Sodium magnesium sulfate deca­hydrate, Na₂Mg(SO₄)₂·10H₂O, a new sulfate salt

The structure of synthetic disodium magnesium disulfate deca­hydrate at 180 K consists of alternating layers of water-coordinated [Mg(H₂O)₆]²⁺ octa­hedra and [Na₂(SO₄)₂(H₂O)₄]^2- sheets, parallel to [100]. The [Mg(H₂O)₆]²⁺ octa­hedra are joined to one another by a single hydrogen bond, the other hydrogen bonds being involved in inter-layer linkage. The Mg²⁺ cation occupies a crystallographic inversion centre. The sodium-sulfate sheets consist of chains of water-sharing [Na(H₂O)₆]⁺ octa­hedra along b, which are then connected by sulfate tetra­hedra through corner-sharing. The associated hydrogen bonds are the result of water-sulfate inter­actions within the sheets themselves. This is believed to be the first structure of a mixed monovalent/divalent cation sulfate deca­hydrate salt.

S1. Comment

Sodium magnesium sulfate decahydrate belongs to a group of sulfate salts having the general formula Na₂Mg(SO₄)₂.nH₂O. Konyaite (n = 5) and blödite (n = 4) are two known mineral phases of this type, and are most commonly found as salt efflorescences associated with marine and lacustrine sediments. Such environments can be found in areas like the Great Konya Basin, Turkey (van Doesburg et al., 1982), the northern Great Plains of North Dakota (Keller et al., 1986a) and western Canada (Last & Ginn, 2005), as well as in the Carrizo Plain, California (Eghbal et al., 1989). Na–Mg sulfate decahydrate is suspected to occur in similar environments, as it readily dehydrates to konyaite. These phases are sensitive to changes in temperature and relative humidity, and precipitate chiefly through evaporative concentration of saline solutions (Keller et al., 1986b).

The behavior and stability of Na₂Mg(SO₄)₂.nH₂O phases and other phases of the Na₂O–MgO–SO₄–H₂O system are related, at least partially, to the arrangement and importance of the hydrogen bonds in their structure. Consequently, numerous studies have focused on solving their crystal structures, and individual phases are relatively well described: blödite, Na₂Mg(SO₄)₂.4H₂O (Rumanova, 1958; Hawthorne, 1985); epsomite, MgSO₄.7H₂O (Baur, 1964); hexahydrite, MgSO₄.6H₂O (Zalkin et al., 1964); vanthoffite, Na₆Mg(SO₄)₄ (Fischer & Hellner, 1964); löweite, Na₁₂Mg₇(SO₄)₁₃.15H₂O (Fang & Robinson, 1970; Nord, 1973); thenardite, Na₂SO₄ (Hawthorne & Ferguson, 1975); mirabilite, Na₂SO₄.10H₂O (Levy & Lisensky, 1978); and konyaite, Na₂Mg(SO₄)₂.5H₂O (Leduc et al., 2009).

The interactions and stability relationships between these phases, however, are poorly understood. Although phase relationships for the system have been partially mapped out (Archibald & Gale, 1924; Blasdale & Robson, 1928; Keller et al., 1986a), and these studies have been tied to field studies of saline soils of the Great Konya Basin by Driessen & Schoorl (1973), the existence of metastable phases, or the status of some of these minerals as being metastable, has been debated. D'Ans (1933) suggested, for instance, that the blödite field of stability could include a metastable phase, which was later found by Friedel (1976) to have the formula Na₂Mg(SO₄)₂.5H₂O. Konyaite was, however, not described officially until 1982 (van Doesburg et al., 1982). Timpson et al. (1986) later questioned its status as a metastable phase, and its structure was only described much later (Leduc et al., 2009). This study introduces another phase to the system.

These sulfates are typically labile, and constitute important components of saline soils, playing a role in desertification, soil contamination, and surface and ground water salinization (Shayan & Lancucki, 1984; Timpson et al., 1986; Keller et al., 1986a; Whittig et al., 1982; Last, 2002). They are also often associated with reactions involving mine waste (Zielinski et al., 2001), and commonly cause damage to concrete structures (Gao et al., 2007), both areas of ongoing concern. Furthermore, they occur in terrestrial environments that are used as analogs to what the Martian surface and subsurface environments are thought to be like (King et al., 2004). The study of these terrestrial analogs has already led to the discovery of a new mineral that is predicted to occur on Mars (Peterson & Wang, 2006; Peterson et al., 2007), and numerous other sulfate phases have been identified on its surface (Christensen et al., 2004; Squyres et al., 2004). The large saline oceans and icy crust of Europa are also believed to include some phases belonging to the Na₂O–MgO–SO₄–H₂O system. (Dalton, 2007; Dalton et al., 2005; Kargel et al., 2000). A greater understanding of the behavior of this system on Earth may therefore be applicable to these other environments.

The decahydrate structure contains two cation sites filled by Mg, in a slightly distorted octahedral arrangement, and Na, in a significantly more distorted octahedral coordination (Fig. 1 and Table 1). Of the five symmetrically unique water molecules, three coordinate exclusively with the Mg cations (O3W, O4W, and O5W), while the other two (O1W and O2W) coordinate the Na cations only.

The Mg octahedra interact with each other by O4W—H4A···O3W^vii [symmetry code: (vii) x, -y +3 /2, z - 1/2] hydrogen bonds alone, whereas the Na polyhedra share edges with one another, forming chains along b. These edges are defined by the sharing of O1W and O2W atoms between Na atoms. The remaining bonds are satisfied by corner-sharing between the Na octahedra and sulfate tetrahedra. This corner-sharing, together with O_water—H···O_sulfate hydrogen bonds involving atoms H1 and H2, links the Na octahedra chains to form sheets perpendicular to a. These sheets are separated by layers of weakly-interacting Mg octahedra (Fig. 2). Several H atoms on the Mg-coordinated water molecules are involved in bonding the [Mg(H₂O)₆]²⁺ layers to the sulfate O atoms of the [Na₂(SO₄)₂(H₂O)₄]^2- layers (Table 2). A bond valence summation was calculated for the structure, following the method of Brown (1981) and using the curve provided by Ferraris & Ivaldi (1988) for long hydrogen bond contributions. The results confirm that the proposed structure solution is reasonable.

The decahydrate structure, while distinct, bears certain similarities to that of both konyaite (n = 5) and blödite (n = 4). These features suggest a trend in the way the initial tetrahydrate structure must be modified to accommodate five and then ten water molecules. All three compounds are monoclinic, with a layered structure where hydrogen bonds are important.

The layers of the blödite structure are described as open sheets composed of water-coordinated Mg–sulfate clusters, [Mg(SO₄)₂(H₂O)₄]^2-, linked by pairs of edge-sharing Na octahedra and hydrogen bonds (Hawthorne, 1985). All sheets are identical, and are tied to one another by corner-sharing between sulfate tetrahedra and both the Mg and the Na octahedra. Hydrogen bonds are also involved in inter-sheet bonding. The Mg octahedra form an integral part of each sheet.

The konyaite structural layers have a much denser arrangement, where all polyhedra share at least one edge with a neighbor, but can share up to three (Leduc et al., 2009). Corner-sharing is secondary and only involved in the formation of chains, which are then bonded together through further edge-sharing to form layers. Inter-layer linkage involves hydrogen bonds exclusively. Two symmetrically independent Na sites are present; an octahedral and an eight-coordinated site are required to accommodate the presence of the `fifth' water molecule that now coordinates the Mg atom. The Na sites still occur in edge-sharing pairs, but the eight-coordinated sites are responsible for the formation of the polyhedral chains, whereas the octahedral sites provide linkage between the chains, effectively creating the layers. The Mg octahedra are located on the outside of each chain, and provide the hydrogen bonds holding the layers to one another.

The decahydrate structure follows the same trend, as the Mg atoms are now coordinated by six water molecules, to accommodate the `extra' water molecules. This limits corner- and edge-sharing for the Mg octahedra, and as a result, they now form a separate layer, whose structure relies entirely on hydrogen bonding. It seems that the structures tend to segregate Na and Mg polyhedra as water content increases. The Na atoms must now coordinate the remaining four water molecules, which again allows for a symmetrically unique Na octahedral site, as in blödite. The Na octahedra no longer occur in pairs, but retain the chain element through edge-sharing. As in konyaite, the chains are assembled together to form the layers, but corner-sharing is involved as in blödite, as opposed to the very compact nature of the konyaite layers which requires edge-sharing to bind chains together. Finally, only hydrogen bonds provide inter-layer linkage in the decahydrate, as they do in konyaite, and account for the tabular habit and cleavage of both compounds. The blödite layers, on the other hand, involve both hydrogen bonding and corner-sharing in sheet-to-sheet linkage.

Several other types of structures exist for compounds having the general formula M₂M'(SO₄)₂.nH₂O, where M is a monovalent cation (typically Na, NH₄ or K, but may include Rb, Cs etc.), M' is a divalent cation (usually Mg, Ca or a transition metal), and n stands for the hydration state. Examples include monohydrates, dihydrates and hexahydrates. No decahydrate analogues (n = 10) were found to have been reported in the literature.

The hexahydrate type of structure can accommodate a variety of cations, the most common of which are NH₄⁺ and K⁺, and Mg²⁺, Ca²⁺ or a first row divalent transition metal. Although the arrangement of the structure slightly varies depending on composition, the overall connectivity is comparable. Therefore, picromerite [K₂Mg(SO₄)₂.6H₂O] (Kannan & Viswamitra, 1965) was selected for comparison, as it is an Mg phase. The structure is composed of undulating layers, where chains of corner-sharing distorted K-centered octahedra are linked by water-coordinated Mg octahedra and sulfate tetrahedra through corner-sharing as well as hydrogen bonding. Aside from the presence of a chain arrangement, this type of structure is more similar to that of blödite than to the decahydrate, as the sheets are all identical, contain both metal sites, and rely on corner-sharing and hydrogen bonding for connectivity.

The decahydrate structure, therefore, includes features present in the structures of other phases having the same general formula. However, the difference in composition of its layers, the chain arrangement present in the sodium sulfate layer and the importance of hydrogen bonding to its overall connectivity distinguish it from the other M₂M'(SO₄)₂.nH₂O phases.

Related literature

For related literature, see: Archibald & Gale (1924); Baur (1964); Blasdale & Robson (1928); Brown (1981); Christensen & others (2004); Corazza & Sabelli (1967); D'Ans (1933); Dalton (2007); Dalton et al. (2005); Doesburg et al. (1982); Driessen & Schoorl (1973); Eghbal et al. (1989); Fang & Robinson (1970); Ferraris & Ivaldi (1988); Fischer & Hellner (1964); Friedel (1976); Gao et al. (2007); Hawthorne (1985); Hawthorne & Ferguson (1975); Kannan & Viswamitra (1965); Keller et al. (1986a, 1986b); King et al. (2004); Kolitsch & Fleck (2006); Last (2002); Last & Ginn (2005); Leduc et al. (2009); Levy & Lisensky (1978); Nord (1973); PANalytical (2006); Peterson & Wang (2006); Peterson et al. (2007); Rumanova (1958); Shayan & Lancucki (1984); Squyres & others (2004); Timpson et al. (1986); Whittig et al. (1982); Zalkin et al. (1964).

S2. Experimental

The crystal used in this study was synthesized following the method described by van Doesburg et al. (1982). Solutions with a 1:1 molar ratio of reagent-grade MgSO₄ and Na₂SO₄ were prepared, dissolving magnesium sulfate (20 g) and sodium sulfate (23.6 g) in distilled water (160 ml). These solutions were evaporated between 297 and 301 K, and 51 to 64% relative humidity, in large Petri dishes with perforated covers. Concentrations sufficient for precipitation were typically reached in 72–96 h. The synthesized crystals have a rhombic habit and measure between < 1 and 5 mm typically, although crystals as large as 2 cm were obtained with slower evaporation rates. The rhombs are soft, colourless, transparent and exhibit a [100] cleavage. A single-crystal fragment of the synthetic material was selected, immersed in mineral oil to prevent dehydration and inserted in a 0.3 mm glass capillary, which was then mounted for liquid-nitrogen-cooled single-crystal X-ray diffraction.

S3. Refinement

H-atom positions were obtained from difference Fourier maps and refined isotropically. The SHELX command SADI was used to restrain the O—H distances to be equal to 0.82 (2) Å.

Computing details

Data collection: APEX2 (Bruker, 2006); cell refinement: SMART (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ATOMS (Dowty, 2003); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and publCIF (Westrip, 2009).

Figures

Fig. 1. The coordination environment of the decahydrate asymmetric unit, showing displacement ellipsoids for non-H atoms at the 70% probability level. H atoms are depicted as spheres of arbitrary radii, and their labels have been omitted for clarity. Dashed lines represent hydrogen bonds. [Symmetry codes: (i) -x + 2, -y + 1, -z + 1; (ii) -x + 2, -y, -z + 1; (iii) x, -y + 1/2, z - 1/2; (iv) -x + 1, -y + 2, -z + 1.]

Fig. 2. The decahydrate structure, as viewed down the b axis. This geometry accounts for the [100] cleavage, as layers are only linked to one another by hydrogen bonds. [In the electronic version of the paper, Mg octahedra (slightly distorted) are green; Na ocathedra (distorted) are orange; sulfate tetrahedra are yellow; O atoms are red; and H atoms are white.]

disodium magnesium disulfate decahydrate

Crystal data

Na2Mg(SO4)2·10H2O	F(000) = 460
Mr = 442.57	Dx = 1.888 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1679 reflections
a = 12.4950 (13) Å	θ = 3.4–27.1°
b = 6.4978 (7) Å	µ = 0.53 mm^−1
c = 9.9943 (11) Å	T = 180 K
β = 106.362 (1)°	Plate, colourless
V = 778.57 (14) Å^3	0.30 × 0.24 × 0.08 mm
Z = 2

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	1527 independent reflections
Radiation source: sealed tube	1355 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.018
ϕ and ω scans	θmax = 26.0°, θmin = 3.4°
Absorption correction: multi-scan (SADABS; Bruker, 2003)	h = −12→15
Tmin = 0.733, Tmax = 0.820	k = −6→8
3655 measured reflections	l = −12→12

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)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.065	All H-atom parameters refined
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0265P)^2 + 0.5898P], with P = (Fo^2 + 2Fc^2)/3
1527 reflections	(Δ/σ)max < 0.001
146 parameters	Δρmax = 0.33 e Å^−3
45 restraints	Δρmin = −0.34 e Å^−3

Special details

Experimental. X-ray powder diffraction techniques were first applied to the synthesized material using a PANalytical X'Pert Pro θ-θ diffractometer equipped with an X'Celerator position-sensitive detector. Cobalt radiation (1.78901 Å) was generated at a setting of 45 kV and 40 mA to collect data over the 5 to 70° 2θ range. A pattern identification search was conducted using the X'Pert Highscore Plus software (PANalytical BV, Almelo, The Netherlands) and the ICDD database (PDF-2 Database, Release 2001, International Centre for Diffraction Data, Newtown Square, Pennsylvania, USA) to verify that the synthesized crystals did not match any currently known phase.

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
Mg1	0.5000	1.0000	0.5000	0.0118 (2)
Na1	0.98090 (6)	0.25420 (12)	0.39701 (8)	0.0170 (2)
S1	0.77908 (4)	0.48352 (7)	0.66966 (5)	0.01112 (13)
O1	0.79840 (11)	0.2644 (2)	0.70858 (14)	0.0168 (3)
O2	0.70931 (11)	0.5762 (2)	0.75259 (13)	0.0158 (3)
O3	0.88624 (11)	0.5912 (2)	0.70219 (14)	0.0188 (3)
O4	0.72047 (11)	0.5005 (2)	0.51904 (13)	0.0154 (3)
O1W	0.89962 (12)	0.5914 (2)	0.39621 (14)	0.0170 (3)
H1A	0.8426 (17)	0.582 (5)	0.419 (3)	0.050 (9)*
H1B	0.888 (2)	0.677 (3)	0.333 (2)	0.031 (7)*
O2W	0.88617 (12)	0.0340 (2)	0.52693 (15)	0.0189 (3)
H2A	0.861 (2)	0.096 (4)	0.583 (2)	0.046 (9)*
H2B	0.8322 (17)	−0.019 (4)	0.472 (2)	0.041 (8)*
O3W	0.40819 (12)	0.8376 (2)	0.61341 (14)	0.0157 (3)
H3A	0.370 (2)	0.903 (4)	0.653 (3)	0.042 (8)*
H3B	0.3726 (19)	0.738 (3)	0.578 (2)	0.035 (8)*
O4W	0.53094 (12)	0.7314 (2)	0.41183 (14)	0.0174 (3)
H4A	0.506 (2)	0.710 (4)	0.3286 (16)	0.031 (7)*
H4B	0.5876 (15)	0.665 (4)	0.443 (2)	0.027 (7)*
O5W	0.63661 (11)	0.9643 (2)	0.66869 (14)	0.0173 (3)
H5A	0.662 (2)	0.852 (3)	0.700 (3)	0.033 (7)*
H5B	0.6866 (17)	1.050 (3)	0.687 (3)	0.033 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mg1	0.0126 (4)	0.0108 (5)	0.0120 (4)	0.0016 (4)	0.0036 (3)	0.0006 (3)
Na1	0.0158 (4)	0.0164 (5)	0.0189 (4)	−0.0011 (3)	0.0049 (3)	0.0014 (3)
S1	0.0114 (2)	0.0099 (3)	0.0125 (2)	0.00026 (18)	0.00411 (17)	−0.00003 (18)
O1	0.0211 (7)	0.0101 (7)	0.0184 (7)	0.0035 (6)	0.0041 (6)	0.0021 (5)
O2	0.0188 (7)	0.0131 (7)	0.0187 (7)	0.0024 (6)	0.0105 (6)	0.0009 (6)
O3	0.0163 (7)	0.0233 (8)	0.0180 (7)	−0.0072 (6)	0.0071 (5)	−0.0053 (6)
O4	0.0148 (7)	0.0165 (8)	0.0138 (6)	0.0016 (5)	0.0021 (5)	0.0013 (5)
O1W	0.0189 (7)	0.0159 (8)	0.0167 (7)	0.0016 (6)	0.0057 (6)	0.0032 (6)
O2W	0.0189 (8)	0.0190 (9)	0.0193 (7)	0.0010 (6)	0.0064 (6)	−0.0037 (6)
O3W	0.0169 (7)	0.0127 (8)	0.0196 (7)	−0.0017 (6)	0.0085 (6)	−0.0016 (6)
O4W	0.0180 (7)	0.0165 (8)	0.0158 (7)	0.0057 (6)	0.0014 (6)	−0.0027 (6)
O5W	0.0160 (7)	0.0117 (8)	0.0207 (7)	0.0003 (6)	−0.0007 (6)	0.0023 (6)

Geometric parameters (Å, º)

Mg1—O4W	2.0405 (14)	S1—O2	1.4888 (13)
Mg1—O5W	2.0466 (14)	O1W—H1A	0.811 (15)
Mg1—O3W	2.1089 (14)	O1W—H1B	0.821 (15)
Na1—O1W^i	2.4018 (16)	O2W—H2A	0.819 (15)
Na1—O1W	2.4139 (17)	O2W—H2B	0.816 (15)
Na1—O2W	2.4495 (17)	O3W—H3A	0.820 (15)
Na1—O2W^ii	2.4765 (17)	O3W—H3B	0.809 (15)
Na1—O1^iii	2.5182 (15)	O4W—H4A	0.814 (14)
Na1—O3^i	2.3822 (15)	O4W—H4B	0.814 (14)
S1—O3	1.4638 (14)	O5W—H5A	0.821 (15)
S1—O1	1.4776 (14)	O5W—H5B	0.820 (15)
S1—O4	1.4810 (13)
O4W—Mg1—O4W^iv	180.00 (7)	O3—S1—O2	109.00 (8)
O4W^iv—Mg1—O5W^iv	92.48 (6)	O1—S1—O2	108.71 (8)
O4W—Mg1—O5W^iv	87.52 (6)	O4—S1—O2	109.66 (8)
O4W—Mg1—O3W^iv	89.89 (6)	S1—O1—Na1^v	106.83 (7)
O4W^iv—Mg1—O3W^iv	90.11 (6)	S1—O3—Na1^i	144.11 (8)
O5W—Mg1—O5W^iv	180.00 (7)	Na1^i—O1W—Na1	102.56 (6)
O5W—Mg1—O3W^iv	92.62 (6)	Na1^i—O1W—H1A	100 (2)
O5W^iv—Mg1—O3W^iv	87.38 (6)	Na1—O1W—H1A	109 (2)
O3W—Mg1—O3W^iv	180.0	Na1^i—O1W—H1B	108.0 (18)
O3^i—Na1—O1W^i	81.07 (5)	Na1—O1W—H1B	126.9 (18)
O3^i—Na1—O1W	87.58 (6)	H1A—O1W—H1B	107 (3)
O3^i—Na1—O2W	164.66 (6)	Na1^ii—O2W—Na1	102.82 (6)
O3^i—Na1—O2W^ii	87.76 (6)	Na1—O2W—H2A	114 (2)
O3^i—Na1—O1^iii	107.42 (5)	Na1^ii—O2W—H2A	121 (2)
O1W^i—Na1—O1W	77.44 (6)	Na1—O2W—H2B	108 (2)
O1W^i—Na1—O2W	93.67 (6)	Na1^ii—O2W—H2B	104 (2)
O1W—Na1—O2W	105.43 (6)	H2A—O2W—H2B	106 (3)
O1W^i—Na1—O2W^ii	81.45 (5)	Mg1—O3W—H3A	119 (2)
O1W—Na1—O2W^ii	158.84 (6)	Mg1—O3W—H3B	118.5 (18)
O1W^i—Na1—O1^iii	151.16 (6)	H3A—O3W—H3B	108 (3)
O1W—Na1—O1^iii	75.50 (5)	Mg1—O4W—H4A	121.5 (18)
O2W—Na1—O1^iii	84.11 (5)	Mg1—O4W—H4B	122.9 (17)
O2W^ii—Na1—O1^iii	125.52 (6)	H4A—O4W—H4B	110 (2)
O2W^ii—Na1—O2W	77.18 (6)	Mg1—O5W—H5A	124.2 (18)
O3—S1—O1	109.31 (8)	Mg1—O5W—H5B	121.1 (18)
O3—S1—O4	110.47 (8)	H5A—O5W—H5B	109 (3)
O1—S1—O4	109.67 (8)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1A···O4	0.81 (2)	2.11 (2)	2.9008 (19)	164 (3)
O1W—H1B···O3^vi	0.82 (2)	1.99 (2)	2.804 (2)	169 (2)
O2W—H2A···O1	0.82 (2)	1.99 (2)	2.804 (2)	175 (3)
O2W—H2B···O2^iii	0.82 (2)	2.32 (2)	3.082 (2)	155 (3)
O3W—H3A···O2^vii	0.82 (2)	1.91 (2)	2.731 (2)	174 (3)
O3W—H3B···O4^viii	0.81 (2)	2.01 (2)	2.822 (2)	177 (3)
O4W—H4A···O3W^vi	0.81 (1)	2.18 (2)	2.979 (2)	168 (2)
O4W—H4B···O4	0.81 (1)	1.94 (2)	2.7529 (19)	178 (3)
O5W—H5A···O2	0.82 (2)	1.92 (2)	2.731 (2)	173 (3)
O5W—H5B···O1^ix	0.82 (2)	1.94 (2)	2.756 (2)	173 (3)

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