Crystal structure of the deuterated hepta­hydrate of potassium phosphate, K₃PO₄·7D₂O

An intricate network of medium-strong O—D⋯O hydrogen bonds consolidates the crystal structure of water-rich K₃PO₄·7D₂O.

Abstract

Deuterated potassium orthophosphate hepta­hydrate, K₃PO₄·7D₂O, crystallizes in the Sohnke space group P2₁, and its absolute structure was determined from 2017 Friedel pairs [Flack parameter 0.004 (16)]. Each of the three crystallographically unique K⁺ cations is surrounded by six water mol­ecules and one oxygen atom from the orthophosphate group, using a threshold for K—O bonds of 3.10 Å. The highly irregular coordination polyhedra are linked by corner- and edge-sharing into a three-dimensional network that is consolidated by an intricate network of O—D⋯O hydrogen bonds of medium strength.

Chemical context  

Following projects devoted to studying the formation and crystal chemistry of hydrous arsenate and phosphate phases of monovalent metals, viz. NaH₂AsO₄ (Ring et al., 2017 ▸), K₂HAsO₄(H₂O)_2.5 and K₂HAsO₄(H₂O)₆ (Stöger et al., 2012 ▸), M ₂HXO₄·2H₂O (M = Rb, Cs; X = P, As; Stöger & Weil, 2014 ▸), and several acidic thallium(I) arsenate phases (Schroffenegger et al., 2019 ▸), we became inter­ested in the system K₃PO₄/H₂O. Although hydrate phases of potassium orthophosphate have been known for a very long time to exist for the 3-hydrate and the 7-hydrate (Gmelin, 1938 ▸), crystal-structure determinations of these two phases or of any other hydrate of K₃PO₄ have not been reported so far. Previous investigations on the trihydrate revealed that the crystal structure of K₃PO₄·3H₂O is incommensurately modulated below 300 K (Stöger, 2020 ▸). To better elucidate the role of hydrogen bonding in this structure with the aid of single-crystal neutron diffraction, we started crystal-growth experiments to obtain the deuterium analogue K₃PO₄·3D₂O. The title compound, K₃PO₄·7D₂O, was the unexpected product of such a crystallization attempt at temperatures below the freezing point of pure water, and its crystal structure is reported here.

Structural commentary  

Taking 3.1 Å as the upper limit of K—O bond lengths in the first coordination sphere, each of the three crystallographically independent potassium cations is surrounded by six water mol­ecules and one oxygen atom of the phosphate group (Fig. 1 ▸). The highly irregular coordination polyhedra show K—O bond lengths ranging between 2.6665 (9) and 3.0151 Å (Table 1 ▸). The overall mean of 2.821 Å for the 21 bonds is in good agreement with the value of 2.861 Å calculated from 469 individual K—O bonds in crystal structures with coordination numbers of 7 for the potassium cation (Gagné & Hawthorne, 2016 ▸). The [K(D₂O)₆O] polyhedra share corners and edges to build up a three-dimensional network (Fig. 2 ▸). Each water mol­ecule is a donor group of two slightly bent O—D⋯O hydrogen bonds, but only two of the water mol­ecules (O3w, O6w) also serve as acceptor groups for one hydrogen bond. All other hydrogen bonds are directed towards the O atoms of the phosphate group, with O1 being twofold, O2 threefold, O3 fourfold and O4 threefold acceptor atoms, respectively (Fig. 3 ▸). Judging from the O⋯O distances [range 2.6931 (12)–2.9025 (13) Å; Table 2 ▸], hydrogen bonds of medium strength are formed in the crystal structure. The PO₄ tetra­hedron shows almost equal P—O bond lengths typical of a fully deprotonated orthophosphate group (mean 1.546 Å), with marginal angular distortions.

Figure 1.

The expanded asymmetric unit of K₃PO₄·7D₂O showing the complete potassium coordination polyhedra. Displacement ellipsoids are displayed at the 74% probability level; O—D⋯O hydrogen bonds are indicated by green lines; symmetry codes refer to Table 1 ▸.

Table 1. Selected bond lengths (Å).

K1—O5w	2.7153 (10)	K2—O6w i	3.0151 (10)
K1—O1w	2.7183 (11)	K3—O2w	2.6665 (9)
K1—O7w	2.7381 (10)	K3—O4iv	2.7867 (9)
K1—O6w	2.7532 (9)	K3—O4w v	2.7983 (10)
K1—O3w	2.8479 (9)	K3—O5w vi	2.8344 (10)
K1—O2w	2.8486 (9)	K3—O1w iv	2.8394 (10)
K1—O1	2.9757 (9)	K3—O7w vi	2.9094 (9)
K2—O1	2.7317 (10)	K3—O5w	2.9246 (10)
K2—O4w	2.7391 (10)	P1—O1	1.5414 (8)
K2—O7w	2.7659 (9)	P1—O2	1.5440 (8)
K2—O1w i	2.7836 (9)	P1—O4	1.5472 (10)
K2—O2w ii	2.8269 (9)	P1—O3	1.5523 (8)
K2—O3w iii	3.0144 (9)

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

Figure 2.

Network of corner- and edge-sharing [KO₇] polyhedra in the crystal structure of K₃PO₄·7D₂O, viewed along [00]. Displacement ellipsoids are displayed at the 90% probability level. For clarity, D atoms are not shown.

Figure 3.

O—D⋯O hydrogen-bonding network (green lines) in the crystal structure of K₃PO₄·7D₂O, viewed along [101]. Displacement ellipsoids are displayed at the 90% probability level.

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1w—D11⋯O3w iv	0.86 (2)	1.91 (2)	2.7255 (13)	158 (2)
O1w—D12⋯O4	0.78 (2)	1.98 (2)	2.7391 (11)	164 (2)
O2w—D21⋯O2iii	0.87 (2)	1.85 (2)	2.7149 (13)	177 (2)
O2w—D22⋯O1	0.73 (2)	1.99 (2)	2.7029 (11)	167 (3)
O3w—D31⋯O1	0.80 (2)	1.97 (2)	2.7242 (11)	159 (2)
O3w—D32⋯O3ii	0.98 (3)	1.77 (3)	2.7395 (14)	171 (2)
O4w—D41⋯O3vii	0.80 (2)	2.10 (2)	2.8870 (14)	169 (2)
O4w—D42⋯O2iii	0.79 (2)	1.97 (2)	2.7679 (13)	177 (2)
O5w—D51⋯O6w vi	0.80 (2)	2.11 (2)	2.9025 (13)	168 (2)
O5w—D52⋯O3viii	0.80 (2)	1.92 (2)	2.6944 (12)	166 (2)
O6w—D61⋯O2viii	0.75 (2)	1.96 (2)	2.7087 (12)	176 (2)
O6w—D62⋯O4ix	0.85 (2)	1.86 (2)	2.6931 (12)	165 (2)
O7w—D71⋯O3ii	0.78 (2)	2.02 (2)	2.7498 (12)	155 (2)
O7w—D72⋯O4vii	0.82 (2)	1.97 (2)	2.7859 (13)	171 (2)

Symmetry codes: (ii) ; (iii) ; (iv) ; (vi) ; (vii) ; (viii) ; (ix) .

A bond-valence analysis (Brown, 2002 ▸), using the parameters of Brese & O’Keeffe (1991 ▸), reveals bond-valence sums (BVS, in valence units) of K1 = 1.18, K2 = 1.08, K3 = 1.11, and P1 = 4.85, in good agreement with the expected values of +1 and +5, respectively. The four oxygen atoms of the orthophosphate tetra­hedron are considerably underbonded and show BVS values of 1.53 (O1), 1.22 (O2), 1.10 (O3) and 1.38 (O4). O1 with the highest BVS of the four phosphate O atoms has two K⁺ cations as additional bonding partners, O4 with the second highest BVS has one additional K⁺ as bonding partner whereas O2 and O3 with the lowest BVS values are solely bonded to the P atom. The four O atoms compensate for underbonding by means of their role as acceptor atoms in hydrogen bonding (see above).

Database survey  

In the Inorganic Structure Database (ICSD; Zagorac et al., 2019 ▸), the crystal structures of not less than 14 different phases in the system K₂O/P₂O₅/H₂O are listed, including partly protonated PO₄ or other condensed phosphate groups, and/or phases with water mol­ecules. The only other phosphates of an alkali metal, thallium or ammonium with a fully deprotonated orthophosphate group are Na₃PO₄(H₂O)₈ (Larbot & Durand, 1983 ▸), Na₃PO₄(H₂O)_0.5 (Averbuch-Pouchot & Durif, 1983 ▸) and (NH₄)₃(PO₄)·3H₂O (Mootz & Wunderlich, 1970 ▸). As a result of the different size of the Na⁺ cation compared to K⁺, the role of NH₄ ⁺ as an active species in hydrogen bonding, and the different amounts of water mol­ecules in these three crystal structures, there is no evident structural relation to K₃PO₄·7D₂O.

Synthesis and crystallization  

Commercial anhydrous K₃PO₄ (Sigma–Aldrich) was dissolved in a small amount of warm D₂O. Cooling to 255 K afforded rod-like crystals of the title hepta­hydrate that grew over night, with maximum edge lengths in the millimetre range.

Refinement  

Crystal data, data collection and structure refinement details are summarized in Table 3 ▸. Positions of the D atoms were located in a difference-Fourier map and were refined freely under consideration of scattering factors for hydrogen atoms.

Table 3. Experimental details.

Crystal data
Chemical formula	K3PO4·7D2O
M r	352.5
Crystal system, space group	Monoclinic, P21
Temperature (K)	100
a, b, c (Å)	7.8325 (7), 9.3406 (8), 8.4471 (7)
β (°)	108.727 (2)
V (Å3)	585.28 (9)
Z	2
Radiation type	Mo Kα
μ (mm−1)	1.34
Crystal size (mm)	0.46 × 0.09 × 0.01
Data collection
Diffractometer	Bruker Kappa APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2016 ▸)
T min, T max	0.54, 0.99
No. of measured, independent and observed [I > 3σ(I)] reflections	9464, 4273, 4127
R int	0.021
(sin θ/λ)max (Å−1)	0.759
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.016, 0.020, 1.02
No. of reflections	4273
No. of parameters	193
Δρmax, Δρmin (e Å−3)	0.16, −0.13
Absolute structure	2017 Friedel pairs used in the refinement (Flack, 1983 ▸)
Absolute structure parameter	0.004 (16)

Computer programs: APEX2 and SAINT-Plus (Bruker, 2016 ▸), SHELXT (Sheldrick, 2015 ▸), JANA2006 (Petříček et al., 2014 ▸), ATOMS (Dowty, 2006 ▸) and publCIF (Westrip, 2010 ▸).

Supplementary Material

CCDC reference: 1976170

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

supplementary crystallographic information

Crystal data

K3PO4·7D2O	F(000) = 348
Mr = 352.5	Dx = 2.000 Mg m−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 7382 reflections
a = 7.8325 (7) Å	θ = 2.6–32.6°
b = 9.3406 (8) Å	µ = 1.34 mm−1
c = 8.4471 (7) Å	T = 100 K
β = 108.727 (2)°	Rod, colourless
V = 585.28 (9) Å3	0.46 × 0.09 × 0.01 mm
Z = 2

Data collection

Bruker Kappa APEXII CCD diffractometer	4273 independent reflections
Radiation source: X-ray tube	4127 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.021
ω– and φ–scans	θmax = 32.6°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2016)	h = −10→11
Tmin = 0.54, Tmax = 0.99	k = −14→14
9464 measured reflections	l = −12→10

Refinement

Refinement on F	1 constraint
R[F2 > 2σ(F2)] = 0.016	Weighting scheme based on measured s.u.'s w = 1/(σ2(F) + 0.0001F2)
wR(F2) = 0.020	(Δ/σ)max = 0.019
S = 1.02	Δρmax = 0.16 e Å−3
4273 reflections	Δρmin = −0.13 e Å−3
193 parameters	Absolute structure: 2017 Friedel pairs used in the refinement (Flack, 1983)
0 restraints	Absolute structure parameter: 0.004 (16)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K1	0.42550 (3)	0.01804 (2)	0.73444 (3)	0.00950 (6)
K2	−0.14458 (3)	−0.00537 (2)	0.62341 (3)	0.00990 (6)
K3	0.52865 (3)	0.39152 (2)	0.81480 (3)	0.01224 (6)
P1	0.02505 (3)	0.04285 (3)	0.25261 (3)	0.00571 (7)
O1	0.08740 (10)	0.03291 (8)	0.44490 (9)	0.00823 (19)
O2	−0.06671 (10)	−0.09902 (8)	0.17723 (10)	0.0101 (2)
O3	−0.10938 (10)	0.16905 (8)	0.19358 (10)	0.0092 (2)
O4	0.18924 (10)	0.07033 (8)	0.19270 (10)	0.0086 (2)
O1w	0.50577 (11)	0.08478 (8)	0.45314 (11)	0.0119 (2)
O2w	0.22528 (11)	0.27301 (8)	0.61723 (11)	0.0106 (2)
O3w	0.23569 (11)	−0.22553 (8)	0.56243 (11)	0.0116 (2)
O4w	−0.18873 (12)	0.20109 (9)	0.83725 (11)	0.0129 (2)
O5w	0.53272 (11)	0.15028 (9)	1.03669 (11)	0.0126 (2)
O6w	0.71314 (11)	−0.16355 (8)	0.86601 (11)	0.0119 (2)
O7w	0.17243 (11)	−0.04581 (9)	0.88427 (10)	0.0103 (2)
D11	0.564 (2)	0.161 (2)	0.442 (2)	0.027 (5)*
D12	0.409 (3)	0.091 (2)	0.390 (3)	0.033 (5)*
D21	0.172 (3)	0.315 (2)	0.680 (2)	0.034 (5)*
D22	0.173 (3)	0.213 (2)	0.570 (3)	0.037 (6)*
D31	0.182 (2)	−0.162 (2)	0.506 (3)	0.031 (5)*
D32	0.179 (3)	−0.261 (3)	0.642 (3)	0.052 (7)*
D41	−0.153 (2)	0.1885 (19)	0.936 (3)	0.022 (4)*
D42	−0.113 (3)	0.258 (3)	0.837 (3)	0.049 (7)*
D51	0.477 (2)	0.2098 (19)	1.068 (2)	0.021 (4)*
D52	0.634 (2)	0.1654 (19)	1.093 (2)	0.023 (4)*
D61	0.776 (3)	−0.143 (2)	0.950 (3)	0.031 (5)*
D62	0.759 (2)	−0.240 (2)	0.842 (2)	0.023 (4)*
D71	0.132 (2)	−0.123 (2)	0.877 (2)	0.023 (4)*
D72	0.166 (2)	−0.0150 (19)	0.973 (2)	0.019 (4)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
K1	0.01055 (8)	0.00951 (9)	0.00895 (9)	0.00141 (6)	0.00384 (7)	0.00041 (7)
K2	0.00815 (8)	0.01323 (9)	0.00836 (9)	0.00028 (7)	0.00272 (7)	−0.00109 (7)
K3	0.01205 (9)	0.00943 (9)	0.01200 (11)	−0.00261 (7)	−0.00067 (8)	0.00104 (7)
P1	0.00639 (10)	0.00552 (10)	0.00530 (11)	−0.00037 (8)	0.00201 (8)	0.00003 (8)
O1	0.0102 (3)	0.0084 (3)	0.0056 (3)	0.0002 (2)	0.0020 (2)	−0.0001 (2)
O2	0.0131 (3)	0.0080 (3)	0.0086 (3)	−0.0040 (3)	0.0027 (3)	−0.0020 (3)
O3	0.0086 (3)	0.0090 (3)	0.0099 (4)	0.0029 (2)	0.0028 (3)	0.0022 (3)
O4	0.0089 (3)	0.0088 (3)	0.0092 (4)	−0.0002 (2)	0.0046 (3)	0.0004 (2)
O1w	0.0078 (3)	0.0150 (4)	0.0114 (4)	−0.0011 (3)	0.0010 (3)	0.0026 (3)
O2w	0.0091 (3)	0.0103 (3)	0.0120 (4)	−0.0011 (3)	0.0026 (3)	−0.0033 (3)
O3w	0.0127 (3)	0.0109 (3)	0.0123 (4)	0.0032 (3)	0.0056 (3)	0.0032 (3)
O4w	0.0182 (4)	0.0112 (3)	0.0102 (4)	−0.0007 (3)	0.0059 (3)	0.0003 (3)
O5w	0.0084 (3)	0.0168 (4)	0.0122 (4)	−0.0016 (3)	0.0030 (3)	−0.0033 (3)
O6w	0.0111 (3)	0.0099 (3)	0.0122 (4)	0.0020 (3)	0.0003 (3)	−0.0024 (3)
O7w	0.0126 (3)	0.0098 (3)	0.0091 (4)	−0.0010 (3)	0.0041 (3)	−0.0008 (3)

Geometric parameters (Å, º)

K1—O5w	2.7153 (10)	K3—O5w	2.9246 (10)
K1—O1w	2.7183 (11)	P1—O1	1.5414 (8)
K1—O7w	2.7381 (10)	P1—O2	1.5440 (8)
K1—O6w	2.7532 (9)	P1—O4	1.5472 (10)
K1—O3w	2.8479 (9)	P1—O3	1.5523 (8)
K1—O2w	2.8486 (9)	O1w—D11	0.86 (2)
K1—O1	2.9757 (9)	O1w—D12	0.778 (18)
K2—O1	2.7317 (10)	O2w—D21	0.87 (2)
K2—O4w	2.7391 (10)	O2w—D22	0.73 (2)
K2—O7w	2.7659 (9)	O3w—D31	0.796 (19)
K2—O1wi	2.7836 (9)	O3w—D32	0.98 (3)
K2—O2wii	2.8269 (9)	O4w—D41	0.80 (2)
K2—O3wiii	3.0144 (9)	O4w—D42	0.79 (2)
K2—O6wi	3.0151 (10)	O5w—D51	0.80 (2)
K3—O2w	2.6665 (9)	O5w—D52	0.795 (17)
K3—O4iv	2.7867 (9)	O6w—D61	0.748 (19)
K3—O4wv	2.7983 (10)	O6w—D62	0.85 (2)
K3—O5wvi	2.8344 (10)	O7w—D71	0.783 (19)
K3—O1wiv	2.8394 (10)	O7w—D72	0.823 (19)
K3—O7wvi	2.9094 (9)
O1—K1—O1w	70.45 (2)	O1wiv—K3—O5wvi	79.89 (3)
O1—K1—O2w	55.25 (2)	O1wiv—K3—O7wvi	114.35 (2)
O1—K1—O3w	55.73 (2)	O2w—K3—O4wv	107.76 (3)
O1—K1—O5w	132.58 (3)	O2w—K3—O5w	84.57 (2)
O1—K1—O6w	139.24 (2)	O2w—K3—O5wvi	112.79 (3)
O1—K1—O7w	78.74 (2)	O2w—K3—O7wvi	159.36 (3)
O1w—K1—O2w	76.14 (3)	O4wv—K3—O5w	67.74 (3)
O1w—K1—O3w	88.09 (3)	O4wv—K3—O5wvi	139.02 (2)
O1w—K1—O5w	128.98 (3)	O4wv—K3—O7wvi	70.82 (3)
O1w—K1—O6w	96.04 (3)	O5w—K3—O5wvi	109.99 (3)
O1w—K1—O7w	149.19 (2)	O5w—K3—O7wvi	75.81 (2)
O2w—K1—O3w	110.59 (2)	O5wvi—K3—O7wvi	69.21 (2)
O2w—K1—O5w	85.18 (3)	O1—P1—O2	109.32 (4)
O2w—K1—O6w	160.60 (2)	O1—P1—O3	109.69 (5)
O2w—K1—O7w	86.75 (3)	O1—P1—O4	109.83 (4)
O3w—K1—O5w	142.78 (3)	O2—P1—O3	109.96 (4)
O3w—K1—O6w	86.52 (2)	O2—P1—O4	109.46 (5)
O3w—K1—O7w	74.04 (3)	O3—P1—O4	108.56 (4)
O5w—K1—O6w	86.26 (3)	K2—O1—P1	123.21 (4)
O5w—K1—O7w	73.48 (3)	K3vii—O4—P1	131.03 (4)
O6w—K1—O7w	107.41 (3)	K1—O1w—K2v	86.80 (2)
O1—K2—O1wi	113.18 (3)	K1—O1w—K3vii	124.16 (3)
O1—K2—O2wii	74.56 (3)	K2v—O1w—K3vii	92.60 (3)
O1—K2—O3wiii	71.77 (3)	K1—O2w—K2iii	146.43 (4)
O1—K2—O4w	121.27 (3)	K1—O2w—K3	81.32 (2)
O1—K2—O6wi	153.61 (2)	K2iii—O2w—K3	95.43 (3)
O1—K2—O7w	82.62 (3)	D21—O2w—D22	113 (3)
O1wi—K2—O2wii	83.93 (2)	K1—O3w—D31	78.3 (13)
O1wi—K2—O3wiii	55.91 (2)	K1—O3w—D32	101.6 (14)
O1wi—K2—O4w	79.41 (3)	D31—O3w—D32	114 (2)
O1wi—K2—O6wi	88.99 (3)	K2—O4w—K3i	131.87 (3)
O1wi—K2—O7w	159.32 (3)	K2—O4w—D41	120.6 (14)
O2wii—K2—O3wiii	107.43 (3)	K2—O4w—D42	102.2 (19)
O2wii—K2—O4w	160.62 (3)	K3i—O4w—D41	99.7 (15)
O2wii—K2—O6wi	94.81 (3)	K3i—O4w—D42	98.8 (17)
O2wii—K2—O7w	114.15 (3)	D41—O4w—D42	95 (2)
O3wiii—K2—O4w	70.97 (3)	K1—O5w—K3viii	89.03 (2)
O3wiii—K2—O6wi	134.55 (3)	K1—O5w—D51	126.3 (11)
O3wiii—K2—O7w	122.36 (2)	K1—O5w—D52	126.4 (16)
O4w—K2—O6wi	75.19 (3)	K3viii—O5w—D51	104.9 (14)
O4w—K2—O7w	80.90 (3)	K3viii—O5w—D52	99.4 (13)
O6wi—K2—O7w	79.91 (3)	D51—O5w—D52	102.5 (18)
O4iv—K3—O1wiv	58.26 (2)	K1—O6w—D61	115.4 (16)
O4iv—K3—O2w	142.03 (3)	K1—O6w—D62	140.5 (11)
O4iv—K3—O4wv	76.51 (3)	D61—O6w—D62	104 (2)
O4iv—K3—O5w	129.11 (2)	K1—O7w—K2	101.53 (3)
O4iv—K3—O5wvi	75.37 (3)	K1—O7w—D71	120.0 (16)
O4iv—K3—O7wvi	58.52 (2)	K1—O7w—D72	127.9 (12)
O1wiv—K3—O2w	85.85 (3)	K2—O7w—D71	80.0 (11)
O1wiv—K3—O4wv	109.19 (3)	K2—O7w—D72	112.2 (11)
O1wiv—K3—O5w	168.35 (2)	D71—O7w—D72	105 (2)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1w—D11···O3wiv	0.86 (2)	1.91 (2)	2.7255 (13)	158 (2)
O1w—D12···O4	0.78 (2)	1.98 (2)	2.7391 (11)	164 (2)
O2w—D21···O2iii	0.87 (2)	1.85 (2)	2.7149 (13)	177 (2)
O2w—D22···O1	0.73 (2)	1.99 (2)	2.7029 (11)	167 (3)
O3w—D31···O1	0.80 (2)	1.97 (2)	2.7242 (11)	159 (2)
O3w—D32···O3ii	0.98 (3)	1.77 (3)	2.7395 (14)	171 (2)
O4w—D41···O3ix	0.80 (2)	2.10 (2)	2.8870 (14)	169 (2)
O4w—D42···O2iii	0.79 (2)	1.97 (2)	2.7679 (13)	177 (2)
O5w—D51···O6wvi	0.80 (2)	2.11 (2)	2.9025 (13)	168 (2)
O5w—D52···O3x	0.80 (2)	1.92 (2)	2.6944 (12)	166 (2)
O6w—D61···O2x	0.75 (2)	1.96 (2)	2.7087 (12)	176 (2)
O6w—D62···O4vii	0.85 (2)	1.86 (2)	2.6931 (12)	165 (2)
O7w—D71···O3ii	0.78 (2)	2.02 (2)	2.7498 (12)	155 (2)
O7w—D72···O4ix	0.82 (2)	1.97 (2)	2.7859 (13)	171 (2)

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