Redetermination of (NH4)2HAsO4

Weil, M.

doi:10.1107/S1600536812043565

Volume 68
Part 11
Page i82
November 2012

Received 14 October 2012
Accepted 20 October 2012
Online 27 October 2012

Key indicators
Single-crystal X-ray study
T = 293 K
Mean (As-O) = 0.002 Å
R = 0.022
wR = 0.055
Data-to-parameter ratio = 16.6
Details

Redetermination of (NH₄)₂HAsO₄

Matthias Weil ^a ^*

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

In comparison with the original determination based on Weissenberg film data [Khan et al. (1970). Acta Cryst. B26, 1889-1892], the current redetermination of diammonium hydrogenarsenate(V) reveals all atoms with anisotropic displacement parameters and all H atoms localized. This allowed an unambiguous assignment of the hydrogen-bonding pattern, which is similar to that of the isotypic phosphate analogue (NH₄)₂HPO₄. The structure of the title compound consists of slightly distorted AsO₃(OH) and NH₄ tetrahedra, linked into a three-dimensional structure by an extensive network of O-HO and N-HO hydrogen bonds.

Related literature

For the previous determination of (NH₄)₂HAsO₄, see: Khan et al. (1970). The arsenate compound is isotypic with the phosphate analogue (NH₄)₂HPO₄ (Khan et al., 1972), for which another modification with Z' = 2 has also recently been described (Kunz et al., 2010).

Experimental

Crystal data

(NH₄)₂HAsO₄
M_r = 176.01
Monoclinic, P 2₁ /c
a = 11.3426 (4) Å
b = 6.8512 (3) Å
c = 8.1130 (3) Å
= 113.784 (4)°
V = 576.92 (4) Å³
Z = 4
Mo K radiation
= 5.82 mm^-1
T = 293 K
0.14 × 0.12 × 0.02 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009) T_min = 0.496, T_max = 0.873
6318 measured reflections
1674 independent reflections
1413 reflections with I > 2(I)
R_int = 0.033

Refinement

R[F² > 2(F²)] = 0.022
wR(F²) = 0.055
S = 1.04
1676 reflections
101 parameters
All H-atom parameters refined
_max = 0.59 e Å^-3
_min = -0.84 e Å^-3

Table 1
Hydrogen-bond geometry (Å, °)

D-HA	D-H	HA	DA	D-HA
N1-H3N1O2ⁱ	0.87 (3)	1.88 (3)	2.750 (2)	178 (3)
N1-H1N1O3ⁱⁱ	0.91 (3)	1.91 (3)	2.780 (3)	158 (2)
N1-H2N1O3ⁱ	0.89 (3)	2.06 (3)	2.930 (3)	167 (2)
N1-H4N1O3ⁱⁱⁱ	0.92 (3)	1.86 (3)	2.777 (2)	173 (3)
N2-H4N2O2	0.92 (3)	2.00 (3)	2.910 (2)	174 (2)
N2-H2N2O2ⁱ	0.89 (3)	1.93 (3)	2.809 (2)	174 (2)
N2-H1N2O4	0.83 (3)	2.02 (3)	2.840 (2)	171 (3)
N2-H3N2O4^iv	0.85 (3)	1.95 (3)	2.793 (2)	176 (3)
O1-H1OO4^v	0.73 (3)	1.89 (3)	2.613 (2)	171 (4)
Symmetry codes: (i) $[x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (ii) -x+1, -y+1, -z+1; (iii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) $[-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (v) $[x, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ATOMS (Dowty, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB6976 ).

Acknowledgements

The X-ray centre of the Vienna University of Technology is acknowledged for providing access to the single-crystal diffractometer.

References

Bruker (2009). APEX2, SAINT and SADABS. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.
Dowty, E. (2006). ATOMS. Shape Software, Kingsport, Tennessee, USA.
Khan, A. A., Roux, J. P. & James, W. J. (1972). Acta Cryst. B28, 2065-2069.
Khan, A. A., Straumanis, E. & James, W. J. (1970). Acta Cryst. B26, 1889-1892.
Kunz, P. C., Wetzel, C. & Spingler, B. (2010). Acta Cryst. E66, i26-i27.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.

inorganic compounds