Received 4 March 2010
In the title compound, C6H7N2O2+·I3-·H2O, the triiodide anions form two-dimensional sheets along the a and c axes. These sheets are separated by the 4-nitroanilinium cations and water molecules, which form part of an extended hydrogen-bonded chain with the triiodide along the c axis, represented by the graph set C33(14). The second important hydrogen-bonding interaction is between the nitro group, the water molecule and the anilinium group, which forms an R22(6) ring and may be the reason for the deviation of the torsion angle between the benzene ring and the nitro group from 180 to 163.2 (4)°. These two strong hydrogen-bonding interactions also cause the benzene rings to pack off-centre from one another, with an edge-on-edge - stacking distance of 3.634 (6) Å and a centroid-centroid separation of 4.843 (2) Å.
For structures of 4-nitroanilinine-monohalide salts, see: Lemmerer & Billing (2006) (bromine) and Ploug-Sørensen & Andersen (1982) (chlorine). For other amine-based triiodide salts, see: Tebbe & Loukili (1998). For a triiodide salt containing a tetraphenylphosphonium cation, see: Parvez et al. (1996). For structure-properties relationships in trihalides, see: Shibaeva & Yagubskii (2004). For graph-set analysis, see: Etter et al. (1990).
Data collection: SMART-NT (Bruker, 1998); cell refinement: SMART-NT; data reduction: SAINT-Plus (Bruker, 1999); program(s) used to solve structure: XS in SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: ZS2032 ).
The University of the Witwatersrand and the National Research Fund (GUN: 2069064) are thanked for the award of a research grant and for providing the infrastructure required to do this work.
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