K3Al2As3O12

Stöger, B.; Weil, M.

doi:10.1107/S1600536812000438

inorganic compounds

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ISSN: 2056-9890

Volume 68| Part 2| February 2012| Page i15

doi:10.1107/S1600536812000438

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K₃Al₂As₃O₁₂

Berthold Stöger ^a and Matthias Weil ^a ^*

^aInstitute for Chemical Technologies and Analytics, Division of Structural Chemistry, Vienna University of Technology, Getreidemarkt 9/164-SC, A-1060 Vienna, Austria
^*Correspondence e-mail: mweil@mail.zserv.tuwien.ac.at

(Received 2 November 2011; accepted 5 January 2012; online 11 January 2012)

Single crystals of K₃Al₂As₃O₁₂, tripotassium dialuminotriarsenate(V), were obtained unintentionally by the reaction of KAsO₃ with a corundum crucible at 973 K. The asymmetric unit contains three K, two Al, three As and 12 O atoms. The structure of the title compound is isotypic with those of other K₃M′₂X₃O₁₂ (M′ = Al, Ga; X = P, As) structures and is made up of a three-dimensional network of corner-sharing [AlO₄] and [AsO₄] tetrahedra. The three K⁺ cations are located in channels running along the [100], [001], [101] and [10 $[\overline{1}]$ ] directions, exhibiting different coordination numbers of 9, 8 and 6, respectively. All corresponding [KO_x] polyhedra are considerably distorted.

Related literature

For a recent review on NASICON-type materials, see: Anantharamulu et al. (2011 ). For isotypic K₃M′₂X₃O₁₂ structures, see: Beaurain et al. (2008 ) and Yakubovich et al. (2008 ) for K₃Ga₂P₃O₁₂; Boughzala et al. (1997 ) for the solid solution K₃Al₂(As_1.92P_1.08)O₁₂; Devi & Vidyasagar (2000 ) for K₃Al₂P₃O₁₂. For the isopointal structure of Tl₃Al₂P₃O₁₂, see: Devi & Vidyasagar (2000). For background to the bond-valence method, see: Brown & Altermatt (1985 ).

Experimental

Crystal data

K₃Al₂As₃O₁₂
M_r = 588
Orthorhombic, P n a 2₁
a = 8.7943 (2) Å
b = 17.4400 (2) Å
c = 8.6610 (3) Å
V = 1328.36 (6) Å³
Z = 4
Mo Kα radiation
μ = 8.63 mm⁻¹
T = 100 K
0.10 × 0.06 × 0.01 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ) T_min = 0.49, T_max = 0.92
52293 measured reflections
9623 independent reflections
8606 reflections with I > 3σ(I)
R_int = 0.038

Refinement

R[F² > 3σ(F²)] = 0.018
wR(F²) = 0.039
S = 0.80
9623 reflections
181 parameters
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.31 e Å⁻³
Absolute structure: Flack (1983 ), 3882 Friedel pairs
Flack parameter: 0.008 (3)

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT-Plus (Bruker, 2008); data reduction: SAINT-Plus; method used to solve structure: coordinates taken from an isotypic structure; program(s) used to refine structure: JANA2006 (Petříček et al., 2006 ); molecular graphics: ATOMS (Dowty, 2006 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536812000438/gw2112sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812000438/gw2112Isup2.hkl

checkCIF report

Comment top

During crystal growth studies of KAsO₃, we inadvertently obtained single crystals with composition K₃Al₂As₃O₁₂ from an attacked corundum crucible. Many oxides with general formula M_xM'₂X₃O₁₂ crystallize with three-dimensional framework structures (Devi & Vidyasagar, 2000) and are of technological interest. Most notably, compounds crystallizing in the NASICON (Na₃Zr₂Si₂PO₁₂) structure type are excellent ion conductors and have been intensely studied. A recent review on compounds with the NASICON structure has been given by Anantharamulu et al. (2011).

The structure of K₃Al₂As₃O₁₂ is isotypic with the phosphate analogue K₃Al₂P₃O₁₂ (Devi & Vidyasagar, 2000), the mixed arsenate/phosphate solid solution K₃Al₂As_1.92P_1.08O₁₂ (Boughzala et al., 1997) and K₃Ga₂P₃O₁₂ (Beaurain et al., 2008; Yakubovich et al., 2008). Trithallium dialuminotriphosphate, Tl₃Al₂P₃O₁₂ (Devi & Vidyasagar, 2000), can be considered as isopointal to the title compound, because it features distinctly different coordinations of the Al sites and the cationic network due to the electron lone pairs of the Tl⁺ ions.

Whereas in the NASICON structure type the M' site is octahedrally and the X site tetrahedrally coordinated, in the title compound both sites exhibit a tetrahedral coordination. Two crystallographically different [AlO₄] and three [AlO₄] tetrahedra, all on general positions, are linked via their corners to a complex three-dimensional network, whereby [AlO₄] units connect only to [AsO₄] units and vice-versa. This network can be decomposed into undulating sheets normal to [010] (Al1, Al2, As1, As2) which are connected by [AsO₄] units (As3) (Fig. 1).

The three different K⁺ cations are located in channels running along the [100] and [001] (K1, K2) (Fig. 1) as well as the [101] and [101] (K3) (Fig. 2) directions. Considering K–O distances up to 3.5 Å as relevant for first coordination spheres, the K⁺ cations are coordinated by 9 (K1), 8 (K1) and 6 (K3) O atoms, respectively, all in the form of irregular [KO_x] polyhedra. The total bond valence sums (parameters: R₀ = 2.132 Å, b = 0.37 (Brown & Altermatt, 1985)), 1.08 (K1), 1.04 (K2) and 0.90 (K3) valence units (v.u.) are close to the expected value of 1 v.u. and point to a slight undersaturation of K3. The coordination of the K⁺ cations is very similar in all isotypic structures. The main difference in these structures pertains to the bond lengths of the XO₄ tetrahedra. Corresponding mean bond lengths are 1.746 Å for AlO₄ and 1.680 Å for AsO₄ tetrahedra in the title compound; 1.737 Å for AlO₄ and 1.527 Å for PO₄ tetrahedra in K₃Al₂P₃O₁₂; 1.730 Å for AlO₄ and 1.615 Å for (As/P)O₄ tetrahedra in K₃Al₂As_1.92P_1.08O₁₂; 1.816 Å for GaO₄ and 1.535 Å for PO₄ tetrahedra in K₃Ga₂P₃O₁₂.

Related literature top

For a recent review on NASICON-type materials, see: Anantharamulu et al. (2011). For isotypic K₃M'₂X₃O₁₂ structures, see: Beaurain et al. (2008) and Yakubovich et al. (2008) for K₃Ga₂P₃O₁₂; Boughzala et al. (1997) for the solid solution K₃Al₂(As_1.92P_1.08)O₁₂; Devi & Vidyasagar (2000) for K₃Al₂P₃O₁₂. For the isopointal structure of Tl₃Al₂P₃O₁₂, see: Devi & Vidyasagar (2000). For background to the bond-valence method, see: Brown & Altermatt (1985).

Experimental top

K₂CO₃ and H₃AsO₄ were obtained commercially and used without purification. 10 g 80%_wt H₃AsO₄ were titrated against an aqueous K₂CO₃ solution using methyl red as indicator. The water was evaporated and the residue recrystallized from water to obtain KH₂AsO₄. This solid was then heated in a corundum crucible at 973 K, cooled to 633 K over 24 h and quenched. Few colourless crystals of the title compound were isolated from the reaction mixture.

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT-Plus (Bruker, 2008); data reduction: SAINT-Plus (Bruker, 2008); program(s) used to solve structure: coordinates taken from an isotypic structure; program(s) used to refine structure: JANA2006 (Petříček et al., 2006); molecular graphics: ATOMS (Dowty, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

	Fig. 1. The crystal structure of K₃Al₂As₃O₁₂ viewed down [100], showing sheets of corner-sharing [AsO₄] and [AlO₄] tetrahedra extending parallel to (010). Displacement ellipsoids are drawn at the 90% probability level.
	Fig. 2. The crystal structure of K₃Al₂As₃O₁₂ viewed down [101]. Displacement ellipsoids are drawn at the 90% probability level.

tripotassium dialuminotriarsenate(V) top

Crystal data top

K₃Al₂As₃O₁₂	F(000) = 1112
M_r = 588	D_x = 2.939 Mg m⁻³
Orthorhombic, Pna2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 54411 reflections
a = 8.7943 (2) Å	θ = 3.3–44.8°
b = 17.4400 (2) Å	µ = 8.63 mm⁻¹
c = 8.6610 (3) Å	T = 100 K
V = 1328.36 (6) Å³	Plate, colourless
Z = 4	0.10 × 0.06 × 0.01 mm

Data collection top

Bruker APEXII CCD diffractometer	9623 independent reflections
Radiation source: X-ray tube	8606 reflections with I > 3σ(I)
Graphite monochromator	R_int = 0.038
ω and ϕ scans	θ_max = 45.1°, θ_min = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −17→17
T_min = 0.49, T_max = 0.92	k = −34→34
52293 measured reflections	l = −15→17

Refinement top

Refinement on F²	Primary atom site location: isomorphous structure methods
R[F² > 2σ(F²)] = 0.018	Weighting scheme based on measured s.u.'s w = 1/(σ²(I) + 0.0004I²)
wR(F²) = 0.039	(Δ/σ)_max = 0.003
S = 0.80	Δρ_max = 0.33 e Å⁻³
9623 reflections	Δρ_min = −0.31 e Å⁻³
181 parameters	Absolute structure: Flack (1983), 3882 Friedel pairs
0 restraints	Absolute structure parameter: 0.008 (3)
1 constraint

Crystal data top

K₃Al₂As₃O₁₂	V = 1328.36 (6) Å³
M_r = 588	Z = 4
Orthorhombic, Pna2₁	Mo Kα radiation
a = 8.7943 (2) Å	µ = 8.63 mm⁻¹
b = 17.4400 (2) Å	T = 100 K
c = 8.6610 (3) Å	0.10 × 0.06 × 0.01 mm

Data collection top

Bruker APEXII CCD diffractometer	9623 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2008)	8606 reflections with I > 3σ(I)
T_min = 0.49, T_max = 0.92	R_int = 0.038
52293 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.018	0 restraints
wR(F²) = 0.039	Δρ_max = 0.33 e Å⁻³
S = 0.80	Δρ_min = −0.31 e Å⁻³
9623 reflections	Absolute structure: Flack (1983), 3882 Friedel pairs
181 parameters	Absolute structure parameter: 0.008 (3)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
As1	0.156896 (11)	0.215743 (6)	0.0009	0.004155 (18)
As2	0.293241 (12)	0.313601 (6)	0.511929 (16)	0.004909 (19)
As3	0.236068 (12)	0.502941 (6)	0.085202 (18)	0.005355 (19)
K1	0.01017 (3)	0.402188 (14)	0.84037 (3)	0.00837 (4)
K2	0.95033 (3)	0.354962 (14)	0.30906 (3)	0.00818 (4)
K3	0.68161 (3)	0.488891 (15)	0.11580 (3)	0.01179 (5)
Al1	0.34851 (4)	0.34012 (2)	0.14668 (4)	0.00492 (7)
Al2	0.13204 (4)	0.16767 (2)	0.65562 (4)	0.00520 (7)
O1	0.29089 (10)	0.15184 (5)	0.03110 (9)	0.00824 (17)
O2	0.02014 (10)	0.20900 (5)	0.13689 (9)	0.00746 (16)
O3	0.21755 (9)	0.30785 (4)	0.00781 (10)	0.00643 (14)
O4	0.06929 (10)	0.20939 (5)	0.82779 (9)	0.00730 (16)
O5	0.17013 (13)	0.37287 (6)	0.58794 (12)	0.0139 (2)
O6	0.47459 (12)	0.34183 (7)	0.53518 (11)	0.0168 (2)
O7	0.27956 (11)	0.22138 (5)	0.57055 (11)	0.01044 (18)
O8	0.26654 (10)	0.30933 (6)	0.31927 (9)	0.00936 (18)
O9	0.07409 (11)	0.46866 (6)	0.15273 (11)	0.01076 (18)
O10	0.29028 (11)	0.57855 (5)	0.19818 (10)	0.00894 (17)
O11	0.23407 (11)	0.52699 (6)	0.90078 (10)	0.01074 (19)
O12	0.37999 (10)	0.43772 (5)	0.12022 (10)	0.00883 (16)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
As1	0.00437 (3)	0.00356 (3)	0.00453 (3)	0.00007 (3)	−0.00035 (3)	−0.00027 (3)
As2	0.00554 (3)	0.00472 (4)	0.00447 (3)	−0.00042 (3)	0.00028 (3)	0.00036 (3)
As3	0.00642 (4)	0.00336 (3)	0.00628 (3)	−0.00018 (3)	−0.00018 (3)	−0.00019 (3)
K1	0.00698 (7)	0.01015 (8)	0.00797 (6)	−0.00039 (6)	0.00040 (5)	0.00102 (6)
K2	0.00765 (8)	0.00734 (8)	0.00955 (7)	0.00014 (6)	0.00017 (6)	0.00078 (6)
K3	0.01516 (10)	0.00792 (9)	0.01230 (8)	−0.00147 (7)	−0.00295 (7)	−0.00020 (6)
Al1	0.00487 (12)	0.00439 (12)	0.00550 (10)	−0.00023 (9)	−0.00019 (9)	−0.00024 (9)
Al2	0.00592 (12)	0.00438 (12)	0.00532 (10)	0.00071 (10)	−0.00068 (9)	−0.00031 (9)
O1	0.0078 (3)	0.0069 (3)	0.0101 (3)	0.0029 (2)	−0.0011 (2)	−0.0004 (2)
O2	0.0062 (3)	0.0094 (3)	0.0067 (2)	−0.0020 (2)	0.0017 (2)	−0.0006 (2)
O3	0.0075 (2)	0.0046 (2)	0.0072 (2)	−0.0014 (2)	−0.0019 (2)	0.0005 (2)
O4	0.0078 (3)	0.0089 (3)	0.0052 (2)	0.0016 (2)	−0.0019 (2)	−0.0019 (2)
O5	0.0193 (4)	0.0088 (3)	0.0138 (3)	0.0037 (3)	0.0083 (3)	−0.0016 (3)
O6	0.0101 (3)	0.0274 (5)	0.0130 (3)	−0.0102 (3)	−0.0069 (3)	0.0108 (3)
O7	0.0121 (3)	0.0056 (3)	0.0136 (3)	0.0006 (2)	0.0041 (2)	0.0026 (2)
O8	0.0094 (3)	0.0144 (4)	0.0043 (2)	−0.0031 (3)	−0.0001 (2)	0.0002 (2)
O9	0.0084 (3)	0.0083 (3)	0.0155 (3)	−0.0023 (2)	0.0031 (2)	0.0001 (3)
O10	0.0131 (3)	0.0043 (3)	0.0094 (3)	−0.0018 (2)	0.0003 (2)	−0.0010 (2)
O11	0.0138 (3)	0.0121 (4)	0.0063 (3)	0.0010 (3)	−0.0004 (2)	0.0016 (2)
O12	0.0085 (3)	0.0044 (3)	0.0136 (3)	0.0006 (2)	−0.0019 (2)	0.0002 (2)

Geometric parameters (Å, º) top

K1—O1ⁱ	2.7084 (9)	Al1—O8	1.7443 (9)
K1—O3ⁱⁱ	2.8524 (8)	Al1—O12	1.7396 (9)
K1—O5	2.6496 (11)	Al2—O4	1.7485 (9)
K1—O9ⁱⁱ	2.9964 (10)	Al2—O6^vii	1.7415 (11)
K1—O9ⁱⁱⁱ	2.8747 (10)	Al2—O7	1.7616 (10)
K1—O10ⁱⁱⁱ	2.9344 (10)	Al2—O10^viii	1.7373 (10)
K1—O11	2.9814 (10)	As1—O1	1.6429 (9)
K2—O1^iv	2.7885 (9)	As1—O2	1.6875 (8)
K2—O2^v	3.0134 (9)	As1—O3	1.6936 (8)
K2—O7^iv	3.0260 (10)	As1—O4^ix	1.6893 (8)
K2—O8^v	2.8939 (10)	As2—O5	1.6352 (10)
K2—O9^v	2.6362 (10)	As2—O6	1.6812 (11)
K2—O11^vi	2.7384 (10)	As2—O7	1.6909 (9)
K3—O1^iv	2.7360 (9)	As2—O8	1.6867 (8)
K3—O5^vi	2.7515 (10)	As3—O9	1.6519 (9)
K3—O11^vi	2.5921 (9)	As3—O10	1.7098 (9)
K3—O12	2.7989 (10)	As3—O11^ix	1.6515 (9)
Al1—O2^iv	1.7376 (9)	As3—O12	1.7285 (9)
Al1—O3	1.7578 (9)

O1ⁱ—K1—O3ⁱⁱ	86.82 (3)	O1^iv—K3—O5^vi	126.59 (3)
O1ⁱ—K1—O5	144.51 (3)	O1^iv—K3—O11^vi	93.38 (3)
O1ⁱ—K1—O9ⁱⁱ	73.59 (3)	O1^iv—K3—O12	92.90 (3)
O1ⁱ—K1—O9ⁱⁱⁱ	115.72 (3)	O5^vi—K3—O11^vi	92.38 (3)
O1ⁱ—K1—O10ⁱⁱⁱ	69.80 (3)	O5^vi—K3—O12	136.86 (3)
O1ⁱ—K1—O11	128.11 (3)	O11^vi—K3—O12	102.95 (3)
O3ⁱⁱ—K1—O5	88.21 (3)	O2^iv—Al1—O3	112.21 (4)
O3ⁱⁱ—K1—O9ⁱⁱ	69.16 (3)	O2^iv—Al1—O8	104.42 (4)
O3ⁱⁱ—K1—O9ⁱⁱⁱ	154.71 (3)	O2^iv—Al1—O12	109.74 (5)
O3ⁱⁱ—K1—O10ⁱⁱⁱ	148.77 (2)	O3—Al1—O8	102.53 (4)
O3ⁱⁱ—K1—O11	84.81 (2)	O3—Al1—O12	109.11 (4)
O5—K1—O9ⁱⁱ	136.06 (3)	O8—Al1—O12	118.68 (5)
O5—K1—O9ⁱⁱⁱ	79.72 (3)	O4—Al2—O6^vii	107.43 (5)
O5—K1—O10ⁱⁱⁱ	98.85 (3)	O4—Al2—O7	111.59 (4)
O5—K1—O11	86.28 (3)	O4—Al2—O10^viii	108.39 (4)
O9ⁱⁱ—K1—O9ⁱⁱⁱ	104.81 (3)	O6^vii—Al2—O7	112.68 (5)
O9ⁱⁱ—K1—O10ⁱⁱⁱ	120.24 (3)	O6^vii—Al2—O10^viii	110.77 (6)
O9ⁱⁱ—K1—O11	55.61 (2)	O7—Al2—O10^viii	105.95 (5)
O9ⁱⁱⁱ—K1—O10ⁱⁱⁱ	56.01 (3)	O1—As1—O2	110.66 (4)
O9ⁱⁱⁱ—K1—O11	72.39 (3)	O1—As1—O3	114.32 (4)
O10ⁱⁱⁱ—K1—O11	125.79 (3)	O1—As1—O4^ix	115.08 (4)
O1^iv—K2—O2^v	68.86 (2)	O2—As1—O3	105.42 (4)
O1^iv—K2—O7^iv	112.20 (3)	O2—As1—O4^ix	106.85 (4)
O1^iv—K2—O8^v	119.86 (2)	O3—As1—O4^ix	103.72 (4)
O1^iv—K2—O9^v	78.24 (3)	O5—As2—O6	113.25 (6)
O1^iv—K2—O11^vi	89.12 (3)	O5—As2—O7	115.67 (5)
O2^v—K2—O7^iv	95.73 (2)	O5—As2—O8	109.52 (5)
O2^v—K2—O8^v	65.61 (2)	O6—As2—O7	108.07 (5)
O2^v—K2—O9^v	107.28 (3)	O6—As2—O8	105.28 (4)
O2^v—K2—O11^vi	154.06 (3)	O7—As2—O8	104.19 (5)
O7^iv—K2—O8^v	109.45 (3)	O9—As3—O10	108.48 (5)
O7^iv—K2—O9^v	156.96 (3)	O9—As3—O11^ix	115.16 (5)
O7^iv—K2—O11^vi	79.62 (3)	O9—As3—O12	109.34 (4)
O8^v—K2—O9^v	79.97 (3)	O10—As3—O11^ix	111.13 (5)
O8^v—K2—O11^vi	140.08 (3)	O10—As3—O12	101.71 (4)
O9^v—K2—O11^vi	80.10 (3)	O11^ix—As3—O12	110.16 (5)

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

Experimental details

Crystal data
Chemical formula	K₃Al₂As₃O₁₂
M_r	588
Crystal system, space group	Orthorhombic, Pna2₁
Temperature (K)	100
a, b, c (Å)	8.7943 (2), 17.4400 (2), 8.6610 (3)
V (Å³)	1328.36 (6)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	8.63
Crystal size (mm)	0.10 × 0.06 × 0.01

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2008)
T_min, T_max	0.49, 0.92
No. of measured, independent and observed [I > 3σ(I)] reflections	52293, 9623, 8606
R_int	0.038
(sin θ/λ)_max (Å⁻¹)	0.997

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.018, 0.039, 0.80
No. of reflections	9623
No. of parameters	181
Δρ_max, Δρ_min (e Å⁻³)	0.33, −0.31
Absolute structure	Flack (1983), 3882 Friedel pairs
Absolute structure parameter	0.008 (3)

Computer programs: APEX2 (Bruker, 2008), SAINT-Plus (Bruker, 2008), coordinates taken from an isotypic structure, JANA2006 (Petříček et al., 2006), ATOMS (Dowty, 2006), publCIF (Westrip, 2010).

References

Anantharamulu, N., Koteswara Rao, K., Rambabu, G., Vijaya Kumar, B., Velchuri Radha & Vithal, M. (2011). J. Mater. Sci. 46, 2821–2837. Google Scholar
Beaurain, M., Astier, R., Lee, A. van der & Armand, P. (2008). Acta Cryst. C64, i5–i8. Web of Science CrossRef CAS IUCr Journals Google Scholar
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