Received 14 October 2012
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.
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).
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 ).
The X-ray centre of the Vienna University of Technology is acknowledged for providing access to the single-crystal diffractometer.
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.