Crystal structures of Na₂SeO₄·1.5H₂O and Na₂SeO₄·10H₂O

The crystal structures of the 1.5- and 10-hydrates of Na₂SeO₄ are isotypic with those of the corresponding chromates.

Abstract

The crystal structures of Na₂SeO₄·1.5H₂O (sodium selenate sesquihydrate) and Na₂SeO₄·10H₂O (sodium selenate deca­hydrate) are isotypic with those of Na₂CrO₄·1.5H₂O and Na₂ XSeO₄·10H₂O (X = S, Cr), respectively. The asymmetric unit of the sesquihydrate contains two Na⁺ cations, one SeO₄ tetra­hedron and one and a half water mol­ecules, the other half being generated by twofold rotation symmetry. The coordination polyhedra of the cations are a distorted monocapped octa­hedron and a square pyramid; these [NaO_x] polyhedra are linked through common edges and corners into a three-dimensional framework structure, the voids of which are filled with the Se atoms of the SeO₄ tetra­hedra. The structure is consolidated by O—H⋯O hydrogen bonds between coordinating water mol­ecules and framework O atoms. The asymmetric unit of the deca­hydrate consists of two Na⁺ cations, one SeO₄ tetra­hedron and ten water mol­ecules. Both Na⁺ cations are octa­hedrally surrounded by water mol­ecules and by edge-sharing condensed into zigzag chains extending parallel to [001]. The SeO₄ tetra­hedra and two uncoordinating water mol­ecules are situated between the chains and are connected to the chains through an intricate network of medium-strength O—H⋯O hydrogen bonds.

Chemical context  

Based on recent studies in the system Na/Se/O/H that revealed dimorphism of the phases NaHSeO₄ and Na₅H₃(SeO₄)₄(H₂O)₂ (Pollitt & Weil, 2014 ▶), we became inter­ested in the structure determination of hydrous phases of Na₂SeO₄. Although the first report of the deca­hydrate of Na₂SeO₄ dates back to 1827 (Mitscherlich, 1827 ▶), a detailed structure report for this compound has not been published so far. Mitscherlich (1827 ▶) also recognized an isomorphic relationship of Na₂SeO₄·10H₂O with Na₂SO₄·10H₂O (Glauber’s salt or mirabilite as a mineral species). This relation was later confirmed by Rosický (1908 ▶) and by Ruben et al. (1961 ▶) on the basis of unit-cell determinations using diffraction methods. Another hydrous phase of Na₂SeO₄ reported in the literature is the metastable hepta­hydrate that crystallized from supersaturated Na₂SeO₄ solutions only when seeded with Na₂SO₄·7H₂O nuclei below 293 K (Belarew, 1965 ▶).

During crystallization studies of aqueous Na₂SeO₄ solutions under different temperature conditions, we were able to isolate crystals not only of the deca­hydrate, but also of the sesqui­hydrate, the crystal structures of which are reported here.

Structural commentary  

Na₂SeO₄·1.5H₂O is isotypic with the corresponding chromate (Kahlenberg, 2012 ▶) and is the second example of the Na₂ XO₄·1.5H₂O structure family. The main building blocks of this structure type are distorted [NaO₅(H₂O)₂] (Na1) monocapped octa­hedra, distorted [NaO₄(H₂O)] square pyramids (Na2) (Fig. 1 ▶) and rather regular XO₄ (X = Se, Cr) tetra­hedra. These building blocks are linked through common corners and edges into a three-dimensional framework structure (Fig. 2 ▶). Hydrogen bonds of the type O—H⋯O between the coord­in­ating water mol­ecules and parts of the framework O atoms provide additional stabilization (Table 1 ▶). The bond lengths (Table 2 ▶) and angles within the individual building blocks of the selenate and chromate structures are more or less identical with mean distances of SeO₄ = 1.641; CrO₄ = 1.651; Na1O₇ = 2.514 (selenate), 2.505 (chromate); Na2O₅ = 2.350 (selenate), 2.360 Å (chromate).

Figure 1.

The NaO₇ and NaO₅ polyhedra in the structure of Na₂SO₄·1.5H₂O. Displacement parameters are drawn at the 99% probability level. [Symmetry codes: (i) , , ; (ii) , , z; (iii) , y, z; (iv) , , ; (v) , y, z; (vi) x, , ; (vii) , , z.]

Figure 2.

The crystal structure of Na₂SO₄·1.5H₂O in a projection along [110]. NaO₅ polyhedra are turquoise, NaO₇ polyhedra are blue, SeO₄ tetra­hedra are red and H atoms are grey. Hydrogen bonds have been omitted for clarity.

Table 1. Hydrogen-bond geometry (Å, °) for 1.5-hydrate.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
OW5—H1⋯O4viii	0.82 (1)	2.13 (1)	2.922 (2)	164 (3)
OW5—H2⋯O3ix	0.82 (1)	2.08 (1)	2.891 (2)	169 (3)
OW6—H3⋯O1vi	0.82 (1)	1.90 (1)	2.703 (2)	167 (4)

Symmetry codes: (vi) ; (viii) ; (ix) .

Table 2. Selected bond lengths (Å) for 1.5-hydrate.

Na1—OW5	2.3660 (18)	Na2—O2iv	2.3301 (18)
Na1—O3i	2.4157 (19)	Na2—OW6v	2.3480 (18)
Na1—O1	2.4379 (18)	Na2—O4vi	2.3651 (19)
Na1—O3ii	2.4594 (16)	Na2—O1vii	2.4103 (18)
Na1—OW5i	2.465 (2)	Se1—O2	1.6350 (14)
Na1—O4iii	2.6057 (19)	Se1—O3	1.6367 (14)
Na1—O2ii	2.8475 (17)	Se1—O4	1.6451 (16)
Na2—O2	2.298 (2)	Se1—O1	1.6481 (15)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) .

Isotypism has been reported for several Na₂ XO₄·10H₂O (X = S, Se, Cr, W, Mo) phases (Ruben et al., 1961 ▶), but only the structures of X = S (Levy & Lisensky, 1978 ▶; Prescott et al., 2001 ▶) and Cr (Kahlenberg, 2012 ▶) have been determined so far. As expected, the general structural set-up in the isotypic Na₂ XO₄·10H₂O structures is very similar. Each of the two Na⁺ cations is octa­hedrally surrounded [mean Na—O distance of the two octa­hedra is 2.420 Å (see Table 3 ▶); sulfate analogue (Prescott et al., 2001 ▶): 2.415 Å; chromate analogue (Kahlenberg, 2012 ▶): 2.423 Å]. The [NaO₆] octa­hedra are linked via edge-sharing into zigzag chains (Fig. 3 ▶) running parallel to [001]. These chains are linked with neighbouring chains and inter­mediate SeO₄ tetra­hedra (mean Se—O distance 1.639; sulfate 1.488, chromate 1.647 Å) and non-coordinating lattice water mol­ecules through O—H⋯O hydrogen bonds of medium strength (Table 4 ▶) to build up the crystal structure (Fig. 4 ▶). The most important difference between the structures of the three Na₂ XO₄·10H₂O (X = S, Se, Cr) phases is the missing disorder of the XO₄ tetra­hedron in the selenate compound that has been observed in the sulfate compound on the basis of single-crystal neutron data (Levy & Lisensky, 1978 ▶) and single-crystal X-ray data (Prescott et al., 2001 ▶), or for the chromate compound on the basis of single-crystal X-ray data (Kahlenberg, 2012 ▶).

Table 3. Selected bond lengths (Å) for 10-hydrate.

Na1—OW5	2.3776 (6)	Na2—OW7	2.3935 (6)
Na1—OW6i	2.4181 (6)	Na2—OW9	2.4325 (6)
Na1—OW11	2.4184 (6)	Na2—OW6	2.4415 (6)
Na1—OW10	2.4194 (6)	Na2—OW10ii	2.4667 (6)
Na1—OW8i	2.4473 (6)	Se1—O41	1.6335 (5)
Na1—OW9i	2.4507 (6)	Se1—O31	1.6394 (5)
Na2—OW12	2.3814 (6)	Se1—O1	1.6398 (5)
Na2—OW5ii	2.3891 (6)	Se1—O21	1.6421 (5)

Symmetry codes: (i) ; (ii) .

Figure 3.

A chain of edge-sharing NaO₆ octa­hedra in the crystal structure of Na₂SO₄·10H₂O. Displacement parameters are drawn at the 99% probability level. [Symmetry code: (i) x, −y − , z − .]

Table 4. Hydrogen-bond geometry (Å, °) for 10-hydrate.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
OW5—H5A⋯O41	0.82 (1)	1.96 (1)	2.7570 (7)	164 (1)
OW5—H5B⋯OW13iii	0.82 (1)	2.00 (1)	2.7980 (7)	165 (1)
OW6—H6A⋯OW14	0.82 (1)	2.02 (1)	2.8301 (7)	168 (1)
OW6—H6B⋯O41ii	0.82 (1)	1.98 (1)	2.7791 (7)	166 (2)
OW7—H7A⋯O1iv	0.82 (1)	1.97 (1)	2.7727 (7)	166 (1)
OW7—H7B⋯OW8v	0.82 (1)	1.95 (1)	2.7542 (7)	168 (1)
OW8—H8A⋯O41ii	0.82 (1)	1.95 (1)	2.7544 (7)	166 (1)
OW8—H8B⋯OW7vi	0.82 (1)	1.99 (1)	2.8076 (7)	178 (1)
OW9—H9A⋯O1vii	0.82 (1)	2.11 (1)	2.9152 (7)	168 (1)
OW9—H9B⋯OW13viii	0.82 (1)	2.04 (1)	2.8596 (7)	177 (1)
OW10—H10A⋯OW14ix	0.82 (1)	2.05 (1)	2.8686 (7)	178 (2)
OW10—H10B⋯O31x	0.82 (1)	2.08 (1)	2.8920 (7)	174 (1)
OW11—H11A⋯O31	0.82 (1)	2.05 (1)	2.8604 (7)	171 (1)
OW11—H11B⋯OW12i	0.82 (1)	1.96 (1)	2.7716 (8)	168 (1)
OW12—H12A⋯O21iv	0.82 (1)	1.92 (1)	2.7359 (7)	179 (1)
OW12—H12B⋯OW11viii	0.82 (1)	1.97 (1)	2.7818 (7)	173 (1)
OW13—H13A⋯O1xi	0.82 (1)	1.98 (1)	2.7932 (7)	172 (1)
OW13—H13B⋯O21x	0.82 (1)	1.98 (1)	2.7931 (7)	170 (1)
OW14—H14A⋯O21xii	0.82 (1)	1.98 (1)	2.8002 (7)	174 (1)
OW14—H14B⋯O31viii	0.82 (1)	2.00 (1)	2.8061 (7)	169 (1)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) ; (viii) ; (ix) ; (x) ; (xi) ; (xii) .

Figure 4.

The crystal structure of Na₂SO₄·10H₂O in a projection along [110]. NaO₆ polyhedra are light blue, SeO₄ tetra­hedra are red, O atoms are white and H atoms are grey. Hydrogen bonds have been omitted for clarity.

Synthesis and crystallization  

Anhydrous Na₂SeO₄ was prepared according to the method compiled by Brauer (1963 ▶) by adding a half-concentrated aqueous selenic acid solution (ca 60 wt%) to an excess of an Na₂CO₃ solution. The resulting solution was heated until a considerable amount of the neutralization product had crystallized. The crystal mush was then separated by suction filtration of the still-hot solution and dried in air. X-ray powder diffraction revealed a single-phase material. The Na₂SeO₄ crystals were then dissolved in small amounts of water and kept at ca 300, 293 and 280 K until complete evaporation of the solvent. According to Rietveld refinements using TOPAS (Bruker, 2013 ▶) the product crystallized at 300 K consisted of Na₂SeO₄ and Na₂SeO₄·1.5H₂O in an approximate 9:1 weight ratio, the product crystallized at 290 K consisted of Na₂SeO₄ and Na₂SeO₄·1.5H₂O in an approximate 5:1 ratio, and the product crystallized at 280 K consisted of Na₂SeO₄, Na₂SeO₄·1.5H₂O and Na₂SeO₄·10H₂O in an approximate 5:4:1 ratio. The crystal forms of the three obtained phases were different and were used for separation. Crystals of the anhydrous phase had mainly a lath-like form, of the sesquihydrate a plate-like form, and of the deca­hydrate a pinacoidal form. All obtained hydrate phases tend to weather when stored under ambient conditions.

Refinement  

Unit-cell determinations revealed isotypic relationships with the corresponding chromate phases (Kahlenberg, 2012 ▶). For better comparison of the isotypic structures, atom labels and the setting of the unit cells of the selenate compounds were retained, and the coordinates of the non-H atoms of the chromate structure were used as starting parameters for refinement [note that the unit cell of Na₂CrO₄·1.5H₂O is given in the non-standard setting F2dd of space group No. 43 (standard setting Fdd2)]. The H atoms of the water mol­ecules were located from difference maps and were refined with a common U _iso parameter and a fixed O—H distance of 0.82 Å. Experimental details are given in Table 1 ▶.

Table 5. Experimental details.

	1.5-hydrate	10-hydrate
Crystal data
Chemical formula	Na2SeO4·1.5H2O	Na2O4Se·10H2O
M r	215.96	369.10
Crystal system, space group	Orthorhombic, F2d d	Monoclinic, P21/c
Temperature (K)	100	100
a, b, c (Å)	6.7533 (8), 8.6299 (10), 35.206 (4)	11.5758 (6), 10.4911 (5), 12.9570 (7)
α, β, γ (°)	90, 90, 90	90, 107.995 (3), 90
V (Å3)	2051.8 (4)	1496.56 (13)
Z	16	4
Radiation type	Mo Kα	Mo Kα
μ (mm−1)	7.43	2.62
Crystal size (mm)	0.20 × 0.15 × 0.10	0.32 × 0.18 × 0.09
Data collection
Diffractometer	Bruker SMART CCD	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2008 ▶)	Multi-scan (SADABS; Bruker, 2013 ▶)
T min, T max	0.488, 0.584	0.642, 0.749
No. of measured, independent and observed [I > 2σ(I)] reflections	8363, 1824, 1723	213856, 11218, 9196
R int	0.032	0.054
(sin θ/λ)max (Å−1)	0.762	0.965
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.019, 0.042, 0.99	0.021, 0.046, 1.05
No. of reflections	1824	11218
No. of parameters	89	215
No. of restraints	4	20
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.91, −0.37	0.48, −0.52
Absolute structure	Flack (1983 ▶), 823 Friedel pairs	–
Absolute structure parameter	0.025 (8)	–

Computer programs: SMART, SAINT, SAINT-Plus and APEX2 (Bruker, 2013 ▶, 2013 ▶), SHELXS97 and SHELXL97 (Sheldrick, 2008 ▶), ATOMS (Dowty, 2006 ▶) and publCIF (Westrip, 2010 ▶).

Supplementary Material

CCDC references: 1004274, 1004275

Additional supporting information: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Crystal data

Na2O4Se·10H2O	F(000) = 752
Mr = 369.10	Dx = 1.638 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 9719 reflections
a = 11.5758 (6) Å	θ = 2.7–40.1°
b = 10.4911 (5) Å	µ = 2.62 mm−1
c = 12.9570 (7) Å	T = 100 K
β = 107.995 (3)°	Fragment, colourless
V = 1496.56 (13) Å3	0.32 × 0.18 × 0.09 mm
Z = 4

Data collection

Bruker APEXII CCD diffractometer	11218 independent reflections
Radiation source: fine-focus sealed tube	9196 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.054
ω and φ scans	θmax = 43.3°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Bruker, 2013)	h = −22→22
Tmin = 0.642, Tmax = 0.749	k = −20→20
213856 measured reflections	l = −24→24

Refinement

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)] = 0.021	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.046	H-atom parameters constrained
S = 1.05	w = 1/[σ2(Fo2) + (0.017P)2 + 0.2899P] where P = (Fo2 + 2Fc2)/3
11218 reflections	(Δ/σ)max = 0.006
215 parameters	Δρmax = 0.48 e Å−3
20 restraints	Δρmin = −0.52 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
Se1	0.752121 (5)	0.139467 (5)	0.740658 (4)	0.00723 (1)
Na1	0.74307 (2)	−0.24486 (3)	0.97851 (2)	0.01112 (5)
Na2	0.75630 (2)	−0.11228 (3)	0.23666 (2)	0.01081 (4)
O1	0.86910 (4)	0.19770 (5)	0.83551 (4)	0.01211 (7)
O21	0.73195 (4)	0.21974 (4)	0.62765 (4)	0.01245 (8)
O31	0.63136 (4)	0.15034 (5)	0.78083 (4)	0.01257 (7)
O41	0.77699 (5)	−0.00971 (4)	0.71826 (4)	0.01330 (8)
OW5	0.85363 (4)	−0.21683 (5)	0.85304 (4)	0.01236 (7)
OW6	0.64473 (4)	−0.27987 (5)	0.11583 (4)	0.01269 (8)
OW7	0.87675 (5)	0.03985 (5)	0.36196 (4)	0.01443 (8)
OW8	0.87052 (5)	−0.42968 (5)	0.05311 (4)	0.01472 (8)
OW9	0.88112 (4)	−0.10907 (5)	0.11623 (4)	0.01306 (8)
OW10	0.61813 (4)	−0.39325 (5)	0.84832 (4)	0.01310 (8)
OW11	0.61541 (5)	−0.06034 (5)	0.91589 (4)	0.01584 (9)
OW12	0.63321 (5)	0.04187 (5)	0.11747 (4)	0.01397 (8)
OW13	0.09783 (5)	−0.14961 (5)	0.94520 (4)	0.01473 (8)
OW14	0.39997 (5)	−0.34873 (5)	0.08502 (4)	0.01467 (8)
H5A	0.8345 (13)	−0.1472 (6)	0.8240 (11)	0.0412 (9)*
H5B	0.9267 (3)	−0.2110 (14)	0.8845 (10)	0.0412 (9)*
H6A	0.5712 (2)	−0.2905 (14)	0.1003 (11)	0.0412 (9)*
H6B	0.6722 (13)	−0.3481 (7)	0.1436 (11)	0.0412 (9)*
H7A	0.8618 (13)	0.1162 (3)	0.3535 (12)	0.0412 (9)*
H7B	0.8709 (12)	0.0169 (13)	0.4206 (5)	0.0412 (9)*
H8A	0.8415 (11)	−0.4602 (12)	0.0978 (8)	0.0412 (9)*
H8B	0.9440 (2)	−0.4401 (13)	0.0788 (10)	0.0412 (9)*
H9A	0.9508 (4)	−0.1364 (12)	0.1394 (11)	0.0412 (9)*
H9B	0.8892 (13)	−0.0359 (5)	0.0973 (11)	0.0412 (9)*
H10A	0.6143 (13)	−0.4669 (4)	0.8683 (11)	0.0412 (9)*
H10B	0.5473 (4)	−0.3767 (12)	0.8146 (10)	0.0412 (9)*
H11A	0.6205 (12)	−0.0062 (10)	0.8719 (8)	0.0412 (9)*
H11B	0.6254 (12)	−0.0213 (11)	0.9728 (6)	0.0412 (9)*
H12A	0.6618 (12)	0.1138 (5)	0.1205 (12)	0.0412 (9)*
H12B	0.5615 (3)	0.0506 (13)	0.1131 (11)	0.0412 (9)*
H13A	0.1146 (13)	−0.1610 (13)	1.0108 (2)	0.0412 (9)*
H13B	0.1423 (10)	−0.1952 (11)	0.9226 (10)	0.0412 (9)*
H14A	0.3586 (11)	−0.3337 (13)	0.0224 (4)	0.0412 (9)*
H14B	0.3809 (12)	−0.2944 (10)	0.1223 (9)	0.0412 (9)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Se1	0.00796 (2)	0.00652 (2)	0.00716 (2)	0.00002 (2)	0.00228 (1)	0.00003 (2)
Na1	0.01190 (11)	0.01128 (11)	0.01052 (11)	−0.00036 (9)	0.00396 (9)	−0.00045 (8)
Na2	0.01176 (11)	0.01011 (10)	0.01050 (10)	0.00016 (9)	0.00333 (8)	0.00013 (8)
O1	0.00993 (17)	0.01300 (18)	0.01144 (17)	−0.00124 (14)	0.00041 (14)	−0.00188 (14)
O21	0.0162 (2)	0.01156 (18)	0.00963 (17)	0.00085 (15)	0.00404 (15)	0.00315 (14)
O31	0.00980 (17)	0.0156 (2)	0.01373 (18)	−0.00012 (15)	0.00571 (14)	−0.00071 (15)
O41	0.0190 (2)	0.00658 (16)	0.01498 (19)	0.00140 (15)	0.00617 (16)	−0.00054 (14)
OW5	0.01162 (18)	0.01215 (18)	0.01230 (18)	−0.00102 (15)	0.00222 (14)	0.00144 (14)
OW6	0.01137 (18)	0.01229 (19)	0.01431 (19)	−0.00005 (15)	0.00381 (15)	0.00107 (14)
OW7	0.0160 (2)	0.01212 (19)	0.01404 (19)	−0.00039 (16)	0.00291 (16)	0.00042 (15)
OW8	0.01307 (19)	0.0172 (2)	0.0149 (2)	0.00141 (16)	0.00583 (16)	0.00232 (16)
OW9	0.01073 (18)	0.01301 (18)	0.0154 (2)	0.00022 (14)	0.00393 (15)	0.00012 (15)
OW10	0.01081 (18)	0.01338 (18)	0.01408 (19)	−0.00065 (15)	0.00237 (15)	0.00038 (15)
OW11	0.0166 (2)	0.0150 (2)	0.0176 (2)	0.00205 (17)	0.00788 (17)	0.00367 (16)
OW12	0.01201 (19)	0.01201 (19)	0.0171 (2)	−0.00065 (15)	0.00339 (16)	0.00122 (15)
OW13	0.01312 (19)	0.0176 (2)	0.01342 (19)	0.00137 (16)	0.00410 (15)	0.00051 (16)
OW14	0.0148 (2)	0.0152 (2)	0.01333 (19)	0.00127 (16)	0.00335 (15)	−0.00077 (15)

Geometric parameters (Å, º)

Na1—OW5	2.3776 (6)	Na2—OW7	2.3935 (6)
Na1—OW6i	2.4181 (6)	Na2—OW9	2.4325 (6)
Na1—OW11	2.4184 (6)	Na2—OW6	2.4415 (6)
Na1—OW10	2.4194 (6)	Na2—OW10ii	2.4667 (6)
Na1—OW8i	2.4473 (6)	Se1—O41	1.6335 (5)
Na1—OW9i	2.4507 (6)	Se1—O31	1.6394 (5)
Na2—OW12	2.3814 (6)	Se1—O1	1.6398 (5)
Na2—OW5ii	2.3891 (6)	Se1—O21	1.6421 (5)
O41—Se1—O31	109.72 (2)	Na1—OW5—H5A	107.3 (10)
O41—Se1—O1	109.88 (3)	Na2iii—OW5—H5A	111.8 (10)
O31—Se1—O1	108.89 (2)	Na1—OW5—H5B	111.1 (10)
O41—Se1—O21	108.50 (2)	Na2iii—OW5—H5B	125.7 (10)
O31—Se1—O21	110.31 (2)	H5A—OW5—H5B	104.6 (14)
O1—Se1—O21	109.53 (2)	Na1iv—OW6—Na2	94.959 (19)
OW5—Na1—OW6i	175.60 (2)	Na1iv—OW6—H6A	122.0 (10)
OW5—Na1—OW11	94.230 (19)	Na2—OW6—H6A	124.0 (10)
OW6i—Na1—OW11	89.467 (19)	Na1iv—OW6—H6B	104.4 (10)
OW5—Na1—OW10	86.270 (19)	Na2—OW6—H6B	106.9 (10)
OW6i—Na1—OW10	95.70 (2)	H6A—OW6—H6B	102.8 (13)
OW11—Na1—OW10	96.28 (2)	Na2—OW7—H7A	120.4 (10)
OW5—Na1—OW8i	88.961 (19)	Na2—OW7—H7B	103.6 (10)
OW6i—Na1—OW8i	87.276 (19)	H7A—OW7—H7B	109.7 (14)
OW11—Na1—OW8i	176.39 (2)	Na1iv—OW8—H8A	105.1 (10)
OW10—Na1—OW8i	85.59 (2)	Na1iv—OW8—H8B	133.6 (10)
OW5—Na1—OW9i	93.341 (19)	H8A—OW8—H8B	105.2 (13)
OW6i—Na1—OW9i	84.368 (19)	Na2—OW9—Na1iv	94.36 (2)
OW11—Na1—OW9i	88.42 (2)	Na2—OW9—H9A	118.2 (10)
OW10—Na1—OW9i	175.30 (2)	Na1iv—OW9—H9A	114.2 (10)
OW8i—Na1—OW9i	89.72 (2)	Na2—OW9—H9B	110.5 (10)
OW12—Na2—OW5ii	171.87 (2)	Na1iv—OW9—H9B	115.8 (10)
OW12—Na2—OW7	95.37 (2)	H9A—OW9—H9B	104.3 (13)
OW5ii—Na2—OW7	90.57 (2)	Na1—OW10—Na2iii	92.153 (19)
OW12—Na2—OW9	85.96 (2)	Na1—OW10—H10A	117.7 (10)
OW5ii—Na2—OW9	99.063 (19)	Na2iii—OW10—H10A	108.3 (10)
OW7—Na2—OW9	95.10 (2)	Na1—OW10—H10B	121.3 (10)
OW12—Na2—OW6	88.92 (2)	Na2iii—OW10—H10B	113.9 (10)
OW5ii—Na2—OW6	85.252 (19)	H10A—OW10—H10B	103.0 (13)
OW7—Na2—OW6	175.61 (2)	Na1—OW11—H11A	128.3 (10)
OW9—Na2—OW6	84.260 (19)	Na1—OW11—H11B	101.3 (10)
OW12—Na2—OW10ii	89.884 (19)	H11A—OW11—H11B	105.1 (13)
OW5ii—Na2—OW10ii	84.965 (19)	Na2—OW12—H12A	116.2 (10)
OW7—Na2—OW10ii	86.209 (19)	Na2—OW12—H12B	120.7 (10)
OW9—Na2—OW10ii	175.74 (2)	H12A—OW12—H12B	106.6 (13)
OW6—Na2—OW10ii	94.743 (19)	H13A—OW13—H13B	108.1 (13)
Na1—OW5—Na2iii	95.178 (19)	H14A—OW14—H14B	105.5 (13)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
OW5—H5A···O41	0.82 (1)	1.96 (1)	2.7570 (7)	164 (1)
OW5—H5B···OW13v	0.82 (1)	2.00 (1)	2.7980 (7)	165 (1)
OW6—H6A···OW14	0.82 (1)	2.02 (1)	2.8301 (7)	168 (1)
OW6—H6B···O41ii	0.82 (1)	1.98 (1)	2.7791 (7)	166 (2)
OW7—H7A···O1vi	0.82 (1)	1.97 (1)	2.7727 (7)	166 (1)
OW7—H7B···OW8iii	0.82 (1)	1.95 (1)	2.7542 (7)	168 (1)
OW8—H8A···O41ii	0.82 (1)	1.95 (1)	2.7544 (7)	166 (1)
OW8—H8B···OW7vii	0.82 (1)	1.99 (1)	2.8076 (7)	178 (1)
OW9—H9A···O1viii	0.82 (1)	2.11 (1)	2.9152 (7)	168 (1)
OW9—H9B···OW13ix	0.82 (1)	2.04 (1)	2.8596 (7)	177 (1)
OW10—H10A···OW14x	0.82 (1)	2.05 (1)	2.8686 (7)	178 (2)
OW10—H10B···O31xi	0.82 (1)	2.08 (1)	2.8920 (7)	174 (1)
OW11—H11A···O31	0.82 (1)	2.05 (1)	2.8604 (7)	171 (1)
OW11—H11B···OW12i	0.82 (1)	1.96 (1)	2.7716 (8)	168 (1)
OW12—H12A···O21vi	0.82 (1)	1.92 (1)	2.7359 (7)	179 (1)
OW12—H12B···OW11ix	0.82 (1)	1.97 (1)	2.7818 (7)	173 (1)
OW13—H13A···O1xii	0.82 (1)	1.98 (1)	2.7932 (7)	172 (1)
OW13—H13B···O21xi	0.82 (1)	1.98 (1)	2.7931 (7)	170 (1)
OW14—H14A···O21xiii	0.82 (1)	1.98 (1)	2.8002 (7)	174 (1)
OW14—H14B···O31ix	0.82 (1)	2.00 (1)	2.8061 (7)	169 (1)

Symmetry codes: (i) x, y, z+1; (ii) x, −y−1/2, z−1/2; (iii) x, −y−1/2, z+1/2; (v) x+1, y, z; (vi) x, −y+1/2, z−1/2; (vii) −x+2, y−1/2, −z+1/2; (viii) −x+2, −y, −z+1; (ix) −x+1, −y, −z+1; (x) −x+1, −y−1, −z+1; (xi) −x+1, y−1/2, −z+3/2; (xii) −x+1, −y, −z+2; (xiii) −x+1, y−1/2, −z+1/2.