The aluminoarsenate Na1.67K1.33Al3(AsO4)4

Bouhassine, M.A.; Boughzala, H.

doi:10.1107/S1600536813033850

inorganic compounds

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Volume 70| Part 1| January 2014| Page i6

https://doi.org/10.1107/S1600536813033850

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The aluminoarsenate Na_1.67K_1.33Al₃(AsO₄)₄

Mohamad Alem Bouhassine ^a and Habib Boughzala ^a ^*

^aLaboratoire des Materiaux et de Cristallochimie, Faculte des Sciences de Tunis, Tunisia
^*Correspondence e-mail: habib.boughzala@ipein.rnu.tn

(Received 20 November 2013; accepted 13 December 2013; online 24 December 2013)

The title compound, sodium potassium trialuminium tetrakis(orthoarsenate), was prepared by solid-state reactions. The anionic framework consists of corrugated layers parallel to (010) and is made up of corner-sharing AlO₆ octahedra (site symmetries .2. and 2/m..) that are connected to isolated AsO₄ tetrahedra (site symmetries .2. and m..) through edge- and corner-sharing. The alkali cations are occupationally disordered. The two K⁺ cations [site symmetries .2. and m..; occupancies 0.314 (7) and 0.035 (12)] are situated in the interlayer space, whereas the smaller Na⁺ cations [both with site symmetry m..; occupancies = 0.725 (14) and 0.112 (14)] are located in the cavities of the anionic framework. The K⁺ cations are surrounded by six and seven O atoms, the Na⁺ cations by seven and nine O atoms. The resulting coordination polyhedra of the two types of cations are highly distorted.

CCDC reference: 977083

Related literature

For further information on this structure type, see: Friaa et al. (2003 ); Haj Abdallah & Haddad (2012 ). For background to the bond-valence method, see: Brown (2002 ).

Experimental

Crystal data

Na_1.67K_1.33Al₃(AsO₄)₄
M_r = 726.95
Orthorhombic, C m c e
a = 10.493 (1) Å
b = 20.395 (4) Å
c = 6.335 (4) Å
V = 1355.7 (9) Å³
Z = 4
Mo Kα radiation
μ = 10.53 mm⁻¹
T = 293 K
0.40 × 0.10 × 0.07 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ) T_min = 0.130, T_max = 0.332
1723 measured reflections
780 independent reflections
717 reflections with I > 2σ(I)
R_int = 0.062
2 standard reflections every 120 min intensity decay: 1.1%

Refinement

R[F² > 2σ(F²)] = 0.038
wR(F²) = 0.112
S = 1.15
780 reflections
84 parameters
1 restraint
Δρ_max = 2.38 e Å⁻³
Δρ_min = −1.33 e Å⁻³

Table 1
Selected bond lengths (Å)

As1—O1	1.642 (5)
As1—O2ⁱ	1.678 (3)
As1—O2	1.678 (3)
As1—O3	1.694 (4)
As2—O4ⁱⁱ	1.648 (3)
As2—O4	1.648 (3)
As2—O5	1.729 (3)
As2—O5ⁱⁱ	1.729 (3)
Al1—O3	1.827 (5)
Al1—O3ⁱⁱⁱ	1.827 (5)
Al1—O5ⁱⁱⁱ	1.947 (3)
Al1—O5^iv	1.947 (3)
Al1—O5ⁱ	1.947 (3)
Al1—O5	1.947 (3)
Al2—O2ⁱⁱ	1.817 (3)
Al2—O2	1.817 (3)
Al2—O4^v	1.924 (3)
Al2—O4^vi	1.924 (3)
Al2—O5ⁱⁱ	1.991 (3)
Al2—O5	1.991 (3)
Symmetry codes: (i) -x, y, z; (ii) $[-x+{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (iii) -x, -y, -z; (iv) x, -y, -z; (v) $[-x+{\script{1\over 2}}, -y, z-{\script{1\over 2}}]$ ; (vi) x, -y, -z+1.

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ); 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, 2006 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 977083

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: https://doi.org/10.1107/S1600536813033850/wm2786sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536813033850/wm2786Isup2.hkl

checkCIF report

Comment top

Na_1.67K_1.33Al₃(AsO₄)₄ is isostructural with K₃Cr₃(AsO₄)₄ (Friaa et al. (2003)) and belongs to the A^IM^III(XO₄)₄ family of compounds (A^I = alkali metal, M^III = Al, Cr, Fe,.. X = As, P) . Its structure consists of AlO₆ octahedra and AsO₄ tetrahedra sharing corners and edges to form a two-dimensional framework (Fig.1) that consists of corrugated layers extending parallel to (010). Each layer lies on a c-glide plane perpendicular to the b axis at y = 0 and y = 1/2. In the asymmetric unit two AlO₆ octahedra are linked to an As1O₄ tetrahedron by sharing corners and to an As2O₄ tetrahedron by sharing edges. The alkali cations are occupationally disordered with occupancies of 0.725 (14), 0.112 (14), 0.314 (7) and 0.035 (12) for Na1, Na2, K1 and K2, leading to the chemical formula Na_1.67K_1.33Al₃(AsO₄)₄. Smaller than K⁺, the seven- and nine-coordinated Na1⁺ and Na2⁺ (r_Na+ = 1.02 Å), are located in cavities surrounded by the anionic framework (Fig. 2). On the other hand, the K1⁺ and K2⁺ cations (r_K+ = 1.38 Å) are surrounded, respectively, by seven and six O atoms and are located in larger sites in the corrugated interlayer space. Using the bond valence method (Brown, 2002), the calculated bond-valence sum values (in valence units) of 5.17, 4.98, 3.04, 3.03, 0.86, 1.11, 0.92, 0.86, respectively, for As1, As2, Al1, Al2, Na1, Na2, K1 and K2 are in good agreement with the expected oxidation states.

A similar distribution of cations was observed in K_1.8Sr_0.6Al₃(AsO₄)₄ (Haj Abdallah et al., 2012). In fact, smaller than K⁺, the Sr²⁺ cations (r_Sr2+ = 1.18 Å) are located in the anionic cavities, on the other hand, K⁺ occupy the interlayer space. The cationic distribution in these two structures make it reasonable to conclude that the interlayer space is reserved for bigger cations and the anionic cavities for smaller cations. To our knowledge, this is the first published structure with occupationally disordered alkali sites in the A^IM^III(XO₄)₄ family of compounds. Reports of some new members of this family will be published soon.

Related literature top

For further information on this structure type, see: Friaa et al. (2003); Haj Abdallah & Haddad (2012). For background to the bond-valence method, see: Brown (2002).

Experimental top

Crystals of Na_1.67K_1.33Al₃(AsO₄)₄ were obtained from a mixture of K₂CO₃, Al₂O₃ and NH₄H₂AsO₄ in the stoichiometric molar ratio K/Al/As=2/3/4. The mixture was finely ground and heated in a porcelain crucible at 723 K for 4 h to eliminate volatile products. The temperature was held at 1173 K during 10 days until fusion was reached. The sample was slowly cooled in a speed of 5 K/ h to 923 K and finally quenched to room temperature. A long wash with boiling water liberated colorless crystals. The qualitative analysis by electron microscope probe of a selected crystal revealed the presence of the different elements in the compound composition. It is most likely that the incorporated sodium stems from the crucible.

Structure description top

For further information on this structure type, see: Friaa et al. (2003); Haj Abdallah & Haddad (2012). For background to the bond-valence method, see: Brown (2002).

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); 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, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

	Fig. 1. Projection of the Na_1.67K_1.33Al₃(AsO₄)₄ structure along [100], showing the K1⁺ and K2⁺ cations in the corrugated interlayer space. Displacement ellipsoids are drawn at the 90% probability level.
	Fig. 2. Cavities limited by the anionic framework hosting Na⁺ cations in the Na_1.67K_1.33Al₃(AsO₄)₄ structure.

Sodium potassium trialuminium tetrakis(orthoarsenate) top

Crystal data top

Na_1.67K_1.33Al₃(AsO₄)₄	F(000) = 1370.4
M_r = 726.95	D_x = 3.563 Mg m⁻³
Orthorhombic, Cmce	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2bc 2	Cell parameters from 25 reflections
a = 10.493 (1) Å	θ = 3.8–27°
b = 20.395 (4) Å	µ = 10.53 mm⁻¹
c = 6.335 (4) Å	T = 293 K
V = 1355.7 (9) Å³	Plate, colourless
Z = 4	0.40 × 0.10 × 0.07 mm

Data collection top

Enraf–Nonius CAD-4 diffractometer	717 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.062
Graphite monochromator	θ_max = 27.0°, θ_min = 3.8°
ω/2θ scans	h = −13→1
Absorption correction: ψ scan (North et al., 1968)	k = −26→1
T_min = 0.130, T_max = 0.332	l = −8→8
1723 measured reflections	2 standard reflections every 120 min
780 independent reflections	intensity decay: 1.1%

Refinement top

Refinement on F²	1 restraint
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F² > 2σ(F²)] = 0.038	Secondary atom site location: difference Fourier map
wR(F²) = 0.112	w = 1/[σ²(F_o²) + (0.0727P)² + 0.5867P] where P = (F_o² + 2F_c²)/3
S = 1.15	(Δ/σ)_max < 0.001
780 reflections	Δρ_max = 2.38 e Å⁻³
84 parameters	Δρ_min = −1.33 e Å⁻³

Crystal data top

Na_1.67K_1.33Al₃(AsO₄)₄	V = 1355.7 (9) Å³
M_r = 726.95	Z = 4
Orthorhombic, Cmce	Mo Kα radiation
a = 10.493 (1) Å	µ = 10.53 mm⁻¹
b = 20.395 (4) Å	T = 293 K
c = 6.335 (4) Å	0.40 × 0.10 × 0.07 mm

Data collection top

Enraf–Nonius CAD-4 diffractometer	717 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.062
T_min = 0.130, T_max = 0.332	2 standard reflections every 120 min
1723 measured reflections	intensity decay: 1.1%
780 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	84 parameters
wR(F²) = 0.112	1 restraint
S = 1.15	Δρ_max = 2.38 e Å⁻³
780 reflections	Δρ_min = −1.33 e Å⁻³

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)
As1	0.0000	0.15486 (3)	0.05909 (10)	0.0075 (3)
As2	0.2500	−0.04448 (3)	0.2500	0.0070 (3)
Al1	0.0000	0.0000	0.0000	0.0063 (5)
Al2	0.2500	0.09187 (10)	0.2500	0.0073 (4)
O1	0.0000	0.2179 (3)	−0.1020 (8)	0.0163 (10)
O2	0.1263 (3)	0.15363 (15)	0.2215 (5)	0.0110 (7)
O3	0.0000	0.0854 (2)	−0.0873 (7)	0.0095 (9)
O4	0.2105 (3)	−0.09062 (16)	0.4534 (4)	0.0102 (6)
O5	0.1364 (3)	0.01511 (13)	0.2027 (5)	0.0086 (6)
Na1	0.0000	0.1628 (3)	0.5513 (7)	0.0350 (18)	0.725 (14)
Na2	0.0000	0.0635 (17)	0.520 (5)	0.042 (12)*	0.112 (14)
K1	0.2125 (6)	0.2737 (3)	0.1075 (10)	0.048 (2)	0.314 (7)
K2	0.2500	0.271 (3)	0.2500	0.03 (2)*	0.035 (12)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
As1	0.0016 (4)	0.0103 (4)	0.0108 (4)	0.000	0.000	0.0013 (2)
As2	0.0039 (4)	0.0086 (4)	0.0084 (4)	0.000	−0.0005 (2)	0.000
Al1	0.0011 (10)	0.0090 (12)	0.0089 (11)	0.000	0.000	0.0003 (10)
Al2	0.0028 (9)	0.0093 (9)	0.0099 (9)	0.000	−0.0001 (6)	0.000
O1	0.020 (3)	0.013 (2)	0.016 (2)	0.000	0.000	0.006 (2)
O2	0.0045 (15)	0.0124 (15)	0.0161 (15)	0.0010 (11)	−0.0040 (13)	−0.0019 (11)
O3	0.006 (2)	0.009 (2)	0.0133 (19)	0.000	0.000	−0.0024 (17)
O4	0.0091 (15)	0.0116 (15)	0.0100 (13)	−0.0029 (12)	0.0009 (12)	0.0017 (11)
O5	0.0033 (14)	0.0105 (15)	0.0120 (13)	0.0023 (11)	−0.0018 (13)	−0.0007 (10)
Na1	0.037 (3)	0.047 (3)	0.020 (3)	0.000	0.000	−0.0033 (19)
K1	0.053 (3)	0.034 (3)	0.059 (4)	−0.029 (3)	0.013 (3)	0.003 (2)

Geometric parameters (Å, º) top

As1—O1	1.642 (5)	O4—Na2^xv	2.284 (9)
As1—O2ⁱ	1.678 (3)	O4—Na1^xv	2.655 (4)
As1—O2	1.678 (3)	O4—K1^xvi	2.795 (6)
As1—O3	1.694 (4)	O4—K2^xvi	3.13 (5)
As2—O4ⁱⁱ	1.648 (3)	O5—Na2	2.66 (3)
As2—O4	1.648 (3)	O5—Na2^xv	2.77 (3)
As2—O5	1.729 (3)	Na1—Na2	2.03 (4)
As2—O5ⁱⁱ	1.729 (3)	Na1—O1^xvii	2.467 (7)
As2—Al2	2.781 (2)	Na1—O2ⁱ	2.481 (5)
Al1—O3	1.827 (5)	Na1—K1^viii	2.603 (8)
Al1—O3ⁱⁱⁱ	1.827 (5)	Na1—K1^xviii	2.603 (8)
Al1—O5ⁱⁱⁱ	1.947 (3)	Na1—O1^xviii	2.619 (8)
Al1—O5^iv	1.947 (3)	Na1—O4^xv	2.655 (4)
Al1—O5ⁱ	1.947 (3)	Na1—O4^vi	2.655 (4)
Al1—O5	1.947 (3)	Na1—O3^xvii	2.781 (7)
Al2—O2ⁱⁱ	1.817 (3)	Na1—K2^xix	3.21 (2)
Al2—O2	1.817 (3)	Na2—O4^vi	2.284 (9)
Al2—O4^v	1.924 (3)	Na2—O4^xv	2.284 (9)
Al2—O4^vi	1.924 (3)	Na2—O3^xvii	2.53 (3)
Al2—O5ⁱⁱ	1.991 (3)	Na2—Na2^xv	2.60 (7)
Al2—O5	1.991 (3)	Na2—O5ⁱ	2.66 (3)
Al2—Na2	3.19 (2)	Na2—O5^vi	2.77 (3)
Al2—Na2^vii	3.19 (2)	Na2—O5^xv	2.77 (3)
Al2—Na1^vii	3.552 (3)	Na2—O2ⁱ	2.95 (3)
Al2—Na1	3.552 (3)	Na2—As2^xiv	3.025 (17)
Al2—K1^viii	3.579 (6)	K1—K2	0.986 (7)
O1—Na1^ix	2.467 (7)	K1—K1^xi	1.846 (12)
O1—Na1^x	2.620 (8)	K1—K1ⁱⁱ	1.969 (14)
O1—K2^x	2.795 (5)	K1—K2^xi	2.47 (2)
O1—K2^xi	2.795 (5)	K1—Na1^x	2.603 (8)
O1—K1ⁱ	2.833 (7)	K1—O4^xx	2.795 (6)
O1—K1	2.833 (7)	K1—O1^xviii	2.896 (6)
O1—K1^x	2.896 (6)	K1—O2^xii	2.999 (7)
O1—K1^xii	2.896 (6)	K1—O1^xi	3.022 (6)
O1—K1^xi	3.022 (6)	K1—O2^xi	3.067 (6)
O1—K1^xiii	3.022 (6)	K2—K1ⁱⁱ	0.986 (7)
O2—Na1	2.481 (5)	K2—K1^viii	2.47 (2)
O2—K1	2.708 (6)	K2—K1^xi	2.47 (2)
O2—K2	2.73 (5)	K2—O2ⁱⁱ	2.73 (5)
O2—Na2	2.95 (3)	K2—O1^xi	2.795 (5)
O2—K1^viii	2.999 (7)	K2—O1^xviii	2.795 (5)
O2—K1^xi	3.067 (6)	K2—O4^xx	3.13 (5)
O2—K1ⁱⁱ	3.166 (7)	K2—O4^xxi	3.13 (5)
O3—Na2^ix	2.53 (3)	K2—Na1^x	3.21 (2)
O3—Na1^ix	2.781 (7)	K2—Na1^xix	3.21 (2)
O4—Al2^xiv	1.924 (3)

O1—As1—O2ⁱ	113.13 (15)	O4^xv—Na2—O2	109.3 (12)
O1—As1—O2	113.13 (15)	O3^xvii—Na2—O2	121.4 (11)
O2ⁱ—As1—O2	104.3 (2)	Na2^xv—Na2—O2	123.8 (17)
O1—As1—O3	108.4 (3)	O5ⁱ—Na2—O2	89.3 (10)
O2ⁱ—As1—O3	108.86 (14)	O5—Na2—O2	60.3 (6)
O2—As1—O3	108.86 (14)	O5^vi—Na2—O2	122.25 (12)
O4ⁱⁱ—As2—O4	110.4 (2)	O5^xv—Na2—O2	175.4 (8)
O4ⁱⁱ—As2—O5	116.04 (14)	O2ⁱ—Na2—O2	53.4 (6)
O4—As2—O5	111.32 (15)	Na1—Na2—As2^xiv	94.7 (8)
O4ⁱⁱ—As2—O5ⁱⁱ	111.32 (15)	O4^vi—Na2—As2^xiv	32.5 (3)
O4—As2—O5ⁱⁱ	116.04 (14)	O4^xv—Na2—As2^xiv	146.6 (14)
O5—As2—O5ⁱⁱ	90.65 (19)	O3^xvii—Na2—As2^xiv	63.2 (6)
O4ⁱⁱ—As2—Al2	124.81 (11)	Na2^xv—Na2—As2^xiv	85.4 (10)
O4—As2—Al2	124.81 (11)	O5ⁱ—Na2—As2^xiv	141.6 (11)
O5—As2—Al2	45.33 (10)	O5—Na2—As2^xiv	81.4 (3)
O5ⁱⁱ—As2—Al2	45.33 (10)	O5^vi—Na2—As2^xiv	34.3 (3)
O3—Al1—O3ⁱⁱⁱ	180.0	O5^xv—Na2—As2^xiv	93.9 (10)
O3—Al1—O5ⁱⁱⁱ	87.19 (13)	O2ⁱ—Na2—As2^xiv	141.0 (10)
O3ⁱⁱⁱ—Al1—O5ⁱⁱⁱ	92.81 (13)	O2—Na2—As2^xiv	89.9 (4)
O3—Al1—O5^iv	87.19 (13)	O2—K1—O4^xx	158.4 (3)
O3ⁱⁱⁱ—Al1—O5^iv	92.81 (13)	K2—K1—O1	136 (2)
O5ⁱⁱⁱ—Al1—O5^iv	94.60 (18)	K1^xi—K1—O1	77.3 (4)
O3—Al1—O5ⁱ	92.80 (13)	K1ⁱⁱ—K1—O1	138.1 (3)
O3ⁱⁱⁱ—Al1—O5ⁱ	87.20 (13)	K2^xi—K1—O1	63.1 (4)
O5ⁱⁱⁱ—Al1—O5ⁱ	85.40 (18)	Na1^x—K1—O1	57.43 (19)
O5^iv—Al1—O5ⁱ	180.0	O2—K1—O1	59.97 (16)
O3—Al1—O5	92.80 (13)	O4^xx—K1—O1	109.1 (3)
O3ⁱⁱⁱ—Al1—O5	87.19 (13)	K2—K1—O1^xviii	74.3 (4)
O5ⁱⁱⁱ—Al1—O5	180.0	K1^xi—K1—O1^xviii	145.9 (4)
O5^iv—Al1—O5	85.40 (18)	K1ⁱⁱ—K1—O1^xviii	74.1 (3)
O5ⁱ—Al1—O5	94.60 (18)	K2^xi—K1—O1^xviii	136.6 (5)
O2ⁱⁱ—Al2—O2	92.3 (2)	Na1^x—K1—O1^xviii	53.00 (18)
O2ⁱⁱ—Al2—O4^v	87.27 (15)	O2—K1—O1^xviii	68.10 (17)
O2—Al2—O4^v	93.78 (15)	O4^xx—K1—O1^xviii	91.3 (2)
O2ⁱⁱ—Al2—O4^vi	93.78 (15)	O1—K1—O1^xviii	73.48 (15)
O2—Al2—O4^vi	87.27 (15)	K2—K1—O2^xii	153 (3)
O4^v—Al2—O4^vi	178.5 (2)	K1^xi—K1—O2^xii	77.6 (4)
O2ⁱⁱ—Al2—O5ⁱⁱ	95.88 (12)	K1ⁱⁱ—K1—O2^xii	150.20 (12)
O2—Al2—O5ⁱⁱ	171.00 (15)	K2^xi—K1—O2^xii	59.0 (10)
O4^v—Al2—O5ⁱⁱ	90.44 (14)	Na1^x—K1—O2^xii	51.99 (17)
O4^vi—Al2—O5ⁱⁱ	88.37 (14)	O2—K1—O2^xii	124.3 (2)
O2ⁱⁱ—Al2—O5	171.00 (15)	O4^xx—K1—O2^xii	52.81 (14)
O2—Al2—O5	95.89 (12)	O1—K1—O2^xii	65.11 (18)
O4^v—Al2—O5	88.37 (14)	O1^xviii—K1—O2^xii	104.9 (3)
O4^vi—Al2—O5	90.44 (14)	K2—K1—O1^xi	67.3 (4)
O5ⁱⁱ—Al2—O5	76.27 (18)	K1^xi—K1—O1^xi	66.1 (4)
O2ⁱⁱ—Al2—As2	133.87 (11)	K1ⁱⁱ—K1—O1^xi	67.1 (3)
O2—Al2—As2	133.87 (11)	K2^xi—K1—O1^xi	81.5 (2)
O4^v—Al2—As2	89.24 (12)	Na1^x—K1—O1^xi	145.6 (2)
O4^vi—Al2—As2	89.24 (12)	O2—K1—O1^xi	112.8 (3)
O5ⁱⁱ—Al2—As2	38.14 (9)	O4^xx—K1—O1^xi	87.10 (17)
O5—Al2—As2	38.14 (9)	O1—K1—O1^xi	143.4 (2)
As1—O2—Al2	129.43 (18)	O1^xviii—K1—O1^xi	140.6 (2)
As1—O3—Al1	129.2 (3)	O2^xii—K1—O1^xi	105.27 (19)
As2—O4—Al2^xiv	135.8 (2)	K2—K1—O2^xi	115.2 (17)
As2—O5—Al1	120.66 (15)	K1^xi—K1—O2^xi	61.0 (3)
As2—O5—Al2	96.54 (14)	K1ⁱⁱ—K1—O2^xi	113.7 (4)
Al1—O5—Al2	131.59 (15)	K2^xi—K1—O2^xi	57.9 (10)
O2—Na1—O3^xvii	130.6 (2)	Na1^x—K1—O2^xi	98.0 (2)
K1^viii—Na1—O3^xvii	99.79 (19)	O2—K1—O2^xi	143.4 (2)
K1^xviii—Na1—O3^xvii	99.79 (19)	O4^xx—K1—O2^xi	55.33 (12)
O1^xviii—Na1—O3^xvii	146.4 (2)	O1—K1—O2^xi	108.0 (2)
O4^xv—Na1—O3^xvii	72.21 (14)	O1^xviii—K1—O2^xi	145.9 (3)
O4^vi—Na1—O3^xvii	72.21 (14)	O2^xii—K1—O2^xi	51.17 (15)
Na2—Na1—As1	81.5 (10)	O1^xi—K1—O2^xi	54.13 (14)
O1^xvii—Na1—As1	155.8 (3)	K1ⁱⁱ—K2—K1	174 (6)
O2ⁱ—Na1—As1	32.36 (9)	K1ⁱⁱ—K2—K1^viii	40.9 (15)
O2—Na1—As1	32.36 (9)	K1—K2—K1^viii	142 (2)
K1^viii—Na1—As1	99.35 (18)	K1ⁱⁱ—K2—K1^xi	142 (2)
K1^xviii—Na1—As1	99.35 (18)	K1—K2—K1^xi	40.9 (15)
O1^xviii—Na1—As1	71.20 (16)	K1^viii—K2—K1^xi	137 (2)
O4^xv—Na1—As1	87.71 (12)	K1ⁱⁱ—K2—O2	107 (3)
O4^vi—Na1—As1	87.71 (12)	K1—K2—O2	78 (3)
O3^xvii—Na1—As1	142.4 (2)	K1^viii—K2—O2	70.1 (11)
Na2—Na1—K2^xix	117.1 (10)	K1^xi—K2—O2	72.0 (11)
O1^xvii—Na1—K2^xix	57.3 (3)	K1ⁱⁱ—K2—O2ⁱⁱ	78 (3)
O2ⁱ—Na1—K2^xix	143.1 (5)	K1—K2—O2ⁱⁱ	107 (3)
O2—Na1—K2^xix	85.70 (14)	K1^viii—K2—O2ⁱⁱ	72.0 (11)
K1^viii—Na1—K2^xix	15.5 (4)	K1^xi—K2—O2ⁱⁱ	70.1 (11)
K1^xviii—Na1—K2^xix	116.0 (8)	O2—K2—O2ⁱⁱ	57.3 (11)
O1^xviii—Na1—K2^xix	75.8 (9)	K1ⁱⁱ—K2—O1^xi	85.9 (5)
O4^xv—Na1—K2^xix	156.7 (5)	K1—K2—O1^xi	93.7 (5)
O4^vi—Na1—K2^xix	63.7 (8)	K1^viii—K2—O1^xi	119.1 (6)
O3^xvii—Na1—K2^xix	85.1 (6)	K1^xi—K2—O1^xi	64.7 (2)
As1—Na1—K2^xix	114.45 (17)	O2—K2—O1^xi	119.6 (16)
Na1—Na2—O4^vi	75.6 (9)	O2ⁱⁱ—K2—O1^xi	69.3 (6)
Na1—Na2—O4^xv	75.6 (9)	K1ⁱⁱ—K2—O1^xviii	93.7 (5)
O4^vi—Na2—O4^xv	150.7 (17)	K1—K2—O1^xviii	85.9 (5)
Na1—Na2—O3^xvii	74.3 (11)	K1^viii—K2—O1^xviii	64.7 (2)
O4^vi—Na2—O3^xvii	83.4 (9)	K1^xi—K2—O1^xviii	119.1 (6)
O4^xv—Na2—O3^xvii	83.4 (9)	O2—K2—O1^xviii	69.3 (6)
Na1—Na2—Na2^xv	180 (2)	O2ⁱⁱ—K2—O1^xviii	119.6 (16)
O4^vi—Na2—Na2^xv	104.4 (9)	O1^xi—K2—O1^xviii	171 (2)
O4^xv—Na2—Na2^xv	104.4 (9)	K1ⁱⁱ—K2—O4^xx	113 (4)
O3^xvii—Na2—Na2^xv	105.8 (19)	K1—K2—O4^xx	62 (3)
Na1—Na2—O5ⁱ	116.3 (13)	K1^viii—K2—O4^xx	133.6 (15)
O4^vi—Na2—O5ⁱ	131.8 (13)	K1^xi—K2—O4^xx	88.7 (8)
O4^xv—Na2—O5ⁱ	67.9 (5)	O2—K2—O4^xx	134.51 (15)
O3^xvii—Na2—O5ⁱ	144.1 (7)	O2ⁱⁱ—K2—O4^xx	151.78 (16)
Na2^xv—Na2—O5ⁱ	63.6 (11)	O1^xi—K2—O4^xx	85.1 (10)
Na1—Na2—O5	116.3 (13)	O1^xviii—K2—O4^xx	86.7 (10)
O4^vi—Na2—O5	67.9 (5)	K1ⁱⁱ—K2—O4^xxi	62 (3)
O4^xv—Na2—O5	131.8 (13)	K1—K2—O4^xxi	113 (4)
O3^xvii—Na2—O5	144.1 (7)	K1^viii—K2—O4^xxi	88.7 (8)
Na2^xv—Na2—O5	63.6 (11)	K1^xi—K2—O4^xxi	133.6 (15)
O5ⁱ—Na2—O5	65.1 (8)	O2—K2—O4^xxi	151.78 (16)
Na1—Na2—O5^vi	120.9 (12)	O2ⁱⁱ—K2—O4^xxi	134.51 (15)
O4^vi—Na2—O5^vi	66.1 (5)	O1^xi—K2—O4^xxi	86.7 (10)
O4^xv—Na2—O5^vi	126.3 (13)	O1^xviii—K2—O4^xxi	85.1 (10)
O3^xvii—Na2—O5^vi	58.6 (7)	O4^xx—K2—O4^xxi	51.3 (9)
Na2^xv—Na2—O5^vi	59.2 (11)	K1ⁱⁱ—K2—Na1^x	132 (2)
O5ⁱ—Na2—O5^vi	122.8 (13)	K1—K2—Na1^x	45.0 (15)
O5—Na2—O5^vi	89.2 (7)	K1^viii—K2—Na1^x	112.6 (2)
Na1—Na2—O5^xv	120.9 (12)	K1^xi—K2—Na1^x	85.8 (3)
O4^vi—Na2—O5^xv	126.3 (13)	O2—K2—Na1^x	87.4 (4)
O4^xv—Na2—O5^xv	66.1 (5)	O2ⁱⁱ—K2—Na1^x	141.5 (14)
O3^xvii—Na2—O5^xv	58.6 (7)	O1^xi—K2—Na1^x	127.1 (11)
Na2^xv—Na2—O5^xv	59.2 (11)	O1^xviii—K2—Na1^x	48.0 (3)
O5ⁱ—Na2—O5^xv	89.2 (7)	O4^xx—K2—Na1^x	49.6 (6)
O5—Na2—O5^xv	122.8 (13)	O4^xxi—K2—Na1^x	83.8 (12)
O5^vi—Na2—O5^xv	62.1 (8)	K1ⁱⁱ—K2—Na1^xix	45.0 (15)
Na1—Na2—O2ⁱ	56.1 (8)	K1—K2—Na1^xix	132 (2)
O4^vi—Na2—O2ⁱ	109.3 (12)	K1^viii—K2—Na1^xix	85.8 (3)
O4^xv—Na2—O2ⁱ	57.4 (6)	K1^xi—K2—Na1^xix	112.6 (2)
O3^xvii—Na2—O2ⁱ	121.4 (11)	O2—K2—Na1^xix	141.5 (14)
Na2^xv—Na2—O2ⁱ	123.8 (17)	O2ⁱⁱ—K2—Na1^xix	87.4 (4)
O5ⁱ—Na2—O2ⁱ	60.3 (6)	O1^xi—K2—Na1^xix	48.0 (3)
O5—Na2—O2ⁱ	89.3 (10)	O1^xviii—K2—Na1^xix	127.1 (11)
O5^vi—Na2—O2ⁱ	175.4 (8)	O4^xx—K2—Na1^xix	83.8 (12)
O5^xv—Na2—O2ⁱ	122.25 (12)	O4^xxi—K2—Na1^xix	49.6 (6)
Na1—Na2—O2	56.1 (8)	Na1^x—K2—Na1^xix	130.3 (18)
O4^vi—Na2—O2	57.4 (6)

Symmetry codes: (i) −x, y, z; (ii) −x+1/2, y, −z+1/2; (iii) −x, −y, −z; (iv) x, −y, −z; (v) −x+1/2, −y, z−1/2; (vi) x, −y, −z+1; (vii) x+1/2, y, −z+1/2; (viii) x, −y+1/2, z+1/2; (ix) x, y, z−1; (x) −x, −y+1/2, z−1/2; (xi) −x+1/2, −y+1/2, −z; (xii) x, −y+1/2, z−1/2; (xiii) x−1/2, −y+1/2, −z; (xiv) −x+1/2, −y, z+1/2; (xv) −x, −y, −z+1; (xvi) x, y−1/2, −z+1/2; (xvii) x, y, z+1; (xviii) −x, −y+1/2, z+1/2; (xix) −x+1/2, −y+1/2, −z+1; (xx) x, y+1/2, −z+1/2; (xxi) −x+1/2, y+1/2, z.

Selected bond lengths (Å) top

As1—O1	1.642 (5)	Al1—O5ⁱⁱⁱ	1.947 (3)
As1—O2ⁱ	1.678 (3)	Al1—O5^iv	1.947 (3)
As1—O2	1.678 (3)	Al1—O5ⁱ	1.947 (3)
As1—O3	1.694 (4)	Al1—O5	1.947 (3)
As2—O4ⁱⁱ	1.648 (3)	Al2—O2ⁱⁱ	1.817 (3)
As2—O4	1.648 (3)	Al2—O2	1.817 (3)
As2—O5	1.729 (3)	Al2—O4^v	1.924 (3)
As2—O5ⁱⁱ	1.729 (3)	Al2—O4^vi	1.924 (3)
Al1—O3	1.827 (5)	Al2—O5ⁱⁱ	1.991 (3)
Al1—O3ⁱⁱⁱ	1.827 (5)	Al2—O5	1.991 (3)

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

References

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