Received 18 October 2011
In the title molecular salt, C5H7N2+·C8H5N2O7-, the 2-aminopyridinium cation is essentially planar, with a maximium deviation of 0.015 (1) Å, while the 2-methoxycarbonyl-4,6-dinitrophenolate anion is slightly twisted away from planarity, with a maximium deviation of 0.187 (1) Å. Deprotonation of the hydroxy O atom was observed. The cation and anion are connected by four bifurcated N-H(O,O) hydrogen bonds, forming a molecular proton-transfer adduct. The dihedral angle between the pyridinium ring in the cation and the benzene ring in the anion is 3.65 (6)°. Every adduct connects to six neighboring adducts by N-HO and C-HO hydrogen bonds, yielding extended layers parallel to the bc plane. There is a weak - interaction between the benzene rings of two neighboring anions; the interplanar spacing and the centroid-centroid separation are 3.309 (1) and 3.69 (1) Å, respectively.
For the structures of molecular proton-transfer adducts containing substituted pyridinium and an acid anion, see Gellert & Hsu (1988); Smith et al. (2000); Jebas et al. (2006); Rademeyer (2007); Hemamalini & Fun (2010a,b,c); Perpétuo & Janczak (2010). For comparable structures, see: Jebas et al. (2006); Perpétuo & Janczak (2010); Hemamalini & Fun (2010a). For the synthesis of 3,5-dinitromethyl salicylate, see: Bartlett & Trachten (1958).
Data collection: RAPID-AUTO (Rigaku, 2008); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEX (McArdle, 1995); software used to prepare material for publication: SHELXL97.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: EZ2268 ).
This project was supported financially by the Natural Science Foundation of China (No. 50971063) and the Natural Science Foundation of Fujian Province (Nos. E0640006, 2003F006, 2010J01042).
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