# Crystal structure of alluaudite-type NaMg3(HPO4)2(PO4)

Ahmed Ould Saleck, Abderrazzak Assani, Mohamed Saadi, Cyrille

Albert-Mercier, Claudine Follet-Houttemane, Lahcen El Ammari

► To cite this version:

Ahmed Ould Saleck, Abderrazzak Assani, Mohamed Saadi, Cyrille Albert-Mercier, Claudine Follet-Houttemane, et al. Crystal structure of alluaudite-type NaMg3(HPO4)2(PO4). Acta crystallographica Section E: Crystallographic communications [2015-..], 2015, 71 (7), pp.813-815. 10.1107/S205698901501155X. hal-03116322

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Distributed under a Creative Commons Attribution 4.0 International License
Acta Cryst.

E

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN 2056-9890

Received 8 June 2015

Accepted 15 June 2015

Edited by M. Weil, Vienna University of
Technology, Austria

**Keywords:** crystal structure; transition metal phosphates; alluaudite structure type; hydrothermal synthesis; hydrogen bonding

CCDC reference: 1406819

**Supporting information:** this article has
supporting information at journals.iucr.org/e

Crystal structure of alluaudite-type
NaMg₃(HPO₄)₂(PO₄)

Ahmed Ould Saleck,ª,ᵇ* Abderrazzak Assani,ª Mohamed Saadi,ª Cyrille Mercier,ᵇ Claudine Folletᵇ and Lahcen El Ammariª

ªLaboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V, Avenue Ibn Battouta, BP 1014, Rabat, Morocco, and ᵇLaboratoire des Matériaux Céramiques et Procédés Associés, EA2443, Université de Valenciennes et du Hainaut-Cambrésis, Boulevard Charles de Gaulle, BP 59600, Maubeuge, France. *Correspondence e-mail: a_ouldsaleck@yahoo.fr

The title compound, sodium trimagnesium bis(hydrogen phosphate) phosphate, was obtained under hydrothermal conditions. In the crystal, two types of [MgO₆] octahedra, one with point group symmetry 2, share edges to build chains extending parallel to [101]. These chains are linked together by two kinds of phosphate tetrahedra, HPO₄ and PO₄, the latter with point group symmetry 2. The three-dimensional framework delimits two different types of channels extending along [001]. One channel hosts the Na⁺ cations (site symmetry 2) surrounded by eight O atoms, with Na—O bond lengths varying between 2.2974 (13) and 2.922 (2) Å. The OH group of the HPO₄ tetrahedron points into the other type of channel and exhibits a strong hydrogen bond to an O atom of the PO₄ tetrahedron on the opposite side.

**1. Chemical context**

By means of hydrothermal processes (Demazeau, 2008; Yoshimura & Byrappa, 2008), we have previously succeeded in the isolation of the mixed-valence manganese phosphates $MMn_2^{II}Mn^{III}(PO_4)_3$ ($M$ = Ba, Pb, Sr) adopting the α-CrPO₄ structure type (Assani *et al.*, 2013; Alhakmi *et al.*, 2013a,b). In addition, within the pseudo-ternary systems Ag₂O–MO–P₂O₅, hydrothermal syntheses have allowed us to obtain other α-CrPO₄ isotype phosphates, viz. Ag₂M₃(HPO₄)(PO₄)₂ ($M$ = Co, Ni) while AgMg₃(HPO₄)₂(PO₄) is found to adopt the alluaudite structure type (Assani *et al.*, 2011a,b,c). Other hydrothermally grown phosphates with the alluaudite structure include AgCo₃(HPO₄)₂(PO₄) (Guesmi & Driss, 2002), AgNi₃(HPO₄)₂(PO₄) (Ben Smail & Jouini, 2002), AMn₃(HPO₄)₂(PO₄) ($A$ = Na, Ag) (Leroux *et al.*, 1995a,b) and NaCo₃(HPO₄)₂(PO₄) (Lii & Shih, 1994). Phosphates belonging to either the α-CrPO₄ or alluaudite structure type or derivatives thereof are still in the focus of research owing to their promising applications as battery materials (Trad *et al.*, 2010; Essehli *et al.*, 2015a,b; Huang *et al.*, 2015).

The crystal structures of alluaudite-type phosphates exhibit channels in which the monovalent cations are localized. Indeed, this is strongly required for conductivity properties. The crystal structure of alluaudite can be formulated by the general formula $(A1)(A2)(M1)(M2)_2(PO_4)_3$, (Moore & Ito, 1979). The two A sites can be occupied by either mono- or divalent medium-sized cations while the two M cationic sites correspond to an octahedral environment generally occupied by transition metal cations. On the basis of literature research, it has been shown that the hydrothermal process allows, in general, stoichiometric phases to be obtained while solid-state

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<figure><img src="image_4.png" /><figcaption>Figure 1</figcaption></figure>

The principal building units in the structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bonds are indicated by dashed lines [Symmetry codes: (i) $x + \frac{1}{2}, y + \frac{1}{2}, z$; (ii) $-x + \frac{3}{2}, y + \frac{1}{2}, -z + \frac{1}{2}$; (iii) $-x + \frac{3}{2}, -y + \frac{3}{2}, -z + 1$; (iv) $-x + \frac{3}{2}, -y + \frac{3}{2}, -z$; (v) $-x + 1, -y + 1, -z$; (vi) $-x + 1, y, -z + \frac{1}{2}$; (vii) $x, -y + 1, z + \frac{1}{2}$; (viii) $x - \frac{1}{2}, -y + \frac{3}{2}, z - \frac{1}{2}$; (ix) $-x + 2, y, -z + \frac{3}{2}$; (x) $-x + 2, -y + 1, -z + 1$; (xi) $x + \frac{1}{2}, -y + \frac{1}{2}, z + \frac{1}{2}$; (xii) $-x + \frac{3}{2}, -y + \frac{1}{2}, -z + 1$; (xiii) $x, -y + 1, z - \frac{1}{2}$]

reactions give rather a statistical distribution of cations on either the *A* or *M* sites, leading to non-stoechiometric compounds (Bouraima *et al.*, 2015; Khmiyas *et al.*, 2015).

In line with our focus of interest, we hydrothermally synthesized the compound $NaMg_3(PO_4)(HPO_4)_2$ and report here its crystal structure.

## 2. Structural commentary

The principal building units of the allaudite structure of the title compound are represented in Fig. 1. The three atoms

<figure><img src="image_5.png" /><figcaption>Figure 2</figcaption></figure>

A sheet resulting from the linkage of kinked chains *via* vertices of $PO_4$ tetrahedra.

<table><caption>Table 1</caption><caption>Selected bond lengths (Å).</caption><tbody><tr><td>Mg1—O3<sup>i</sup></td><td>2.1224 (13)</td><td>Na1—O3</td><td>2.8840 (19)</td></tr><tr><td>Mg1—O1<sup>ii</sup></td><td>2.1312 (12)</td><td>Na1—O1<sup>vii</sup></td><td>2.922 (2)</td></tr><tr><td>Mg1—O4</td><td>2.1669 (14)</td><td>P1—O1<sup>viii</sup></td><td>1.5372 (12)</td></tr><tr><td>Mg2—O6</td><td>2.0234 (13)</td><td>P1—O1</td><td>1.5372 (12)</td></tr><tr><td>Mg2—O3<sup>ii</sup></td><td>2.0686 (13)</td><td>P1—O2<sup>viii</sup></td><td>1.5476 (13)</td></tr><tr><td>Mg2—O2</td><td>2.0696 (14)</td><td>P1—O2</td><td>1.5476 (13)</td></tr><tr><td>Mg2—O5<sup>iii</sup></td><td>2.0729 (13)</td><td>P2—O5</td><td>1.5234 (12)</td></tr><tr><td>Mg2—O5<sup>iv</sup></td><td>2.0955 (13)</td><td>P2—O6</td><td>1.5263 (12)</td></tr><tr><td>Mg2—O1<sup>v</sup></td><td>2.1153 (14)</td><td>P2—O3</td><td>1.5349 (13)</td></tr><tr><td>Na1—O6</td><td>2.2974 (13)</td><td>P2—O4</td><td>1.5806 (13)</td></tr><tr><td>Na1—O6<sup>vi</sup></td><td>2.4386 (13)</td><td></td><td></td></tr></tbody></table>

Symmetry codes: (i) $x - \frac{1}{2}, -y + \frac{1}{2}, z - \frac{1}{2}$; (ii) $x, -y + 1, z - \frac{1}{2}$; (iii) $-x + \frac{1}{2}, y + \frac{1}{2}, -z + \frac{1}{2}$; (iv) $x, -y + 1, z + \frac{1}{2}$; (v) $-x + \frac{1}{2}, -y + \frac{1}{2}, -z + 1$; (vi) $-x + 1, -y + \frac{1}{2}, -z + 1$; (vii) $x + \frac{1}{2}, -y + \frac{3}{2}, z + \frac{1}{2}$; (viii) $-x, y, -z + \frac{1}{2}$.

<table><caption>Table 2</caption><caption>Hydrogen-bond geometry (Å, °).</caption><thead><tr><th>D—H···A</th><th>D—H</th><th>H···A</th><th>D···A</th><th>D—H···A</th></tr></thead><tbody><tr><td>O4—H4···O2</td><td>0.93</td><td>1.57</td><td>2.4932 (17)</td><td>174</td></tr></tbody></table>

$Mg1$, $Na1$ and $P1$ are located on a twofold rotation axis (Wyckoff position 4e). Selected interatomic distances are compiled in Table 1. The three-dimensional framework of this structure consists of kinked chains of edge-sharing $MgO_6$ octahedra running parallel to [101]. The chains are held together by regular $P1O_4$ phosphate groups, forming sheets perpendicular to [010], as shown in Fig. 2. The stacked sheets delimit two types of channels along [001]. One of the channels is occupied by $Na^+$ cations surrounded by eight oxygen atoms (Table 1), whereas the second channel contains the hydrogen atoms of the $HP2O_4$ tetrahedra, as shown in Fig. 3. They form strong hydrogen bonds (Table 2, Figs. 1 and 3) with one of the oxygen atoms of $PO_4$ tetrahedra on opposite sides.

<figure><img src="image_6.png" /><figcaption>Figure 3</figcaption></figure>

Polyhedral representation of the $NaMg_3(HPO_4)_2(PO_4)$ structure showing channels along [001]. The O—H···O hydrogen bonds are indicated by dashed lines.
<table><caption>**Table 3**
Experimental details.</caption><tbody><tr><td>Crystal data</td><td></td></tr><tr><td>Chemical formula</td><td>NaMg<sub>3</sub>(HPO<sub>4</sub>)<sub>2</sub>(PO<sub>4</sub>)</td></tr><tr><td>M<sub>r</sub></td><td>382.85</td></tr><tr><td>Crystal system, space group</td><td>Monoclinic, C2/c</td></tr><tr><td>Temperature (K)</td><td>296</td></tr><tr><td>a, b, c (Å)</td><td>11.8064 (6), 12.0625 (7), 6.4969 (4)</td></tr><tr><td>β (°)</td><td>113.805 (2)</td></tr><tr><td>V (Å<sup>3</sup>)</td><td>846.54 (8)</td></tr><tr><td>Z</td><td>4</td></tr><tr><td>Radiation type</td><td>Mo Kα</td></tr><tr><td>μ (mm<sup>-1</sup>)</td><td>1.06</td></tr><tr><td>Crystal size (mm)</td><td>0.36 × 0.24 × 0.18</td></tr><tr><td>Data collection</td><td></td></tr><tr><td>Diffractometer</td><td>Bruker X8 APEX</td></tr><tr><td>Absorption correction</td><td>Multi-scan (SADABS; Bruker, 2009)</td></tr><tr><td>T<sub>min</sub>, T<sub>max</sub></td><td>0.504, 0.748</td></tr><tr><td>No. of measured, independent and observed [I > 2σ(I)] reflections</td><td>9797, 1291, 1138</td></tr><tr><td>R<sub>int</sub></td><td>0.038</td></tr><tr><td>(sin θ/λ)<sub>max</sub> (Å<sup>-1</sup>)</td><td>0.714</td></tr><tr><td>Refinement</td><td></td></tr><tr><td>R[F<sup>2</sup> > 2σ(F<sup>2</sup>)], wR(F<sup>2</sup>), S</td><td>0.025, 0.072, 1.09</td></tr><tr><td>No. of reflections</td><td>1291</td></tr><tr><td>No. of parameters</td><td>88</td></tr><tr><td>H-atom treatment</td><td>H-atom parameters constrained</td></tr><tr><td>Δρ<sub>max</sub>, Δρ<sub>min</sub> (e Å<sup>-3</sup>)</td><td>0.57, -0.54</td></tr></tbody></table>

Computer programs: *APEX2* and *SAINT* (Bruker, 2009), *SHELXS* (Sheldrick, 2008), *SHELXL2013* (Sheldrick, 2015), *ORTEP-3 for Windows* (Farrugia, 2012). *DIAMOND* (Brandenburg, 2006) and *publCIF* (Westrip, 2010).

### 3. Synthesis and crystallization

Colourless parallelepiped-shaped crystals of the title compound were grown under hydrothermal conditions, starting from a mixture of Na<sub>4</sub>P<sub>2</sub>O<sub>7</sub>·10H<sub>2</sub>O, MgO and H<sub>3</sub>PO<sub>4</sub> (85 wt%) in the molar ratio Na<sub>4</sub>P<sub>2</sub>O<sub>7</sub>·10H<sub>2</sub>O:MgO:H<sub>3</sub>PO<sub>4</sub> = 1:3:3. The hydrothermal reaction was conducted in a 23 ml Teflon-lined autoclave, filled to 50% with distilled water and under autogenous pressure at 483 K for four days.

### 4. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The minimum and maximum electron densities are located 0.71 and 0.17 Å from O5 and H4, respectively. The O-bound H atom was initially located in a difference map and refined with an O—H distance restraint of 0.93 Å, and with U<sub>iso</sub>(H) = 1.5U<sub>eq</sub>(O).

### Acknowledgements

The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements and Mohammed V University, Rabat, Morocco, for financial support.

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Acta Cryst. (2015). E71, 813-815 [doi:10.1107/S205698901501155X]

# Crystal structure of alluaudite-type NaMg₃(HPO₄)₂(PO₄)

Ahmed Ould Saleck, Abderrazzak Assani, Mohamed Saadi, Cyrille Mercier, Claudine Follet and
Lahcen El Ammari

## Computing details

Data collection: *APEX2* (Bruker, 2009); cell refinement: *SAINT* (Bruker, 2009); data reduction: *SAINT* (Bruker, 2009); program(s) used to solve structure: *SHELXS* (Sheldrick, 2008); program(s) used to refine structure: *SHELXL2013* (Sheldrick, 2015); molecular graphics: *ORTEP-3 for Windows* (Farrugia, 2012) and *DIAMOND* (Brandenburg, 2006); software used to prepare material for publication: *publCIF* (Westrip, 2010).

## Sodium trimagnesium bis(hydrogen phosphate) phosphate

### Crystal data

<table><tr><td>NaMg<sub>3</sub>(HPO<sub>4</sub>)<sub>2</sub>(PO<sub>4</sub>)</td><td><i>F</i>(000) = 760</td></tr><tr><td><i>M</i><sub>r</sub> = 382.85</td><td><i>D</i><sub>x</sub> = 3.004 Mg m<sup>-3</sup></td></tr><tr><td>Monoclinic, <i>C</i>2/<i>c</i></td><td>Mo <i>K</i>α radiation, <i>λ</i> = 0.71073 Å</td></tr><tr><td><i>a</i> = 11.8064 (6) Å</td><td>Cell parameters from 1291 reflections</td></tr><tr><td><i>b</i> = 12.0625 (7) Å</td><td><i>θ</i> = 2.5–30.5°</td></tr><tr><td><i>c</i> = 6.4969 (4) Å</td><td><i>μ</i> = 1.06 mm<sup>-1</sup></td></tr><tr><td><i>β</i> = 113.805 (2)°</td><td><i>T</i> = 296 K</td></tr><tr><td><i>V</i> = 846.54 (8) Å<sup>3</sup></td><td>Block, colourless</td></tr><tr><td><i>Z</i> = 4</td><td>0.36 × 0.24 × 0.18 mm</td></tr></table>

### Data collection

<table><tr><td>Bruker X8 APEX</td><td>9797 measured reflections</td></tr><tr><td>diffractometer</td><td>1291 independent reflections</td></tr><tr><td>Radiation source: fine-focus sealed tube</td><td>1138 reflections with <i>I</i> > 2σ(<i>I</i>)</td></tr><tr><td>Graphite monochromator</td><td><i>R</i><sub>int</sub> = 0.038</td></tr><tr><td><i>φ</i> and <i>ω</i> scans</td><td><i>θ</i><sub>max</sub> = 30.5°, <i>θ</i><sub>min</sub> = 2.5°</td></tr><tr><td>Absorption correction: multi-scan<br>(SADABS; Bruker, 2009)</td><td><i>h</i> = −16→16</td></tr><tr><td><i>T</i><sub>min</sub> = 0.504, <i>T</i><sub>max</sub> = 0.748</td><td><i>k</i> = −17→17</td></tr><tr><td></td><td><i>l</i> = −9→8</td></tr></table>

### Refinement

<table><tr><td>Refinement on <i>F</i><sup>2</sup></td><td>Hydrogen site location: difference Fourier map</td></tr><tr><td>Least-squares matrix: full</td><td>H-atom parameters constrained</td></tr><tr><td><i>R</i>[<i>F</i><sup>2</sup> > 2σ(<i>F</i><sup>2</sup>)] = 0.025</td><td><i>w</i> = 1/[σ<sup>2</sup>(<i>F</i><sub>o</sub><sup>2</sup>) + (0.0362<i>P</i>)<sup>2</sup> + 1.4203<i>P</i>]<br>where <i>P</i> = (<i>F</i><sub>o</sub><sup>2</sup> + 2<i>F</i><sub>c</sub><sup>2</sup>)/3</td></tr><tr><td><i>wR</i>(<i>F</i><sup>2</sup>) = 0.072</td><td>(Δ/σ)<sub>max</sub> < 0.001</td></tr><tr><td><i>S</i> = 1.09</td><td>Δρ<sub>max</sub> = 0.57 e Å<sup>-3</sup></td></tr><tr><td>1291 reflections</td><td>Δρ<sub>min</sub> = −0.54 e Å<sup>-3</sup></td></tr><tr><td>88 parameters</td><td></td></tr><tr><td>0 restraints</td><td></td></tr></table>
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.

<table><caption>Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²)</caption><thead><tr><th></th><th>x</th><th>y</th><th>z</th><th>U<sub>iso</sub>*/U<sub>eq</sub></th></tr></thead><tbody><tr><td>Mg1</td><td>0.0000</td><td>0.27947 (7)</td><td>0.2500</td><td>0.00857 (18)</td></tr><tr><td>Mg2</td><td>0.29000 (6)</td><td>0.66219 (5)</td><td>0.37489 (10)</td><td>0.00643 (14)</td></tr><tr><td>Na1</td><td>0.5000</td><td>0.52321 (14)</td><td>0.7500</td><td>0.0308 (4)</td></tr><tr><td>P1</td><td>0.0000</td><td>0.68659 (5)</td><td>0.2500</td><td>0.00564 (14)</td></tr><tr><td>P2</td><td>0.28093 (4)</td><td>0.38887 (3)</td><td>0.38603 (7)</td><td>0.00494 (11)</td></tr><tr><td>O1</td><td>0.03662 (11)</td><td>0.75858 (10)</td><td>0.4624 (2)</td><td>0.0078 (2)</td></tr><tr><td>O2</td><td>0.10795 (12)</td><td>0.61003 (10)</td><td>0.2634 (2)</td><td>0.0084 (2)</td></tr><tr><td>O3</td><td>0.34567 (12)</td><td>0.32859 (10)</td><td>0.6116 (2)</td><td>0.0073 (2)</td></tr><tr><td>O4</td><td>0.14051 (11)</td><td>0.40754 (10)</td><td>0.3420 (2)</td><td>0.0085 (2)</td></tr><tr><td>H4</td><td>0.1241</td><td>0.4816</td><td>0.3033</td><td>0.013*</td></tr><tr><td>O5</td><td>0.28443 (11)</td><td>0.32046 (10)</td><td>0.1916 (2)</td><td>0.0068 (2)</td></tr><tr><td>O6</td><td>0.34273 (12)</td><td>0.50140 (10)</td><td>0.4000 (2)</td><td>0.0076 (2)</td></tr></tbody></table>

<table><caption>Atomic displacement parameters (Å²)</caption><thead><tr><th></th><th>U<sup>11</sup></th><th>U<sup>22</sup></th><th>U<sup>33</sup></th><th>U<sup>12</sup></th><th>U<sup>13</sup></th><th>U<sup>23</sup></th></tr></thead><tbody><tr><td>Mg1</td><td>0.0081 (4)</td><td>0.0088 (4)</td><td>0.0094 (4)</td><td>0.000</td><td>0.0041 (3)</td><td>0.000</td></tr><tr><td>Mg2</td><td>0.0073 (3)</td><td>0.0057 (3)</td><td>0.0067 (3)</td><td>0.0004 (2)</td><td>0.0031 (2)</td><td>0.0001 (2)</td></tr><tr><td>Na1</td><td>0.0118 (6)</td><td>0.0691 (11)</td><td>0.0091 (6)</td><td>0.000</td><td>0.0016 (5)</td><td>0.000</td></tr><tr><td>P1</td><td>0.0051 (3)</td><td>0.0063 (3)</td><td>0.0044 (3)</td><td>0.000</td><td>0.0007 (2)</td><td>0.000</td></tr><tr><td>P2</td><td>0.0060 (2)</td><td>0.00431 (19)</td><td>0.0043 (2)</td><td>-0.00006 (14)</td><td>0.00177 (16)</td><td>-0.00011 (14)</td></tr><tr><td>O1</td><td>0.0063 (6)</td><td>0.0110 (5)</td><td>0.0054 (5)</td><td>-0.0010 (4)</td><td>0.0014 (5)</td><td>-0.0022 (4)</td></tr><tr><td>O2</td><td>0.0060 (6)</td><td>0.0073 (5)</td><td>0.0114 (6)</td><td>0.0010 (4)</td><td>0.0031 (5)</td><td>-0.0007 (4)</td></tr><tr><td>O3</td><td>0.0086 (6)</td><td>0.0080 (5)</td><td>0.0049 (5)</td><td>0.0020 (4)</td><td>0.0024 (5)</td><td>0.0016 (4)</td></tr><tr><td>O4</td><td>0.0073 (6)</td><td>0.0058 (5)</td><td>0.0131 (6)</td><td>0.0009 (4)</td><td>0.0048 (5)</td><td>0.0004 (5)</td></tr><tr><td>O5</td><td>0.0077 (6)</td><td>0.0077 (5)</td><td>0.0052 (5)</td><td>0.0003 (4)</td><td>0.0028 (5)</td><td>-0.0009 (4)</td></tr><tr><td>O6</td><td>0.0083 (6)</td><td>0.0051 (5)</td><td>0.0093 (6)</td><td>-0.0014 (4)</td><td>0.0035 (5)</td><td>-0.0002 (4)</td></tr></tbody></table>

<table><caption>Geometric parameters (Å, °)</caption><tr><td>Mg1—O3<sup>i</sup></td><td>2.1224 (13)</td><td>Na1—O6<sup>x</sup></td><td>2.4386 (13)</td></tr><tr><td>Mg1—O3<sup>ii</sup></td><td>2.1224 (13)</td><td>Na1—O3</td><td>2.8840 (19)</td></tr><tr><td>Mg1—O1<sup>iii</sup></td><td>2.1312 (12)</td><td>Na1—O3<sup>ix</sup></td><td>2.8840 (19)</td></tr><tr><td>Mg1—O1<sup>iv</sup></td><td>2.1312 (12)</td><td>Na1—O1<sup>xi</sup></td><td>2.922 (2)</td></tr><tr><td>Mg1—O4<sup>v</sup></td><td>2.1669 (14)</td><td>Na1—O1<sup>viii</sup></td><td>2.922 (2)</td></tr><tr><td>Mg1—O4</td><td>2.1669 (14)</td><td>P1—O1<sup>v</sup></td><td>1.5372 (12)</td></tr><tr><td>Mg2—O6</td><td>2.0234 (13)</td><td>P1—O1</td><td>1.5372 (12)</td></tr><tr><td>Mg2—O3<sup>iii</sup></td><td>2.0686 (13)</td><td>P1—O2<sup>v</sup></td><td>1.5476 (13)</td></tr><tr><td>Mg2—O2</td><td>2.0696 (14)</td><td>P1—O2</td><td>1.5476 (13)</td></tr></table>
<table>
  <tbody>
    <tr>
      <td>Mg2—O5<sup>vi</sup></td>
      <td>2.0729 (13)</td>
      <td>P2—O5</td>
      <td>1.5234 (12)</td>
    </tr>
    <tr>
      <td>Mg2—O5<sup>vii</sup></td>
      <td>2.0955 (13)</td>
      <td>P2—O6</td>
      <td>1.5263 (12)</td>
    </tr>
    <tr>
      <td>Mg2—O1<sup>viii</sup></td>
      <td>2.1153 (14)</td>
      <td>P2—O3</td>
      <td>1.5349 (13)</td>
    </tr>
    <tr>
      <td>Na1—O6</td>
      <td>2.2974 (13)</td>
      <td>P2—O4</td>
      <td>1.5806 (13)</td>
    </tr>
    <tr>
      <td>Na1—O6<sup>ix</sup></td>
      <td>2.2974 (13)</td>
      <td>O4—H4</td>
      <td>0.9269</td>
    </tr>
    <tr>
      <td>Na1—O6<sup>vii</sup></td>
      <td>2.4386 (13)</td>
      <td></td>
      <td></td>
    </tr>
    <tr>
      <td>O3<sup>i</sup>—Mg1—O3<sup>ii</sup></td>
      <td>104.23 (8)</td>
      <td>O6<sup>vii</sup>—Na1—O6<sup>x</sup></td>
      <td>166.01 (10)</td>
    </tr>
    <tr>
      <td>O3<sup>i</sup>—Mg1—O1<sup>iii</sup></td>
      <td>86.53 (5)</td>
      <td>O6—Na1—O3</td>
      <td>56.06 (5)</td>
    </tr>
    <tr>
      <td>O3<sup>ii</sup>—Mg1—O1<sup>iii</sup></td>
      <td>78.23 (5)</td>
      <td>O6<sup>ix</sup>—Na1—O3</td>
      <td>111.84 (7)</td>
    </tr>
    <tr>
      <td>O3<sup>i</sup>—Mg1—O1<sup>iv</sup></td>
      <td>78.23 (5)</td>
      <td>O6<sup>vii</sup>—Na1—O3</td>
      <td>62.51 (5)</td>
    </tr>
    <tr>
      <td>O3<sup>ii</sup>—Mg1—O1<sup>iv</sup></td>
      <td>86.53 (5)</td>
      <td>O6<sup>x</sup>—Na1—O3</td>
      <td>105.27 (6)</td>
    </tr>
    <tr>
      <td>O1<sup>iii</sup>—Mg1—O1<sup>iv</sup></td>
      <td>155.13 (8)</td>
      <td>O6—Na1—O3<sup>ix</sup></td>
      <td>111.84 (7)</td>
    </tr>
    <tr>
      <td>O3<sup>i</sup>—Mg1—O4<sup>v</sup></td>
      <td>83.70 (5)</td>
      <td>O6<sup>ix</sup>—Na1—O3<sup>ix</sup></td>
      <td>56.06 (5)</td>
    </tr>
    <tr>
      <td>O3<sup>ii</sup>—Mg1—O4<sup>v</sup></td>
      <td>170.20 (5)</td>
      <td>O6<sup>vii</sup>—Na1—O3<sup>ix</sup></td>
      <td>105.27 (6)</td>
    </tr>
    <tr>
      <td>O1<sup>iii</sup>—Mg1—O4<sup>v</sup></td>
      <td>108.38 (5)</td>
      <td>O6<sup>x</sup>—Na1—O3<sup>ix</sup></td>
      <td>62.51 (5)</td>
    </tr>
    <tr>
      <td>O1<sup>iv</sup>—Mg1—O4<sup>v</sup></td>
      <td>89.53 (5)</td>
      <td>O3—Na1—O3<sup>ix</sup></td>
      <td>71.02 (6)</td>
    </tr>
    <tr>
      <td>O3<sup>i</sup>—Mg1—O4</td>
      <td>170.20 (5)</td>
      <td>O6—Na1—O1<sup>xi</sup></td>
      <td>118.48 (6)</td>
    </tr>
    <tr>
      <td>O3<sup>ii</sup>—Mg1—O4</td>
      <td>83.70 (5)</td>
      <td>O6<sup>ix</sup>—Na1—O1<sup>xi</sup></td>
      <td>74.30 (5)</td>
    </tr>
    <tr>
      <td>O1<sup>iii</sup>—Mg1—O4</td>
      <td>89.53 (5)</td>
      <td>O6<sup>vii</sup>—Na1—O1<sup>xi</sup></td>
      <td>84.97 (5)</td>
    </tr>
    <tr>
      <td>O1<sup>iv</sup>—Mg1—O4</td>
      <td>108.38 (5)</td>
      <td>O6<sup>x</sup>—Na1—O1<sup>xi</sup></td>
      <td>107.88 (6)</td>
    </tr>
    <tr>
      <td>O4<sup>v</sup>—Mg1—O4</td>
      <td>89.05 (7)</td>
      <td>O3—Na1—O1<sup>xi</sup></td>
      <td>146.62 (4)</td>
    </tr>
    <tr>
      <td>O6—Mg2—O3<sup>iii</sup></td>
      <td>85.88 (5)</td>
      <td>O3<sup>ix</sup>—Na1—O1<sup>xi</sup></td>
      <td>129.17 (3)</td>
    </tr>
    <tr>
      <td>O6—Mg2—O2</td>
      <td>88.80 (5)</td>
      <td>O6—Na1—O1<sup>viii</sup></td>
      <td>74.30 (5)</td>
    </tr>
    <tr>
      <td>O3<sup>iii</sup>—Mg2—O2</td>
      <td>111.03 (6)</td>
      <td>O6<sup>ix</sup>—Na1—O1<sup>viii</sup></td>
      <td>118.48 (7)</td>
    </tr>
    <tr>
      <td>O6—Mg2—O5<sup>vi</sup></td>
      <td>172.05 (6)</td>
      <td>O6<sup>vii</sup>—Na1—O1<sup>viii</sup></td>
      <td>107.88 (6)</td>
    </tr>
    <tr>
      <td>O3<sup>iii</sup>—Mg2—O5<sup>vi</sup></td>
      <td>91.58 (5)</td>
      <td>O6<sup>x</sup>—Na1—O1<sup>viii</sup></td>
      <td>84.97 (5)</td>
    </tr>
    <tr>
      <td>O2—Mg2—O5<sup>vi</sup></td>
      <td>85.07 (5)</td>
      <td>O3—Na1—O1<sup>viii</sup></td>
      <td>129.17 (3)</td>
    </tr>
    <tr>
      <td>O6—Mg2—O5<sup>vii</sup></td>
      <td>98.45 (5)</td>
      <td>O3<sup>ix</sup>—Na1—O1<sup>viii</sup></td>
      <td>146.62 (4)</td>
    </tr>
    <tr>
      <td>O3<sup>iii</sup>—Mg2—O5<sup>vii</sup></td>
      <td>162.38 (6)</td>
      <td>O1<sup>xi</sup>—Na1—O1<sup>viii</sup></td>
      <td>51.46 (6)</td>
    </tr>
    <tr>
      <td>O2—Mg2—O5<sup>vii</sup></td>
      <td>86.23 (5)</td>
      <td>O1<sup>v</sup>—P1—O1</td>
      <td>111.21 (10)</td>
    </tr>
    <tr>
      <td>O5<sup>vi</sup>—Mg2—O5<sup>vii</sup></td>
      <td>86.22 (5)</td>
      <td>O1<sup>v</sup>—P1—O2<sup>v</sup></td>
      <td>111.07 (7)</td>
    </tr>
    <tr>
      <td>O6—Mg2—O1<sup>viii</sup></td>
      <td>100.87 (6)</td>
      <td>O1—P1—O2<sup>v</sup></td>
      <td>108.34 (7)</td>
    </tr>
    <tr>
      <td>O3<sup>iii</sup>—Mg2—O1<sup>viii</sup></td>
      <td>79.79 (5)</td>
      <td>O1<sup>v</sup>—P1—O2</td>
      <td>108.34 (7)</td>
    </tr>
    <tr>
      <td>O2—Mg2—O1<sup>viii</sup></td>
      <td>166.18 (6)</td>
      <td>O1—P1—O2</td>
      <td>111.07 (7)</td>
    </tr>
    <tr>
      <td>O5<sup>vi</sup>—Mg2—O1<sup>viii</sup></td>
      <td>86.06 (5)</td>
      <td>O2<sup>v</sup>—P1—O2</td>
      <td>106.73 (10)</td>
    </tr>
    <tr>
      <td>O5<sup>vii</sup>—Mg2—O1<sup>viii</sup></td>
      <td>82.62 (5)</td>
      <td>O5—P2—O6</td>
      <td>111.03 (7)</td>
    </tr>
    <tr>
      <td>O6—Na1—O6<sup>ix</sup></td>
      <td>166.85 (10)</td>
      <td>O5—P2—O3</td>
      <td>111.42 (7)</td>
    </tr>
    <tr>
      <td>O6—Na1—O6<sup>vii</sup></td>
      <td>86.56 (4)</td>
      <td>O6—P2—O3</td>
      <td>108.82 (7)</td>
    </tr>
    <tr>
      <td>O6<sup>ix</sup>—Na1—O6<sup>vii</sup></td>
      <td>91.84 (4)</td>
      <td>O5—P2—O4</td>
      <td>107.74 (7)</td>
    </tr>
    <tr>
      <td>O6—Na1—O6<sup>x</sup></td>
      <td>91.84 (4)</td>
      <td>O6—P2—O4</td>
      <td>108.99 (7)</td>
    </tr>
    <tr>
      <td>O6<sup>ix</sup>—Na1—O6<sup>x</sup></td>
      <td>86.56 (4)</td>
      <td>O3—P2—O4</td>
      <td>108.78 (7)</td>
    </tr>
  </tbody>
</table>

Symmetry codes: (i) x-1/2, -y+1/2, z-1/2; (ii) -x+1/2, -y+1/2, -z+1; (iii) x, -y+1, z-1/2; (iv) -x, -y+1, -z+1; (v) -x, y, -z+1/2; (vi) -x+1/2, y+1/2, -z+1/2; (vii) x, -y+1, z+1/2; (viii) -x+1/2, -y+3/2, -z+1; (ix) -x+1, y, -z+3/2; (x) -x+1, -y+1, -z+1; (xi) x+1/2, -y+3/2, z+1/2.
Hydrogen-bond geometry (Å, °)

<table><thead><tr><th>D—H···A</th><th>D—H</th><th>H···A</th><th>D···A</th><th>D—H···A</th></tr></thead><tbody><tr><td>O4—H4···O2</td><td>0.93</td><td>1.57</td><td>2.4932 (17)</td><td>174</td></tr></tbody></table>