CsGa(HAsO4)2, the first Ga representative of the RbAl(HAsO4)2 structure type

Schwendtner, K.; Kolitsch, U.

doi:10.1107/S2056989019002081

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Volume 75| Part 3| March 2019| Pages 346-349

https://doi.org/10.1107/S2056989019002081

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CsGa(HAsO₄)₂, the first Ga representative of the RbAl(HAsO₄)₂ structure type

Karolina Schwendtner ^a ^* and Uwe Kolitsch ^b

^aInstitute for Chemical Technology and Analytics, Division of Structural Chemistry, TU Wien, Getreidemarkt 9/164-SC, 1060 Vienna, Austria, and ^bNaturhistorisches Museum, Burgring 7, 1010 Vienna, and Institut für Mineralogie und Kristallographie, Universität Wien, Althanstrasse 14, 1090 Wien, Austria
^*Correspondence e-mail: karolina.schwendtner@tuwien.ac.at

Edited by A. Van der Lee, Université de Montpellier II, France (Received 29 January 2019; accepted 6 February 2019; online 8 February 2019)

The crystal structure of hydrothermally synthesized (T = 493 K, 7 d) caesium gallium bis[hydrogen arsenate(V)], CsGa(HAsO₄)₂, was solved by single-crystal X-ray diffraction. The compound crystallizes in the common RbAl(HAsO₄)₂ structure type (R32) and consists of a basic tetrahedral–octahedral framework topology that houses Cs⁺ cations in its channels. The AsO₄ tetrahedron is disordered over two positions with site occupancy factors of 0.946 (1) and 0.054 (1). Strong hydrogen bonds strengthen the network. The structure was refined as inversion twin.

Keywords: crystal structure; CsGa(HAsO₄)₂; arsenate; hydrogen arsenate.

CCDC reference: 1895785

1. Chemical context

Compounds with mixed tetrahedral–octahedral (T–O) framework structures are characterized by a broad range of different atomic arrangements. These topologies result in several interesting properties such as ion exchange (Masquelier et al., 1996 ) and ion conductivity (Chouchene et al., 2017 ), as well as unusual piezoelectric (Ren et al., 2015 ), magnetic (Ouerfelli et al., 2007 ) or non-linear optical features (frequency doubling; Sun et al., 2017 ).

CsGa(HAsO₄)₂ was obtained during our extensive experimental study of the system M⁺–M³⁺–As⁵⁺–O–(H) (M⁺ = Li, Na, K, Rb, Cs, Ag, Tl, NH₄; M³⁺ = Al, Ga, In, Sc, Fe, Cr, Tl), which resulted in the discovery of an unusually large variety of new structure types (Schwendtner & Kolitsch, 2004 , 2005 , 2007a ,b ,c , 2017a , 2018a , 2019 ; Schwendtner, 2006 ). One atomic arrangement, the RbFe(HPO₄)₂ type (Lii & Wu, 1994 ; rhombohedral, R $[\overline{3}]$ c), and its two relatives, the CsAl₂As(HAsO₄)₆ type (Schwendtner & Kolitsch, 2018a, rhombohedral, R $[\overline{3}]$ c) and the RbAl(HAsO₄)₂ type (Schwendtner & Kolitsch, 2018a, rhombohedral, R32), were found to exhibit a large crystal–chemical flexibility, which allows the incorporation of a wide variety of M⁺ and M³⁺ cations. So far the RbFe(HPO₄)₂-type is represented by eight arsenate members with the following M⁺M³⁺ combinations: TlAl, (NH₄)Ga, RbIn, RbGa, RbAl, RbFe, CsIn and CsFe (Schwendtner & Kolitsch, 2017b , 2018a,b ,c ,e ). Six arsenates of the CsAl₂As(HAsO₄)₆ type are known with the following M⁺M³⁺ combinations: RbGa, CsGa, TlGa, RbAl, CsAl and CsFe (Schwendtner & Kolitsch, 2018a,c,d ). CsGa(HAsO₄)₂ represents the third representative of the RbAl(HAsO₄)₂-type atomic arrangement, of which previously only the two M⁺M³⁺ combinations RbAl and CsFe (Schwendtner & Kolitsch, 2018a) were known. The 12-coordinated M⁺ cations present in these types of compounds are rather large (M = Cs, Rb, Tl and NH₄), with ionic radii ranging from 1.70 to 1.88 Å (Shannon, 1976 ). No members containing K⁺ or any smaller M⁺ cations are presently known, suggesting that the ionic radius of K⁺ (1.64 Å, Shannon, 1976) is already slightly too small for this type of framework. The ionic radii of the six-coordinated M³⁺ cations (M = Al, Cr, Fe, Ga, In) range from 0.535 to 0.800 Å (Shannon, 1976) and nearly all M³⁺ cations we studied are represented in these types of compounds, with the exception of Sc³⁺ and Tl³⁺. Syntheses aimed at preparing (NH₄)Sc(HAsO₄)₂, RbSc(HAsO₄)₂ and TlSc(HAsO₄)₂ instead led to the crystallization of the diarsenate compounds (NH₄)ScAs₂O₇ (Kolitsch, 2004 ), RbScAs₂O₇ (Schwendtner & Kolitsch, 2004) and TlScAs₂O₇ (Baran et al., 2006 ), respectively.

There exist only three other Cs–Ga arsenates: The structurally closely related CsGa₂As(HAsO₄)₆ (Schwendtner & Kolitsch, 2018b), in which one third of the M³⁺O₆ octahedra are replaced by AsO₆ octahedra; CsGa(H₂AsO₄)(H_1.5AsO₄)₂ (Schwendtner & Kolitsch, 2005) which was encountered in the same synthesis batch as the title compound; and Cs₂Ga₃(As₃O₁₀)(AsO₄)₂ (Lin & Lii, 1996 ).

2. Structural commentary

CsGa(HAsO₄)₂ is a representative of the RbAl(HAsO₄)₂ structure type (R32; Schwendtner & Kolitsch, 2018a) and has a basic tetrahedral–octahedral framework structure featuring interpenetrating channels, which host the M⁺ cations (Fig. 1). This structure type is closely related to the RbFe(HPO₄)₂ structure type (R $[\overline{3}]$ c; Lii & Wu, 1994), the RbAl₂As(HAsO₄)₆ type (R $[\overline{3}]$ c; Schwendtner & Kolitsch, 2018a) and the triclinic (NH₄)Fe(HPO₄)₂ type (P $[\overline{1}]$ ; Yakubovich, 1993 ). The fundamental building unit in all these structure types contains M³⁺O₆ octahedra, which are connected via their six corners to six protonated AsO₄ tetrahedra, thereby forming an M³⁺As₆O₂₄ unit. These units are in turn connected via three corners to other M³⁺O₆ octahedra. The free, protonated corner of each AsO₄ tetrahedron forms a medium-to-strong hydrogen bond (Table 1) to the neighbouring M³⁺As₆O₂₄ group (Fig. 2a,b). The M³⁺As₆O₂₄ units are arranged in layers perpendicular to the c_hex axis (Fig. 1). The units within these layers are held together by medium–strong hydrogen bonds (Table 2). Nearly all of the representatives of these closely related structure types show pseudo-hexagonal to pseudo-octahedral crystal habits. In line with this observation, CsGa(HAsO₄)₂ forms tiny pseudo-hexagonal platelets.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O4—H⋯O3ⁱⁱⁱ	0.81 (4)	1.78 (4)	2.589 (5)	175 (6)
Symmetry code: (iii) -x+y+1, -x+1, z.

Table 2
Selected bond lengths (Å)

Cs1—O4 (6×)	3.338 (3)	As—O1	1.659 (3)
Cs1—O2 (6×)	3.451 (3)	As—O2	1.667 (3)
Cs2—O4 (3×)	3.014 (3)	As—O3	1.691 (3)
Cs2—O1 (3×)	3.445 (3)	As—O4	1.740 (3)
Cs2—O4 (3×)	3.459 (3)	AsB—O1	1.625 (7)
Cs2—O3 (3×)	3.516 (3)	AsB—O3B	1.66 (6)
Ga1—O2 (3×)	1.958 (3)	AsB—O4Bⁱ	1.69 (6)
Ga1—O3 (3×)	1.982 (3)	AsB—O2Bⁱⁱ	1.76 (7)
Ga2—O1 (6×)	1.967 (3)
Symmetry codes: (i) -y+1, x-y, z; (ii) -x+y, -x, z.

Figure 1
General outline of the crystal structure of CsGa(HAsO₄)₂ viewed along a. Only the main AsO₄ tetrahedra are shown (the AsB-centred tetrahedra are omitted for clarity). Hydrogen bonds are shown as blue dotted lines.

Figure 2
Detailed view of the different layers in the structure of CsGa(HAsO₄)_2. The alternative AsBO₄ tetrahedra, the alternative hydrogen bonds and OB atoms are shown in transparent mode. (a) The layer showing the Ga1As₆O₂₄ group including the alternative AsBO₄ tetrahedra. (b) The layer showing the Ga2As₆O₂₄ group including the alternative AsBO₄ tetrahedra and the strongly overbonded Cs2 atom in its void.

The two Cs atoms in the framework voids are 12-coordinated. While the average Cs1—O bond length, 3.395 Å, is slightly longer than the grand mean average of 3.377 Å (Gagné & Hawthorne, 2016 ), it fits the low bond-valence sum (BVS) of 0.84 valence units (v.u.) which was calculated with the bond-valence parameters of Gagné & Hawthorne (2015 ). In contrast, the average Cs2—O bond length is slightly shorter (3.359 Å) and the individual Cs2—O bond lengths (Table 2) show a much wider bond-length range, resulting in a much too high bond-valence sum of 1.38 v.u. This is mainly caused by four very short Cs2—O bond lengths of only 3.014 Å, although even shorter Cs—O bond lengths, as low as 2.910 Å, have been reported for 12-coordinated Cs⁺ cations (Gagné & Hawthorne, 2016).

The Ga atoms at the centre of the two GaO₆ octahedra are also slightly overbonded with BVSs of 3.05 and 3.07 v.u., and average Ga—O bond lengths of 1.970 and 1.967 Å for Ga1 and Ga2, respectively. These values are somewhat shorter than the grand mean average for six-coordinated Ga of 1.978 Å (Gagné & Hawthorne, 2018 ). The AsO₄ tetrahedra show the typical bond-length geometry of HAsO₄ groups with three short and one long As—O bond. The average As—O bond length (1.689 Å) is very close to the observed average of HAsO₄ groups (1.687 Å; Schwendtner & Kolitsch, 2019), but the As—O bond length to the protonated O4 atom (1.740 Å, Table 2) is notably longer than the average of 1.728 Å for As—OH bonds in singly protonated AsO₄ groups (Schwendtner & Kolitsch, 2019). The BVS for the As atom is close to ideal with 4.98 v.u. All its O ligands are underbonded to a varying degree, with BVSs ranging from 1.39 v.u. for O4 to 1.92 v.u. for O1.

The As atom is characterized by a split position. The AsB site, 1.27 Å away from the main As position, has a refined occupancy of about 5%. The AsB site shares one apical ligand (O1) with the main AsO₄ tetrahedron and has three additional low-occupancy O atoms (O2B, O3B and O4B) as remaining ligands. The split position can roughly be explained by a mirror plane in (110). The average AsB—O bond length of 1.684 Å is slightly shorter than the corresponding value of the main AsO₄ tetrahedron (1.689 Å), and the AsB—O bonds also show a wider bond-length range (Table 2). The calculated BVS for the AsB site (5.09 v.u.) is reasonable considering the high estimated uncertainty of this value in view of the relatively large positional and bond-length errors for the AsB site (Table 2).

3. Synthesis and crystallization

Small pseudo-hexagonal colorless platelets of CsGa(HAsO₄)₂ were prepared hydrothermally (T = 493 K, 7 d) in a Teflon-lined stainless steel autoclave from a mixture of Cs₂CO₃, Ga₂O₃ (approximate molar ratio Cs:Ga of 1:1), arsenic acid and distilled water. Enough arsenic acid was added to keep the pH between about 1.5 and 0.5. The Teflon cylinders were filled with distilled water up to approximately 80% of their inner volume. Initial and final pH values were about 1.5 and 1, respectively. The platelets were accompanied by large colourless glassy prisms of CsGa(H₂AsO₄)(H_1.5AsO₄)₂ (Schwendtner & Kolitsch, 2005), which made up about 80% of the reaction products.

4. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3.

Table 3
Experimental details

Crystal data
Chemical formula	CsGa(HAsO₄)₂
M_r	482.49
Crystal system, space group	Trigonal, R32:H
Temperature (K)	293
a, c (Å)	8.481 (1), 27.050 (5)
V (Å³)	1685.0 (5)
Z	9
Radiation type	Mo Kα
μ (mm⁻¹)	17.24
Crystal size (mm)	0.03 × 0.03 × 0.01

Data collection
Diffractometer	Nonius KappaCCD single-crystal four-circle
Absorption correction	Multi-scan (HKL SCALEPACK; Otwinowski et al., 2003 )
T_min, T_max	0.626, 0.846
No. of measured, independent and observed [I > 2σ(I)] reflections	2738, 1375, 1283
R_int	0.018
(sin θ/λ)_max (Å⁻¹)	0.757

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.019, 0.042, 1.07
No. of reflections	1375
No. of parameters	76
No. of restraints	2
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.72, −0.74
Absolute structure	Refined as an inversion twin
Absolute structure parameter	0.46 (2)
Computer programs: COLLECT (Nonius, 2003 ), HKL DENZO and SCALEPACK (Otwinowski et al., 2003), SHELXS97 (Sheldrick, 2008 ), SHELXL2016 (Sheldrick, 2015 ), DIAMOND (Brandenburg, 2005 ) and publCIF (Westrip, 2010 ).

The refinement of CsGa(HAsO₄)₂ revealed a considerable residual electron-density peak of 5.1 e Å⁻³ 1.27 Å away from As and 1.62 Å away from the O1 site. The corresponding position can be generated by a mirror plane in (110) and therefore was assumed to be an alternative flipped As position (sharing the same O1 atom), similar to what was encountered in related TlAl(HAsO₄) and CsIn(HAsO₄)₂ (R $[\overline{3}]$ c type; Schwendtner & Kolitsch, 2017b, 2018e). An inclusion of the alternative position led to a considerable drop in the conventional R factor and weight parameters and the highest residual electron densities also decreased considerably. Three electron-density peaks between 1.15 and 1.19 e Å⁻³ close to this AsB position could be attributed to the O ligands of this flipped AsO₄ tetrahedra and, after including them into the structure model, the conventional R factor dropped from 3.5 to 1.99%. The remaining highest residual electron densities of 0.72 and −0.74 e Å⁻³ are located close to the Cs positions. The occupancy of the alternative As position (Fig. 2) refined to about 5%, while the independently refined occupancy of the main As position was about 95%. For the final refinement, the displacement parameters of the AsB, O2B, O3B and O4B sites were restrained to be the same as that of the main AsO₄ tetrahedron position, and the occupancy sums of both tetrahedra were restrained to give a total occupancy of 1.00. The structure was refined as inversion twin with a Flack parameter of 0.46 (2).

Supporting information

CCDC reference: 1895785

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989019002081/vn2142sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989019002081/vn2142Isup2.hkl

checkCIF report

Computing details top

Data collection: COLLECT (Nonius, 2003); cell refinement: HKL SCALEPACK (Otwinowski et al., 2003); data reduction: HKL DENZO and SCALEPACK (Otwinowski et al., 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2005); software used to prepare material for publication: publCIF (Westrip, 2010).

Caesium gallium bis[hydrogen arsenate(V)] top

Crystal data top

CsGa(HAsO₄)₂	D_x = 4.279 Mg m⁻³
M_r = 482.49	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R32:H	Cell parameters from 1370 reflections
a = 8.481 (1) Å	θ = 2.3–32.5°
c = 27.050 (5) Å	µ = 17.24 mm⁻¹
V = 1685.0 (5) Å³	T = 293 K
Z = 9	Tiny hexagonal platelets, colourless
F(000) = 1962	0.03 × 0.03 × 0.01 mm

Data collection top

Nonius KappaCCD single-crystal four-circle diffractometer	1283 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.018
φ and ω scans	θ_max = 32.5°, θ_min = 2.3°
Absorption correction: multi-scan (HKL SCALEPACK; Otwinowski et al., 2003)	h = −12→12
T_min = 0.626, T_max = 0.846	k = −10→10
2738 measured reflections	l = −40→40
1375 independent reflections

Refinement top

Refinement on F²	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F² > 2σ(F²)] = 0.019	w = 1/[σ²(F_o²) + (0.0194P)² + 2.6152P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.042	(Δ/σ)_max < 0.001
S = 1.07	Δρ_max = 0.72 e Å⁻³
1375 reflections	Δρ_min = −0.74 e Å⁻³
76 parameters	Extinction correction: SHELXL2016 (Sheldrick, 2015), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
2 restraints	Extinction coefficient: 0.00041 (4)
Primary atom site location: structure-invariant direct methods	Absolute structure: Refined as an inversion twin
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.46 (2)

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refined as a 2-component inversion twin.

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
O1	0.2225 (4)	0.1039 (5)	0.04039 (9)	0.0161 (5)
Cs1	0.333333	0.666667	0.166667	0.02717 (16)
Cs2	0.333333	0.666667	0.00046 (2)	0.02105 (12)
Ga1	0.000000	0.000000	0.17439 (2)	0.00792 (13)
Ga2	0.000000	0.000000	0.000000	0.00791 (17)
As	0.29653 (6)	0.22380 (6)	0.09219 (2)	0.00852 (10)	0.9461 (12)
O2	0.1465 (4)	0.2152 (5)	0.13347 (13)	0.0110 (6)	0.9461 (12)
O3	0.4566 (4)	0.1811 (5)	0.11541 (11)	0.0110 (5)	0.9461 (12)
O4	0.4135 (4)	0.4521 (4)	0.07510 (12)	0.0151 (5)	0.9461 (12)
AsB	0.2984 (10)	0.0710 (10)	0.0923 (3)	0.00852 (10)	0.0540 (12)
O2B	0.081 (9)	0.213 (10)	0.134 (2)	0.0110 (6)	0.0540 (12)
O3B	0.457 (7)	0.265 (8)	0.117 (2)	0.0110 (5)	0.0540 (12)
O4B	0.549 (8)	0.587 (7)	0.077 (2)	0.0151 (5)	0.0540 (12)
H	0.510 (7)	0.474 (8)	0.0874 (17)	0.017 (13)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0123 (12)	0.0253 (16)	0.0101 (11)	0.0090 (14)	−0.0040 (9)	−0.0056 (13)
Cs1	0.0313 (2)	0.0313 (2)	0.0188 (3)	0.01567 (12)	0.000	0.000
Cs2	0.02470 (15)	0.02470 (15)	0.01374 (19)	0.01235 (8)	0.000	0.000
Ga1	0.00859 (18)	0.00859 (18)	0.0066 (3)	0.00430 (9)	0.000	0.000
Ga2	0.0088 (3)	0.0088 (3)	0.0062 (4)	0.00438 (13)	0.000	0.000
As	0.00777 (17)	0.01075 (19)	0.00680 (16)	0.00446 (15)	−0.00031 (14)	0.00020 (14)
O2	0.0107 (14)	0.0127 (13)	0.0097 (12)	0.0060 (13)	0.0045 (11)	0.0008 (10)
O3	0.0110 (13)	0.0138 (14)	0.0104 (12)	0.0078 (10)	−0.0029 (11)	−0.0029 (11)
O4	0.0103 (14)	0.0123 (14)	0.0207 (14)	0.0042 (12)	−0.0013 (12)	0.0052 (12)
AsB	0.00777 (17)	0.01075 (19)	0.00680 (16)	0.00446 (15)	−0.00031 (14)	0.00020 (14)
O2B	0.0107 (14)	0.0127 (13)	0.0097 (12)	0.0060 (13)	0.0045 (11)	0.0008 (10)
O3B	0.0110 (13)	0.0138 (14)	0.0104 (12)	0.0078 (10)	−0.0029 (11)	−0.0029 (11)
O4B	0.0103 (14)	0.0123 (14)	0.0207 (14)	0.0042 (12)	−0.0013 (12)	0.0052 (12)

Geometric parameters (Å, º) top

O1—AsB	1.625 (7)	Ga1—O3^iv	1.982 (3)
O1—As	1.659 (3)	Ga1—O3^xi	1.982 (3)
O1—Ga2	1.967 (3)	Ga1—O3^xii	1.982 (3)
O1—Cs2ⁱ	3.445 (3)	As—O2	1.667 (3)
Cs1—O4	3.338 (3)	As—O3	1.691 (3)
Cs1—O4ⁱⁱ	3.338 (3)	As—O4	1.740 (3)
Cs1—O4ⁱⁱⁱ	3.338 (3)	As—H	1.99 (6)
Cs1—O4^iv	3.338 (3)	O4—H	0.81 (4)
Cs1—O4^v	3.338 (3)	AsB—O3B	1.66 (6)
Cs1—O4^vi	3.338 (3)	AsB—O4B^xiii	1.69 (6)
Cs1—O2^iv	3.451 (3)	AsB—O2B^x	1.76 (7)
Cs1—O2ⁱⁱ	3.451 (3)	O4B—H	0.88 (7)
Cs1—O2	3.451 (3)	Cs1—O4 (6x)	3.338 (3)
Cs1—O2ⁱⁱⁱ	3.451 (3)	Cs1—O2 (6x)	3.451 (3)
Cs1—O2^v	3.451 (3)	Cs2—O4 (3x)	3.014 (3)
Cs1—O2^vi	3.451 (3)	Cs2—O1 (3x)	3.445 (3)
Cs1—H	3.46 (5)	Cs2—O4 (3x)	3.459 (3)
Cs2—O4ⁱⁱⁱ	3.014 (3)	Cs2—O3 (3x)	3.516 (3)
Cs2—O4ⁱⁱ	3.014 (3)	Ga1—O2 (3x)	1.958 (3)
Cs2—O4	3.014 (3)	Ga1—O3 (3x)	1.982 (3)
Cs2—O4^vii	3.459 (3)	Ga2—O1 (6x)	1.967 (3)
Cs2—O4^viii	3.459 (3)	As—O1	1.659 (3)
Cs2—O4ⁱ	3.459 (3)	As—O2	1.667 (3)
Cs2—O3ⁱ	3.516 (3)	As—O3	1.691 (3)
Cs2—O3^vii	3.516 (3)	As—O4	1.740 (3)
Cs2—O3^viii	3.516 (3)	AsB—O1	1.625 (7)
Ga1—O2^ix	1.958 (3)	AsB—O3B	1.66 (6)
Ga1—O2	1.958 (3)	AsB—O4B^xiii	1.69 (6)
Ga1—O2^x	1.958 (3)	AsB—O2B^x	1.76 (7)

As—O1—Ga2	136.69 (19)	O1^vii—Cs2—O4ⁱ	124.15 (7)
AsB—O1—Cs2ⁱ	87.7 (3)	O1ⁱ—Cs2—O4ⁱ	46.56 (8)
As—O1—Cs2ⁱ	87.31 (11)	O1^viii—Cs2—O4ⁱ	63.74 (8)
Ga2—O1—Cs2ⁱ	127.46 (10)	O4^vii—Cs2—O4ⁱ	88.64 (8)
O4—Cs1—O4ⁱⁱ	70.99 (9)	O4^viii—Cs2—O4ⁱ	88.64 (8)
O4—Cs1—O4ⁱⁱⁱ	70.99 (9)	O4ⁱⁱⁱ—Cs2—O3ⁱ	159.00 (8)
O4ⁱⁱ—Cs1—O4ⁱⁱⁱ	70.99 (9)	O4ⁱⁱ—Cs2—O3ⁱ	115.45 (8)
O4—Cs1—O4^iv	99.40 (11)	O4—Cs2—O3ⁱ	115.32 (8)
O4ⁱⁱ—Cs1—O4^iv	123.13 (11)	O1^vii—Cs2—O3ⁱ	80.58 (7)
O4ⁱⁱⁱ—Cs1—O4^iv	160.35 (10)	O1ⁱ—Cs2—O3ⁱ	45.29 (7)
O4—Cs1—O4^v	123.13 (11)	O1^viii—Cs2—O3ⁱ	90.53 (7)
O4ⁱⁱ—Cs1—O4^v	160.35 (10)	O4^vii—Cs2—O3ⁱ	43.57 (8)
O4ⁱⁱⁱ—Cs1—O4^v	99.40 (11)	O4^viii—Cs2—O3ⁱ	80.71 (8)
O4^iv—Cs1—O4^v	70.99 (9)	O4ⁱ—Cs2—O3ⁱ	46.05 (8)
O4—Cs1—O4^vi	160.35 (10)	O4ⁱⁱⁱ—Cs2—O3^vii	115.45 (8)
O4ⁱⁱ—Cs1—O4^vi	99.40 (11)	O4ⁱⁱ—Cs2—O3^vii	115.32 (8)
O4ⁱⁱⁱ—Cs1—O4^vi	123.13 (11)	O4—Cs2—O3^vii	159.00 (8)
O4^iv—Cs1—O4^vi	70.99 (9)	O1^vii—Cs2—O3^vii	45.29 (7)
O4^v—Cs1—O4^vi	70.99 (9)	O1ⁱ—Cs2—O3^vii	90.53 (7)
O4—Cs1—O2^iv	63.50 (8)	O1^viii—Cs2—O3^vii	80.58 (7)
O4ⁱⁱ—Cs1—O2^iv	126.94 (7)	O4^vii—Cs2—O3^vii	46.05 (8)
O4ⁱⁱⁱ—Cs1—O2^iv	115.11 (8)	O4^viii—Cs2—O3^vii	43.57 (8)
O4^iv—Cs1—O2^iv	46.21 (8)	O4ⁱ—Cs2—O3^vii	80.71 (8)
O4^v—Cs1—O2^iv	72.50 (8)	O3ⁱ—Cs2—O3^vii	46.22 (9)
O4^vi—Cs1—O2^iv	114.43 (8)	O4ⁱⁱⁱ—Cs2—O3^viii	115.32 (8)
O4—Cs1—O2ⁱⁱ	114.43 (8)	O4ⁱⁱ—Cs2—O3^viii	159.00 (8)
O4ⁱⁱ—Cs1—O2ⁱⁱ	46.21 (8)	O4—Cs2—O3^viii	115.45 (8)
O4ⁱⁱⁱ—Cs1—O2ⁱⁱ	72.51 (8)	O1^vii—Cs2—O3^viii	90.53 (7)
O4^iv—Cs1—O2ⁱⁱ	126.94 (8)	O1ⁱ—Cs2—O3^viii	80.58 (7)
O4^v—Cs1—O2ⁱⁱ	115.11 (8)	O1^viii—Cs2—O3^viii	45.29 (7)
O4^vi—Cs1—O2ⁱⁱ	63.50 (8)	O4^vii—Cs2—O3^viii	80.71 (8)
O2^iv—Cs1—O2ⁱⁱ	169.02 (11)	O4^viii—Cs2—O3^viii	46.05 (8)
O4—Cs1—O2	46.21 (8)	O4ⁱ—Cs2—O3^viii	43.57 (8)
O4ⁱⁱ—Cs1—O2	72.50 (8)	O3ⁱ—Cs2—O3^viii	46.22 (9)
O4ⁱⁱⁱ—Cs1—O2	114.43 (8)	O3^vii—Cs2—O3^viii	46.22 (9)
O4^iv—Cs1—O2	63.50 (8)	O2^ix—Ga1—O2	91.18 (14)
O4^v—Cs1—O2	126.94 (7)	O2^ix—Ga1—O2^x	91.18 (14)
O4^vi—Cs1—O2	115.11 (8)	O2—Ga1—O2^x	91.18 (14)
O2^iv—Cs1—O2	56.73 (11)	O2^ix—Ga1—O3^iv	176.98 (13)
O2ⁱⁱ—Cs1—O2	113.48 (5)	O2—Ga1—O3^iv	91.84 (14)
O4—Cs1—O2ⁱⁱⁱ	72.50 (8)	O2^x—Ga1—O3^iv	88.69 (14)
O4ⁱⁱ—Cs1—O2ⁱⁱⁱ	114.43 (8)	O2^ix—Ga1—O3^xi	88.69 (14)
O4ⁱⁱⁱ—Cs1—O2ⁱⁱⁱ	46.21 (8)	O2—Ga1—O3^xi	176.98 (13)
O4^iv—Cs1—O2ⁱⁱⁱ	115.11 (8)	O2^x—Ga1—O3^xi	91.84 (14)
O4^v—Cs1—O2ⁱⁱⁱ	63.50 (9)	O3^iv—Ga1—O3^xi	88.30 (14)
O4^vi—Cs1—O2ⁱⁱⁱ	126.94 (8)	O2^ix—Ga1—O3^xii	91.84 (14)
O2^iv—Cs1—O2ⁱⁱⁱ	76.70 (11)	O2—Ga1—O3^xii	88.69 (14)
O2ⁱⁱ—Cs1—O2ⁱⁱⁱ	113.48 (5)	O2^x—Ga1—O3^xii	176.98 (13)
O2—Cs1—O2ⁱⁱⁱ	113.48 (5)	O3^iv—Ga1—O3^xii	88.30 (14)
O4—Cs1—O2^v	126.94 (8)	O3^xi—Ga1—O3^xii	88.30 (14)
O4ⁱⁱ—Cs1—O2^v	115.11 (8)	O2^ix—Ga1—Cs2^xiv	124.43 (10)
O4ⁱⁱⁱ—Cs1—O2^v	63.50 (9)	O2—Ga1—Cs2^xiv	124.43 (10)
O4^iv—Cs1—O2^v	114.43 (8)	O2^x—Ga1—Cs2^xiv	124.43 (10)
O4^v—Cs1—O2^v	46.21 (8)	O3^iv—Ga1—Cs2^xiv	53.54 (10)
O4^vi—Cs1—O2^v	72.50 (8)	O3^xi—Ga1—Cs2^xiv	53.54 (10)
O2^iv—Cs1—O2^v	113.48 (5)	O3^xii—Ga1—Cs2^xiv	53.54 (10)
O2ⁱⁱ—Cs1—O2^v	76.70 (11)	O1—Ga2—O1^xv	176.3 (2)
O2—Cs1—O2^v	169.02 (11)	O1—Ga2—O1^ix	92.14 (11)
O2ⁱⁱⁱ—Cs1—O2^v	56.74 (11)	O1^xv—Ga2—O1^ix	90.55 (19)
O4—Cs1—O2^vi	115.11 (8)	O1—Ga2—O1^xvi	85.29 (19)
O4ⁱⁱ—Cs1—O2^vi	63.50 (8)	O1^xv—Ga2—O1^xvi	92.13 (11)
O4ⁱⁱⁱ—Cs1—O2^vi	126.94 (7)	O1^ix—Ga2—O1^xvi	176.3 (2)
O4^iv—Cs1—O2^vi	72.50 (8)	O1—Ga2—O1^x	92.14 (11)
O4^v—Cs1—O2^vi	114.43 (8)	O1^xv—Ga2—O1^x	85.29 (19)
O4^vi—Cs1—O2^vi	46.21 (8)	O1^ix—Ga2—O1^x	92.13 (11)
O2^iv—Cs1—O2^vi	113.48 (5)	O1^xvi—Ga2—O1^x	90.55 (19)
O2ⁱⁱ—Cs1—O2^vi	56.73 (11)	O1—Ga2—O1ⁱ	90.55 (19)
O2—Cs1—O2^vi	76.70 (11)	O1^xv—Ga2—O1ⁱ	92.13 (11)
O2ⁱⁱⁱ—Cs1—O2^vi	169.02 (11)	O1^ix—Ga2—O1ⁱ	85.29 (19)
O2^v—Cs1—O2^vi	113.48 (5)	O1^xvi—Ga2—O1ⁱ	92.13 (11)
O4—Cs1—H	13.6 (7)	O1^x—Ga2—O1ⁱ	176.3 (2)
O4ⁱⁱ—Cs1—H	84.3 (7)	O1—As—O2	119.51 (15)
O4ⁱⁱⁱ—Cs1—H	71.9 (10)	O1—As—O3	106.29 (15)
O4^iv—Cs1—H	94.7 (9)	O2—As—O3	114.75 (17)
O4^v—Cs1—H	109.6 (7)	O1—As—O4	106.75 (16)
O4^vi—Cs1—H	164.9 (10)	O2—As—O4	102.97 (16)
O2^iv—Cs1—H	53.6 (8)	O3—As—O4	105.36 (17)
O2ⁱⁱ—Cs1—H	126.1 (7)	O1—As—Cs2ⁱ	66.48 (10)
O2—Cs1—H	51.8 (10)	O2—As—Cs2ⁱ	169.73 (12)
O2ⁱⁱⁱ—Cs1—H	62.9 (9)	O3—As—Cs2ⁱ	68.86 (11)
O2^v—Cs1—H	119.3 (10)	O4—As—Cs2ⁱ	66.81 (11)
O2^vi—Cs1—H	126.0 (9)	O1—As—Cs1	143.32 (12)
O4ⁱⁱⁱ—Cs2—O4ⁱⁱ	80.04 (10)	O2—As—Cs1	54.72 (12)
O4ⁱⁱⁱ—Cs2—O4	80.04 (10)	O3—As—Cs1	108.02 (11)
O4ⁱⁱ—Cs2—O4	80.04 (10)	O4—As—Cs1	51.41 (11)
O4ⁱⁱⁱ—Cs2—O1^vii	90.97 (8)	Cs2ⁱ—As—Cs1	115.260 (12)
O4ⁱⁱ—Cs2—O1^vii	74.30 (8)	O1—As—H	117.5 (13)
O4—Cs2—O1^vii	153.94 (8)	O2—As—H	110.9 (13)
O4ⁱⁱⁱ—Cs2—O1ⁱ	153.94 (8)	O3—As—H	81.6 (12)
O4ⁱⁱ—Cs2—O1ⁱ	90.97 (8)	O4—As—H	24.0 (12)
O4—Cs2—O1ⁱ	74.30 (8)	Cs2ⁱ—As—H	59.4 (13)
O1^vii—Cs2—O1ⁱ	110.22 (4)	Cs1—As—H	56.4 (13)
O4ⁱⁱⁱ—Cs2—O1^viii	74.30 (8)	As—O2—Ga1	122.30 (19)
O4ⁱⁱ—Cs2—O1^viii	153.94 (8)	As—O2—Cs1	102.06 (14)
O4—Cs2—O1^viii	90.97 (8)	Ga1—O2—Cs1	127.77 (14)
O1^vii—Cs2—O1^viii	110.22 (4)	As—O3—Ga1^xvii	129.62 (19)
O1ⁱ—Cs2—O1^viii	110.22 (4)	As—O3—Cs2ⁱ	84.49 (12)
O4ⁱⁱⁱ—Cs2—O4^vii	136.20 (4)	Ga1^xvii—O3—Cs2ⁱ	99.51 (12)
O4ⁱⁱ—Cs2—O4^vii	78.31 (9)	As—O4—Cs2	132.43 (15)
O4—Cs2—O4^vii	131.91 (5)	As—O4—Cs1	104.56 (13)
O1^vii—Cs2—O4^vii	46.56 (8)	Cs2—O4—Cs1	89.95 (9)
O1ⁱ—Cs2—O4^vii	63.74 (8)	As—O4—Cs2ⁱ	85.66 (12)
O1^viii—Cs2—O4^vii	124.15 (7)	Cs2—O4—Cs2ⁱ	98.06 (9)
O4ⁱⁱⁱ—Cs2—O4^viii	78.31 (9)	Cs1—O4—Cs2ⁱ	157.27 (10)
O4ⁱⁱ—Cs2—O4^viii	131.91 (5)	As—O4—H	96 (4)
O4—Cs2—O4^viii	136.20 (4)	Cs2—O4—H	130 (4)
O1^vii—Cs2—O4^viii	63.74 (8)	Cs1—O4—H	92 (3)
O1ⁱ—Cs2—O4^viii	124.15 (7)	Cs2ⁱ—O4—H	67 (3)
O1^viii—Cs2—O4^viii	46.56 (8)	O1—AsB—O3B	112 (2)
O4^vii—Cs2—O4^viii	88.64 (8)	O1—AsB—O4B^xiii	105.6 (18)
O4ⁱⁱⁱ—Cs2—O4ⁱ	131.91 (5)	O3B—AsB—O4B^xiii	104 (3)
O4ⁱⁱ—Cs2—O4ⁱ	136.20 (4)	O1—AsB—O2B^x	116 (2)
O4—Cs2—O4ⁱ	78.32 (9)	AsB^xviii—O4B—H	105 (6)

Symmetry codes: (i) y, x, −z; (ii) −x+y, −x+1, z; (iii) −y+1, x−y+1, z; (iv) −x+2/3, −x+y+1/3, −z+1/3; (v) x−y+2/3, −y+4/3, −z+1/3; (vi) y−1/3, x+1/3, −z+1/3; (vii) x−y, −y+1, −z; (viii) −x+1, −x+y+1, −z; (ix) −y, x−y, z; (x) −x+y, −x, z; (xi) y−1/3, x−2/3, −z+1/3; (xii) x−y−1/3, −y+1/3, −z+1/3; (xiii) −y+1, x−y, z; (xiv) x−1/3, y−2/3, z+1/3; (xv) −x, −x+y, −z; (xvi) x−y, −y, −z; (xvii) y+2/3, x+1/3, −z+1/3; (xviii) −x+y+1, −x+1, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O4—H···O3^xviii	0.81 (4)	1.78 (4)	2.589 (5)	175 (6)

Symmetry code: (xviii) −x+y+1, −x+1, z.

Acknowledgements

The authors acknowledge the TU Wien University Library for financial support through its Open Access Funding Program.

Funding information

Funding for this research was provided by: Austrian Academy of Sciences (award No. Doc fForte Fellowship to K. Schwendtner).

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