Structure of uranium(VI) oxide dihydrate, UO₃·2H₂O; synthetic meta-schoepite (UO₂)₄O(OH)₆·5H₂O

The structure of uranium oxide dihydrate, also known as meta-schoepite (UO₂)₄O(OH)₆·5H₂O, has been determined from a synthetic single crystal. The structure, at 150 K, space group Pbcn, lattice constants a = 14.6861 (4), b = 13.9799 (3) and c = 16.7063 (5) Å, consists of layers of stoichiometry (UO₂)₄O(OH)₆, formed from edge-sharing UO₇ pentagonal bipyramids, interleaved with hydrogen-bonded water molecules. Three of the layer hydroxyl groups are linked through hydrogen bonding to single water molecules and the three remaining OH units form interactions with water molecules that each act as acceptors in two hydrogen bonds. One of the water molecules in the inter-layer region is disordered over two symmetry-related sites and forms hydrogen-bonded interactions only within the layer and with the uranyl O atoms. The relationship of the structure of meta-schoepite to that of schoepite is discussed in detail.

Computing details

Data collection: DENZO (Otwinowski and Minor, 1997) COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski and Minor, 1997) and COLLECT (Hooft, 1998); data reduction: DENZO (Otwinowski and Minor, 1997) and COLLECT (Hooft, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).

(s92)

Crystal data

H16O20U4	Dx = 4.989 Mg m^−3
Mr = 1288.25	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbcn	Cell parameters from 16680 reflections
a = 14.6861 (4) Å	θ = 2.0–25.8°
b = 13.9799 (3) Å	µ = 37.75 mm^−1
c = 16.7063 (5) Å	T = 298 K
V = 3429.97 (16) Å^3	Tablet, yellow
Z = 8	0.03 × 0.02 × 0.01 mm
F(000) = 4352

Data collection

Enraf Nonius KappaCCD area detector diffractometer	3255 independent reflections
Radiation source: Enraf Nonius FR591 rotating anode	2106 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.090
Detector resolution: 9.091 pixels/mm pixels mm^-1	θmax = 25.8°, θmin = 2.0°
ψ and θ scans to fill Ewald sphere	h = −16→17
Absorption correction: empirical (using intensity measurements) SORTAV (Blessing 1995, 1997)'	k = −12→17
Tmin = 0.519, Tmax = 0.778	l = −20→20
16680 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.104	H-atom parameters not defined
S = 0.95	w = 1/[σ^2(Fo^2) + (0.047P)^2] where P = (Fo^2 + 2Fc^2)/3
3255 reflections	(Δ/σ)max = 0.001
119 parameters	Δρmax = 2.98 e Å^−3
0 restraints	Δρmin = −2.84 e Å^−3

Special details

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
U1	0.23453 (4)	0.74724 (4)	0.36301 (4)	0.01561 (18)
U2	0.29656 (5)	0.77012 (4)	0.59321 (4)	0.01655 (19)
U3	0.25426 (5)	0.51155 (4)	0.22973 (4)	0.01706 (19)
U4	0.25432 (5)	0.51460 (4)	0.50131 (4)	0.01630 (19)
O1	0.1802 (9)	0.7479 (7)	0.5935 (8)	0.032 (3)*
O2	0.1438 (8)	0.4529 (7)	0.2244 (7)	0.028 (3)*
O3	0.1293 (8)	0.7449 (7)	0.4127 (7)	0.026 (3)*
O4	0.4167 (7)	0.7849 (7)	0.5914 (7)	0.022 (3)*
O5	0.3642 (8)	0.5633 (7)	0.2359 (7)	0.026 (3)*
O6	0.1416 (7)	0.5579 (7)	0.5179 (7)	0.023 (3)*
O7	0.3385 (8)	0.7524 (7)	0.3101 (8)	0.034 (3)*
O8	0.3692 (8)	0.4724 (7)	0.4845 (7)	0.025 (3)*
O9	0.2652 (7)	0.9236 (7)	0.6079 (7)	0.019 (3)*
O10	0.2028 (8)	0.3615 (6)	0.4591 (7)	0.019 (3)*
O11	0.3125 (7)	0.6719 (6)	0.4737 (6)	0.016 (3)*
O12	0.2152 (7)	0.5667 (7)	0.3635 (7)	0.021 (3)*
O13	0.3121 (7)	0.6007 (7)	0.6270 (6)	0.019 (3)*
O14	0.1846 (7)	0.6852 (7)	0.2342 (7)	0.022 (3)*
O15	0.1863 (7)	0.8888 (6)	0.3066 (6)	0.018 (3)*
O16	0.0000	0.7609 (12)	0.2500	0.049 (5)*
O17	0.5015 (9)	0.4409 (9)	0.1386 (9)	0.048 (4)*
O18	−0.0253 (10)	0.6223 (10)	0.5870 (10)	0.060 (4)*
O19	0.0314 (9)	0.5621 (8)	0.3391 (8)	0.046 (4)*
O20	−0.0119 (11)	0.8529 (11)	0.5792 (10)	0.081 (5)*
O21	0.517 (3)	0.758 (2)	0.287 (2)	0.096 (13)*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
U1	0.0283 (4)	0.0136 (3)	0.0049 (4)	−0.0004 (2)	−0.0002 (3)	−0.0006 (3)
U2	0.0292 (4)	0.0131 (3)	0.0074 (3)	0.0008 (3)	−0.0012 (3)	−0.0012 (3)
U3	0.0320 (4)	0.0135 (3)	0.0057 (4)	0.0002 (2)	−0.0001 (3)	0.0001 (2)
U4	0.0296 (4)	0.0126 (3)	0.0068 (4)	−0.0008 (2)	0.0016 (3)	0.0007 (2)

Geometric parameters (Å, º)

U1—O3	1.754 (12)	U3—O15^iv	2.315 (10)
U1—O7	1.766 (13)	U3—O12	2.433 (11)
U1—O15	2.303 (9)	U3—O13^v	2.475 (10)
U1—O11	2.416 (10)	U3—O14	2.636 (10)
U1—O14	2.433 (11)	U3—U4^v	3.8334 (9)
U1—O10^i	2.445 (10)	U3—U2^iii	3.8827 (8)
U1—O12	2.540 (9)	U4—O6	1.784 (11)
U1—U2	3.9651 (9)	U4—O8	1.810 (11)
U1—U3	3.9873 (8)	U4—O9^iv	2.207 (10)
U1—U4	4.0001 (8)	U4—O10	2.378 (10)
U2—O1	1.737 (13)	U4—O11	2.403 (9)
U2—O4	1.777 (11)	U4—O12	2.481 (11)
U2—O9	2.208 (9)	U4—O13	2.565 (11)
U2—O11	2.434 (10)	U4—U2^iv	3.8205 (8)
U2—O13	2.446 (9)	U4—U3^vi	3.8334 (9)
U2—O14^ii	2.452 (11)	O9—U4^i	2.207 (10)
U2—O10^i	2.578 (10)	O9—U3^ii	2.246 (11)
U2—U4^i	3.8205 (8)	O10—U1^iv	2.445 (10)
U2—U3^ii	3.8827 (8)	O10—U2^iv	2.578 (10)
U2—U4	3.9373 (8)	O13—U3^vi	2.475 (10)
U3—O5	1.773 (11)	O14—U2^iii	2.452 (11)
U3—O2	1.820 (11)	O15—U3^i	2.315 (10)
U3—O9^iii	2.246 (11)	O21—O21^vii	1.32 (7)
O3—U1—O7	177.8 (5)	O5—U3—O13^v	89.2 (4)
O3—U1—O15	86.5 (4)	O2—U3—O13^v	89.2 (4)
O7—U1—O15	91.5 (4)	O9^iii—U3—O13^v	70.8 (3)
O3—U1—O11	92.7 (5)	O15^iv—U3—O13^v	77.6 (4)
O7—U1—O11	89.5 (5)	O12—U3—O13^v	156.7 (3)
O15—U1—O11	146.5 (3)	O5—U3—O14	88.6 (4)
O3—U1—O14	98.4 (5)	O2—U3—O14	94.0 (4)
O7—U1—O14	80.4 (5)	O9^iii—U3—O14	66.7 (3)
O15—U1—O14	81.4 (3)	O15^iv—U3—O14	144.5 (3)
O11—U1—O14	131.6 (3)	O12—U3—O14	65.8 (3)
O3—U1—O10^i	91.9 (4)	O13^v—U3—O14	137.5 (3)
O7—U1—O10^i	88.6 (5)	O5—U3—U4^v	95.5 (4)
O15—U1—O10^i	79.9 (3)	O2—U3—U4^v	84.8 (4)
O11—U1—O10^i	66.6 (3)	O9^iii—U3—U4^v	30.3 (2)
O14—U1—O10^i	158.0 (3)	O15^iv—U3—U4^v	118.8 (3)
O3—U1—O12	83.2 (4)	O12—U3—U4^v	160.9 (2)
O7—U1—O12	98.0 (4)	O13^v—U3—U4^v	41.4 (2)
O15—U1—O12	145.1 (4)	O14—U3—U4^v	96.7 (2)
O11—U1—O12	67.5 (3)	O5—U3—U2^iii	83.6 (4)
O14—U1—O12	67.4 (3)	O2—U3—U2^iii	98.9 (4)
O10^i—U1—O12	133.5 (3)	O9^iii—U3—U2^iii	29.1 (2)
O3—U1—U2	75.2 (4)	O15^iv—U3—U2^iii	168.9 (3)
O7—U1—U2	106.5 (4)	O12—U3—U2^iii	104.2 (2)
O15—U1—U2	113.5 (3)	O13^v—U3—U2^iii	99.0 (2)
O11—U1—U2	35.3 (2)	O14—U3—U2^iii	38.5 (2)
O14—U1—U2	162.9 (2)	U4^v—U3—U2^iii	59.353 (15)
O10^i—U1—U2	39.1 (2)	O5—U3—U1	72.3 (3)
O12—U1—U2	95.9 (3)	O2—U3—U1	109.5 (4)
O3—U1—U3	108.2 (3)	O9^iii—U3—U1	99.4 (2)
O7—U1—U3	72.0 (3)	O15^iv—U3—U1	109.3 (3)
O15—U1—U3	120.2 (3)	O12—U3—U1	37.6 (2)
O11—U1—U3	91.9 (2)	O13^v—U3—U1	159.4 (2)
O14—U1—U3	40.0 (2)	O14—U3—U1	36.4 (2)
O10^i—U1—U3	151.5 (2)	U4^v—U3—U1	129.40 (2)
O12—U1—U3	35.8 (3)	U2^iii—U3—U1	70.394 (17)
U2—U1—U3	126.269 (19)	O6—U4—O8	179.2 (5)
O3—U1—U4	77.0 (3)	O6—U4—O9^iv	87.1 (4)
O7—U1—U4	105.0 (3)	O8—U4—O9^iv	93.4 (4)
O15—U1—U4	163.2 (3)	O6—U4—O10	93.2 (4)
O11—U1—U4	33.8 (2)	O8—U4—O10	87.6 (4)
O14—U1—U4	104.1 (2)	O9^iv—U4—O10	71.3 (4)
O10^i—U1—U4	97.1 (2)	O6—U4—O11	92.8 (4)
O12—U1—U4	36.7 (3)	O8—U4—O11	86.4 (4)
U2—U1—U4	59.246 (14)	O9^iv—U4—O11	136.7 (4)
U3—U1—U4	69.231 (16)	O10—U4—O11	151.6 (4)
O1—U2—O4	176.3 (5)	O6—U4—O12	80.2 (4)
O1—U2—O9	88.2 (4)	O8—U4—O12	99.6 (5)
O4—U2—O9	95.5 (4)	O9^iv—U4—O12	152.5 (4)
O1—U2—O11	89.7 (5)	O10—U4—O12	85.2 (3)
O4—U2—O11	87.5 (4)	O11—U4—O12	68.6 (3)
O9—U2—O11	131.3 (4)	O6—U4—O13	91.2 (4)
O1—U2—O13	85.3 (4)	O8—U4—O13	88.4 (4)
O4—U2—O13	91.4 (4)	O9^iv—U4—O13	69.7 (3)
O9—U2—O13	159.2 (4)	O10—U4—O13	140.4 (3)
O11—U2—O13	68.5 (3)	O11—U4—O13	67.1 (3)
O1—U2—O14^ii	98.9 (5)	O12—U4—O13	134.3 (3)
O4—U2—O14^ii	82.8 (5)	O6—U4—U2^iv	93.4 (3)
O9—U2—O14^ii	70.7 (4)	O8—U4—U2^iv	87.3 (3)
O11—U2—O14^ii	157.0 (3)	O9^iv—U4—U2^iv	30.1 (3)
O13—U2—O14^ii	90.8 (3)	O10—U4—U2^iv	41.5 (3)
O1—U2—O10^i	95.4 (5)	O11—U4—U2^iv	164.8 (3)
O4—U2—O10^i	85.6 (4)	O12—U4—U2^iv	126.2 (2)
O9—U2—O10^i	67.4 (3)	O13—U4—U2^iv	98.9 (2)
O11—U2—O10^i	64.3 (3)	O6—U4—U3^vi	83.0 (4)
O13—U2—O10^i	132.8 (3)	O8—U4—U3^vi	97.1 (4)
O14^ii—U2—O10^i	135.1 (3)	O9^iv—U4—U3^vi	30.9 (3)
O1—U2—U4^i	88.2 (3)	O10—U4—U3^vi	102.1 (3)
O4—U2—U4^i	94.8 (3)	O11—U4—U3^vi	106.2 (2)
O9—U2—U4^i	30.1 (3)	O12—U4—U3^vi	162.0 (2)
O11—U2—U4^i	101.2 (2)	O13—U4—U3^vi	39.6 (2)
O13—U2—U4^i	167.8 (3)	U2^iv—U4—U3^vi	60.965 (16)
O14^ii—U2—U4^i	100.4 (2)	O6—U4—U2	77.2 (3)
O10^i—U2—U4^i	37.7 (2)	O8—U4—U2	102.1 (3)
O1—U2—U3^ii	87.1 (4)	O9^iv—U4—U2	103.2 (3)
O4—U2—U3^ii	96.3 (3)	O10—U4—U2	169.3 (3)
O9—U2—U3^ii	29.6 (3)	O11—U4—U2	35.8 (2)
O11—U2—U3^ii	160.7 (2)	O12—U4—U2	97.6 (2)
O13—U2—U3^ii	130.1 (3)	O13—U4—U2	37.1 (2)
O14^ii—U2—U3^ii	42.0 (2)	U2^iv—U4—U2	133.30 (3)
O10^i—U2—U3^ii	97.0 (2)	U3^vi—U4—U2	72.447 (18)
U4^i—U2—U3^ii	59.682 (16)	O6—U4—U1	75.3 (3)
O1—U2—U4	71.6 (3)	O8—U4—U1	104.1 (3)
O4—U2—U4	104.8 (3)	O9^iv—U4—U1	157.7 (3)
O9—U2—U4	153.1 (3)	O10—U4—U1	122.5 (3)
O11—U2—U4	35.3 (2)	O11—U4—U1	34.0 (2)
O13—U2—U4	39.3 (3)	O12—U4—U1	37.7 (2)
O14^ii—U2—U4	128.6 (2)	O13—U4—U1	96.6 (2)
O10^i—U2—U4	96.4 (2)	U2^iv—U4—U1	160.95 (2)
U4^i—U2—U4	128.62 (2)	U3^vi—U4—U1	130.73 (2)
U3^ii—U2—U4	155.78 (2)	U2—U4—U1	59.933 (15)
O1—U2—U1	76.2 (4)	U4^i—O9—U2	119.8 (5)
O4—U2—U1	102.8 (4)	U4^i—O9—U3^ii	118.8 (4)
O9—U2—U1	98.0 (3)	U2—O9—U3^ii	121.3 (5)
O11—U2—U1	35.0 (2)	U4—O10—U1^iv	131.5 (5)
O13—U2—U1	99.6 (3)	U4—O10—U2^iv	100.8 (4)
O14^ii—U2—U1	168.0 (2)	U1^iv—O10—U2^iv	104.2 (3)
O10^i—U2—U1	36.7 (2)	U4—O11—U1	112.2 (4)
U4^i—U2—U1	68.745 (17)	U4—O11—U2	108.9 (4)
U3^ii—U2—U1	126.09 (2)	U1—O11—U2	109.7 (4)
U4—U2—U1	60.820 (15)	U3—O12—U4	134.8 (4)
O5—U3—O2	177.3 (5)	U3—O12—U1	106.6 (4)
O5—U3—O9^iii	90.2 (5)	U4—O12—U1	105.6 (4)
O2—U3—O9^iii	91.4 (5)	U2—O13—U3^vi	137.9 (5)
O5—U3—O15^iv	85.8 (4)	U2—O13—U4	103.6 (4)
O2—U3—O15^iv	91.7 (4)	U3^vi—O13—U4	99.0 (3)
O9^iii—U3—O15^iv	148.2 (4)	U1—O14—U2^iii	136.4 (4)
O5—U3—O12	91.8 (5)	U1—O14—U3	103.7 (4)
O2—U3—O12	88.7 (5)	U2^iii—O14—U3	99.4 (4)
O9^iii—U3—O12	132.4 (3)	U1—O15—U3^i	138.4 (5)
O15^iv—U3—O12	79.3 (3)

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