721169 (10)	0.152007 (9)	0.00526 (4)
O1	0.5032 (3)	0.5786 (2)	0.10655 (18)	0.0103 (4)
O2	0.3232 (3)	0.8648 (2)	0.19911 (18)	0.0091 (4)
O3	0.2643 (3)	0.6031 (2)	0.28641 (18)	0.0082 (4)
O5	0.1465 (3)	0.6550 (2)	0.05335 (18)	0.0083 (4)
O4	0.3585 (3)	0.7973 (2)	−0.04722 (18)	0.0096 (4)
O8	0.6415 (3)	0.8435 (2)	0.10897 (18)	0.0112 (4)
O9	0.6149 (3)	0.7076 (2)	0.3302 (2)	0.0125 (5)
O7	0.8885 (3)	0.7764 (2)	0.21059 (19)	0.0112 (4)
O6	−0.1157 (3)	0.6646 (2)	−0.04255 (18)	0.0093 (4)
C1	0.2569 (4)	0.6268 (3)	0.3903 (2)	0.0065 (6)
C2	0.1216 (4)	0.5613 (3)	0.4453 (2)	0.0050 (5)
C3	0.0179 (4)	0.6342 (3)	0.5063 (2)	0.0054 (5)
C5	0.8015 (4)	0.8427 (3)	0.1337 (2)	0.0069 (5)
C4	0.1018 (4)	0.4272 (3)	0.4383 (2)	0.0064 (6)
C6	0.0162 (4)	0.7181 (3)	0.0055 (2)	0.0065 (5)
N1	0.8845 (4)	0.5051 (3)	0.1615 (3)	0.0107 (5)
H1	0.852 (5)	0.507 (4)	0.089 (4)	0.022 (11)*
H2	0.980 (6)	0.463 (4)	0.185 (4)	0.031 (13)*
H3	0.813 (6)	0.468 (4)	0.190 (4)	0.030 (13)*
H4	0.905 (6)	0.590 (5)	0.190 (4)	0.035 (13)*
H6	0.571 (6)	0.706 (4)	0.381 (4)	0.031 (14)*
H5	0.716 (7)	0.748 (5)	0.355 (4)	0.041 (14)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
U1	0.00418 (6)	0.00674 (6)	0.00524 (5)	−0.00009 (4)	0.00189 (4)	0.00013 (4)
O1	0.0106 (11)	0.0116 (11)	0.0092 (10)	0.0035 (9)	0.0032 (8)	0.0001 (8)
O2	0.0094 (11)	0.0093 (11)	0.0096 (10)	−0.0007 (8)	0.0045 (8)	−0.0028 (8)
O3	0.0085 (11)	0.0096 (10)	0.0069 (10)	−0.0019 (8)	0.0023 (8)	−0.0015 (8)
O5	0.0059 (10)	0.0079 (10)	0.0106 (10)	0.0008 (8)	−0.0001 (8)	0.0004 (8)
O4	0.0090 (11)	0.0132 (11)	0.0073 (10)	0.0058 (8)	0.0034 (8)	0.0035 (8)
O8	0.0062 (11)	0.0136 (11)	0.0141 (11)	−0.0020 (9)	0.0027 (8)	0.0039 (9)
O9	0.0083 (12)	0.0229 (14)	0.0068 (11)	−0.0051 (10)	0.0026 (9)	0.0000 (9)
O7	0.0112 (11)	0.0108 (11)	0.0118 (11)	0.0005 (9)	0.0029 (9)	0.0057 (9)
O6	0.0091 (11)	0.0083 (10)	0.0103 (10)	0.0009 (9)	0.0011 (8)	0.0003 (9)
C1	0.0055 (14)	0.0061 (14)	0.0081 (13)	0.0026 (11)	0.0014 (11)	0.0018 (10)
C2	0.0024 (13)	0.0100 (14)	0.0027 (12)	−0.0001 (11)	0.0005 (10)	−0.0005 (10)
C3	0.0047 (13)	0.0054 (13)	0.0055 (13)	0.0001 (10)	−0.0005 (10)	−0.0001 (10)
C5	0.0099 (14)	0.0047 (13)	0.0074 (13)	−0.0004 (11)	0.0056 (11)	−0.0023 (11)
C4	0.0040 (14)	0.0094 (14)	0.0061 (13)	0.0015 (11)	0.0016 (10)	−0.0001 (11)
C6	0.0062 (14)	0.0082 (14)	0.0065 (13)	−0.0007 (11)	0.0048 (10)	0.0005 (11)
N1	0.0113 (15)	0.0110 (14)	0.0108 (14)	0.0006 (11)	0.0045 (11)	0.0019 (11)

Geometric parameters (Å, º) top

U1—O1	1.760 (2)	O6—C6	1.240 (4)
U1—O2	1.771 (2)	C1—O4ⁱⁱ	1.269 (4)
U1—O5	2.348 (2)	C1—C2	1.510 (4)
U1—O8	2.349 (2)	C2—C4	1.391 (4)
U1—O9	2.425 (2)	C2—C3	1.402 (4)
U1—O4	2.437 (2)	C3—C4ⁱⁱⁱ	1.397 (4)
U1—O3	2.452 (2)	C3—C6ⁱⁱ	1.520 (4)
O3—C1	1.256 (4)	C5—C4^iv	1.514 (4)
O5—C6	1.276 (4)	C4—C3ⁱⁱⁱ	1.397 (4)
O4—C1ⁱ	1.269 (3)	C4—C5^v	1.514 (4)
O8—C5	1.264 (4)	C6—C3ⁱ	1.520 (4)
O7—C5	1.247 (4)

O1—U1—O2	179.34 (10)	C6—O5—U1	132.53 (19)
O1—U1—O5	89.70 (9)	C1ⁱ—O4—U1	138.25 (19)
O2—U1—O5	90.90 (9)	C5—O8—U1	138.1 (2)
O1—U1—O8	90.27 (9)	O3—C1—O4ⁱⁱ	123.4 (3)
O2—U1—O8	89.48 (9)	O3—C1—C2	119.0 (3)
O5—U1—O8	136.52 (7)	O4ⁱⁱ—C1—C2	117.6 (2)
O1—U1—O9	87.94 (9)	C4—C2—C3	119.3 (3)
O2—U1—O9	91.41 (9)	C4—C2—C1	120.1 (3)
O5—U1—O9	145.87 (8)	C3—C2—C1	120.6 (3)
O8—U1—O9	77.55 (8)	C4ⁱⁱⁱ—C3—C2	120.5 (3)
O1—U1—O4	89.55 (8)	C4ⁱⁱⁱ—C3—C6ⁱⁱ	116.7 (2)
O2—U1—O4	90.93 (8)	C2—C3—C6ⁱⁱ	122.5 (3)
O5—U1—O4	67.67 (7)	O7—C5—O8	126.2 (3)
O8—U1—O4	68.85 (7)	O7—C5—C4^iv	116.3 (3)
O9—U1—O4	146.29 (8)	O8—C5—C4^iv	117.5 (3)
O1—U1—O3	92.95 (9)	C2—C4—C3ⁱⁱⁱ	120.1 (3)
O2—U1—O3	86.99 (8)	C2—C4—C5^v	122.6 (3)
O5—U1—O3	71.12 (7)	C3ⁱⁱⁱ—C4—C5^v	117.2 (3)
O8—U1—O3	152.22 (7)	O6—C6—O5	123.0 (3)
O9—U1—O3	75.01 (8)	O6—C6—C3ⁱ	117.0 (3)
O4—U1—O3	138.70 (7)	O5—C6—C3ⁱ	120.0 (3)
C1—O3—U1	129.60 (19)

Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) x, −y+3/2, z+1/2; (iii) −x, −y+1, −z+1; (iv) −x+1, y+1/2, −z+1/2; (v) −x+1, y−1/2, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O9—H6···O4ⁱⁱ	0.74 (5)	2.02 (5)	2.700 (3)	152 (5)
O9—H5···O6^vi	0.91 (6)	1.88 (5)	2.744 (3)	158 (4)
O9—H5···O7	0.91 (6)	2.38 (5)	2.884 (3)	115 (4)
N1—H3···O2^v	0.81 (5)	2.12 (5)	2.908 (4)	165 (5)
N1—H1···O5^vii	0.85 (4)	2.36 (4)	2.990 (4)	131 (3)
N1—H1···O6^viii	0.85 (4)	2.29 (4)	2.905 (4)	130 (3)
N1—H4···O7	0.94 (5)	1.94 (5)	2.851 (4)	162 (5)

Symmetry codes: (ii) x, −y+3/2, z+1/2; (v) −x+1, y−1/2, −z+1/2; (vi) x+1, −y+3/2, z+1/2; (vii) −x+1, −y+1, −z; (viii) x+1, y, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O9—H6···O4ⁱ	0.74 (5)	2.02 (5)	2.700 (3)	152 (5)
O9—H5···O6ⁱⁱ	0.91 (6)	1.88 (5)	2.744 (3)	158 (4)
O9—H5···O7	0.91 (6)	2.38 (5)	2.884 (3)	115 (4)
N1—H3···O2ⁱⁱⁱ	0.81 (5)	2.12 (5)	2.908 (4)	165 (5)
N1—H1···O5^iv	0.85 (4)	2.36 (4)	2.990 (4)	131 (3)
N1—H1···O6^v	0.85 (4)	2.29 (4)	2.905 (4)	130 (3)
N1—H4···O7	0.94 (5)	1.94 (5)	2.851 (4)	162 (5)

Symmetry codes: (i) x, −y+3/2, z+1/2; (ii) x+1, −y+3/2, z+1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) −x+1, −y+1, −z; (v) x+1, y, z.

Acknowledgements

The study was funded by the Office of Basic Energy Sciences of the US Department of Energy as part of the Materials Science of Actinides Energy Frontier Research Center (grant No. DE-SC0001089).

References

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