Na7Al3(As2O7)4

Fakhar Bourguiba, N.; Driss, A.

doi:10.1107/S1600536813020151

inorganic compounds

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ISSN: 2056-9890

Volume 69| Part 8| August 2013| Page i53

doi:10.1107/S1600536813020151

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Na₇Al₃(As₂O₇)₄

Noura Fakhar Bourguiba ^a ^* and Ahmed Driss ^a

^aLaboratoire de Matériaux et Cristallochimie, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092 Manar II Tunis, Tunisia
^*Correspondence e-mail: n.f.bourguiba@live.fr

(Received 5 July 2013; accepted 21 July 2013; online 31 July 2013)

The title compound, heptasodium trialuminium tetrakis(diarsenate), has been isolated as single crystals from a solid-state reaction. Its structure, which is isotypic with that of the Na₇Fe₃(X₂O₇)₄ (X = As, P) family of compounds, consists of AlO₆ octahedra sharing their vertices with As₂O₇ groups, forming a three-dimensional [Al₃(As₂O₇)₄]_∞ framework incorporating channels occupied by the sodium ions. One of the aluminium ions lies on a crystallographic twofold axis. The sodium ions are situated over ten positions (one with site symmetry 2), all but one of which are partially occupied.

Related literature

For isotopic compounds, see: Masquelier & d'Yvoire (1991 ); Masquelier et al. (1990 , 1994 ); Quarez et al.(2009 , 2010 ). For bond lengths and angles in related structures, see: Driss & Jouini (1994 ); Masquelier et al. (1995 ). For structural relationships, see: Lii et al. (1989 ); Hwu & Willis (1991 ); Boughzala et al. (1993); Boughzala & Jouini (1995 ); Lin & Lii (1996 ); Fukuoka et al. (2003 ); Ouerfelli et al. (2007 ). For bond-valence parameters, see: Brown & Altermatt (1985 ).

Experimental

Crystal data

Na₇Al₃(As₂O₇)₄
M_r = 1289.23
Monoclinic, C 2/c
a = 9.800 (1) Å
b = 8.468 (1) Å
c = 28.637 (2) Å
β = 94.14 (1)°
V = 2370.3 (4) Å³
Z = 4
Mo Kα radiation
μ = 11.50 mm⁻¹
T = 298 K
0.25 × 0.20 × 0.10 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ) T_min = 0.759, T_max = 0.891
3958 measured reflections
2583 independent reflections
2150 reflections with I > 2σ(I)
R_int = 0.056
2 standard reflections every 120 min intensity decay: 1.1%

Refinement

R[F² > 2σ(F²)] = 0.034
wR(F²) = 0.085
S = 1.10
2583 reflections
221 parameters
Δρ_max = 1.27 e Å⁻³
Δρ_min = −0.98 e Å⁻³

Table 1
Selected bond lengths (Å)

Al1—O12ⁱ	1.906 (4)
Al1—O12	1.906 (4)
Al1—O1ⁱⁱ	1.932 (4)
Al1—O1ⁱⁱⁱ	1.932 (4)
Al1—O3	1.994 (4)
Al1—O3ⁱ	1.994 (4)
Al2—O14	1.920 (4)
Al2—O10^iv	1.933 (4)
Al2—O7^iv	1.942 (4)
Al2—O5	1.947 (4)
Al2—O9^v	1.955 (4)
Al2—O6ⁱⁱ	2.000 (4)
As1—O2	1.651 (4)
As1—O1	1.676 (4)
As1—O3	1.689 (4)
As1—O4	1.776 (4)
As2—O13	1.638 (4)
As2—O14	1.675 (4)
As2—O12	1.686 (4)
As2—O4	1.769 (4)
As3—O7	1.668 (4)
As3—O5	1.671 (4)
As3—O6	1.677 (4)
As3—O11	1.736 (4)
As4—O8	1.646 (4)
As4—O10	1.676 (4)
As4—O9	1.679 (4)
As4—O11	1.760 (4)
Symmetry codes: (i) $[-x, y, -z+{\script{1\over 2}}]$ ; (ii) $[x-{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ ; (iii) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) -x+1, -y, -z+1; (v) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ .

Data collection: CAD-4 EXPRESS (Duisenberg, 1992 ; Macíček & Yordanov, 1992 ); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1998 ); software used to prepare material for publication: WinGX (Farrugia, 2012 ).

Supporting information

Crystal structure: contains datablock I. DOI: 10.1107/S1600536813020151/hb7105sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813020151/hb7105Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536813020151/hb7105Isup3.cml

checkCIF report

Comment top

A new family of compounds Na₇M₃(X₂O₇)₄ (M = Fe, Al, Cr, Ga; X = P, As) studied by Masquelier et al. (1994) present interesting ion conductivity properties. In this family line, a structural study was carried out only for Na₇Fe₃(As₂O₇)₄ and Na₇Fe₃(P₂O₇)₄ compounds by Masquelier et al.(1990, 1991). In addition, another structural study was conducted to isotypes compounds Na₅Ag₂Fe₃(As₂O₇)₄ and Na₂Ag₅Fe₃(P₂O₇)₄ by Quarez et al. (2009). Also, electrical measurements were also made by Quarez et al. (2009) for Ag₇Fe₃(X₂O₇)₄ (X = As, P) compounds. However, as for the Na₇Al₃(As₂O₇)₄ compound no structural analysis has been reported so far.

The structure of compound Na₇Al₃(As₂O₇)₄ shows a three-dimensional anionic framework [Al₃(As₂O₇) ₄]_∞ composed of octahedron AlO₆ sharing vertices with As₂O₇ groups. This framework defines the interstitial spaces in which the Na ⁺ ions are located in a partially disordered distribution to ensure the electrical neutrality. The single unit [Al₃(As₂O₇)₄]^7- consists of an octahedron Al1O₆ and two octahedra Al2O₆ related to As₂O₇ group by sharing vertices (Fig. 1). The two aluminium atoms occupy two crystallographically independent sites: the aluminium Al1 is in special position 4e of a symmetry equal to 2; whereas the Al2 is in general position of 8f. In this unit, the connection between the octahedra Al1O₆ and Al2O₆ is provided by the group As1As2O₇ through oxygen atom O14. In this structure, the units [Al₃(As₂O₇)₄]^7- are inter-related thanks to composite bridges of types Al—O—As and As—O—Al respectively. These bridges are located between the octahedra AlO₆ and As₂O₇ diarsenates groups in order to handle two types of parallel layers to the (a, b) plan. According to (010) (Fig. 2), a projection of the structure shows that the anionic framework consists of a succession of layers as follow: A: [Al1(As2As3O₇)₂]_∞ and B: [(Al2As3As4O₇)₂]_∞ perpendicular to c alternately. In the layers A, the only components are Octahedra Al1O₆, whereas other aluminium octahedra Al2O₆ shape layers B.

On the one hand, in the layer A, each octahedron Al1O₆ is connected to two groups As1As2O₇ by sharing both a vertex and two other groups As1As2O₇ such as the Al1O₆ octahedron shares two of its vertices with the same group As₂O₇. By rotation around the fold axis, these groups are equivalent (Fig. 3). This mode of connection is found in phosphates: ARu₂(P₂O₇)₂ (A = Li, Na, Ag) (Fukuoka et al., 2003.), NaMo₂(P₂O₇)₂ (Hwu et al., 1991), and SrV₂(P₂O₇)₂ (Lii et al., 1989).

On the other hand, in the layer B, each octahedron Al2O₆ is connected to four As₂O₇ groups through the formation of composite bridges Al—O—As and the division of two vertices with a fifth group As₂O₇ (Fig. 3). This layer is formed by AlAs₂O₁₁ units related through the formation of Al—O—As composed bridges. This type of M—O—As bond between MAs₂O₁₁ units (M = Al, Ga, Fe) is situated in the following isostructural compounds: RbAlAs₂O₇ (Boughzala et al., 1993), KAlAs₂O₇ (Boughzala et al., 1995), KGaAs₂O₇ (Lin et al., 1996) and TlFe_0.22Al_0.78As₂O₇ (Ouerfelli et al., 2007).

The O14 oxygen atom guarantees the bond between the layers A and B through the bridges Al2—O14—As2.

The anionic framework [Al₃(As₂O₇)₄]_∞ can be also described as alternate stacking of octahedral AlO₆ layers and As₂O₇ groups layers parallel to (101) (Fig. 4).

In this structure, the sodium ions are distributed through ten crystallographic sites in the interstices of the anionic network. The first type of the site corresponding to 8f position is totally occupied by the Na1 cation which is localized in the layer B. As for the nine other sites, they are partially occupied. And these can be arranged into groups of three sets: (Na2A—Na2B—Na2C), (Na3A—Na3B) and (Na4A—Na4B—Na4C—Na4D). Different sites of the same group are too close to be occupied simultaneously. As a result, the total number of Na⁺ ions for each group is less than or equal to one. These sodium ions are predominantly located in the layer A and they are distributed in the vicinity of two plans parallel to (001) respectively to dimensions z ≈ 0.15 and z ≈ 0.35. Also, the Na2B site, located on the binary axis, occupies an intermediate position (z = 1/4). Examination of geometric factors in the structure shows that they are in accordance with those found in the literature (Driss et al., 1994; Masquelier et al., 1995.). In addition, the use of the BVS method for the calculation of different valences of bonds, using the empirical formula of Brown (Brown & Altermatt, 1985), does satisfy the expected values of ion charge: Al1 (2.73), Al2 (2.69), As1 (4.90), As2 (4.98), As3 (5.01), As4 (5.00), Na1 (1.16), Na2A (0.87), Na2B (1.13), Na2C (0.79), Na3A (1.00), Na3B (1.03), Na4A (0.97), Na4B (0.95), Na4C (1.01), Na4D (0, 93). In order to use these structural data and to connect them to the physicochemical properties, especially ion-conducting electrical measurements through a complex impedance bridge are in progress.

Related literature top

For isotopic compounds, see: Masquelier & D'Yvoire (1991); Masquelier et al. (1990, 1994); Quarez et al.(2009, 2010). For bond lengths and angles in related structures, see: Driss & Jouini (1994); Masquelier et al. (1995). For structural relationships, see: Lii et al. (1989); Hwu & Willis (1991); Boughzala et al. (1993); Boughzala & Jouini (1995); Lin & Lii (1996); Fukuoka et al. (2003); Ouerfelli et al. (2007). For bond-valence parameters, see: Brown & Altermatt (1985).

Experimental top

The crystals related to the Na₇Al₃ (As₂O₇)₄ phase were obtained from reactants: NaHCO₃ (Prolabo, 27778), Al₂O₃ (Riedel-de Haen, 167305) NH₄H₂AsO₄ (prepared in the laboratory, JCPDS-775), taken in molar proportions: Na: A l: As = 10: 1: 9. Finely ground, the mixture was put in a porcelain crucible, placed in an oven and preheated in air at 673 K for 24 h to remove volatiles. After that, the mixture is raised to a synthesis temperature close to the melting 968 K through stages of 100 degrees followed by grinding. The mixture is then left at this temperature for a week to promote germination and growth of crystals. The final residue undergoes a first slow cooling (5 ° / half day, at 800 K) and a second fast (50 ° / h) to room temperature. Transparent crystals of prismatic form, clear outline and sufficient size for measurements of intensities, have been separated from the stream by successive hot water washes.

Computing details top

Data collection: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); cell refinement: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1998); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures top

	Fig. 1. Part of Na₇Al₃ (As2O₇) ₄ structure. The ellipsoids were defined with 50% probability. [Symmetry code: (i): - x, y, - z + 0.5; (ii): x - 1/2, y - 1/2, z; (iii): - x + 1/2, y - 1/2, - z + 0.5; (iv): - x + 1, - y, - z + 1; (v): -x + 1/2, - y + 1/2, - z + 1].
	Fig. 2. Projection of Na₇Al₃(As₂O₇)₄ structure along [010]. The Na sites are numbered. The picture indicates the location of the A and B layers and the π planes at z ≈ 0.15 and 0.35.
	Fig. 3. Arrangement of Al1O₆ octahedra and As1As2O₇ groups in the A-layer and arrangement of Al2O₆ octahedra and As3As4O₇ groups in the B-layer.
	Fig. 4. Alternate stacking of octahedral AlO₆ layers and As₂O₇ groups layers parallel to (-101).

Heptasodium trialuminium tetrakis(diarsenate) top

Crystal data top

Na₇Al₃(As₂O₇)₄	F(000) = 2416
M_r = 1289.23	D_x = 3.613 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 25 reflections
a = 9.800 (1) Å	θ = 10–15°
b = 8.468 (1) Å	µ = 11.50 mm⁻¹
c = 28.637 (2) Å	T = 298 K
β = 94.14 (1)°	Parallelipiped, colorless
V = 2370.3 (4) Å³	0.25 × 0.20 × 0.1 mm
Z = 4

Data collection top

Enraf–Nonius CAD-4 diffractometer	2150 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.056
Graphite monochromator	θ_max = 27.0°, θ_min = 2.9°
ω/2θ scans	h = −12→3
Absorption correction: ψ scan (North et al., 1968)	k = −1→10
T_min = 0.759, T_max = 0.891	l = −36→36
3958 measured reflections	2 standard reflections every 120 min
2583 independent reflections	intensity decay: 1.1%

Refinement top

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)] = 0.034	w = 1/[σ²(F_o²) + (0.0314P)² + 24.9095P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.085	(Δ/σ)_max = 0.001
S = 1.10	Δρ_max = 1.27 e Å⁻³
2583 reflections	Δρ_min = −0.98 e Å⁻³
221 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00057 (6)

Crystal data top

Na₇Al₃(As₂O₇)₄	V = 2370.3 (4) Å³
M_r = 1289.23	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 9.800 (1) Å	µ = 11.50 mm⁻¹
b = 8.468 (1) Å	T = 298 K
c = 28.637 (2) Å	0.25 × 0.20 × 0.1 mm
β = 94.14 (1)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	2150 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.056
T_min = 0.759, T_max = 0.891	2 standard reflections every 120 min
3958 measured reflections	intensity decay: 1.1%
2583 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	0 restraints
wR(F²) = 0.085	w = 1/[σ²(F_o²) + (0.0314P)² + 24.9095P] where P = (F_o² + 2F_c²)/3
S = 1.10	Δρ_max = 1.27 e Å⁻³
2583 reflections	Δρ_min = −0.98 e Å⁻³
221 parameters

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Al1	0.0000	0.1057 (3)	0.2500	0.0082 (4)
Al2	0.31736 (15)	−0.02622 (18)	0.43636 (5)	0.0069 (3)
As1	0.30056 (5)	0.28137 (6)	0.246216 (18)	0.00898 (15)
As2	0.21753 (5)	0.15080 (6)	0.338657 (18)	0.00927 (15)
As3	0.58680 (5)	0.20071 (6)	0.464306 (18)	0.00733 (14)
As4	0.48861 (5)	0.34009 (6)	0.557696 (18)	0.00774 (14)
O1	0.3645 (4)	0.4537 (5)	0.26651 (14)	0.0149 (8)
O2	0.3734 (4)	0.2071 (5)	0.20087 (13)	0.0149 (8)
O3	0.1281 (4)	0.2823 (5)	0.23865 (14)	0.0148 (8)
O4	0.3327 (4)	0.1491 (4)	0.29386 (13)	0.0119 (8)
O5	0.4404 (4)	0.1537 (5)	0.43395 (15)	0.0170 (9)
O6	0.6943 (4)	0.2857 (5)	0.42888 (14)	0.0145 (8)
O7	0.6569 (4)	0.0529 (4)	0.49622 (13)	0.0120 (8)
O8	0.5686 (4)	0.4760 (5)	0.59037 (13)	0.0148 (8)
O9	0.3192 (4)	0.3690 (5)	0.54893 (14)	0.0142 (8)
O10	0.5262 (4)	0.1554 (4)	0.57538 (14)	0.0133 (8)
O11	0.5459 (4)	0.3542 (4)	0.50101 (13)	0.0139 (8)
O12	0.0599 (4)	0.1063 (5)	0.31482 (14)	0.0162 (8)
O13	0.2283 (5)	0.3289 (5)	0.36098 (15)	0.0210 (9)
O14	0.2752 (4)	−0.0052 (5)	0.37014 (13)	0.0162 (8)
Na1	−0.2221 (3)	−0.1225 (3)	0.44633 (9)	0.0249 (6)
Na2A	0.5268 (10)	−0.0466 (12)	0.3075 (4)	0.017 (2)*	0.24
Na2B	0.5000	0.0010 (13)	0.2500	0.013 (2)*	0.28
Na2C	0.5094 (8)	−0.0556 (10)	0.3269 (3)	0.0236 (18)*	0.32
Na3A	0.0283 (5)	−0.1551 (6)	0.35860 (17)	0.0186 (11)*	0.58
Na3B	−0.0112 (8)	−0.1372 (9)	0.3504 (3)	0.0118 (16)*	0.33
Na4A	−0.233 (2)	0.100 (3)	0.3543 (7)	0.016 (4)*	0.13
Na4B	−0.1483 (11)	0.2292 (14)	0.3505 (3)	0.024 (2)*	0.27
Na4C	−0.1939 (9)	0.0862 (10)	0.3420 (3)	0.0220 (17)*	0.35
Na4D	−0.184 (2)	0.175 (3)	0.3538 (7)	0.025 (4)*	0.14

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Al1	0.0067 (9)	0.0083 (10)	0.0094 (10)	0.000	0.0000 (8)	0.000
Al2	0.0071 (7)	0.0064 (7)	0.0072 (7)	0.0000 (6)	−0.0004 (5)	0.0007 (6)
As1	0.0065 (2)	0.0108 (3)	0.0096 (3)	−0.00147 (19)	0.00072 (18)	0.00172 (19)
As2	0.0100 (3)	0.0103 (3)	0.0074 (3)	−0.0014 (2)	0.00003 (18)	0.0014 (2)
As3	0.0066 (2)	0.0081 (3)	0.0074 (3)	0.00032 (19)	0.00102 (18)	0.00067 (19)
As4	0.0076 (2)	0.0075 (3)	0.0083 (3)	−0.00002 (19)	0.00122 (18)	−0.00046 (18)
O1	0.0154 (19)	0.0102 (19)	0.019 (2)	−0.0034 (16)	0.0032 (15)	−0.0008 (16)
O2	0.0134 (18)	0.017 (2)	0.0151 (19)	−0.0001 (16)	0.0077 (14)	−0.0027 (16)
O3	0.0036 (16)	0.016 (2)	0.025 (2)	−0.0003 (15)	0.0023 (14)	0.0049 (17)
O4	0.0077 (16)	0.0145 (19)	0.0136 (18)	0.0026 (15)	0.0024 (14)	0.0037 (15)
O5	0.0125 (18)	0.0120 (19)	0.025 (2)	−0.0018 (15)	−0.0103 (16)	−0.0004 (16)
O6	0.0127 (18)	0.017 (2)	0.0149 (19)	0.0003 (16)	0.0066 (14)	0.0055 (16)
O7	0.0139 (18)	0.0114 (19)	0.0103 (18)	0.0063 (15)	−0.0011 (14)	0.0018 (15)
O8	0.0169 (19)	0.0147 (19)	0.013 (2)	−0.0044 (16)	0.0005 (15)	−0.0055 (15)
O9	0.0089 (17)	0.0145 (19)	0.019 (2)	0.0014 (15)	0.0009 (15)	0.0017 (16)
O10	0.0145 (18)	0.0076 (18)	0.018 (2)	0.0010 (15)	0.0025 (15)	0.0047 (15)
O11	0.025 (2)	0.0084 (18)	0.0088 (18)	0.0017 (16)	0.0077 (15)	0.0018 (15)
O12	0.0063 (16)	0.024 (2)	0.018 (2)	−0.0019 (16)	−0.0012 (14)	0.0011 (17)
O13	0.035 (2)	0.0112 (19)	0.017 (2)	−0.0013 (18)	0.0032 (17)	−0.0012 (17)
O14	0.022 (2)	0.0135 (19)	0.013 (2)	−0.0012 (16)	−0.0021 (15)	0.0030 (16)
Na1	0.0255 (13)	0.0141 (12)	0.0370 (15)	−0.0030 (10)	0.0148 (11)	−0.0035 (11)

Geometric parameters (Å, º) top

Al1—O12ⁱ	1.906 (4)	Na2B—O3^ix	2.274 (10)
Al1—O12	1.906 (4)	Na2B—O3ⁱⁱⁱ	2.274 (10)
Al1—O1ⁱⁱ	1.932 (4)	Na2B—O4^viii	2.477 (7)
Al1—O1ⁱⁱⁱ	1.932 (4)	Na2B—O2^viii	2.512 (9)
Al1—O3	1.994 (4)	Na2C—O13^ix	2.492 (9)
Al1—O3ⁱ	1.994 (4)	Na2C—O3ⁱⁱⁱ	2.619 (9)
Al2—O14	1.920 (4)	Na2C—O2^viii	2.652 (10)
Al2—O10^iv	1.933 (4)	Na2C—O12^ix	2.931 (9)
Al2—O7^iv	1.942 (4)	Na2C—O10^iv	2.968 (11)
Al2—O5	1.947 (4)	Na3A—O2ⁱⁱⁱ	2.330 (6)
Al2—O9^v	1.955 (4)	Na3A—O8^v	2.353 (6)
Al2—O6ⁱⁱ	2.000 (4)	Na3A—O6ⁱⁱ	2.545 (7)
As1—O2	1.651 (4)	Na3A—O5ⁱⁱ	2.879 (6)
As1—O1	1.676 (4)	Na3A—O13ⁱⁱ	2.949 (7)
As1—O3	1.689 (4)	Na3B—O8^v	2.279 (8)
As1—O4	1.776 (4)	Na3B—O2ⁱⁱⁱ	2.451 (8)
As2—O13	1.638 (4)	Na3B—O13ⁱⁱ	2.608 (9)
As2—O14	1.675 (4)	Na3B—O1ⁱⁱ	2.725 (9)
As2—O12	1.686 (4)	Na3B—O4ⁱⁱ	2.807 (8)
As2—O4	1.769 (4)	Na3B—O6ⁱⁱ	2.980 (9)
As3—O7	1.668 (4)	Na4A—O2ⁱ	2.213 (19)
As3—O5	1.671 (4)	Na4A—O8^v	2.271 (19)
As3—O6	1.677 (4)	Na4A—O13ⁱⁱ	2.33 (2)
As3—O11	1.736 (4)	Na4A—O6^vii	2.79 (2)
As4—O8	1.646 (4)	Na4B—O14^x	2.449 (11)
As4—O10	1.676 (4)	Na4B—O8^v	2.512 (11)
As4—O9	1.679 (4)	Na4B—O10^v	2.555 (11)
As4—O11	1.760 (4)	Na4B—O2ⁱ	2.568 (11)
Na1—O8^v	2.265 (5)	Na4B—O3ⁱ	2.613 (11)
Na1—O9^vi	2.302 (5)	Na4B—O6^vii	2.854 (11)
Na1—O7^vii	2.429 (4)	Na4C—O8^v	2.278 (8)
Na1—O13ⁱⁱ	2.492 (5)	Na4C—O2ⁱ	2.310 (9)
Na1—O5ⁱⁱ	2.517 (5)	Na4C—O13ⁱⁱ	2.384 (9)
Na1—O9ⁱⁱ	2.938 (5)	Na4C—O1ⁱⁱ	2.538 (10)
Na1—O11ⁱⁱ	2.966 (5)	Na4C—O3ⁱ	2.954 (9)
Na1—O10^vi	3.013 (5)	Na4D—O8^v	2.28 (2)
Na2A—O2^viii	2.380 (11)	Na4D—O2ⁱ	2.36 (2)
Na2A—O3ⁱⁱⁱ	2.420 (10)	Na4D—O6^vii	2.70 (2)
Na2A—O13^ix	2.631 (11)	Na4D—O14^x	2.78 (3)
Na2A—O3^ix	2.692 (12)	Na4D—O10^v	2.85 (2)
Na2A—O12^ix	2.962 (11)	Na4D—O3ⁱ	2.89 (2)

O12ⁱ—Al1—O12	179.7 (3)	O2—As1—O4	107.54 (19)
O12ⁱ—Al1—O1ⁱⁱ	94.10 (18)	O1—As1—O4	103.99 (19)
O12—Al1—O1ⁱⁱ	86.13 (17)	O3—As1—O4	102.82 (18)
O12ⁱ—Al1—O1ⁱⁱⁱ	86.13 (17)	O13—As2—O14	120.4 (2)
O12—Al1—O1ⁱⁱⁱ	94.10 (18)	O13—As2—O12	113.3 (2)
O1ⁱⁱ—Al1—O1ⁱⁱⁱ	96.5 (3)	O14—As2—O12	107.8 (2)
O12ⁱ—Al1—O3	89.56 (18)	O13—As2—O4	105.3 (2)
O12—Al1—O3	90.19 (17)	O14—As2—O4	100.13 (19)
O1ⁱⁱ—Al1—O3	172.35 (19)	O12—As2—O4	108.58 (18)
O1ⁱⁱⁱ—Al1—O3	90.44 (16)	O7—As3—O5	114.24 (19)
O12ⁱ—Al1—O3ⁱ	90.19 (17)	O7—As3—O6	113.67 (19)
O12—Al1—O3ⁱ	89.56 (18)	O5—As3—O6	109.9 (2)
O1ⁱⁱ—Al1—O3ⁱ	90.44 (16)	O7—As3—O11	109.49 (18)
O1ⁱⁱⁱ—Al1—O3ⁱ	172.35 (19)	O5—As3—O11	105.4 (2)
O3—Al1—O3ⁱ	82.8 (2)	O6—As3—O11	103.15 (19)
O14—Al2—O10^iv	89.86 (18)	O8—As4—O10	113.3 (2)
O14—Al2—O7^iv	174.86 (18)	O8—As4—O9	114.1 (2)
O10^iv—Al2—O7^iv	93.40 (17)	O10—As4—O9	111.99 (19)
O14—Al2—O5	88.99 (18)	O8—As4—O11	107.83 (19)
O10^iv—Al2—O5	86.32 (18)	O10—As4—O11	105.32 (18)
O7^iv—Al2—O5	95.18 (18)	O9—As4—O11	103.31 (19)
O14—Al2—O9^v	92.74 (18)	As1—O1—Al1^xi	137.9 (2)
O10^iv—Al2—O9^v	170.74 (18)	As1—O3—Al1	127.7 (2)
O7^iv—Al2—O9^v	84.66 (17)	As2—O4—As1	117.7 (2)
O5—Al2—O9^v	84.85 (18)	As3—O5—Al2	132.7 (2)
O14—Al2—O6ⁱⁱ	83.26 (17)	As3—O6—Al2^xi	132.6 (2)
O10^iv—Al2—O6ⁱⁱ	90.59 (17)	As3—O7—Al2^iv	130.6 (2)
O7^iv—Al2—O6ⁱⁱ	92.73 (17)	As4—O9—Al2^v	138.8 (2)
O5—Al2—O6ⁱⁱ	171.67 (19)	As4—O10—Al2^iv	129.4 (2)
O9^v—Al2—O6ⁱⁱ	98.54 (17)	As3—O11—As4	127.6 (2)
O2—As1—O1	115.63 (19)	As2—O12—Al1	127.1 (2)
O2—As1—O3	112.7 (2)	As2—O14—Al2	130.2 (2)
O1—As1—O3	112.73 (19)

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

Selected bond lengths (Å) top

Al1—O12ⁱ	1.906 (4)	As1—O3	1.689 (4)
Al1—O12	1.906 (4)	As1—O4	1.776 (4)
Al1—O1ⁱⁱ	1.932 (4)	As2—O13	1.638 (4)
Al1—O1ⁱⁱⁱ	1.932 (4)	As2—O14	1.675 (4)
Al1—O3	1.994 (4)	As2—O12	1.686 (4)
Al1—O3ⁱ	1.994 (4)	As2—O4	1.769 (4)
Al2—O14	1.920 (4)	As3—O7	1.668 (4)
Al2—O10^iv	1.933 (4)	As3—O5	1.671 (4)
Al2—O7^iv	1.942 (4)	As3—O6	1.677 (4)
Al2—O5	1.947 (4)	As3—O11	1.736 (4)
Al2—O9^v	1.955 (4)	As4—O8	1.646 (4)
Al2—O6ⁱⁱ	2.000 (4)	As4—O10	1.676 (4)
As1—O2	1.651 (4)	As4—O9	1.679 (4)
As1—O1	1.676 (4)	As4—O11	1.760 (4)

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

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