New M+, M3+-arsenates – the framework structures of AgM3+(HAsO4)2 (M3+ = Al, Ga) and M+GaAs2O7 (M+ = Na, Ag)

Schwendtner, K.; Kolitsch, U.

doi:10.1107/S2056989017005631

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Volume 73| Part 5| May 2017| Pages 785-790

https://doi.org/10.1107/S2056989017005631

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New M⁺, M³⁺-arsenates – the framework structures of AgM³⁺(HAsO₄)₂ (M³⁺ = Al, Ga) and M⁺GaAs₂O₇ (M⁺ = Na, Ag)

Karolina Schwendtner ^a ^* and Uwe Kolitsch ^b,^c

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

Edited by S. Parkin, University of Kentucky, USA (Received 28 March 2017; accepted 13 April 2017; online 28 April 2017)

The crystal structures of hydrothermally synthesized silver(I) aluminium bis[hydrogen arsenate(V)], AgAl(HAsO₄)₂, silver(I) gallium bis[hydrogen arsenate(V)], AgGa(HAsO₄)₂, silver gallium diarsenate(V), AgGaAs₂O₇, and sodium gallium diarsenate(V), NaGaAs₂O₇, were determined from single-crystal X-ray diffraction data collected at room temperature. The first two compounds are representatives of the MCV-3 structure type known for KSc(HAsO₄)₂, which is characterized by a three-dimensional anionic framework of corner-sharing alternating M³⁺O₆ octahedra (M = Al, Ga) and singly protonated AsO₄ tetrahedra. Intersecting channels parallel to [101] and [110] host the Ag⁺ cations, which are positionally disordered in the Ga compound, but not in the Al compound. The hydrogen bonds are relatively strong, with O⋯O donor–acceptor distances of 2.6262 (17) and 2.6240 (19) Å for the Al and Ga compounds, respectively. The two diarsenate compounds are representatives of the NaAlAs₂O₇ structure type, characterized by an anionic framework topology built of M³⁺O₆ octahedra (M = Al, Ga) sharing corners with diarsenate groups, and M⁺ cations (M = Ag) hosted in the voids of the framework. Both structures are characterized by a staggered conformation of the As₂O₇ groups.

Keywords: crystal structure; AgAl(HAsO₄)₂; AgGa(HAsO₄)₂; AgGaAs₂O₇; NaGaAs₂O₇.

CCDC references: 1543927; 1543926; 1543925; 1543924

1. Chemical context

Metal arsenates often form tetrahedral–octahedral framework structures with potentially interesting properties, such as ion conductivity, ion exchange and catalytic properties (Masquelier et al., 1990 , 1994a ,b , 1995 , 1996 ; Medvedev et al., 2003 ; Ouerfelli et al., 2007a , 2008 ; Pintard-Scrépel et al., 1983 ; Rousse et al., 2013 ). A detailed study of the system M⁺–M³⁺–As–O–(H) was therefore conducted, and a wide variety of new compounds and structure types were found and have been published (Schwendtner, 2006 ; Schwendtner & Kolitsch, 2004a ,b , 2005 , 2007a ,b ,c ,d ). Thus far, three different structure types for M¹⁺M³⁺(HAsO₄)₂ compounds have been reported. Two of them are very common and were first described for isotypic phosphate compounds. The (H₃O)Fe(HPO₄)₂ type (Vencato et al., 1989 ) is also adopted by β-CsSc(HAsO₄)₂ (Schwendtner & Kolitsch, 2004b), while the (NH₄)Fe(HPO₄)₂ type (Yakubovich, 1993 ) is adopted by α-CsSc(HAsO₄)₂ (Schwendtner & Kolitsch, 2004 ) and (NH₄)Fe(HAsO₄)₂ (Ouerfelli et al., 2014 ). The KSc(HAsO₄)₂ type (Schwendtner & Kolitsch, 2004a) has so far been the only known example; the two new protonated arsenates presented here are two further representatives of this structure type.

M⁺M³⁺As₂O₇ compounds crystallize in six known structure types, some of them isotypic to phosphates or silicates. The CaZrSi₂O₇ type (mineral gittinsite; Roelofsen-Ahl & Peterson, 1989 ) is also adopted by LiFeAs₂O₇ (Wang et al., 1994 ), LiM³⁺As₂O₇ (M³⁺ = Al, Ga, Sc) and NaScAs₂O₇ (Schwendtner & Kolitsch, 2007d). The NaInAs₂O₇ type (Belam et al., 1997 ) has no other known members. The TlInAs₂O₇ type (M⁺ = Tl, Rb, NH₄) (Schwendtner, 2006) is also adopted by KFeAs₂O₇ (Ouerfelli et al., 2007b ). The RbAlAs₂O₇ type (Boughzala et al., 1993 ) is also known for M¹⁺ = Tl, Cs (Boughzala & Jouini, 1992 ), M¹⁺ = K (Boughzala & Jouini, 1995 ), and is further represented by KGaAs₂O₇ (Lin & Lii, 1996 ), KCrAs₂O₇ (Siegfried et al., 2004 ) and the mixed (Al/Fe) compound TlAl_0.78Fe_0.22As₂O₇ (Ouerfelli et al., 2007a). The KAlP₂O₇ type is extremely common for phosphates and also has five examples that are arsenates, M⁺ScAs₂O₇ with M⁺ = NH₄ (Kolitsch, 2004), Rb (Schwendtner & Kolitsch, 2004a), and Tl (Baran et al., 2006 ), as well as CsCrAs₂O₇ (Bouhassine & Boughzala, 2015 ), and the mixed (Al/Cr) compound K(Al_0.75Cr_0.25)As₂O₇ (Bouhassine & Boughzala, 2017 ). The NaAlAs₂O₇ type (Driss & Jouini, 1994 ) is also known for AgFeAs₂O₇ and NaFeAs₂O₇ (Ouerfelli et al., 2004 ), and the M1²⁺M2²⁺ representative CaCuAs₂O₇ (Chen & Wang, 1996 ). The two diarsenates presented here also adopt the NaAlAs₂O₇ structure type.

2. Structural commentary

AgAl(HAsO₄)₂ and AgGa(HAsO₄)₂ are isotypic and crystallize in the monoclinic (C2/c) microporous framework structure of KSc(HAsO₄)₂ (Schwendtner & Kolitsch, 2004a). The asymmetric unit contains one Ag, one Ga/Al, one As, four O and one H sites (Fig. 1). The Al/Ga atoms lie on a special position (twofold rotation axis) and the Ag⁺ cation is situated on an inversion centre. In the case of AgGa(HAsO₄)₂, the Ag⁺ cation occupies a split position (Fig. 1b), where Ag1 sits on the inversion centre, with a freely refined occupancy of 0.75 (2). The second site (Ag2) is only 0.31 (3) Å away from Ag1 and has a freely refined occupancy of 0.123 (10). In total, this leads to a composition of one Ag atom per formula unit. The slightly distorted M³⁺O₆ octahedra share corners with six hydrogen arsenate tetrahedra to form a three-dimensional, anionic framework structure with narrow irregular channels parallel to [101] and [110] (Fig. 2), which host the Ag⁺ cations. The latter show a rather irregular [6 + 2]-coordination in both compounds. However, it is well known that Ag atoms tolerate a broad spectrum of coordination spheres (Müller-Buschbaum, 2004 ).

Figure 1
The principal building units of (a) AgAl(HAsO₄)₂ and (b) AgGa(HAsO₄)₂, shown as displacement ellipsoids at the 70% probability level. The H atom is shown as a sphere with arbitrary radius. Part (b) shows the split position for Ag in AgGa(HAsO₄)₂. [Symmetry codes: (ii) −x, y, −z + $[{1\over 2}]$ ; (iii) x + $[{1\over 2}]$ , y + $[{1\over 2}]$ , z; (iv) −x + $[{1\over 2}]$ , y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ; (vii) −x + $[{1\over 2}]$ , −y + $[{1\over 2}]$ , −z; (viii) x + $[{1\over 2}]$ , −y + $[{1\over 2}]$ , z − $[{1\over 2}]$ .]

Figure 2
View of the framework structure of (a) AgAl(HAsO₄)₂ along [101] and (b) isotypic AgGa(HAsO₄)₂ along [110]. The M³⁺O₆ octahedra (M = Al, Ga) are corner-linked to HAsO₄ tetrahedra. Both views show small micropores in which the Ag⁺ cations are situated; the split Ag position (see text) and hydrogen bonds (dashed lines) are indicated in (b).

The protonated apex of the AsO₄ tetrahedron is involved in a relatively strong hydrogen bond with O4⋯O2(x, −y + 1, z + $[{1\over 2}]$ ) = 2.6212 (17) and 2.6240 (19) Å for the Al (Table 2) and Ga compounds (Table 4), respectively, which runs roughly perpendicular to the (101) plane (Fig. 2). The As—OH bond lengths (Tables 1 and 3) are considerably elongated in comparison to the three remaining As—O bonds (Ferraris & Ivaldi, 1984 ), but at 1.7161 (10) Å for the Al and 1.7096 (12) Å for the Ga compound are slightly shorter than the average As—OH bond length in HAsO₄²⁻ anions of 1.72 (3) Å (Schwendtner, 2008 ). The bonds to non-protonated O ligands are shorter than the average mean As—O bond length for inorganic arsenates (1.686 Å; Schwendtner, 2008), and fit well with the data for As bonds to non-protonated O atoms in H_1–3AsO₄ groups [average 1.669 Å, Schwendtner, 2008; 1.670 Å, AgAl(HAsO₄)₂; 1.675 Å, AgGa(HAsO₄)₂]. The average bond lengths for the AlO₆ and GaO₆ octahedra agree well with published averages (Baur, 1981 ; Overweg et al., 1999 ). Bond-valence sums were calculated using the bond-valence parameters of Brown & Altermatt (1985 ), and amount to 0.88/0.90 (Ag1), 0.89 (Ag2), 3.05/3.16 (Al/Ga), 5.05/5.02 (As), 2.04/2.06 (O1), 1.85/1.85 (O2), 1.90/2.01 (O3) and 1.22/1.21 (O4 = OH; H atom not considered for calculation) valence units for AgAl(HAsO₄)₂ and AgGa(HAsO₄)₂, respectively. These results are reasonably close to the ideal values; the underbonded O2 is an acceptor of the strong hydrogen bond. Compared to isotypic KSc(HAsO₄)₂, the cell lengths and the hydrogen bonds of the two new compounds are considerably shorter. As a result of the similar ionic radii of Al³⁺ and Ga³⁺, these two compounds have similar unit-cell parameters. The Ga compound is slightly compressed along the a axis (smaller β), but elongated along the b axis; the c axis is not affected.

Table 2
Hydrogen-bond geometry (Å, °) for AgAl(HAsO₄)₂

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O4—H⋯O2^v	0.89 (1)	1.81 (2)	2.6212 (17)	151 (3)
Symmetry code: (v) $[x, -y+1, z+{\script{1\over 2}}]$ .

Table 4
Hydrogen-bond geometry (Å, °) for AgGa(HAsO₄)₂

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O4—H⋯O2^viii	0.80 (3)	1.89 (3)	2.6240 (19)	153 (3)
Symmetry code: (viii) $[x, -y+1, z+{\script{1\over 2}}]$ .

Table 1
Selected bond lengths (Å) for AgAl(HAsO₄)₂

Ag1—O1	2.4040 (11)	Al—O3^iv	1.9167 (10)
Ag1—O3ⁱ	2.6362 (11)	As—O2	1.6683 (9)
Ag1—O4ⁱⁱ	2.8202 (13)	As—O1	1.6697 (10)
Ag1—O2	3.1259 (11)	As—O3	1.6710 (11)
Al—O1	1.8920 (10)	As—O4	1.7161 (10)
Al—O2ⁱⁱⁱ	1.8955 (11)
Symmetry codes: (i) $[-x+1, y, -z+{\script{1\over 2}}]$ ; (ii) $[x, -y+1, z-{\script{1\over 2}}]$ ; (iii) $[x-{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ ; (iv) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ .

Table 3
Selected bond lengths (Å) for AgGa(HAsO₄)₂

Ag1—O1	2.3600 (12)	Ag2—O2ⁱⁱⁱ	3.116 (18)
Ag1—O3ⁱ	2.5864 (12)	Ag2—O2	3.185 (17)
Ag1—O4ⁱⁱ	3.0574 (15)	Ga—O1	1.9591 (11)
Ag1—O2	3.1352 (12)	Ga—O2^vi	1.9641 (11)
Ag2—O1	2.357 (17)	Ga—O3^vii	1.9799 (12)
Ag2—O1ⁱⁱⁱ	2.402 (18)	As—O2	1.6719 (11)
Ag2—O3ⁱ	2.48 (2)	As—O3	1.6753 (12)
Ag2—O3^iv	2.73 (3)	As—O1	1.6773 (11)
Ag2—O4^v	2.83 (2)	As—O4	1.7096 (12)
Symmetry codes: (i) $[-x+1, y, -z+{\script{1\over 2}}]$ ; (ii) $[x, -y+1, z-{\script{1\over 2}}]$ ; (iii) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z]$ ; (iv) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (v) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (vi) $[x-{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ ; (vii) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ .

The two diarsenates AgGaAs₂O₇ and NaGaAs₂O₇ crystallize in space group P2₁/c and are isotypic to NaAlAs₂O₇ (Driss & Jouini, 1994). The asymmetric unit contains one Ag/Na, one Ga, two As and seven O sites, all of which occupy general positions (Fig. 3). The basic building block is an As₂O₇ group, which is connected to the GaO₆ octahedra by two corners. The other four free O ligands are connected to different GaO₆ octahedra to form a three-dimensional framework structure (Fig. 4). The As2—O_bridge distances [1.755 (3), 1.756 (3) Å] are nearly identical to the literature value of 1.755 Å for the average As—O_bridge bond length in diarsenates (Schwendtner & Kolitsch, 2007d), whereas the As1—O_bridge distances [1.781 (3), 1.777 (3) Å] are further elongated. The average bond lengths of both AsO₄ tetrahedra are slightly longer than the literature value of 1.688 Å (Schwendtner & Kolitsch, 2007d) for the average As—O bond length in As₂O₇ groups. The As—O—As angle is very close to the average value of As₂O₇ groups in a staggered conformation (124.2°, Schwendtner & Kolitsch, 2007d) for both compounds (see Tables 5 and 6).

Table 5
Selected geometric parameters (Å, °) for AgGa(As₂O₇)

Ag—O1ⁱ	2.353 (3)	Ga—O6^v	1.985 (3)
Ag—O6ⁱⁱ	2.361 (3)	Ga—O7ⁱ	2.015 (3)
Ag—O3	2.440 (3)	As1—O2	1.653 (3)
Ag—O7ⁱⁱⁱ	2.529 (3)	As1—O1	1.668 (3)
Ag—O7^iv	2.600 (3)	As1—O3	1.679 (3)
Ag—O4	2.766 (3)	As1—O4	1.781 (3)
Ga—O2^v	1.939 (3)	As2—O5^vi	1.655 (3)
Ga—O3	1.957 (3)	As2—O7	1.674 (3)
Ga—O1ⁱⁱⁱ	1.973 (3)	As2—O6	1.675 (3)
Ga—O5	1.975 (3)	As2—O4	1.755 (3)

As2—O4—As1	124.65 (15)
Symmetry codes: (i) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) -x+2, -y+1, -z+1; (iii) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (iv) $[-x+2, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (v) -x+1, -y+1, -z+1; (vi) x+1, y, z.

Table 6
Selected geometric parameters (Å, °) for NaGa(As₂O₇)

Na—O1ⁱ	2.289 (4)	Ga—O6^v	1.987 (3)
Na—O6ⁱⁱ	2.360 (4)	Ga—O7ⁱ	2.042 (3)
Na—O3	2.364 (4)	As1—O2	1.655 (3)
Na—O7ⁱⁱⁱ	2.468 (4)	As1—O1	1.664 (3)
Na—O7^iv	2.479 (4)	As1—O3	1.676 (3)
Na—O4	2.624 (4)	As1—O4	1.777 (3)
Ga—O2^v	1.940 (3)	As2—O5^vi	1.661 (3)
Ga—O1ⁱⁱⁱ	1.952 (3)	As2—O6	1.671 (3)
Ga—O3	1.960 (3)	As2—O7	1.678 (3)
Ga—O5	1.967 (3)	As2—O4	1.756 (3)

As2—O4—As1	124.73 (19)
Symmetry codes: (i) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) -x+2, -y+1, -z+1; (iii) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (iv) $[-x+2, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (v) -x+1, -y+1, -z+1; (vi) x+1, y, z.

Figure 3
The principal building units of AgGaAs₂O₇ shown as displacement ellipsoids at the 70% probability level. [Symmetry codes: (ii) −x, y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ; (iii) −x, −y, −z; (iv) x, −y − $[{1\over 2}]$ , z − $[{1\over 2}]$ .]

Figure 4
View of the framework structure of AgGaAs₂O₇ along (a) [100] and (b) [110].

The GaO₆ octahedra are slightly distorted and the average Ga—O bond lengths are close to the literature values (∼1.96 Å; Overweg et al., 1999). The Na⁺ and Ag⁺ cations show a strongly distorted octahedral coordination. The calculated bond-valence sums using the parameters of Brown & Altermatt (1985) for Ag, Ga and As, and Wood & Palenik (1999 ) for Na, amount to 1.06/1.00 (Ag/Na), 3.11/3.11 (Ga), 4.90/4.93 (As1), 4.96/4.93 (As2), 2.08/2.11 (O1), 1.93/1.92 (O2), 2.01/2.01 (O3), 2.08/2.10 (O4), 1.87/1.86 (O5), 2.03/1.99 (O6), and 2.03/1.99 (O7) valence units for AgGaAs₂O₇ and NaGaAs₂O₇, respectively.

3. Synthesis and crystallization

The compounds were grown by hydrothermal synthesis at 493 K (7 d, autogeneous pressure, slow furnace cooling) using Teflon-lined stainless-steel autoclaves with an approximate filling volume of 2 cm³. Reagent-grade Ag₂CO₃, Ga₂O₃, α-Al₂O₃, Na₂CO₃, and H₃AsO₄·0.5H₂O were used as starting reagents in approximate volume ratios of M⁺:M³⁺:As of 1:1:2. The vessels were filled with distilled water to about 70% of their inner volumes, which led to final pH values of < 1 for all synthesis batches except NaGaAs₂O₇ (pH 1.5). The reaction products were washed thoroughly with distilled water, filtered and dried at room temperature.

The two hydrogen arsenates formed pseudo-dipyramidal colourless crystals up to 2 mm in length (yield > 95% for the Al compound with minor amounts of AgCl, explained by the reaction of Ag⁺ with remnants of concentrated hot HCl used for standard cleaning of the Teflon vessels before each new experiment; Fig. 5a). The crystals of AgGa(HAsO₄)₂ (Fig. 5c) were accompanied by about 20% of AgGaAs₂O₇ as pseudo-orthorhombic platelets (Fig. 5d). NaGaAs₂O₇ crystallized as small, colourless platelets with a diamond-shaped outline (yield 100%) (Fig. 5b).

Figure 5
SEM micrographs of hydrothermally synthesized crystals of (a) AgAl(HAsO₄)₂, (b) NaGaAs₂O₇, (c) AgGa(HAsO₄)₂ and (d) AgGaAs₂O₇.

Measured X-ray powder diffraction diagrams of the NaGaAs₂O₇ and AgAl(HAsO₄)₂ synthesis batches were deposited at the International Centre for Diffraction Data under PDF number 57-0162 (Prem et al., 2005 ) for NaGaAs₂O₇ and 57-0161 (Prem et al., 2005) for AgAl(HAsO₄)₂.

4. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 7.

Table 7
Experimental details

	AgAl(HAsO₄)₂	AgGa(HAsO₄)₂	AgGa(AsO₇)	NaGa(As₂O₇)
Crystal data
M_r	414.71	457.45	354.55	439.43
Crystal system, space group	Monoclinic, C2/c	Monoclinic, C2/c	Monoclinic, P2₁/c	Monoclinic, P2₁/c
Temperature (K)	293	293	293	293
a, b, c (Å)	7.842 (2), 9.937 (2), 8.686 (2)	7.826 (2), 10.216 (2), 8.694 (2)	6.987 (1), 8.266 (2), 9.677 (2)	7.049 (1), 8.368 (2), 9.735 (2)
β (°)	108.45 (3)	107.77 (3)	107.50 (3)	108.47 (3)
V (Å³)	642.1 (3)	661.9 (3)	533.0 (2)	544.7 (2)
Z	4	4	4	4
Radiation type	Mo Kα	Mo Kα	Mo Kα	Mo Kα
μ (mm⁻¹)	13.51	16.96	17.55	20.58
Crystal size (mm)	0.15 × 0.08 × 0.07	0.18 × 0.10 × 0.10	0.07 × 0.07 × 0.02	0.10 × 0.08 × 0.02

Data collection
Diffractometer	Nonius KappaCCD single-crystal four-circle	Nonius KappaCCD single-crystal four-circle	Nonius KappaCCD single-crystal four-circle	Nonius KappaCCD single-crystal four-circle
Absorption correction	Multi-scan (HKL SCALEPACK; Otwinowski et al., 2003 )	Multi-scan (HKL SCALEPACK; Otwinowski et al., 2003)	Multi-scan (HKL SCALEPACK; Otwinowski et al., 2003)	Multi-scan (HKL SCALEPACK; Otwinowski et al., 2003)
T_min, T_max	0.236, 0.451	0.150, 0.282	0.373, 0.720	0.233, 0.684
No. of measured, independent and observed [I > 2σ(I)] reflections	2751, 1408, 1354	2852, 1460, 1402	3015, 1557, 1336	3849, 1982, 1775
R_int	0.011	0.012	0.023	0.022
(sin θ/λ)_max (Å⁻¹)	0.806	0.806	0.704	0.757

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.014, 0.037, 1.10	0.015, 0.037, 1.15	0.033, 0.090, 1.04	0.033, 0.089, 1.05
No. of reflections	1408	1460	1557	1982
No. of parameters	62	73	100	100
No. of restraints	1	0	0	0
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement	All H-atom parameters refined	–	–
Δρ_max, Δρ_min (e Å⁻³)	0.55, −0.60	0.66, −0.50	1.54, −1.49	2.29, −2.38
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 ).

For easier comparison, the atomic positions of the isotypic compounds KSc(HAsO₄)₂ (Schwendtner & Kolitsch, 2004) and NaAlAs₂O₇ (Driss & Jouini, 1994) were used for the final refinement. The O—H distance was restrained to 0.9 (2) Å for AgAl(HAsO₄)₂ and refined freely for AgGa(HAsO₄)₂.

Remaining electron densities are below 1 e Å⁻³ for the two hydrogen arsenates. The remaining maximum and minimum electron densities in the final difference-Fourier maps are located close to the As1 atom (0.87/0.78 Å) for NaGaAs₂O₇, and close to the Ag atom (0.73/0.66 Å) for AgGaAs₂O₇.

Supporting information

CCDC references: 1543927; 1543926; 1543925; 1543924

Crystal structure: contains datablocks AgAlHAsO42, AgGaHAsO42, AgGaAs2O7, NaGaAs2O7. DOI: https://doi.org/10.1107/S2056989017005631/pk2600sup1.cif

Structure factors: contains datablock AgAlHAsO42. DOI: https://doi.org/10.1107/S2056989017005631/pk2600AgAlHAsO42sup2.hkl

Structure factors: contains datablock AgGaHAsO42. DOI: https://doi.org/10.1107/S2056989017005631/pk2600AgGaHAsO42sup3.hkl

Structure factors: contains datablock AgGaAs2O7. DOI: https://doi.org/10.1107/S2056989017005631/pk2600AgGaAs2O7sup4.hkl

Structure factors: contains datablock NaGaAs2O7. DOI: https://doi.org/10.1107/S2056989017005631/pk2600NaGaAs2O7sup5.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989017005631/pk2600NaGaAs2O7sup6.cml

checkCIF report

Computing details top

For all compounds, 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).

(AgAlHAsO42) Silver(I) aluminium bis[hydrogen arsenate(V)] top

Crystal data top

AgAl(HAsO₄)₂	F(000) = 768
M_r = 414.71	D_x = 4.290 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.842 (2) Å	Cell parameters from 1477 reflections
b = 9.937 (2) Å	θ = 2.0–35.0°
c = 8.686 (2) Å	µ = 13.51 mm⁻¹
β = 108.45 (3)°	T = 293 K
V = 642.1 (3) Å³	Pseudo-dipyramidal glassy, colourless
Z = 4	0.15 × 0.08 × 0.07 mm

Data collection top

Nonius KappaCCD single-crystal four-circle diffractometer	1354 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.011
φ and ω scans	θ_max = 34.9°, θ_min = 3.4°
Absorption correction: multi-scan (HKL SCALEPACK; Otwinowski et al., 2003)	h = −12→12
T_min = 0.236, T_max = 0.451	k = −16→16
2751 measured reflections	l = −13→13
1408 independent reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F² > 2σ(F²)] = 0.014	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.037	w = 1/[σ²(F_o²) + (0.018P)² + 0.890P] where P = (F_o² + 2F_c²)/3
S = 1.10	(Δ/σ)_max = 0.001
1408 reflections	Δρ_max = 0.55 e Å⁻³
62 parameters	Δρ_min = −0.60 e Å⁻³
1 restraint	Extinction correction: SHELXL2016 (Sheldrick, 2015), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0114 (3)

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.

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

	x	y	z	U_iso*/U_eq
Ag1	0.250000	0.250000	0.000000	0.03518 (7)
Al	0.000000	0.13916 (5)	0.250000	0.00554 (9)
As	0.27443 (2)	0.40001 (2)	0.35945 (2)	0.00508 (5)
O1	0.17964 (13)	0.26607 (10)	0.24940 (12)	0.00972 (16)
O2	0.32668 (13)	0.50141 (10)	0.22800 (11)	0.00973 (16)
O3	0.44856 (12)	0.35479 (10)	0.51919 (11)	0.00870 (15)
O4	0.12010 (13)	0.48544 (12)	0.42496 (12)	0.01492 (19)
H	0.153 (4)	0.487 (3)	0.5324 (12)	0.047 (9)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ag1	0.06317 (16)	0.02460 (10)	0.03540 (12)	−0.01037 (9)	0.04068 (11)	−0.00702 (8)
Al	0.0059 (2)	0.0053 (2)	0.0052 (2)	0.000	0.00145 (16)	0.000
As	0.00555 (6)	0.00526 (7)	0.00416 (6)	−0.00071 (3)	0.00115 (4)	0.00007 (3)
O1	0.0112 (4)	0.0086 (4)	0.0102 (4)	−0.0057 (3)	0.0045 (3)	−0.0046 (3)
O2	0.0113 (4)	0.0100 (4)	0.0069 (3)	−0.0043 (3)	0.0014 (3)	0.0027 (3)
O3	0.0087 (3)	0.0117 (4)	0.0045 (3)	0.0024 (3)	0.0004 (3)	0.0009 (3)
O4	0.0113 (4)	0.0234 (5)	0.0104 (4)	0.0070 (4)	0.0038 (3)	−0.0026 (4)

Geometric parameters (Å, º) top

Ag1—O1ⁱ	2.4040 (11)	Al—O2^vii	1.8955 (11)
Ag1—O1	2.4040 (11)	Al—O2^v	1.8955 (11)
Ag1—O3ⁱⁱ	2.6362 (11)	Al—O3^viii	1.9167 (10)
Ag1—O3ⁱⁱⁱ	2.6362 (11)	Al—O3ⁱⁱⁱ	1.9167 (10)
Ag1—O4^iv	2.8202 (13)	As—O2	1.6683 (9)
Ag1—O4^v	2.8202 (13)	As—O1	1.6697 (10)
Ag1—O2	3.1259 (11)	As—O3	1.6710 (11)
Ag1—O2ⁱ	3.1259 (11)	As—O4	1.7161 (10)
Al—O1	1.8920 (10)	O4—H	0.886 (10)
Al—O1^vi	1.8920 (10)

O1—Al—O1^vi	96.40 (7)	O1^vi—Al—O3ⁱⁱⁱ	94.10 (5)
O1—Al—O2^vii	172.66 (4)	O2^vii—Al—O3ⁱⁱⁱ	90.59 (5)
O1^vi—Al—O2^vii	88.33 (5)	O2^v—Al—O3ⁱⁱⁱ	92.00 (5)
O1—Al—O2^v	88.33 (5)	O3^viii—Al—O3ⁱⁱⁱ	176.41 (7)
O1^vi—Al—O2^v	172.66 (4)	O2—As—O1	104.53 (5)
O2^vii—Al—O2^v	87.54 (7)	O2—As—O3	114.68 (5)
O1—Al—O3^viii	94.10 (5)	O1—As—O3	111.09 (5)
O1^vi—Al—O3^viii	83.49 (5)	O2—As—O4	106.25 (6)
O2^vii—Al—O3^viii	92.00 (5)	O1—As—O4	110.56 (5)
O2^v—Al—O3^viii	90.59 (5)	O3—As—O4	109.54 (5)
O1—Al—O3ⁱⁱⁱ	83.49 (5)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O4—H···O2^ix	0.89 (1)	1.81 (2)	2.6212 (17)	151 (3)

Symmetry code: (ix) x, −y+1, z+1/2.

(AgGaHAsO42) Silver(I) gallium bis[hydrogen arsenate(V)] top

Crystal data top

AgGa(HAsO₄)₂	F(000) = 840
M_r = 457.45	D_x = 4.590 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.826 (2) Å	Cell parameters from 1519 reflections
b = 10.216 (2) Å	θ = 2.0–35.0°
c = 8.694 (2) Å	µ = 16.96 mm⁻¹
β = 107.77 (3)°	T = 293 K
V = 661.9 (3) Å³	Large pseudo-dipyramidal glassy, colourless
Z = 4	0.18 × 0.10 × 0.10 mm

Data collection top

Nonius KappaCCD single-crystal four-circle diffractometer	1402 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.012
φ and ω scans	θ_max = 35.0°, θ_min = 3.4°
Absorption correction: multi-scan (HKL SCALEPACK; Otwinowski et al., 2003)	h = −12→12
T_min = 0.150, T_max = 0.282	k = −16→16
2852 measured reflections	l = −14→13
1460 independent reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F² > 2σ(F²)] = 0.015	All H-atom parameters refined
wR(F²) = 0.037	w = 1/[σ²(F_o²) + (0.015P)² + 0.940P] where P = (F_o² + 2F_c²)/3
S = 1.15	(Δ/σ)_max = 0.037
1460 reflections	Δρ_max = 0.66 e Å⁻³
73 parameters	Δρ_min = −0.50 e Å⁻³
0 restraints	Extinction correction: SHELXL2016 (Sheldrick, 2015), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0133 (3)

Special details top

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ag1	0.250000	0.250000	0.000000	0.0335 (9)	0.75 (2)
Ag2	0.284 (3)	0.2351 (14)	0.019 (2)	0.0316 (18)	0.123 (10)
Ga	0.000000	0.13670 (2)	0.250000	0.00500 (5)
As	0.27567 (2)	0.39556 (2)	0.35733 (2)	0.00482 (5)
O1	0.18942 (15)	0.26190 (10)	0.24943 (13)	0.00983 (18)
O2	0.32045 (15)	0.49738 (11)	0.22405 (13)	0.01055 (19)
O3	0.45491 (14)	0.35629 (11)	0.51333 (13)	0.00948 (18)
O4	0.11608 (16)	0.46896 (14)	0.42534 (15)	0.0169 (2)
H	0.148 (4)	0.487 (3)	0.519 (4)	0.033 (8)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ag1	0.051 (2)	0.0368 (14)	0.0271 (9)	−0.0173 (12)	0.0327 (12)	−0.0125 (9)
Ag2	0.049 (4)	0.0249 (16)	0.035 (3)	−0.015 (2)	0.034 (3)	−0.0064 (14)
Ga	0.00555 (9)	0.00478 (9)	0.00482 (9)	0.000	0.00182 (6)	0.000
As	0.00564 (7)	0.00525 (7)	0.00364 (7)	−0.00073 (4)	0.00153 (5)	−0.00003 (4)
O1	0.0114 (4)	0.0093 (4)	0.0101 (5)	−0.0057 (3)	0.0053 (4)	−0.0045 (3)
O2	0.0122 (4)	0.0110 (4)	0.0068 (4)	−0.0060 (3)	0.0003 (3)	0.0036 (4)
O3	0.0085 (4)	0.0135 (4)	0.0053 (4)	0.0032 (3)	0.0004 (3)	0.0011 (4)
O4	0.0116 (5)	0.0299 (6)	0.0094 (5)	0.0081 (4)	0.0035 (4)	−0.0047 (4)

Geometric parameters (Å, º) top

Ag1—O1ⁱ	2.3600 (12)	Ag2—O2	3.185 (17)
Ag1—O1	2.3600 (12)	Ga—O1	1.9591 (11)
Ag1—O3ⁱⁱ	2.5864 (12)	Ga—O1^vi	1.9591 (11)
Ag1—O3ⁱⁱⁱ	2.5864 (12)	Ga—O2^vii	1.9641 (11)
Ag1—O4^iv	3.0574 (15)	Ga—O2^v	1.9641 (11)
Ag1—O4^v	3.0574 (15)	Ga—O3^viii	1.9799 (12)
Ag1—O2	3.1352 (12)	Ga—O3ⁱⁱⁱ	1.9799 (12)
Ag2—O1	2.357 (17)	As—O2	1.6719 (11)
Ag2—O1ⁱ	2.402 (18)	As—O3	1.6753 (12)
Ag2—O3ⁱⁱ	2.48 (2)	As—O1	1.6773 (11)
Ag2—O3ⁱⁱⁱ	2.73 (3)	As—O4	1.7096 (12)
Ag2—O4^v	2.83 (2)	O4—H	0.80 (3)
Ag2—O2ⁱ	3.116 (18)

O1—Ga—O1^vi	98.48 (7)	O3^viii—Ga—O3ⁱⁱⁱ	175.86 (6)
O1—Ga—O2^vii	171.19 (5)	O2—As—O3	114.16 (6)
O1^vi—Ga—O2^vii	87.59 (5)	O2—As—O1	104.63 (6)
O1—Ga—O2^v	87.59 (5)	O3—As—O1	110.64 (6)
O1^vi—Ga—O2^v	171.19 (5)	O2—As—O4	107.25 (7)
O2^vii—Ga—O2^v	87.12 (7)	O3—As—O4	110.16 (6)
O1—Ga—O3^viii	94.82 (5)	O1—As—O4	109.80 (6)
O1^vi—Ga—O3^viii	82.46 (5)	O2—As—O3	114.16 (6)
O2^vii—Ga—O3^viii	92.29 (5)	O2—As—O1	104.63 (6)
O2^v—Ga—O3^viii	90.71 (5)	O3—As—O1	110.64 (6)
O1—Ga—O3ⁱⁱⁱ	82.46 (5)	O2—As—O4	107.25 (7)
O1^vi—Ga—O3ⁱⁱⁱ	94.82 (5)	O3—As—O4	110.16 (6)
O2^vii—Ga—O3ⁱⁱⁱ	90.71 (5)	O1—As—O4	109.80 (6)
O2^v—Ga—O3ⁱⁱⁱ	92.29 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O4—H···O2^ix	0.80 (3)	1.89 (3)	2.6240 (19)	153 (3)

Symmetry code: (ix) x, −y+1, z+1/2.

(AgGaAs2O7) Silver(I) gallium diarsenate(V) top

Crystal data top

AgGa(As₂O₇)	F(000) = 800
M_r = 439.43	D_x = 5.359 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.049 (1) Å	Cell parameters from 2105 reflections
b = 8.368 (2) Å	θ = 2.0–32.6°
c = 9.735 (2) Å	µ = 20.58 mm⁻¹
β = 108.47 (3)°	T = 293 K
V = 544.7 (2) Å³	Pseudo-orthorhombic platelets, colourless
Z = 4	0.10 × 0.08 × 0.02 mm

Data collection top

Nonius KappaCCD single-crystal four-circle diffractometer	1775 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.022
φ and ω scans	θ_max = 32.5°, θ_min = 3.1°
Absorption correction: multi-scan (HKL SCALEPACK; Otwinowski et al., 2003)	h = −10→10
T_min = 0.233, T_max = 0.684	k = −12→12
3849 measured reflections	l = −14→14
1982 independent reflections

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F² > 2σ(F²)] = 0.033	Secondary atom site location: difference Fourier map
wR(F²) = 0.089	w = 1/[σ²(F_o²) + (0.0619P)² + 0.6339P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max < 0.001
1982 reflections	Δρ_max = 2.29 e Å⁻³
100 parameters	Δρ_min = −2.38 e Å⁻³

Special details top

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

	x	y	z	U_iso*/U_eq
Ag	0.81152 (5)	0.13552 (4)	0.47918 (4)	0.02028 (11)
Ga	0.28442 (6)	0.28038 (5)	0.49133 (4)	0.00810 (11)
As1	0.52020 (5)	0.41622 (4)	0.28916 (4)	0.00783 (10)
As2	0.94310 (5)	0.54112 (4)	0.29927 (4)	0.00759 (10)
O1	0.3828 (4)	0.4083 (3)	0.1148 (3)	0.0108 (5)
O2	0.5231 (4)	0.5961 (3)	0.3601 (3)	0.0118 (5)
O3	0.4848 (4)	0.2646 (3)	0.3914 (3)	0.0107 (5)
O4	0.7697 (4)	0.3871 (3)	0.2876 (3)	0.0118 (5)
O5	0.1621 (4)	0.4491 (3)	0.3489 (3)	0.0117 (5)
O6	0.9278 (4)	0.6807 (3)	0.4187 (3)	0.0126 (5)
O7	0.8992 (4)	0.6146 (3)	0.1321 (3)	0.0113 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ag	0.01549 (17)	0.01302 (15)	0.0269 (2)	−0.00362 (10)	−0.00097 (13)	0.00458 (11)
Ga	0.0088 (2)	0.00743 (18)	0.00749 (19)	0.00004 (12)	0.00177 (15)	0.00004 (12)
As1	0.00867 (19)	0.00705 (17)	0.00701 (17)	−0.00073 (11)	0.00144 (13)	−0.00004 (11)
As2	0.00788 (18)	0.00726 (17)	0.00707 (18)	0.00035 (11)	0.00158 (13)	0.00016 (11)
O1	0.0143 (13)	0.0076 (11)	0.0076 (11)	0.0007 (9)	−0.0008 (10)	0.0002 (8)
O2	0.0133 (13)	0.0080 (11)	0.0113 (12)	−0.0024 (9)	0.0002 (10)	−0.0026 (9)
O3	0.0125 (12)	0.0096 (11)	0.0114 (11)	0.0030 (9)	0.0056 (10)	0.0040 (9)
O4	0.0104 (12)	0.0080 (11)	0.0164 (13)	−0.0007 (9)	0.0033 (10)	0.0003 (9)
O5	0.0075 (11)	0.0128 (11)	0.0144 (13)	0.0043 (9)	0.0030 (10)	0.0060 (10)
O6	0.0122 (13)	0.0141 (12)	0.0120 (12)	−0.0042 (10)	0.0043 (10)	−0.0052 (10)
O7	0.0129 (13)	0.0124 (12)	0.0074 (11)	0.0015 (9)	0.0013 (10)	0.0020 (9)

Geometric parameters (Å, º) top

Ag—O1ⁱ	2.353 (3)	Ga—O6^v	1.985 (3)
Ag—O6ⁱⁱ	2.361 (3)	Ga—O7ⁱ	2.015 (3)
Ag—O3	2.440 (3)	As1—O2	1.653 (3)
Ag—O7ⁱⁱⁱ	2.529 (3)	As1—O1	1.668 (3)
Ag—O7^iv	2.600 (3)	As1—O3	1.679 (3)
Ag—O4	2.766 (3)	As1—O4	1.781 (3)
Ga—O2^v	1.939 (3)	As2—O5^vi	1.655 (3)
Ga—O3	1.957 (3)	As2—O7	1.674 (3)
Ga—O1ⁱⁱⁱ	1.973 (3)	As2—O6	1.675 (3)
Ga—O5	1.975 (3)	As2—O4	1.755 (3)

O1ⁱ—Ag—O6ⁱⁱ	165.93 (10)	O3—Ga—O7ⁱ	94.90 (12)
O1ⁱ—Ag—O3	81.53 (10)	O1ⁱⁱⁱ—Ga—O7ⁱ	81.24 (11)
O6ⁱⁱ—Ag—O3	112.42 (10)	O5—Ga—O7ⁱ	91.08 (12)
O1ⁱ—Ag—O7ⁱⁱⁱ	64.14 (9)	O6^v—Ga—O7ⁱ	86.83 (11)
O6ⁱⁱ—Ag—O7ⁱⁱⁱ	106.19 (10)	O2—As1—O1	112.81 (13)
O3—Ag—O7ⁱⁱⁱ	126.87 (9)	O2—As1—O3	115.14 (14)
O2^v—Ga—O3	87.83 (12)	O1—As1—O3	115.19 (13)
O2^v—Ga—O1ⁱⁱⁱ	86.80 (11)	O2—As1—O4	104.27 (13)
O3—Ga—O1ⁱⁱⁱ	94.54 (11)	O1—As1—O4	104.04 (14)
O2^v—Ga—O5	100.89 (12)	O3—As1—O4	103.55 (13)
O3—Ga—O5	85.56 (11)	O5^vi—As2—O7	108.84 (14)
O1ⁱⁱⁱ—Ga—O5	172.30 (11)	O5^vi—As2—O6	112.38 (15)
O2^v—Ga—O6^v	91.74 (12)	O7—As2—O6	112.71 (14)
O3—Ga—O6^v	173.63 (11)	O5^vi—As2—O4	104.10 (13)
O1ⁱⁱⁱ—Ga—O6^v	91.78 (12)	O7—As2—O4	107.22 (13)
O5—Ga—O6^v	88.28 (11)	O6—As2—O4	111.12 (14)
O2^v—Ga—O7ⁱ	167.90 (11)	As2—O4—As1	124.65 (15)

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

(NaGaAs2O7) Sodium gallium diarsenate(V) top

Crystal data top

NaGa(AsO₇)	F(000) = 656
M_r = 354.55	D_x = 4.418 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.987 (1) Å	Cell parameters from 2065 reflections
b = 8.266 (2) Å	θ = 3–30°
c = 9.677 (2) Å	µ = 17.55 mm⁻¹
β = 107.50 (3)°	T = 293 K
V = 533.0 (2) Å³	Small platelets with diamond-shaped outline, colourless
Z = 4	0.07 × 0.07 × 0.02 mm

Data collection top

Nonius KappaCCD single-crystal four-circle diffractometer	1336 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.023
φ and ω scans	θ_max = 30.0°, θ_min = 3.1°
Absorption correction: multi-scan (HKL SCALEPACK; Otwinowski et al., 2003)	h = −9→9
T_min = 0.373, T_max = 0.720	k = −11→11
3015 measured reflections	l = −13→13
1557 independent reflections

Refinement top

Refinement on F²	100 parameters
Least-squares matrix: full	0 restraints
R[F² > 2σ(F²)] = 0.033	w = 1/[σ²(F_o²) + (0.060P)² + 1.1P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.090	(Δ/σ)_max < 0.001
S = 1.04	Δρ_max = 1.54 e Å⁻³
1557 reflections	Δρ_min = −1.49 e Å⁻³

Special details top

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

	x	y	z	U_iso*/U_eq
Na	0.8070 (3)	0.1389 (2)	0.4691 (2)	0.0212 (4)
Ga	0.28177 (7)	0.27455 (6)	0.49377 (5)	0.00989 (14)
As1	0.51759 (7)	0.41477 (5)	0.29095 (5)	0.00962 (13)
As2	0.94401 (7)	0.53707 (5)	0.29682 (5)	0.00931 (13)
O1	0.3798 (5)	0.4129 (4)	0.1176 (3)	0.0128 (6)
O2	0.5235 (5)	0.5967 (4)	0.3635 (4)	0.0132 (6)
O3	0.4850 (5)	0.2586 (4)	0.3921 (4)	0.0126 (6)
O4	0.7683 (5)	0.3827 (4)	0.2891 (4)	0.0137 (6)
O5	0.1637 (5)	0.4423 (4)	0.3491 (3)	0.0134 (6)
O6	0.9305 (5)	0.6834 (4)	0.4127 (4)	0.0140 (6)
O7	0.9038 (5)	0.6014 (4)	0.1260 (3)	0.0117 (6)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Na	0.0190 (10)	0.0122 (9)	0.0286 (10)	−0.0006 (8)	0.0013 (8)	0.0005 (8)
Ga	0.0130 (3)	0.0074 (2)	0.0096 (2)	0.00006 (16)	0.00367 (19)	0.00009 (16)
As1	0.0125 (2)	0.0070 (2)	0.0090 (2)	−0.00080 (15)	0.00274 (17)	0.00001 (15)
As2	0.0120 (2)	0.0073 (2)	0.0086 (2)	0.00045 (15)	0.00308 (17)	0.00032 (15)
O1	0.0175 (17)	0.0087 (14)	0.0102 (14)	−0.0003 (12)	0.0011 (12)	0.0012 (12)
O2	0.0167 (16)	0.0064 (14)	0.0164 (15)	−0.0015 (11)	0.0049 (13)	−0.0028 (12)
O3	0.0166 (16)	0.0087 (14)	0.0146 (15)	0.0022 (12)	0.0080 (13)	0.0035 (12)
O4	0.0098 (15)	0.0121 (14)	0.0198 (16)	0.0002 (12)	0.0055 (12)	0.0001 (12)
O5	0.0130 (16)	0.0124 (14)	0.0142 (15)	0.0039 (12)	0.0029 (13)	0.0043 (12)
O6	0.0188 (17)	0.0120 (15)	0.0139 (14)	−0.0035 (12)	0.0088 (13)	−0.0043 (12)
O7	0.0157 (16)	0.0116 (14)	0.0082 (13)	0.0022 (12)	0.0042 (12)	0.0033 (12)

Geometric parameters (Å, º) top

Na—O1ⁱ	2.289 (4)	Ga—O6^v	1.987 (3)
Na—O6ⁱⁱ	2.360 (4)	Ga—O7ⁱ	2.042 (3)
Na—O3	2.364 (4)	As1—O2	1.655 (3)
Na—O7ⁱⁱⁱ	2.468 (4)	As1—O1	1.664 (3)
Na—O7^iv	2.479 (4)	As1—O3	1.676 (3)
Na—O4	2.624 (4)	As1—O4	1.777 (3)
Ga—O2^v	1.940 (3)	As2—O5^vi	1.661 (3)
Ga—O1ⁱⁱⁱ	1.952 (3)	As2—O6	1.671 (3)
Ga—O3	1.960 (3)	As2—O7	1.678 (3)
Ga—O5	1.967 (3)	As2—O4	1.756 (3)

O1ⁱ—Na—O6ⁱⁱ	163.76 (16)	O1ⁱⁱⁱ—Ga—O6^v	91.80 (14)
O1ⁱ—Na—O3	80.93 (13)	O3—Ga—O6^v	173.31 (13)
O6ⁱⁱ—Na—O3	114.82 (15)	O5—Ga—O6^v	89.46 (14)
O1ⁱ—Na—O7ⁱⁱⁱ	65.73 (13)	O2^v—Ga—O7ⁱ	168.13 (13)
O6ⁱⁱ—Na—O7ⁱⁱⁱ	99.98 (14)	O1ⁱⁱⁱ—Ga—O7ⁱ	80.66 (14)
O3—Na—O7ⁱⁱⁱ	126.13 (14)	O3—Ga—O7ⁱ	95.74 (13)
O1ⁱ—Na—O7^iv	101.56 (14)	O5—Ga—O7ⁱ	91.80 (13)
O6ⁱⁱ—Na—O7^iv	69.89 (12)	O6^v—Ga—O7ⁱ	87.01 (13)
O3—Na—O7^iv	137.74 (14)	O2—As1—O1	111.67 (16)
O7ⁱⁱⁱ—Na—O7^iv	91.40 (12)	O2—As1—O3	116.27 (16)
O1ⁱ—Na—O4	116.75 (14)	O1—As1—O3	116.25 (16)
O6ⁱⁱ—Na—O4	75.75 (13)	O2—As1—O4	103.93 (16)
O3—Na—O4	64.59 (11)	O1—As1—O4	105.16 (17)
O7ⁱⁱⁱ—Na—O4	168.81 (15)	O3—As1—O4	101.46 (16)
O7^iv—Na—O4	77.43 (12)	O5^vi—As2—O6	111.76 (17)
O2^v—Ga—O1ⁱⁱⁱ	87.52 (13)	O5^vi—As2—O7	108.37 (16)
O2^v—Ga—O3	86.31 (14)	O6—As2—O7	113.90 (16)
O1ⁱⁱⁱ—Ga—O3	94.67 (14)	O5^vi—As2—O4	103.91 (16)
O2^v—Ga—O5	100.04 (14)	O6—As2—O4	112.00 (16)
O1ⁱⁱⁱ—Ga—O5	172.28 (14)	O7—As2—O4	106.27 (16)
O3—Ga—O5	84.37 (14)	As2—O4—As1	124.73 (19)
O2^v—Ga—O6^v	92.25 (14)

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

Acknowledgements

The experimental work was done by the authors at the University of Vienna, Institute for Mineralogy and Crystallography.

Funding information

Funding for this research was provided by: Austrian Academy of Sciences, Doc Fforte Fellowship to Karolina Schwendtner.

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