(NH₄)₂WTe₂O₈ at 5.09 GPa: a single-crystal study using synchrotron radiation

The polar crystal structure of diammonium [octaoxidodi­tellurato(IV)]tungstate, (NH₄)₂WTe₂O₈, was studied at high pressures using single-crystal X-ray diffraction in a diamond-anvil cell at the HASYLAB synchrotron (DESY, Hamburg, Germany). No phase transition was observed up to 7.16 GPa. However, a full structure determination at 5.09 GPa shows that the coordination number of one of the two non-equivalent Te atoms has decreased from four to three.

Computing details

Data collection: XDS (Kabsch, 2010); cell refinement: XDS (Kabsch, 2010); data reduction: XDS (Kabsch, 2010) JANA2006 (Petricek et al., 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1997); program(s) used to refine structure: JANA2006 (Petricek et al., 2006); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: JANA2006 (Petricek et al., 2006).

Diammonium [oxtaoxidoditellurato(IV)]tungstate

Crystal data

(NH4)2WTe2O8	F(000) = 520
Mr = 603.1	Dx = 4.912 Mg m^−3
Monoclinic, P21	Synchrotron radiation, λ = 0.3978 Å
Hall symbol: P 2yb	Cell parameters from 1027 reflections
a = 6.443 (1) Å	θ = 1.8–21.2°
b = 6.883 (1) Å	µ = 4.24 mm^−1
c = 9.301 (1) Å	T = 295 K
β = 98.8 (2)°	Irregular plate shape, colourless
V = 407.7 (2) Å^3	0.03 × 0.01 × 0.01 mm
Z = 2

Data collection

Huber diffractometer	599 independent reflections
Radiation source: Beamline D3, Hasylab	599 reflections with I > 3σ(I)
ROMO monochromator	Rint = 0.142
rotation method scans	θmax = 21.2°, θmin = 1.8°
Absorption correction: numerical (JANA2006; Petricek et al., 2006)	h = −10→10
Tmin = 0.471, Tmax = 0.610	k = −11→10
1027 measured reflections	l = −8→9

Refinement

Refinement on F	H-atom parameters not defined?
R[F > 3σ(F)] = 0.112	Weighting scheme based on measured s.u.'s w = 1/(σ^2(F) + 0.0001F^2)
wR(F) = 0.095	(Δ/σ)max = 0.006
S = 2.27	Δρmax = 4.55 e Å^−3
599 reflections	Δρmin = −4.06 e Å^−3
48 parameters	Absolute structure: refinement as inversion twin
0 restraints	Absolute structure parameter: 0.0 (1)
0 constraints

Special details

Experimental. Synchrotron data: Beamline D3, Hasylab, Hamburg, Germany

Refinement. Te, O and N isotropic. Displacement parameters of O restricted to be equal. Displacement parameters of N not refined. No H-atoms taken into account.

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

	x	y	z	Uiso*/Ueq
W1	0.3239 (6)	0.4253	0.2616 (11)	0.017 (3)
Te1	0.5450 (9)	0.2104 (8)	0.0057 (16)	0.0052 (14)*
Te2	0.4640 (10)	0.4748 (8)	0.6432 (18)	0.0073 (16)*
O1	0.180 (9)	0.255 (7)	0.296 (15)	0.006 (5)*
O2	0.127 (8)	0.593 (7)	0.169 (14)	0.006 (5)*
O3	0.441 (9)	0.572 (7)	0.442 (15)	0.006 (5)*
O4	0.290 (9)	0.274 (7)	0.084 (14)	0.006 (5)*
O5	0.566 (9)	0.240 (7)	0.290 (14)	0.006 (5)*
O6	0.565 (9)	0.564 (7)	0.157 (15)	0.006 (5)*
O7	0.509 (8)	0.385 (6)	−0.148 (16)	0.006 (5)*
O8	0.177 (7)	0.391 (6)	0.591 (13)	0.006 (5)*
N1	0.034 (10)	0.964 (9)	0.107 (17)	0.007*
N2	0.868 (11)	0.519 (8)	0.402 (19)	0.007*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
W1	0.0070 (14)	0.0070 (12)	0.037 (9)	−0.0018 (19)	0.000 (3)	0.003 (3)

Geometric parameters (Å, º)

W1—O1	1.55 (7)	O2—O4	2.60 (10)
W1—O2	1.83 (7)	O2—O6	2.85 (9)
W1—O3	2.00 (11)	O2—N1	2.67 (8)
W1—O4	1.93 (12)	O2—N1^vii	2.76 (18)
W1—O5	2.00 (5)	O2—N2^vi	2.96 (19)
W1—O6	2.18 (9)	O3—O5	2.87 (12)
Te1—O2^i	2.97 (10)	O3—O5^ii	2.75 (18)
Te1—O4	1.95 (9)	O3—O6	2.88 (19)
Te1—O5	2.64 (13)	O3—O8	2.66 (13)
Te1—O6	2.81 (8)	O3—N2	2.86 (11)
Te1—O6^i	1.87 (11)	O4—O5	2.42 (14)
Te1—O7	1.85 (12)	O4—O6	2.69 (8)
Te1—O7^i	2.65 (9)	O4—O6^i	2.94 (16)
Te2—O1^ii	2.98 (6)	O4—O7	2.86 (17)
Te2—O3	1.97 (13)	O4—N1^v	2.72 (9)
Te2—O3^iii	2.97 (6)	O4—N1^vii	2.84 (13)
Te2—O5^ii	1.94 (6)	O5—O6	2.55 (11)
Te2—O7^iv	2.02 (14)	O5—O7^i	2.79 (11)
Te2—O8	1.93 (5)	O5—N2	2.82 (9)
O1—O2	2.61 (10)	O6—O7^viii	2.25 (7)
O1—O3	2.95 (10)	O6—N2	2.78 (17)
O1—O4	2.19 (18)	O7—O8^ix	2.98 (14)
O1—O5	2.49 (9)	O7—N1^i	2.96 (8)
O1—O8	2.90 (18)	O8—N2^vi	2.60 (13)
O1—N1^v	2.73 (14)	O8—N2^iii	2.58 (7)
O1—N2^vi	2.99 (12)
O1—W1—O2	100 (3)	O6^i—Te1—O7	74 (4)
O1—W1—O3	112 (6)	O6^i—Te1—O7^i	84 (4)
O1—W1—O4	77 (5)	O7—Te1—O7^i	157 (3)
O1—W1—O5	88 (3)	O1^ii—Te2—O3	85 (3)
O1—W1—O6	156 (4)	O1^ii—Te2—O3^iii	118.1 (17)
O2—W1—O3	103 (3)	O1^ii—Te2—O5^ii	56 (2)
O2—W1—O4	87 (4)	O1^ii—Te2—O7^iv	91 (3)
O2—W1—O5	159 (5)	O1^ii—Te2—O8	157.0 (17)
O2—W1—O6	90 (3)	O3—Te2—O3^iii	93 (3)
O3—W1—O4	165 (3)	O3—Te2—O5^ii	89 (4)
O3—W1—O5	91 (3)	O3—Te2—O7^iv	176 (2)
O3—W1—O6	87 (4)	O3—Te2—O8	86 (4)
O4—W1—O5	76 (4)	O3^iii—Te2—O5^ii	174 (2)
O4—W1—O6	82 (4)	O3^iii—Te2—O7^iv	88 (3)
O5—W1—O6	75 (3)	O3^iii—Te2—O8	83 (2)
O2^i—Te1—O4	168 (4)	O5^ii—Te2—O7^iv	89 (4)
O2^i—Te1—O5	130 (2)	O5^ii—Te2—O8	103 (2)
O2^i—Te1—O6	122 (2)	O7^iv—Te2—O8	98 (4)
O2^i—Te1—O6^i	68 (3)	W1—O1—Te2^iii	94 (3)
O2^i—Te1—O7	77 (3)	W1—O2—Te1^viii	86 (2)
O2^i—Te1—O7^i	102 (2)	W1—O3—Te2	126 (3)
O4—Te1—O5	62 (4)	W1—O3—Te2^ii	108 (5)
O4—Te1—O6	66 (2)	Te2—O3—Te2^ii	126 (4)
O4—Te1—O6^i	101 (4)	W1—O4—Te1	117 (3)
O4—Te1—O7	97 (4)	W1—O5—Te1	90 (4)
O4—Te1—O7^i	80 (3)	W1—O5—Te2^iii	122 (4)
O5—Te1—O6	56 (3)	Te1—O5—Te2^iii	105 (4)
O5—Te1—O6^i	144 (3)	W1—O6—Te1	81.9 (16)
O5—Te1—O7	135 (3)	W1—O6—Te1^viii	113 (3)
O5—Te1—O7^i	64 (3)	Te1—O6—Te1^viii	94 (5)
O6—Te1—O6^i	149 (3)	Te1—O7—Te1^viii	100 (6)
O6—Te1—O7	80 (4)	Te1—O7—Te2^ix	158 (5)
O6—Te1—O7^i	119 (4)

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