Crystal chemistry of transition metal diarsenates M₂As₂O₇ (M = Mn, Co, Ni, Zn): variants of the thortveitite structure

The structures of the 3d divalent transition-metal diarsenates M₂As₂O₇ (M = Mn, Co, Ni, Zn) can be considered as variants of the monoclinic (C2/m) thortveitite [Sc₂Si₂O₇] structure type with a ≃ 6.7, b ≃ 8.5, c ≃ 4.7 Å, α ≃ 90, β ≃ 102, γ ≃ 90° and Z = 2. Co₂As₂O₇ and Ni₂As₂O₇ are dimorphic. Their high-temperature (β) polymorphs adopt the thortveitite aristotype structure in C2/m, whereas their low-temperature (α) polymorphs are hettotypes and crystallize with larger unit cells in the triclinic crystal system in space groups P and P1, respectively. Mn₂As₂O₇ undergoes no phase transition and likewise adopts the thortveitite structure type in C2/m. Zn₂As₂O₇ has an incommensurately modulated crystal structure [C2/m(α,0,γ)0s] with q = [0.3190 (1), 0, 0.3717 (1)] at ambient conditions and transforms reversibly to a commensurately modulated structure with Z = 12 (I2/c) below 273 K. The Zn phase resembles the structures and phase transitions of Cr₂P₂O₇. Besides descriptions of the low-temperature Co₂As₂O₇, Ni₂As₂O₇ and Zn₂As₂O₇ structures as five-, three- and sixfold superstructures of the thortveitite-type basic structure, the superspace approach can also be applied to descriptions of all the commensurate structures. In addition to the ternary M₂As₂O₇ phases, the quaternary phase (Ni,Co)₂As₂O₇ was prepared and structurally characterized. In contrast to the previously published crystal structure of the mineral petewilliamsite, which has the same idealized formula and has been described as a 15-fold superstructure of the thortveitite-type basic structure in space group C2, synthetic (Ni,Co)₂As₂O₇ can be considered as a solid solution adopting the α-Ni₂As₂O₇ structure type. Differences of the two structure models for (Ni,Co)₂As₂O₇ are discussed.

Computing details

Data collection: CAD-4 (Nonius, 1989) for Mn2As2O7; SMART (Bruker, 2004) for alpha-Co2As2O7, alpha-Ni2As2O7, alpha-Co2As2O7-superspace, alpha-Ni2As2O7-superspace; APEX2 (Bruker, 2004) for alpha-Zn2As2O7, beta-Zn2As2O7-superspace, alpha-Zn2As2O7-superspace. Cell refinement: CAD-4 for Mn2As2O7; SAINT (Bruker, 2004) for alpha-Co2As2O7, alpha-Ni2As2O7, alpha-Co2As2O7-superspace, alpha-Ni2As2O7-superspace; APEX2 for alpha-Zn2As2O7, beta-Zn2As2O7-superspace, alpha-Zn2As2O7-superspace. Data reduction: HELENA implemented in PLATON (Spek, 2009) for Mn2As2O7; SAINT for alpha-Co2As2O7, alpha-Ni2As2O7, alpha-Co2As2O7-superspace, alpha-Ni2As2O7-superspace; APEX2 for alpha-Zn2As2O7, beta-Zn2As2O7-superspace, alpha-Zn2As2O7-superspace. Program(s) used to solve structure: SHELXS (Sheldrick, 2008) for Mn2As2O7, alpha-Co2As2O7, alpha-Ni2As2O7, alpha-Zn2As2O7, alpha-Co2As2O7-superspace, alpha-Ni2As2O7-superspace, alpha-Zn2As2O7-superspace; coordinates taken from an isotypic compound for beta-Zn2As2O7-superspace. For all structures, program(s) used to refine structure: Jana2006 (Petricek, Dusek & Palatinus, 2006). Molecular graphics: Atoms (Dowty, 2006) for Mn2As2O7; ATOMS (Dowty, 2006) for alpha-Co2As2O7, alpha-Ni2As2O7, alpha-Zn2As2O7, alpha-Co2As2O7-superspace, alpha-Ni2As2O7-superspace, alpha-Zn2As2O7-superspace. For all structures, software used to prepare material for publication: Jana2006 (Petricek, Dusek & Palatinus, 2006).

Dimanganese(II) diarsenate(V) (Mn2As2O7)

Crystal data

As2Mn2O7	F(000) = 344
Mr = 371.7	Dx = 4.462 Mg m^−3
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2y	Cell parameters from 25 reflections
a = 6.7454 (8) Å	θ = 10.2–16.6°
b = 8.7561 (10) Å	µ = 16.42 mm^−1
c = 4.8004 (7) Å	T = 295 K
β = 102.723 (12)°	Trigonal plate, light pink
V = 276.57 (6) Å^3	0.29 × 0.29 × 0.14 mm
Z = 2

Data collection

Nonius CAD-4 diffractometer	937 reflections with I > 3σ(I)
Radiation source: X-ray tube	Rint = 0.040
Graphite monochromator	θmax = 41.9°, θmin = 3.9°
θ/2θ–scan	h = −12→12
Absorption correction: numerical HABITUS (Herrendorf, 1997)	k = −16→16
Tmin = 0.061, Tmax = 0.222	l = −9→9
3857 measured reflections	3 standard reflections every 120 min
1012 independent reflections	intensity decay: none

Refinement

Refinement on F	0 constraints
R[F^2 > 2σ(F^2)] = 0.037	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
wR(F^2) = 0.045	(Δ/σ)max = 0.001
S = 3.26	Δρmax = 3.39 e Å^−3
1012 reflections	Δρmin = −3.00 e Å^−3
32 parameters	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
0 restraints	Extinction coefficient: 8500 (300)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
As	0.77188 (4)	0	0.59340 (6)	0.00737 (9)
Mn	0.5	0.19269 (5)	0	0.00933 (11)
O1	0.6069 (4)	0	0.2792 (5)	0.0115 (5)
O2	1	0	0.5	0.063 (3)
O3	0.7673 (3)	−0.1587 (2)	0.7836 (4)	0.0135 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
As	0.00475 (14)	0.01204 (15)	0.00509 (14)	0	0.00062 (8)	0
Mn	0.00768 (18)	0.01120 (18)	0.00854 (19)	0	0.00056 (13)	0
O1	0.0126 (9)	0.0133 (8)	0.0062 (7)	0	−0.0034 (6)	0
O2	0.013 (2)	0.114 (8)	0.069 (6)	0	0.026 (3)	0
O3	0.0152 (7)	0.0139 (6)	0.0109 (6)	0.0046 (5)	0.0017 (5)	0.0042 (5)

Geometric parameters (Å, º)

As—O1	1.666 (2)	Mn—O1^ii	2.1765 (14)
As—O2	1.6949 (3)	Mn—O3^iii	2.1259 (18)
As—O3	1.6663 (18)	Mn—O3^iv	2.1259 (18)
As—O3^i	1.6663 (18)	Mn—O3^v	2.290 (2)
Mn—O1	2.1765 (14)	Mn—O3^vi	2.290 (2)
O1—As—O2	103.01 (10)	O1^ii—Mn—O3^vi	78.86 (9)
O1—As—O3	114.00 (7)	O3^iii—Mn—O3^iv	104.49 (7)
O1—As—O3^i	114.00 (7)	O3^iii—Mn—O3^v	74.40 (7)
O2—As—O3	105.80 (7)	O3^iii—Mn—O3^vi	115.36 (7)
O2—As—O3^i	105.80 (7)	O3^iv—Mn—O3^v	115.36 (7)
O3—As—O3^i	112.96 (9)	O3^iv—Mn—O3^vi	74.40 (7)
O1—Mn—O1^ii	78.36 (6)	O3^v—Mn—O3^vi	165.05 (7)
O1—Mn—O3^iii	152.18 (9)	As—O1—Mn	128.48 (5)
O1—Mn—O3^iv	93.72 (7)	As—O1—Mn^vii	128.48 (5)
O1—Mn—O3^v	78.86 (9)	Mn—O1—Mn^vii	101.64 (9)
O1—Mn—O3^vi	89.51 (9)	As—O2—As^viii	180
O1^ii—Mn—O3^iii	93.72 (7)	As—O3—Mn^ix	132.65 (12)
O1^ii—Mn—O3^iv	152.18 (9)	As—O3—Mn^v	117.93 (10)
O1^ii—Mn—O3^v	89.51 (9)	Mn^ix—O3—Mn^v	105.60 (8)

Symmetry codes: (i) x, −y, z; (ii) −x+1, y, −z; (iii) x−1/2, y+1/2, z−1; (iv) −x+3/2, y+1/2, −z+1; (v) −x+1, −y, −z+1; (vi) x, −y, z−1; (vii) −x+1, −y, −z; (viii) −x+2, y, −z+1; (ix) x+1/2, y−1/2, z+1.

Dicobalt(II) diarsenate(V) (alpha-Co2As2O7)

Crystal data

As2Co2O7	Z = 5
Mr = 379.7	F(000) = 880
Triclinic, P1	Dx = 4.852 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 32.9920 (16) Å	Cell parameters from 4217 reflections
b = 5.3332 (4) Å	θ = 2.7–30.5°
c = 8.9775 (6) Å	µ = 19.00 mm^−1
α = 58.472 (1)°	T = 295 K
β = 149.011 (1)°	Plate, purple
γ = 126.976 (1)°	0.18 × 0.15 × 0.02 mm
V = 649.64 (9) Å^3

Data collection

Bruker SMART CCD diffractometer	3866 independent reflections
Radiation source: X-ray tube	3229 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.055
ω–scan	θmax = 30.5°, θmin = 2.6°
Absorption correction: numerical Habitus (Herrendorf, 1997)	h = −46→46
Tmin = 0.109, Tmax = 0.590	k = −7→7
7549 measured reflections	l = −12→12

Refinement

Refinement on F	0 constraints
R[F^2 > 2σ(F^2)] = 0.029	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
wR(F^2) = 0.034	(Δ/σ)max = 0.019
S = 1.63	Δρmax = 1.60 e Å^−3
3866 reflections	Δρmin = −1.51 e Å^−3
251 parameters	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
0 restraints	Extinction coefficient: 7440 (100)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
As-1	0.27563 (2)	0.03232 (9)	0.56295 (8)	0.0079 (5)
As-2	0.47399 (2)	0.00583 (8)	0.59727 (8)	0.0068 (5)
As-3	0.67185 (2)	−0.05706 (9)	0.62346 (8)	0.0076 (5)
As-4	0.86954 (2)	0.01986 (9)	0.57451 (8)	0.0075 (5)
As-5	1.07605 (2)	−0.00107 (8)	0.60689 (8)	0.0072 (5)
Co-1	0.06274 (3)	−0.37766 (12)	0.00903 (11)	0.0091 (7)
Co-2	0.26180 (3)	−0.40089 (12)	0.04059 (11)	0.0094 (7)
Co-3	0.46174 (3)	−0.37253 (12)	−0.00686 (11)	0.0092 (7)
Co-4	0.66162 (3)	−0.36786 (12)	0.01759 (10)	0.0084 (7)
Co-5	0.86573 (3)	−0.37974 (12)	0.00489 (11)	0.0106 (8)
O1-1	0.17566 (15)	0.0155 (6)	0.2690 (5)	0.010 (4)
O1-2	0.37450 (16)	−0.0054 (6)	0.2803 (5)	0.013 (4)
O1-3	0.57949 (16)	−0.0203 (6)	0.2798 (5)	0.010 (4)
O1-4	0.77240 (15)	0.0383 (6)	0.2694 (5)	0.009 (4)
O1-5	0.97981 (15)	0.0013 (6)	0.2713 (5)	0.011 (4)
O2-1	0.29463 (17)	0.1850 (6)	0.3946 (6)	0.012 (4)
O2-2	0.5	0	0.5	0.043 (12)
O2-4	0.8777 (2)	0.0154 (8)	0.4099 (7)	0.027 (5)
O3-1	0.07553 (17)	−0.3309 (6)	−0.2078 (5)	0.011 (4)
O3-2	0.28454 (18)	−0.3095 (7)	−0.2960 (6)	0.021 (5)
O3-3	0.47856 (17)	−0.3219 (6)	−0.2100 (5)	0.012 (4)
O3-4	0.67558 (16)	−0.3741 (6)	−0.1717 (5)	0.010 (4)
O3-5	0.88238 (17)	−0.3044 (6)	−0.2202 (6)	0.014 (4)
O3b-1	−0.14025 (16)	−0.3239 (6)	0.2087 (5)	0.011 (4)
O3b-2	0.05849 (16)	−0.3418 (6)	0.2281 (6)	0.012 (4)
O3b-3	0.25466 (16)	−0.2855 (6)	0.2053 (5)	0.010 (4)
O3b-4	0.46118 (16)	−0.3325 (6)	0.2223 (6)	0.012 (4)
O3b-5	0.65334 (16)	−0.3196 (6)	0.2078 (6)	0.012 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
As-1	0.00633 (18)	0.00675 (17)	0.00749 (17)	0.00243 (14)	0.00476 (16)	−0.00076 (13
As-2	0.00616 (17)	0.00639 (17)	0.00662 (17)	0.00235 (13)	0.00477 (16)	−0.00031 (13
As-3	0.00682 (18)	0.00631 (17)	0.00732 (17)	0.00229 (13)	0.00508 (16)	−0.00068 (13
As-4	0.00626 (18)	0.00705 (17)	0.00681 (17)	0.00247 (14)	0.00466 (16)	−0.00055 (13
As-5	0.00632 (18)	0.00694 (17)	0.00655 (17)	0.00267 (14)	0.00466 (16)	−0.00030 (13
Co-1	0.0081 (2)	0.0072 (2)	0.0097 (2)	0.00271 (19)	0.0067 (2)	−0.00016 (19)
Co-2	0.0081 (2)	0.0076 (2)	0.0105 (2)	0.00224 (19)	0.0068 (2)	−0.00163 (19)
Co-3	0.0080 (2)	0.0074 (2)	0.0101 (2)	0.00222 (19)	0.0069 (2)	−0.00089 (19)
Co-4	0.0082 (2)	0.0073 (2)	0.0085 (2)	0.00300 (19)	0.0065 (2)	0.00030 (18)
Co-5	0.0088 (2)	0.0074 (2)	0.0112 (2)	0.00354 (19)	0.0071 (2)	−0.00007 (19)
O1-1	0.0043 (12)	0.0084 (12)	0.0084 (12)	0.0011 (10)	0.0041 (11)	−0.0013 (10)
O1-2	0.0053 (12)	0.0085 (12)	0.0085 (12)	0.0011 (10)	0.0028 (11)	−0.0025 (10)
O1-3	0.0066 (12)	0.0100 (12)	0.0071 (12)	0.0045 (10)	0.0037 (11)	0.0000 (10)
O1-4	0.0056 (12)	0.0079 (12)	0.0067 (11)	0.0025 (10)	0.0038 (11)	0.0000 (9)
O1-5	0.0049 (12)	0.0075 (12)	0.0072 (12)	0.0017 (10)	0.0027 (11)	−0.0016 (10)
O2-1	0.0174 (14)	0.0133 (13)	0.0156 (13)	0.0081 (11)	0.0143 (13)	0.0026 (11)
O2-2	0.070 (4)	0.042 (3)	0.075 (4)	0.013 (3)	0.069 (4)	−0.002 (3)
O2-4	0.0264 (17)	0.051 (2)	0.0222 (15)	0.0225 (17)	0.0195 (15)	0.0034 (15)
O3-1	0.0155 (14)	0.0077 (12)	0.0123 (12)	0.0071 (11)	0.0114 (12)	0.0041 (10)
O3-2	0.0208 (16)	0.0116 (14)	0.0216 (15)	0.0107 (12)	0.0157 (15)	0.0060 (12)
O3-3	0.0161 (14)	0.0084 (12)	0.0125 (12)	0.0083 (11)	0.0118 (12)	0.0051 (10)
O3-4	0.0147 (13)	0.0075 (12)	0.0121 (12)	0.0061 (10)	0.0115 (12)	0.0035 (10)
O3-5	0.0165 (14)	0.0090 (13)	0.0152 (13)	0.0090 (11)	0.0125 (13)	0.0051 (11)
O3b-1	0.0087 (13)	0.0081 (12)	0.0109 (12)	0.0004 (10)	0.0072 (12)	−0.0033 (10)
O3b-2	0.0106 (13)	0.0102 (13)	0.0143 (13)	−0.0007 (10)	0.0098 (12)	−0.0051 (10)
O3b-3	0.0083 (13)	0.0073 (12)	0.0127 (12)	−0.0017 (10)	0.0080 (12)	−0.0053 (10)
O3b-4	0.0097 (13)	0.0088 (12)	0.0131 (12)	0.0001 (10)	0.0086 (12)	−0.0042 (10)
O3b-5	0.0087 (13)	0.0135 (13)	0.0133 (13)	−0.0019 (10)	0.0082 (12)	−0.0084 (11)

Geometric parameters (Å, º)

As-1—O1-1	1.679 (3)	Co-2—O1-2	2.121 (2)
As-1—O2-1	1.750 (7)	Co-2—O1-4^v	2.090 (3)
As-1—O3-2^i	1.614 (3)	Co-2—O2-1^viii	2.406 (3)
As-1—O3b-5^ii	1.668 (4)	Co-2—O3-4^vi	2.105 (6)
As-2—O1-2	1.674 (3)	Co-2—O3b-1^vii	2.052 (3)
As-2—O2-2	1.6868 (10)	Co-2—O3b-3	2.084 (7)
As-2—O3-3^i	1.667 (3)	Co-3—O1-3	2.093 (2)
As-2—O3b-4^ii	1.662 (3)	Co-3—O1-3^v	2.142 (3)
As-3—O1-3	1.676 (2)	Co-3—O3-3	2.179 (7)
As-3—O2-1^ii	1.745 (7)	Co-3—O3-3^vi	2.072 (5)
As-3—O3-4^i	1.693 (3)	Co-3—O3b-4	2.193 (7)
As-3—O3b-3^ii	1.673 (3)	Co-3—O3b-5^vi	2.054 (4)
As-4—O1-4	1.682 (3)	Co-4—O1-2^v	2.087 (3)
As-4—O2-4	1.726 (9)	Co-4—O1-4	2.143 (2)
As-4—O3-5^i	1.666 (3)	Co-4—O3-2^vi	1.983 (3)
As-4—O3b-2^ii	1.670 (3)	Co-4—O3-4	2.126 (7)
As-5—O1-5	1.663 (2)	Co-4—O3b-4^vi	2.111 (3)
As-5—O2-4^iii	1.705 (9)	Co-4—O3b-5	2.098 (7)
As-5—O3-1^iv	1.677 (3)	Co-5—O1-1^v	2.031 (3)
As-5—O3b-1^ii	1.674 (4)	Co-5—O1-5	2.113 (2)
Co-1—O1-1	2.130 (2)	Co-5—O3-1^vi	2.015 (5)
Co-1—O1-5^v	2.093 (3)	Co-5—O3-5	2.310 (7)
Co-1—O3-1	2.192 (7)	Co-5—O3b-1^ix	2.177 (7)
Co-1—O3-5^vi	2.048 (5)	Co-5—O3b-3^vi	2.160 (3)
Co-1—O3b-2	2.196 (7)	O2-1—O3-4^v	2.461 (9)
Co-1—O3b-2^vii	2.074 (4)
O1-1—As-1—O2-1	98.0 (2)	O1-4—Co-4—O3-2^vi	98.02 (10)
O1-1—As-1—O3-2^i	112.72 (15)	O1-4—Co-4—O3-4	93.63 (19)
O1-1—As-1—O3b-5^ii	115.9 (2)	O1-4—Co-4—O3b-4^vi	154.3 (3)
O2-1—As-1—O3-2^i	110.5 (3)	O1-4—Co-4—O3b-5	81.99 (19)
O2-1—As-1—O3b-5^ii	100.3 (2)	O3-2^vi—Co-4—O3-4	86.9 (2)
O3-2^i—As-1—O3b-5^ii	116.69 (16)	O3-2^vi—Co-4—O3b-4^vi	96.94 (13)
O1-2—As-2—O2-2	103.3 (2)	O3-2^vi—Co-4—O3b-5	96.0 (2)
O1-2—As-2—O3-3^i	110.48 (16)	O3-4—Co-4—O3b-4^vi	107.97 (19)
O1-2—As-2—O3b-4^ii	113.0 (2)	O3-4—Co-4—O3b-5	175.04 (10)
O2-2—As-2—O3-3^i	106.8 (3)	O3b-4^vi—Co-4—O3b-5	75.7 (2)
O2-2—As-2—O3b-4^ii	108.8 (2)	O1-1^v—Co-5—O1-5	79.94 (9)
O3-3^i—As-2—O3b-4^ii	113.74 (19)	O1-1^v—Co-5—O3-1^vi	151.7 (3)
O1-3—As-3—O2-1^ii	105.9 (2)	O1-1^v—Co-5—O3-5	78.8 (2)
O1-3—As-3—O3-4^i	120.67 (15)	O1-1^v—Co-5—O3b-1^ix	89.7 (2)
O1-3—As-3—O3b-3^ii	112.47 (14)	O1-1^v—Co-5—O3b-3^vi	95.66 (12)
O2-1^ii—As-3—O3-4^i	91.4 (3)	O1-5—Co-5—O3-1^vi	92.78 (14)
O2-1^ii—As-3—O3b-3^ii	107.1 (2)	O1-5—Co-5—O3-5	87.43 (19)
O3-4^i—As-3—O3b-3^ii	115.51 (17)	O1-5—Co-5—O3b-1^ix	82.2 (2)
O1-4—As-4—O2-4	96.9 (2)	O1-5—Co-5—O3b-3^vi	156.9 (3)
O1-4—As-4—O3-5^i	117.74 (17)	O3-1^vi—Co-5—O3-5	73.6 (2)
O1-4—As-4—O3b-2^ii	111.9 (2)	O3-1^vi—Co-5—O3b-1^ix	116.60 (19)
O2-4—As-4—O3-5^i	107.4 (3)	O3-1^vi—Co-5—O3b-3^vi	100.93 (14)
O2-4—As-4—O3b-2^ii	110.6 (3)	O3-5—Co-5—O3b-1^ix	165.70 (10)
O3-5^i—As-4—O3b-2^ii	111.23 (16)	O3-5—Co-5—O3b-3^vi	114.11 (17)
O1-5—As-5—O2-4^iii	108.5 (3)	O3b-1^ix—Co-5—O3b-3^vi	75.11 (19)
O1-5—As-5—O3-1^iv	112.62 (14)	As-1—O1-1—Co-1	129.0 (2)
O1-5—As-5—O3b-1^ii	114.17 (18)	As-1—O1-1—Co-5^v	125.75 (15)
O2-4^iii—As-5—O3-1^iv	102.8 (3)	Co-1—O1-1—Co-5^v	101.69 (9)
O2-4^iii—As-5—O3b-1^ii	105.0 (2)	As-2—O1-2—Co-2	129.04 (17)
O3-1^iv—As-5—O3b-1^ii	112.7 (2)	As-2—O1-2—Co-4^v	124.50 (17)
O1-1—Co-1—O1-5^v	78.17 (9)	Co-2—O1-2—Co-4^v	104.20 (8)
O1-1—Co-1—O3-1	89.95 (19)	As-3—O1-3—Co-3	128.71 (15)
O1-1—Co-1—O3-5^vi	97.07 (13)	As-3—O1-3—Co-3^v	133.82 (13)
O1-1—Co-1—O3b-2	82.56 (19)	Co-3—O1-3—Co-3^v	97.18 (9)
O1-1—Co-1—O3b-2^vii	153.9 (3)	As-4—O1-4—Co-2^v	125.0 (2)
O1-5^v—Co-1—O3-1	81.2 (2)	As-4—O1-4—Co-4	122.31 (18)
O1-5^v—Co-1—O3-5^vi	156.3 (3)	Co-2^v—O1-4—Co-4	103.33 (9)
O1-5^v—Co-1—O3b-2	92.0 (2)	As-5—O1-5—Co-1^v	130.36 (13)
O1-5^v—Co-1—O3b-2^vii	88.97 (12)	As-5—O1-5—Co-5	129.44 (15)
O3-1—Co-1—O3-5^vi	75.6 (2)	Co-1^v—O1-5—Co-5	100.19 (9)
O3-1—Co-1—O3b-2	170.79 (10)	As-1—O2-1—As-3^ii	133.15 (17)
O3-1—Co-1—O3b-2^vii	110.57 (19)	As-1—O2-1—Co-2^x	132.2 (3)
O3-5^vi—Co-1—O3b-2	110.6 (2)	As-1—O2-1—O3-4^v	176.6 (3)
O3-5^vi—Co-1—O3b-2^vii	103.37 (14)	As-3^ii—O2-1—Co-2^x	94.0 (3)
O3b-2—Co-1—O3b-2^vii	75.3 (2)	As-3^ii—O2-1—O3-4^v	43.45 (18)
O1-2—Co-2—O1-4^v	76.16 (9)	Co-2^x—O2-1—O3-4^v	51.23 (14)
O1-2—Co-2—O2-1^viii	105.17 (9)	As-2—O2-2—As-2^ii	180
O1-2—Co-2—O3-4^vi	88.32 (17)	As-4—O2-4—As-5^iii	156.43 (16)
O1-2—Co-2—O3b-1^vii	158.2 (2)	As-5^xi—O3-1—Co-1	120.4 (3)
O1-2—Co-2—O3b-3	82.6 (2)	As-5^xi—O3-1—Co-5^vi	126.1 (4)
O1-4^v—Co-2—O2-1^viii	175.1 (3)	Co-1—O3-1—Co-5^vi	108.08 (15)
O1-4^v—Co-2—O3-4^vi	119.1 (2)	As-1^xii—O3-2—Co-4^vi	159.42 (17)
O1-4^v—Co-2—O3b-1^vii	93.69 (11)	As-2^xii—O3-3—Co-3	117.2 (3)
O1-4^v—Co-2—O3b-3	96.6 (2)	As-2^xii—O3-3—Co-3^vi	131.9 (4)
O2-1^viii—Co-2—O3-4^vi	65.7 (2)	Co-3—O3-3—Co-3^vi	106.84 (15)
O2-1^viii—Co-2—O3b-1^vii	83.45 (11)	As-3^xii—O3-4—Co-2^vi	107.3 (3)
O2-1^viii—Co-2—O3b-3	79.02 (19)	As-3^xii—O3-4—Co-4	116.7 (3)
O3-4^vi—Co-2—O3b-1^vii	113.42 (16)	As-3^xii—O3-4—O2-1^v	45.14 (19)
O3-4^vi—Co-2—O3b-3	139.78 (14)	Co-2^vi—O3-4—Co-4	131.33 (14)
O3b-1^vii—Co-2—O3b-3	79.4 (2)	Co-2^vi—O3-4—O2-1^v	63.0 (2)
O1-3—Co-3—O1-3^v	82.82 (9)	Co-4—O3-4—O2-1^v	160.12 (17)
O1-3—Co-3—O3-3	88.34 (19)	As-4^xii—O3-5—Co-1^vi	139.9 (4)
O1-3—Co-3—O3-3^vi	89.04 (14)	As-4^xii—O3-5—Co-5	115.2 (3)
O1-3—Co-3—O3b-4	81.9 (2)	Co-1^vi—O3-5—Co-5	102.69 (15)
O1-3—Co-3—O3b-5^vi	156.7 (3)	As-5^ii—O3b-1—Co-2^vii	130.6 (4)
O1-3^v—Co-3—O3-3	83.9 (2)	As-5^ii—O3b-1—Co-5^xiii	120.1 (3)
O1-3^v—Co-3—O3-3^vi	155.9 (3)	Co-2^vii—O3b-1—Co-5^xiii	102.43 (17)
O1-3^v—Co-3—O3b-4	90.4 (2)	As-4^ii—O3b-2—Co-1	114.2 (3)
O1-3^v—Co-3—O3b-5^vi	94.77 (13)	As-4^ii—O3b-2—Co-1^vii	135.2 (4)
O3-3—Co-3—O3-3^vi	73.2 (2)	Co-1—O3b-2—Co-1^vii	104.73 (17)
O3-3—Co-3—O3b-4	169.26 (9)	As-3^ii—O3b-3—Co-2	112.5 (3)
O3-3—Co-3—O3b-5^vi	114.58 (19)	As-3^ii—O3b-3—Co-5^vi	143.5 (4)
O3-3^vi—Co-3—O3b-4	111.01 (19)	Co-2—O3b-3—Co-5^vi	101.92 (16)
O3-3^vi—Co-3—O3b-5^vi	101.41 (15)	As-2^ii—O3b-4—Co-3	118.1 (3)
O3b-4—Co-3—O3b-5^vi	74.9 (2)	As-2^ii—O3b-4—Co-4^vi	132.7 (4)
O1-2^v—Co-4—O1-4	75.76 (8)	Co-3—O3b-4—Co-4^vi	101.92 (16)
O1-2^v—Co-4—O3-2^vi	162.8 (3)	As-1^ii—O3b-5—Co-3^vi	130.0 (4)
O1-2^v—Co-4—O3-4	77.6 (2)	As-1^ii—O3b-5—Co-4	122.0 (3)
O1-2^v—Co-4—O3b-4^vi	95.00 (11)	Co-3^vi—O3b-5—Co-4	107.25 (18)
O1-2^v—Co-4—O3b-5	99.0 (2)

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

Dinickel(II) diarsenate(V) (alpha-Ni2As2O7)

Crystal data

As2Ni2O7	Z = 3
Mr = 379.2	F(000) = 534
Triclinic, P1	Dx = 5.002 Mg m^−3
Hall symbol: P 1	Mo Kα radiation, λ = 0.71069 Å
a = 19.497 (4) Å	Cell parameters from 2877 reflections
b = 5.297 (1) Å	θ = 2.8–30.5°
c = 8.868 (2) Å	µ = 20.51 mm^−1
α = 58.32 (2)°	T = 295 K
β = 148.78 (2)°	Plate, orange
γ = 127.30 (2)°	0.23 × 0.18 × 0.08 mm
V = 377.5 (3) Å^3

Data collection

Bruker SMART CCD diffractometer	5394 independent reflections
Radiation source: X-ray tube	5331 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.067
ω–scan	θmax = 32.5°, θmin = 2.2°
Absorption correction: numerical HABITUS (Herrendorf, 1997)	h = −29→29
Tmin = 0.109, Tmax = 0.554	k = −8→8
13779 measured reflections	l = −13→13

Refinement

Refinement on F	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
R[F^2 > 2σ(F^2)] = 0.027	(Δ/σ)max = 0.010
wR(F^2) = 0.032	Δρmax = 1.40 e Å^−3
S = 1.76	Δρmin = −0.71 e Å^−3
5394 reflections	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
297 parameters	Extinction coefficient: 9700 (110)
0 restraints	Absolute structure: refine
3 constraints	Absolute structure parameter: 0.02 (1)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Asa-1	0.54807	0.007024	0.399531	0.0033 (4)
Asa-2	0.87341 (4)	0.97840 (11)	0.43318 (10)	0.0034 (4)
Asa-3	0.21129 (4)	0.01567 (11)	0.38482 (10)	0.0034 (4)
Asb-1	0.11668 (5)	0.03636 (11)	0.56138 (10)	0.0035 (4)
Asb-2	0.46283 (5)	0.01797 (11)	0.59537 (9)	0.0031 (4)
Asb-3	0.78772 (5)	0.94458 (13)	0.62573 (11)	0.0035 (4)
Nia-1	0.90034 (5)	0.42113 (13)	0.93690 (13)	0.0047 (6)
Nia-2	0.22986 (5)	0.38572 (12)	0.97991 (11)	0.0047 (6)
Nia-3	0.56287 (6)	0.37955 (13)	0.99322 (12)	0.0048 (6)
Nib-1	0.77376 (5)	0.64895 (13)	0.01614 (11)	0.0043 (6)
Nib-2	0.11473 (6)	0.64033 (13)	0.98747 (13)	0.0052 (6)
Nib-3	0.43943 (5)	0.64117 (13)	0.98719 (11)	0.0048 (6)
O1a-1	0.7173 (3)	0.0194 (6)	0.7007 (5)	0.005 (3)
O1a-2	0.0431 (3)	0.0021 (6)	0.7230 (5)	0.005 (3)
O1a-3	0.3735 (3)	0.0129 (6)	0.7265 (5)	0.006 (3)
O1b-1	0.9536 (3)	0.0562 (6)	0.2529 (5)	0.007 (3)
O1b-2	0.3010 (3)	0.0150 (6)	0.2508 (5)	0.007 (3)
O1b-3	0.6351 (3)	0.9876 (6)	0.2705 (5)	0.005 (3)
O2-1	0.5444 (3)	0.0119 (8)	0.5822 (6)	0.016 (4)
O2-2	0.8394 (3)	0.7920 (6)	0.6049 (5)	0.006 (3)
O2-3	0.1330 (3)	0.0239 (8)	0.4026 (6)	0.019 (4)
O3a-1	0.8576 (3)	0.3220 (7)	0.3101 (6)	0.014 (4)
O3a-2	0.2165 (3)	0.3519 (6)	0.2033 (5)	0.006 (3)
O3a-3	0.5356 (3)	0.3355 (6)	0.2010 (6)	0.008 (3)
O3b-1	0.8004 (3)	0.6258 (6)	0.8445 (5)	0.006 (3)
O3b-2	0.1398 (3)	0.7093 (6)	0.7724 (6)	0.008 (3)
O3b-3	0.4591 (3)	0.6790 (6)	0.7741 (6)	0.007 (3)
O3c-1	0.7530 (3)	0.7022 (7)	0.1893 (6)	0.007 (3)
O3c-2	0.1061 (3)	0.6858 (6)	0.2045 (6)	0.007 (3)
O3c-3	0.4310 (3)	0.6776 (6)	0.2101 (6)	0.008 (3)
O3d-1	0.9205 (3)	0.2907 (6)	0.7978 (6)	0.007 (3)
O3d-2	0.2397 (3)	0.3629 (6)	0.7626 (6)	0.007 (3)
O3d-3	0.5669 (3)	0.3525 (6)	0.7704 (6)	0.008 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Asa-1	0.00297 (14)	0.00395 (16)	0.00315 (15)	0.00153 (12)	0.00251 (13)	0.00044 (12
Asa-2	0.00293 (13)	0.00387 (15)	0.00303 (14)	0.00147 (11)	0.00226 (13)	0.00009 (11
Asa-3	0.00323 (13)	0.00435 (16)	0.00296 (14)	0.00176 (11)	0.00250 (13)	0.00045 (11
Asb-1	0.00265 (14)	0.00406 (16)	0.00274 (15)	0.00134 (11)	0.00201 (13)	0.00018 (11
Asb-2	0.00299 (14)	0.00390 (16)	0.00298 (14)	0.00134 (12)	0.00250 (13)	0.00019 (11
Asb-3	0.00310 (13)	0.00359 (15)	0.00306 (14)	0.00141 (11)	0.00241 (13)	0.00046 (11
Nia-1	0.00500 (18)	0.00476 (19)	0.00568 (18)	0.00156 (15)	0.00448 (16)	−0.00011 (1
Nia-2	0.00468 (18)	0.0044 (2)	0.0051 (2)	0.00178 (16)	0.00401 (17)	0.00045 (15)
Nia-3	0.00443 (19)	0.0048 (2)	0.0056 (2)	0.00128 (15)	0.00415 (18)	−0.00021 (15)
Nib-1	0.00476 (19)	0.0051 (2)	0.0048 (2)	0.00195 (15)	0.00411 (18)	0.00034 (15)
Nib-2	0.00464 (18)	0.0047 (2)	0.00548 (19)	0.00216 (15)	0.00394 (17)	0.00064 (15)
Nib-3	0.00422 (18)	0.0049 (2)	0.00498 (19)	0.00187 (15)	0.00366 (17)	0.00044 (15)
O1a-1	0.0024 (9)	0.0049 (11)	0.0026 (10)	0.0006 (8)	0.0013 (9)	−0.0009 (8)
O1a-2	0.0031 (10)	0.0068 (11)	0.0033 (10)	0.0025 (8)	0.0019 (9)	0.0001 (8)
O1a-3	0.0026 (10)	0.0059 (11)	0.0022 (10)	0.0011 (8)	0.0008 (9)	−0.0009 (8)
O1b-1	0.0046 (10)	0.0071 (11)	0.0064 (10)	0.0031 (8)	0.0039 (9)	0.0010 (8)
O1b-2	0.0033 (10)	0.0046 (11)	0.0040 (10)	0.0023 (8)	0.0015 (9)	0.0006 (8)
O1b-3	0.0052 (10)	0.0057 (11)	0.0033 (10)	0.0047 (8)	0.0027 (9)	0.0022 (8)
O2-1	0.0173 (13)	0.0290 (16)	0.0161 (13)	0.0102 (12)	0.0143 (12)	−0.0007 (12)
O2-2	0.0103 (10)	0.0074 (11)	0.0087 (10)	0.0049 (9)	0.0087 (9)	0.0025 (8)
O2-3	0.0191 (14)	0.038 (2)	0.0153 (13)	0.0168 (14)	0.0140 (12)	0.0025 (13)
O3a-1	0.0188 (13)	0.0098 (12)	0.0142 (13)	0.0109 (10)	0.0129 (12)	0.0064 (9)
O3a-2	0.0110 (11)	0.0052 (11)	0.0083 (11)	0.0053 (9)	0.0087 (10)	0.0034 (8)
O3a-3	0.0123 (11)	0.0046 (11)	0.0100 (11)	0.0042 (9)	0.0101 (10)	0.0031 (8)
O3b-1	0.0119 (11)	0.0058 (11)	0.0095 (11)	0.0054 (9)	0.0100 (10)	0.0038 (8)
O3b-2	0.0125 (11)	0.0069 (11)	0.0101 (11)	0.0079 (9)	0.0100 (10)	0.0057 (9)
O3b-3	0.0113 (11)	0.0044 (11)	0.0104 (12)	0.0051 (9)	0.0101 (11)	0.0050 (9)
O3c-1	0.0042 (10)	0.0090 (12)	0.0075 (11)	−0.0018 (9)	0.0045 (10)	−0.0053 (9)
O3c-2	0.0051 (10)	0.0055 (11)	0.0080 (11)	−0.0014 (9)	0.0053 (10)	−0.0030 (8)
O3c-3	0.0054 (10)	0.0055 (11)	0.0079 (11)	−0.0019 (9)	0.0049 (10)	−0.0040 (9)
O3d-1	0.0066 (10)	0.0057 (11)	0.0109 (11)	−0.0022 (8)	0.0078 (10)	−0.0041 (8)
O3d-2	0.0048 (10)	0.0062 (11)	0.0076 (11)	−0.0014 (9)	0.0047 (9)	−0.0037 (9)
O3d-3	0.0062 (10)	0.0090 (12)	0.0083 (11)	0.0007 (9)	0.0056 (10)	−0.0033 (9)

Geometric parameters (Å, º)

Asa-1—O1a-1	1.695 (3)	Nia-2—O1a-2	2.070 (2)
Asa-1—O2-1	1.694 (8)	Nia-2—O1b-2^v	2.049 (3)
Asa-1—O3a-3	1.658 (3)	Nia-2—O3a-2^v	2.116 (7)
Asa-1—O3c-3^i	1.665 (3)	Nia-2—O3b-2	2.053 (5)
Asa-2—O1a-2^ii	1.690 (3)	Nia-2—O3c-3^v	2.052 (4)
Asa-2—O2-2	1.757 (6)	Nia-2—O3d-2	2.162 (7)
Asa-2—O3a-1^iii	1.618 (4)	Nia-3—O1a-3	2.048 (2)
Asa-2—O3c-1	1.675 (4)	Nia-3—O1b-3^vii	2.144 (3)
Asa-3—O1a-3	1.674 (2)	Nia-3—O3a-3^v	2.192 (7)
Asa-3—O2-3	1.690 (8)	Nia-3—O3b-3	2.076 (5)
Asa-3—O3a-2	1.680 (3)	Nia-3—O3c-1^v	2.026 (3)
Asa-3—O3c-2^i	1.673 (4)	Nia-3—O3d-3	2.122 (7)
Asb-1—O1b-1^iv	1.682 (3)	Nib-1—O1a-1^viii	2.115 (3)
Asb-1—O2-3	1.726 (8)	Nib-1—O1b-1^iii	2.087 (2)
Asb-1—O3b-2^i	1.675 (3)	Nib-1—O3a-1	1.967 (3)
Asb-1—O3d-2	1.680 (3)	Nib-1—O3b-1^ix	2.056 (7)
Asb-2—O1b-2	1.671 (2)	Nib-1—O3c-1	2.064 (7)
Asb-2—O2-1	1.712 (8)	Nib-1—O3d-3^ix	2.090 (3)
Asb-2—O3b-3^i	1.671 (3)	Nib-2—O1a-2^iii	2.011 (3)
Asb-2—O3d-3	1.677 (4)	Nib-2—O1b-2^x	2.051 (2)
Asb-3—O1a-1^iii	2.231 (7)	Nib-2—O3a-2^v	2.010 (5)
Asb-3—O1b-3	1.692 (2)	Nib-2—O3b-2	2.158 (7)
Asb-3—O2-2	1.779 (7)	Nib-2—O3c-2^v	2.210 (7)
Asb-3—O3b-1	1.709 (3)	Nib-2—O3d-1^iv	2.116 (3)
Asb-3—O3d-1^iii	1.680 (2)	Nib-3—O1a-3^iii	2.019 (3)
Nia-1—O1a-1	2.084 (2)	Nib-3—O1b-3^v	2.049 (2)
Nia-1—O1b-1^v	2.105 (3)	Nib-3—O3a-3^v	2.026 (5)
Nia-1—O2-2	2.170 (3)	Nib-3—O3b-3	2.124 (7)
Nia-1—O3b-1	2.131 (6)	Nib-3—O3c-3^v	2.228 (7)
Nia-1—O3c-2^vi	2.021 (3)	Nib-3—O3d-2	2.041 (4)
Nia-1—O3d-1	2.051 (7)
O1a-1—Asa-1—O2-1	95.4 (2)	O3a-1—Nib-1—O3c-1	91.5 (2)
O1a-1—Asa-1—O3a-3	109.89 (16)	O3a-1—Nib-1—O3d-3^ix	95.04 (13)
O1a-1—Asa-1—O3c-3^i	113.0 (2)	O3b-1^ix—Nib-1—O3c-1	176.47 (10)
O2-1—Asa-1—O3a-3	111.4 (3)	O3b-1^ix—Nib-1—O3d-3^ix	107.3 (2)
O2-1—Asa-1—O3c-3^i	112.8 (3)	O3c-1—Nib-1—O3d-3^ix	75.2 (2)
O3a-3—Asa-1—O3c-3^i	113.08 (17)	O1a-2^iii—Nib-2—O1b-2^x	80.29 (10)
O1a-2^ii—Asa-2—O2-2	98.9 (2)	O1a-2^iii—Nib-2—O3a-2^v	156.7 (3)
O1a-2^ii—Asa-2—O3a-1^iii	113.06 (15)	O1a-2^iii—Nib-2—O3b-2	82.5 (2)
O1a-2^ii—Asa-2—O3c-1	115.9 (3)	O1a-2^iii—Nib-2—O3c-2^v	87.6 (2)
O2-2—Asa-2—O3a-1^iii	108.5 (3)	O1a-2^iii—Nib-2—O3d-1^iv	96.76 (13)
O2-2—Asa-2—O3c-1	99.8 (2)	O1b-2^x—Nib-2—O3a-2^v	92.32 (14)
O3a-1^iii—Asa-2—O3c-1	117.54 (15)	O1b-2^x—Nib-2—O3b-2	89.2 (2)
O1a-3—Asa-3—O2-3	107.5 (3)	O1b-2^x—Nib-2—O3c-2^v	81.2 (2)
O1a-3—Asa-3—O3a-2	112.09 (14)	O1b-2^x—Nib-2—O3d-1^iv	155.9 (3)
O1a-3—Asa-3—O3c-2^i	113.22 (18)	O3a-2^v—Nib-2—O3b-2	75.2 (2)
O2-3—Asa-3—O3a-2	104.1 (3)	O3a-2^v—Nib-2—O3c-2^v	113.28 (19)
O2-3—Asa-3—O3c-2^i	105.4 (2)	O3a-2^v—Nib-2—O3d-1^iv	98.68 (14)
O3a-2—Asa-3—O3c-2^i	113.7 (2)	O3b-2—Nib-2—O3c-2^v	167.28 (11)
O1b-1^iv—Asb-1—O2-3	97.6 (2)	O3b-2—Nib-2—O3d-1^iv	114.23 (18)
O1b-1^iv—Asb-1—O3b-2^i	118.99 (17)	O3c-2^v—Nib-2—O3d-1^iv	74.81 (19)
O1b-1^iv—Asb-1—O3d-2	112.2 (2)	O1a-3^iii—Nib-3—O1b-3^v	83.72 (9)
O2-3—Asb-1—O3b-2^i	105.6 (3)	O1a-3^iii—Nib-3—O3a-3^v	156.9 (3)
O2-3—Asb-1—O3d-2	111.0 (3)	O1a-3^iii—Nib-3—O3b-3	84.0 (2)
O3b-2^i—Asb-1—O3d-2	110.41 (15)	O1a-3^iii—Nib-3—O3c-3^v	89.7 (2)
O1b-2—Asb-2—O2-1	106.5 (3)	O1a-3^iii—Nib-3—O3d-2	89.32 (13)
O1b-2—Asb-2—O3b-3^i	112.41 (13)	O1b-3^v—Nib-3—O3a-3^v	88.89 (14)
O1b-2—Asb-2—O3d-3	113.79 (18)	O1b-3^v—Nib-3—O3b-3	90.3 (2)
O2-1—Asb-2—O3b-3^i	102.0 (3)	O1b-3^v—Nib-3—O3c-3^v	83.8 (2)
O2-1—Asb-2—O3d-3	104.6 (3)	O1b-3^v—Nib-3—O3d-2	156.2 (3)
O3b-3^i—Asb-2—O3d-3	116.0 (2)	O3a-3^v—Nib-3—O3b-3	74.1 (2)
O1a-1^iii—Asb-3—O1b-3	83.9 (2)	O3a-3^v—Nib-3—O3c-3^v	111.36 (19)
O1a-1^iii—Asb-3—O2-2	165.92 (12)	O3a-3^v—Nib-3—O3d-2	105.48 (14)
O1a-1^iii—Asb-3—O3b-1	78.4 (2)	O3b-3—Nib-3—O3c-3^v	171.75 (10)
O1a-1^iii—Asb-3—O3d-1^iii	84.4 (3)	O3b-3—Nib-3—O3d-2	111.62 (19)
O1b-3—Asb-3—O2-2	102.2 (2)	O3c-3^v—Nib-3—O3d-2	73.4 (2)
O1b-3—Asb-3—O3b-1	125.57 (14)	Asa-1—O1a-1—Asb-3^i	115.5 (2)
O1b-3—Asb-3—O3d-1^iii	113.57 (12)	Asa-1—O1a-1—Nia-1	126.60 (19)
O2-2—Asb-3—O3b-1	87.8 (3)	Asa-1—O1a-1—Nib-1^vii	119.9 (2)
O2-2—Asb-3—O3d-1^iii	104.3 (2)	Asb-3^i—O1a-1—Nia-1	88.3 (2)
O3b-1—Asb-3—O3d-1^iii	115.25 (15)	Asb-3^i—O1a-1—Nib-1^vii	92.81 (19)
O1a-1—Nia-1—O1b-1^v	75.42 (9)	Nia-1—O1a-1—Nib-1^vii	104.53 (9)
O1a-1—Nia-1—O2-2	103.32 (9)	Asa-2^xi—O1a-2—Nia-2	130.0 (2)
O1a-1—Nia-1—O3b-1	90.96 (18)	Asa-2^xi—O1a-2—Nib-2^i	126.16 (15)
O1a-1—Nia-1—O3c-2^vi	155.4 (2)	Nia-2—O1a-2—Nib-2^i	100.67 (10)
O1a-1—Nia-1—O3d-1	80.0 (2)	Asa-3—O1a-3—Nia-3	130.65 (15)
O1b-1^v—Nia-1—O2-2	178.29 (18)	Asa-3—O1a-3—Nib-3^i	129.49 (13)
O1b-1^v—Nia-1—O3b-1	110.3 (2)	Nia-3—O1a-3—Nib-3^i	99.81 (9)
O1b-1^v—Nia-1—O3c-2^vi	91.94 (11)	Asb-1^xii—O1b-1—Nia-1^ix	124.0 (2)
O1b-1^v—Nia-1—O3d-1	95.7 (2)	Asb-1^xii—O1b-1—Nib-1^i	120.90 (18)
O2-2—Nia-1—O3b-1	68.5 (2)	Nia-1^ix—O1b-1—Nib-1^i	104.77 (9)
O2-2—Nia-1—O3c-2^vi	89.65 (11)	Asb-2—O1b-2—Nia-2^ix	129.75 (13)
O2-2—Nia-1—O3d-1	85.18 (19)	Asb-2—O1b-2—Nib-2^xiii	130.10 (15)
O3b-1—Nia-1—O3c-2^vi	113.36 (18)	Nia-2^ix—O1b-2—Nib-2^xiii	100.04 (9)
O3b-1—Nia-1—O3d-1	149.45 (12)	Asb-3—O1b-3—Nia-3^viii	135.03 (15)
O3c-2^vi—Nia-1—O3d-1	80.4 (2)	Asb-3—O1b-3—Nib-3^ix	127.88 (14)
O1a-2—Nia-2—O1b-2^v	78.98 (10)	Nia-3^viii—O1b-3—Nib-3^ix	95.79 (9)
O1a-2—Nia-2—O3a-2^v	92.0 (2)	Asa-1—O2-1—Asb-2	152.34 (14)
O1a-2—Nia-2—O3b-2	96.95 (14)	Asa-2—O2-2—Asb-3	126.09 (16)
O1a-2—Nia-2—O3c-3^v	155.4 (3)	Asa-2—O2-2—Nia-1	132.6 (3)
O1a-2—Nia-2—O3d-2	83.8 (2)	Asb-3—O2-2—Nia-1	99.2 (3)
O1b-2^v—Nia-2—O3a-2^v	83.3 (2)	Asa-3—O2-3—Asb-1	157.73 (15)
O1b-2^v—Nia-2—O3b-2	158.0 (3)	Asa-2^i—O3a-1—Nib-1	157.1 (2)
O1b-2^v—Nia-2—O3c-3^v	89.44 (12)	Asa-3—O3a-2—Nia-2^ix	119.8 (3)
O1b-2^v—Nia-2—O3d-2	90.9 (2)	Asa-3—O3a-2—Nib-2^ix	126.3 (4)
O3a-2^v—Nia-2—O3b-2	75.2 (2)	Nia-2^ix—O3a-2—Nib-2^ix	106.13 (15)
O3a-2^v—Nia-2—O3c-3^v	108.2 (2)	Asa-1—O3a-3—Nia-3^ix	114.6 (3)
O3a-2^v—Nia-2—O3d-2	173.44 (11)	Asa-1—O3a-3—Nib-3^ix	135.1 (4)
O3b-2—Nia-2—O3c-3^v	101.52 (15)	Nia-3^ix—O3a-3—Nib-3^ix	106.66 (16)
O3b-2—Nia-2—O3d-2	110.25 (19)	Asb-3—O3b-1—Nia-1	103.0 (3)
O3c-3^v—Nia-2—O3d-2	74.6 (2)	Asb-3—O3b-1—Nib-1^v	113.2 (3)
O1a-3—Nia-3—O1b-3^vii	80.68 (9)	Nia-1—O3b-1—Nib-1^v	140.30 (14)
O1a-3—Nia-3—O3a-3^v	89.2 (2)	Asb-1^iii—O3b-2—Nia-2	140.1 (4)
O1a-3—Nia-3—O3b-3	90.85 (14)	Asb-1^iii—O3b-2—Nib-2	114.9 (3)
O1a-3—Nia-3—O3c-1^v	157.7 (3)	Nia-2—O3b-2—Nib-2	103.12 (15)
O1a-3—Nia-3—O3d-3	82.8 (2)	Asb-2^iii—O3b-3—Nia-3	128.1 (4)
O1b-3^vii—Nia-3—O3a-3^v	85.3 (2)	Asb-2^iii—O3b-3—Nib-3	117.6 (3)
O1b-3^vii—Nia-3—O3b-3	155.7 (3)	Nia-3—O3b-3—Nib-3	107.41 (16)
O1b-3^vii—Nia-3—O3c-1^v	95.61 (13)	Asa-2—O3c-1—Nia-3^ix	129.9 (4)
O1b-3^vii—Nia-3—O3d-3	90.6 (2)	Asa-2—O3c-1—Nib-1	123.5 (3)
O3a-3^v—Nia-3—O3b-3	71.7 (2)	Nia-3^ix—O3c-1—Nib-1	106.58 (19)
O3a-3^v—Nia-3—O3c-1^v	112.5 (2)	Asa-3^iii—O3c-2—Nia-1^xiv	130.3 (4)
O3a-3^v—Nia-3—O3d-3	171.48 (9)	Asa-3^iii—O3c-2—Nib-2^ix	120.1 (3)
O3b-3—Nia-3—O3c-1^v	100.43 (15)	Nia-1^xiv—O3c-2—Nib-2^ix	99.75 (18)
O3b-3—Nia-3—O3d-3	111.06 (19)	Asa-1^iii—O3c-3—Nia-2^ix	134.8 (4)
O3c-1^v—Nia-3—O3d-3	75.3 (2)	Asa-1^iii—O3c-3—Nib-3^ix	114.7 (3)
O1a-1^viii—Nib-1—O1b-1^iii	75.17 (9)	Nia-2^ix—O3c-3—Nib-3^ix	104.54 (18)
O1a-1^viii—Nib-1—O3a-1	163.8 (3)	Asb-3^i—O3d-1—Nia-1	107.0 (3)
O1a-1^viii—Nib-1—O3b-1^ix	74.4 (2)	Asb-3^i—O3d-1—Nib-2^xii	150.4 (4)
O1a-1^viii—Nib-1—O3c-1	103.0 (2)	Nia-1—O3d-1—Nib-2^xii	101.95 (17)
O1a-1^viii—Nib-1—O3d-3^ix	95.68 (11)	Asb-1—O3d-2—Nia-2	113.0 (3)
O1b-1^iii—Nib-1—O3a-1	99.78 (9)	Asb-1—O3d-2—Nib-3	134.0 (4)
O1b-1^iii—Nib-1—O3b-1^ix	93.8 (2)	Nia-2—O3d-2—Nib-3	107.37 (17)
O1b-1^iii—Nib-1—O3c-1	83.1 (2)	Asb-2—O3d-3—Nia-3	118.6 (3)
O1b-1^iii—Nib-1—O3d-3^ix	154.0 (3)	Asb-2—O3d-3—Nib-1^v	130.1 (4)
O3a-1—Nib-1—O3b-1^ix	90.8 (2)	Nia-3—O3d-3—Nib-1^v	102.21 (17)

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

Dizinc(II) diarsenate(V) (alpha-Zn2As2O7)

Crystal data

As2O7Zn2	F(000) = 2184
Mr = 392.6	Dx = 4.886 Mg m^−3
Monoclinic, I2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -I 2yc	Cell parameters from 10939 reflections
a = 20.5802 (3) Å	θ = 3.5–44.9°
b = 8.4360 (1) Å	µ = 21.28 mm^−1
c = 9.6180 (1) Å	T = 240 K
β = 106.5640 (7)°	Plate, colourless
V = 1600.53 (3) Å^3	0.18 × 0.12 × 0.02 mm
Z = 12

Data collection

Bruker APEXII CCD diffractometer	6626 independent reflections
Radiation source: X-ray tube	4899 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.048
ω– and φ–scans	θmax = 45.0°, θmin = 2.1°
Absorption correction: multi-scan SADABS (Bruker, 2008)	h = −21→40
Tmin = 0.361, Tmax = 0.749	k = −16→16
39828 measured reflections	l = −19→18

Refinement

Refinement on F	0 constraints
R[F^2 > 2σ(F^2)] = 0.023	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
wR(F^2) = 0.032	(Δ/σ)max = 0.002
S = 1.23	Δρmax = 1.01 e Å^−3
6626 reflections	Δρmin = −0.90 e Å^−3
151 parameters	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
0 restraints	Extinction coefficient: 1910 (50)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
As-1	0.258447 (7)	−0.016048 (17)	0.297700 (15)	0.00454 (3)
As-2	0.596944 (7)	−0.000579 (18)	0.287254 (16)	0.00519 (3)
As-3	0.930450 (7)	−0.014497 (18)	0.799505 (15)	0.00486 (4)
Zn-1	0.181506 (9)	−0.18777 (2)	−0.01985 (2)	0.00741 (4)
Zn-2	0.486477 (9)	−0.18695 (2)	0.018840 (19)	0.00698 (4)
Zn-3	0.835592 (8)	−0.18678 (2)	0.001230 (19)	0.00661 (4)
O1-1	0.20546 (6)	−0.00848 (13)	0.13002 (11)	0.0078 (3)
O1-2	0.53133 (6)	0.01142 (13)	0.13653 (12)	0.0070 (2)
O1-3	0.86895 (6)	0.00046 (13)	0.14238 (12)	0.0074 (2)
O2-1	0.33871 (6)	−0.05413 (17)	0.28695 (15)	0.0154 (3)
O2-2	1	−0.0844 (2)	0.75	0.0136 (5)
O3-1	0.24586 (6)	−0.17238 (13)	0.39308 (12)	0.0079 (3)
O3-2	0.59151 (6)	−0.15981 (13)	0.38681 (12)	0.0078 (3)
O3-3	0.94481 (6)	−0.15382 (14)	0.39066 (13)	0.0130 (3)
O3-4	0.26127 (6)	−0.15497 (13)	0.88728 (12)	0.0081 (3)
O3-5	0.61163 (6)	−0.16112 (14)	0.88652 (14)	0.0136 (3)
O3-6	0.91458 (6)	−0.16593 (13)	0.89733 (12)	0.0082 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
As-1	0.00491 (5)	0.00483 (6)	0.00373 (5)	0.00005 (4)	0.00097 (4)	0.00006 (4)
As-2	0.00513 (5)	0.00531 (5)	0.00443 (5)	−0.00086 (4)	0.00021 (4)	0.00072 (4)
As-3	0.00452 (6)	0.00519 (6)	0.00444 (6)	−0.00044 (4)	0.00059 (4)	0.00060 (4)
Zn-1	0.00796 (7)	0.00556 (7)	0.00729 (7)	0.00006 (5)	−0.00011 (5)	−0.00006 (5)
Zn-2	0.00738 (7)	0.00545 (7)	0.00721 (7)	−0.00028 (5)	0.00064 (5)	0.00013 (5)
Zn-3	0.00653 (7)	0.00555 (7)	0.00732 (7)	0.00035 (5)	0.00124 (5)	−0.00010 (5)
O1-1	0.0111 (4)	0.0060 (4)	0.0045 (4)	0.0009 (3)	−0.0008 (3)	−0.0003 (3)
O1-2	0.0070 (4)	0.0067 (4)	0.0054 (4)	−0.0014 (3)	−0.0012 (3)	0.0001 (3)
O1-3	0.0076 (4)	0.0065 (4)	0.0059 (4)	0.0001 (3)	−0.0018 (3)	−0.0005 (3)
O2-1	0.0077 (4)	0.0219 (6)	0.0191 (6)	0.0025 (4)	0.0077 (4)	0.0021 (5)
O2-2	0.0075 (6)	0.0144 (7)	0.0218 (8)	0	0.0089 (6)	0
O3-1	0.0083 (4)	0.0069 (4)	0.0091 (4)	0.0012 (3)	0.0033 (3)	0.0039 (3)
O3-2	0.0080 (4)	0.0075 (4)	0.0086 (4)	0.0017 (3)	0.0034 (3)	0.0039 (3)
O3-3	0.0146 (5)	0.0089 (5)	0.0135 (5)	0.0037 (4)	0.0004 (4)	0.0051 (4)
O3-4	0.0093 (4)	0.0066 (4)	0.0089 (4)	0.0021 (3)	0.0034 (3)	0.0036 (3)
O3-5	0.0161 (5)	0.0085 (5)	0.0132 (5)	0.0034 (4)	−0.0007 (4)	0.0036 (4)
O3-6	0.0088 (4)	0.0082 (4)	0.0088 (4)	0.0019 (3)	0.0045 (3)	0.0035 (3)

Geometric parameters (Å, º)

As-1—O1-1	1.6707 (10)	Zn-1—O3-1^v	2.0183 (10)
As-1—O2-1	1.7146 (13)	Zn-1—O3-4^vi	2.0990 (13)
As-1—O3-1	1.6683 (11)	Zn-1—O3-5^vii	1.9405 (12)
As-1—O3-4^i	1.6729 (11)	Zn-2—O1-2	2.0828 (10)
As-2—O1-2	1.6790 (10)	Zn-2—O1-2^iv	2.0609 (11)
As-2—O2-1^ii	1.7338 (14)	Zn-2—O3-2^ii	2.0693 (13)
As-2—O3-2	1.6718 (12)	Zn-2—O3-3^viii	1.9646 (12)
As-2—O3-5^i	1.6429 (12)	Zn-2—O3-6^vii	2.0272 (11)
As-3—O1-3^iii	1.6761 (10)	Zn-3—O1-1^iv	2.1006 (11)
As-3—O2-2	1.7354 (6)	Zn-3—O1-3	2.0683 (11)
As-3—O3-3^iii	1.6506 (12)	Zn-3—O3-1^ii	2.1977 (13)
As-3—O3-6	1.6731 (12)	Zn-3—O3-2^viii	2.0406 (10)
Zn-1—O1-1	2.0502 (11)	Zn-3—O3-4^ix	2.0897 (10)
Zn-1—O1-3^iv	2.0655 (10)	Zn-3—O3-6^vi	2.1443 (13)
O1-1—As-1—O2-1	108.90 (6)	O1-1^iv—Zn-3—O3-1^ii	90.32 (5)
O1-1—As-1—O3-1	113.58 (5)	O1-1^iv—Zn-3—O3-2^viii	157.47 (5)
O1-1—As-1—O3-4^i	112.42 (5)	O1-1^iv—Zn-3—O3-4^ix	94.41 (4)
O2-1—As-1—O3-1	100.85 (6)	O1-1^iv—Zn-3—O3-6^vi	83.34 (5)
O2-1—As-1—O3-4^i	107.46 (6)	O1-3—Zn-3—O3-1^ii	78.95 (4)
O3-1—As-1—O3-4^i	112.74 (6)	O1-3—Zn-3—O3-2^viii	94.67 (4)
O1-2—As-2—O2-1^ii	100.43 (6)	O1-3—Zn-3—O3-4^ix	152.68 (5)
O1-2—As-2—O3-2	111.98 (5)	O1-3—Zn-3—O3-6^vi	95.13 (5)
O1-2—As-2—O3-5^i	114.90 (6)	O3-1^ii—Zn-3—O3-2^viii	109.51 (5)
O2-1^ii—As-2—O3-2	102.13 (6)	O3-1^ii—Zn-3—O3-4^ix	74.76 (4)
O2-1^ii—As-2—O3-5^i	114.83 (7)	O3-1^ii—Zn-3—O3-6^vi	172.12 (4)
O3-2—As-2—O3-5^i	111.44 (6)	O3-2^viii—Zn-3—O3-4^ix	100.93 (4)
O1-3^iii—As-3—O2-2	104.27 (4)	O3-2^viii—Zn-3—O3-6^vi	75.93 (5)
O1-3^iii—As-3—O3-3^iii	113.14 (5)	O3-4^ix—Zn-3—O3-6^vi	110.28 (5)
O1-3^iii—As-3—O3-6	110.04 (5)	As-1—O1-1—Zn-1	127.62 (6)
O2-2—As-3—O3-3^iii	113.65 (7)	As-1—O1-1—Zn-3^iv	130.55 (6)
O2-2—As-3—O3-6	101.74 (7)	Zn-1—O1-1—Zn-3^iv	100.43 (4)
O3-3^iii—As-3—O3-6	113.09 (6)	As-2—O1-2—Zn-2	122.92 (6)
O1-1—Zn-1—O1-3^iv	79.50 (4)	As-2—O1-2—Zn-2^iv	127.04 (6)
O1-1—Zn-1—O3-1^v	91.05 (4)	Zn-2—O1-2—Zn-2^iv	102.92 (4)
O1-1—Zn-1—O3-4^vi	98.14 (5)	As-3^i—O1-3—Zn-1^iv	126.01 (6)
O1-1—Zn-1—O3-5^vii	143.97 (6)	As-3^i—O1-3—Zn-3	132.05 (6)
O1-3^iv—Zn-1—O3-1^v	163.16 (5)	Zn-1^iv—O1-3—Zn-3	101.01 (4)
O1-3^iv—Zn-1—O3-4^vi	89.04 (5)	As-1—O2-1—As-2^ii	146.94 (9)
O1-3^iv—Zn-1—O3-5^vii	93.00 (5)	As-3—O2-2—As-3^x	140.28 (11)
O3-1^v—Zn-1—O3-4^vi	78.45 (5)	As-1—O3-1—Zn-1^v	126.15 (6)
O3-1^v—Zn-1—O3-5^vii	102.69 (5)	As-1—O3-1—Zn-3^ii	123.81 (6)
O3-4^vi—Zn-1—O3-5^vii	117.08 (5)	Zn-1^v—O3-1—Zn-3^ii	102.68 (5)
O1-2—Zn-2—O1-2^iv	77.08 (4)	As-2—O3-2—Zn-2^ii	121.80 (6)
O1-2—Zn-2—O3-2^ii	87.24 (5)	As-2—O3-2—Zn-3^viii	130.74 (7)
O1-2—Zn-2—O3-3^viii	99.04 (4)	Zn-2^ii—O3-2—Zn-3^viii	104.12 (5)
O1-2—Zn-2—O3-6^vii	160.52 (5)	As-3^i—O3-3—Zn-2^viii	145.17 (9)
O1-2^iv—Zn-2—O3-2^ii	103.81 (5)	As-1^iii—O3-4—Zn-1^xi	114.60 (6)
O1-2^iv—Zn-2—O3-3^viii	140.28 (6)	As-1^iii—O3-4—Zn-3^xii	137.21 (7)
O1-2^iv—Zn-2—O3-6^vii	94.14 (4)	Zn-1^xi—O3-4—Zn-3^xii	103.70 (5)
O3-2^ii—Zn-2—O3-3^viii	115.57 (5)	As-2^iii—O3-5—Zn-1^xiii	143.54 (9)
O3-2^ii—Zn-2—O3-6^vii	77.91 (5)	As-3—O3-6—Zn-2^xiii	124.35 (7)
O3-3^viii—Zn-2—O3-6^vii	98.72 (5)	As-3—O3-6—Zn-3^xi	128.33 (6)
O1-1^iv—Zn-3—O1-3	78.29 (4)	Zn-2^xiii—O3-6—Zn-3^xi	101.94 (5)

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

Zinc(II) diarsenate(V) (beta-Zn2As2O7-superspace)

Crystal data

As2O7Zn2	Z = 2
Mr = 392.6	F(000) = 364
Monoclinic, C2/m(α0γ)0s†	Dx = 4.971 Mg m^−3
q = 0.3190(1)a* + 0.3717(1)c*	Mo Kα radiation, λ = 0.71069 Å
a = 6.7248 (1) Å	µ = 21.65 mm^−1
b = 8.4605 (2) Å	T = 293 K
c = 4.7791 (1) Å	Fragment, colourless
β = 105.319 (1)°	0.12 × 0.10 × 0.05 mm
V = 262.22 (1) Å^3

† Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, −x₄+1/2; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, x₄+1/2; (5) x₁+1/2, x₂+1/2, x₃, x₄; (6) −x₁+1/2, x₂+1/2, −x₃, −x₄+1/2; (7) −x₁+1/2, −x₂+1/2, −x₃, −x₄; (8) x₁+1/2, −x₂+1/2, x₃, x₄+1/2.

Data collection

Bruker APEXII CCD diffractometer	Rint = 0.042
Radiation source: X-ray tube	θmax = 56.1°, θmin = 2.0°
Graphite monochromator	h = −16→15
24775 measured reflections	k = −18→19
8539 independent reflections	l = −11→10
3694 reflections with I > 3σ(I)

Refinement

Refinement on F	1 constraint
R[F^2 > 2σ(F^2)] = 0.029	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0004F^2)
wR(F^2) = 0.046	(Δ/σ)max = 0.031
S = 0.92	Δρmax = 1.22 e Å^−3
8539 reflections	Δρmin = −1.28 e Å^−3
135 parameters	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
0 restraints	Extinction coefficient: 880 (40)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
As	0.778336 (16)	0	0.59371 (2)	0.00733 (2)
Zn	0.5	0.189961 (17)	0	0.01183 (3)
O1	0.60159 (13)	0	0.27379 (17)	0.00955 (15)
O2	1	−0.0555 (3)	0.5	0.0320 (6)	0.5
O3	0.77638 (11)	−0.16236 (8)	0.78521 (14)	0.01460 (16)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
As	0.00722 (4)	0.00790 (4)	0.00575 (4)	0	−0.00025 (2)	0
Zn	0.01428 (6)	0.00676 (5)	0.01090 (5)	0	−0.00292 (4)	0
O1	0.0107 (2)	0.0090 (2)	0.0068 (2)	0	−0.00145 (19)	0
O2	0.0133 (6)	0.0439 (12)	0.0440 (11)	0	0.0168 (7)	0
O3	0.0189 (3)	0.0106 (2)	0.0128 (2)	0.0046 (2)	0.0016 (2)	0.00398 (17)

Geometric parameters (Å, º)

	Average	Minimum	Maximum
As—O1	1.6725 (14)	1.6689 (14)	1.6768 (14)
As—O2	1.721 (2)	1.6769 (10)	1.7735 (13)
As—O2^i	1.722 (2)	1.6769 (10)	1.7735 (13)
As—O3	1.662 (4)	1.636 (4)	1.687 (4)
As—O3^ii	1.661 (4)	1.636 (4)	1.687 (4)
Zn—O1	2.079 (2)	2.033 (2)	2.1311 (19)
Zn—O1^iii	2.078 (2)	2.033 (2)	2.1216 (19)
Zn—O3^iv	2.020 (4)	1.929 (5)	2.119 (4)
Zn—O3^v	2.018 (4)	1.929 (5)	2.119 (4)
Zn—O3^vi	2.361 (5)	2.126 (5)	2.800 (5)
Zn—O3^vii	2.358 (5)	2.126 (5)	2.796 (5)
O1—As—O2	103.35 (13)	94.55 (12)	111.01 (14)
O1—As—O2^i	103.20 (13)	94.55 (12)	111.01 (14)
O1—As—O3	113.36 (14)	112.34 (14)	117.19 (14)
O1—As—O3^ii	113.37 (14)	112.34 (14)	117.19 (14)
O2—As—O3	99.7 (2)	97.5 (2)	100.48 (19)
O2—As—O3^ii	113.1 (2)	110.2 (2)	114.7 (2)
O2^i—As—O3	113.1 (2)	110.2 (2)	114.7 (2)
O2^i—As—O3^ii	99.7 (2)	97.5 (2)	100.48 (19)
O3—As—O3^ii	112.7 (2)	111.3 (2)	114.2 (2)
O1—Zn—O1^iii	77.94 (10)	76.55 (7)	79.56 (12)
O1—Zn—O3^iv	151.32 (16)	134.53 (16)	158.71 (16)
O1—Zn—O3^v	94.65 (13)	89.91 (13)	97.16 (13)
O1—Zn—O3^vi	79.20 (13)	72.39 (11)	86.16 (13)
O1—Zn—O3^vii	92.00 (13)	82.13 (11)	98.39 (16)
O1^iii—Zn—O3^iv	94.61 (13)	89.76 (13)	97.16 (13)
O1^iii—Zn—O3^v	151.52 (16)	135.17 (16)	158.76 (16)
O1^iii—Zn—O3^vi	91.93 (13)	81.86 (11)	98.39 (16)
O1^iii—Zn—O3^vii	79.30 (13)	72.78 (11)	86.21 (13)
O3^iv—Zn—O3^v	103.2 (2)	101.09 (18)	110.43 (18)
O3^iv—Zn—O3^vi	73.57 (18)	62.59 (16)	75.96 (19)
O3^iv—Zn—O3^vii	113.93 (19)	109.99 (19)	129.33 (18)
O3^v—Zn—O3^vi	113.78 (19)	109.99 (19)	128.51 (18)
O3^v—Zn—O3^vii	73.68 (18)	62.79 (16)	75.99 (18)
O3^vi—Zn—O3^vii	168.44 (19)	163.26 (16)	171.79 (18)
As—O1—Zn	127.66 (7)	123.81 (7)	130.48 (7)
As—O1—Zn^viii	127.69 (7)	123.81 (7)	130.48 (7)
Zn—O1—Zn^viii	101.85 (9)	100.92 (8)	103.70 (8)
As—O2—As^ix	150.7 (2)	149.18 (16)	152.9 (3)
As—O3—Zn^x	133.1 (3)	117.8 (3)	142.6 (3)
As—O3—Zn^vi	116.4 (2)	107.7 (2)	123.2 (2)
Zn^x—O3—Zn^vi	106.4 (2)	103.2 (2)	118.8 (2)

Symmetry codes: (i) −x₁+2, −x₂, −x₃+1, −x₄; (ii) x₁, −x₂, x₃, x₄+1/2; (iii) −x₁+1, x₂, −x₃, −x₄+1/2; (iv) x₁−1/2, x₂+1/2, x₃−1, x₄; (v) −x₁+3/2, x₂+1/2, −x₃+1, −x₄+1/2; (vi) −x₁+1, −x₂, −x₃+1, −x₄; (vii) x₁, −x₂, x₃−1, x₄+1/2; (viii) −x₁+1, −x₂, −x₃, −x₄; (ix) −x₁+2, x₂, −x₃+1, −x₄+1/2; (x) x₁+1/2, x₂−1/2, x₃+1, x₄.

Dicobalt(II) diarsenate(V) (alpha-Co2As2O7-superspace)

Crystal data

As2Co2O7	Z = 2
Mr = 379.7	F(000) = 352
Triclinic, C1(αβγ)0†	Dx = 4.851 Mg m^−3
q = 0.20000a* + 0.20000b* + 0.20000c*	Mo Kα radiation, λ = 0.71069 Å
a = 6.598 (1) Å	Cell parameters from 4217 reflections
b = 8.523 (1) Å	θ = 2.7–30.5°
c = 4.751 (1) Å	µ = 19.00 mm^−1
α = 89.30 (1)°	T = 295 K
β = 103.359 (5)°	Plate, purple
γ = 88.771 (3)°	0.18 × 0.15 × 0.02 mm
V = 259.85 (7) Å^3

† Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, −x₂, −x₃, −x₄; (3) x₁+1/2, x₂+1/2, x₃, x₄; (4) −x₁+1/2, −x₂+1/2, −x₃, −x₄.

Data collection

Bruker SMART CCD diffractometer	3866 independent reflections
Radiation source: X-ray tube	3229 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.055
ω–scan	θmax = 30.5°, θmin = 2.6°
Absorption correction: numerical Habitus (Herrendorf, 1997)	h = −9→9
Tmin = 0.109, Tmax = 0.590	k = −12→12
7549 measured reflections	l = −7→7

Refinement

Refinement on F	0 constraints
R[F^2 > 2σ(F^2)] = 0.029	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
wR(F^2) = 0.034	(Δ/σ)max = 0.019
S = 1.63	Δρmax = −1.50 e Å^−3
3866 reflections	Δρmin = 1.61 e Å^−3
251 parameters	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
0 restraints	Extinction coefficient: 7440 (100)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
As	0.77406 (3)	−0.00001 (2)	0.59301 (4)	0.00739 (6)
Co	0.49045 (4)	−0.18987 (3)	0.01305 (6)	0.00934 (8)
O1	0.6050 (2)	0.00294 (16)	0.2739 (3)	0.0105 (4)
O2	1	0	0.5	0.0244 (7)
O3	0.7818 (2)	−0.16407 (15)	−0.2212 (3)	0.0136 (4)
O3b	−0.7667 (2)	−0.16032 (17)	0.2144 (3)	0.0114 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
As	0.00785 (10)	0.00669 (10)	0.00696 (10)	0.00061 (6)	0.00037 (7)	−0.00052 (7)
Co	0.00960 (13)	0.00740 (13)	0.00999 (13)	0.00064 (9)	0.00020 (10)	−0.00049 (9)
O1	0.0131 (6)	0.0084 (6)	0.0076 (6)	−0.0005 (5)	−0.0028 (5)	−0.0011 (5)
O2	0.0121 (10)	0.0342 (13)	0.0300 (11)	0.0014 (8)	0.0116 (9)	0.0021 (10)
O3	0.0160 (7)	0.0088 (6)	0.0147 (6)	0.0034 (5)	0.0013 (5)	0.0047 (5)
O3b	0.0121 (6)	0.0096 (6)	0.0129 (6)	−0.0014 (5)	0.0029 (5)	−0.0053 (5)

Bond lengths (Å)

	Average	Minimum	Maximum
As1—O1	1.663 (4)	1.614 (3)	1.693 (4)
As1—O2	1.669 (3)	1.662 (3)	1.674 (3)
As1—O3	1.675 (3)	1.663 (3)	1.682 (3)
As1—O4	1.723 (3)	1.6868 (5)	1.750 (3)
Co1—O1	2.045 (3)	1.983 (3)	2.105 (4)
Co1—O2^i	2.149 (4)	2.084 (4)	2.196 (4)
Co1—O2^ii	2.090 (3)	2.052 (3)	2.160 (3)
Co1—O3^iii	2.089 (3)	2.031 (3)	2.142 (3)

Symmetry codes: (i) x₁−1/2, x₂+1/2, x₃, x₄; (ii) −x₁−4, −x₂, −x₃+1, −x₄; (iii) x₁−1/2, x₂+1/2, x₃−1, x₄.

Dinickel(II) diarsenate(V) (alpha-Ni2As2O7-superspace)

Crystal data

As2Ni2O7	Z = 2
Mr = 379.2	F(000) = 356
Triclinic, C1(αβγ)0†	Dx = 5.002 Mg m^−3
q = 0.33333a* + 0.33333b* + 0.33333c*	Mo Kα radiation, λ = 0.71069 Å
a = 6.499 Å	Cell parameters from 2877 reflections
b = 8.4276 Å	θ = 2.8–30.5°
c = 4.7223 Å	µ = 20.51 mm^−1
α = 89.19 (7)°	T = 295 K
β = 103.28 (5)°	Plate, orange
γ = 89.46 (3)°	0.23 × 0.18 × 0.08 mm
V = 251.7 (3) Å^3

† Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) x₁+1/2, x₂+1/2, x₃, x₄.

Data collection

Bruker SMART CCD diffractometer	5394 independent reflections
Radiation source: X-ray tube	5331 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.067
ω–scan	θmax = 32.5°, θmin = 2.2°
Absorption correction: numerical HABITUS (Herrendorf, 1997)	h = −10→10
Tmin = 0.109, Tmax = 0.554	k = −13→13
13779 measured reflections	l = −7→7

Refinement

Refinement on F	3 constraints
R[F^2 > 2σ(F^2)] = 0.027	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
wR(F^2) = 0.032	(Δ/σ)max = 0.012
S = 1.76	Δρmax = 1.40 e Å^−3
5394 reflections	Δρmin = −0.71 e Å^−3
296 parameters	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
0 restraints	Extinction coefficient: 9700 (110)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Asa	0.226744	1.000183	0.405842	0.00335 (6)
Asb	0.77326 (5)	−1.00018 (4)	0.59416 (6)	0.00337 (6)
Nia	0.52533 (5)	1.19773 (4)	0.97000 (7)	0.00477 (8)
Nib	0.50925 (5)	0.82174 (4)	0.99693 (7)	0.00477 (8)
O1a	0.4114 (3)	1.0057 (2)	0.7167 (4)	0.0053 (4)
O1b	0.6218 (3)	1.0098 (2)	1.2580 (4)	0.0063 (4)
O2	0.0157 (3)	0.9713 (2)	0.5299 (4)	0.0138 (4)
O3a	0.2033 (3)	1.16825 (19)	1.2381 (4)	0.0094 (4)
O3b	0.7666 (3)	0.8357 (2)	0.7970 (4)	0.0072 (4)
O3c	0.2445 (3)	0.8443 (2)	1.2013 (4)	0.0073 (4)
O3d	0.7825 (3)	1.1677 (2)	0.7769 (4)	0.0073 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Asa	0.00282 (9)	0.00406 (10)	0.00305 (10)	−0.00031 (7)	0.00043 (7)	0.00033 (7)
Asb	0.00319 (9)	0.00385 (9)	0.00293 (9)	−0.00053 (6)	0.00040 (7)	0.00028 (7)
Nia	0.00410 (13)	0.00468 (13)	0.00546 (13)	−0.00047 (10)	0.00092 (11)	0.00005 (10)
Nib	0.00407 (12)	0.00488 (13)	0.00508 (13)	−0.00031 (9)	0.00050 (10)	0.00047 (10)
O1a	0.0066 (7)	0.0059 (7)	0.0027 (7)	−0.0008 (5)	−0.0007 (6)	−0.0005 (5)
O1b	0.0069 (6)	0.0058 (7)	0.0046 (7)	0.0007 (5)	−0.0018 (5)	0.0012 (5)
O2	0.0046 (6)	0.0249 (9)	0.0134 (7)	0.0008 (5)	0.0054 (5)	0.0014 (6)
O3a	0.0108 (7)	0.0065 (7)	0.0109 (7)	0.0028 (5)	0.0031 (6)	0.0043 (5)
O3b	0.0061 (7)	0.0057 (7)	0.0100 (7)	0.0014 (6)	0.0027 (6)	0.0048 (6)
O3c	0.0078 (7)	0.0067 (7)	0.0079 (7)	−0.0029 (6)	0.0023 (6)	−0.0041 (6)
O3d	0.0065 (7)	0.0070 (7)	0.0089 (7)	−0.0021 (5)	0.0026 (5)	−0.0037 (6)

Bond lengths (Å)

	Average	Minimum	Maximum
Asa—O3a	1.685 (3)	1.671 (3)	1.709 (3)
Asa—O3b	1.679 (3)	1.677 (3)	1.680 (3)
Asa—O1a	1.682 (2)	1.671 (2)	1.692 (2)
Asa—O2	1.739 (3)	1.712 (3)	1.779 (3)
Asb—O3c	1.671 (3)	1.665 (3)	1.675 (3)
Asb—O3d	1.652 (3)	1.618 (3)	1.680 (3)
Asb—O1b	1.686 (2)	1.674 (2)	1.695 (2)
Asb—O2	1.714 (3)	1.690 (3)	1.757 (3)
Nia—O3a	2.087 (3)	2.053 (3)	2.131 (3)
Nia—O3c^i	2.033 (3)	2.021 (3)	2.052 (3)
Nia—O3b^ii	2.112 (3)	2.051 (3)	2.162 (3)
Nia—O1a^iii	2.099 (2)	2.049 (2)	2.144 (2)
Nia—O1b^iv	2.067 (3)	2.048 (3)	2.084 (3)
Nib—O3a	2.112 (3)	2.056 (3)	2.158 (3)
Nib—O3c^v	2.167 (3)	2.064 (3)	2.228 (3)
Nib—O3b^iv	2.082 (3)	2.041 (2)	2.116 (3)
Nib—O1a^i	2.062 (2)	2.049 (2)	2.087 (3)
Nib—O3d^vi	2.001 (3)	1.967 (3)	2.026 (3)
Nib—O1b^vii	2.048 (3)	2.011 (2)	2.115 (3)

Symmetry codes: (i) x₁, x₂, x₃−1, x₄; (ii) x₁−1/2, x₂+1/2, x₃, x₄; (iii) x₁−1/2, x₂+1/2, x₃−1, x₄; (iv) x₁+1/2, x₂+1/2, x₃, x₄; (v) x₁+1, x₂, x₃−1, x₄; (vi) x₁+1/2, x₂+1/2, x₃−1, x₄; (vii) x₁+1, x₂, x₃, x₄.

Zinc(II) diarsenate(V) (alpha-Zn2As2O7-superspace)

Crystal data

As2O7Zn2	F(000) = 364
Mr = 392.6	Dx = 4.886 Mg m^−3
Monoclinic, C2/m(α0γ)0s†	Mo Kα radiation, λ = 0.71073 Å
q = -0.33333a* + 0.50000c*	Cell parameters from 10939 reflections
a = 6.8601 (1) Å	θ = 3.5–44.9°
b = 8.4366 (1) Å	µ = 21.28 mm^−1
c = 4.8090 (1) Å	T = 240 K
β = 106.5640 (7)°	Plate, colourless
V = 266.76 (1) Å^3	0.18 × 0.12 × 0.02 mm
Z = 2

† Symmetry operations: (1) x₁, x₂, x₃, x₄; (2) −x₁, x₂, −x₃, −x₄+1/2; (3) −x₁, −x₂, −x₃, −x₄; (4) x₁, −x₂, x₃, x₄+1/2; (5) x₁+1/2, x₂+1/2, x₃, x₄; (6) −x₁+1/2, x₂+1/2, −x₃, −x₄+1/2; (7) −x₁+1/2, −x₂+1/2, −x₃, −x₄; (8) x₁+1/2, −x₂+1/2, x₃, x₄+1/2.

Data collection

Bruker APEXII CCD diffractometer	4899 reflections with I > 3σ(I)
Radiation source: X-ray tube	Rint = 0.048
Graphite monochromator	θmax = 45.0°, θmin = 2.1°
Absorption correction: multi-scan SADABS (Bruker, 2008)	h = −7→14
Tmin = 0.361, Tmax = 0.749	k = −16→16
39828 measured reflections	l = −10→10
6626 independent reflections

Refinement

Refinement on F	0 constraints
R[F^2 > 2σ(F^2)] = 0.023	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
wR(F^2) = 0.032	(Δ/σ)max = 0.033
S = 1.24	Δρmax = 1.04 e Å^−3
6626 reflections	Δρmin = −0.94 e Å^−3
149 parameters	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
0 restraints	Extinction coefficient: 1920 (50)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Zn	0.5	0.187161 (13)	0	0.00700 (3)
As	0.785841 (14)	0	0.58964 (2)	0.00487 (2)
O1	0.60574 (12)	0	0.27260 (16)	0.00742 (16)
O2	1	0	0.5	0.0148 (3)
O3	0.78483 (9)	−0.16134 (7)	0.78056 (12)	0.00979 (12)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn	0.00729 (5)	0.00552 (4)	0.00727 (5)	0	0.00060 (3)	0
As	0.00486 (4)	0.00511 (4)	0.00420 (4)	0	0.00059 (3)	0
O1	0.0086 (3)	0.0064 (2)	0.0052 (2)	0	−0.0013 (2)	0
O2	0.0077 (4)	0.0195 (5)	0.0199 (5)	0	0.0081 (3)	0
O3	0.0109 (2)	0.00777 (18)	0.0103 (2)	0.00233 (14)	0.00237 (16)	0.00395 (15)