Received 19 September 2012
The anion of the title salt, C6H9N2+·C6H4NO3-, undergoes an enol-to-keto tautomerism during the crystallization. In the crystal structure, the cation and anion are held together by a relatively short N-HO hydrogen bond, and the two anions are further connected to each other by a pair of N-HO hydrogen bonds with an R22(8) ring motif, thus forming a centrosymmetric 2 + 2 aggregate. The aggregates are further linked through weak N-HO and C-HO hydrogen bonds, resulting a three-dimensional network.
For details of 2-aminopyridine and its derivatives, see: Banerjee & Murugavel (2004); Bis & Zaworotko (2005); Bis et al. (2006). For details of 6-hydroxypicolinic acid, see: Sun et al. (2004); Soares-Santos et al. (2003). For a related structure, see: Sawada & Ohashi (1998). For hydrogen-bond motifs, see: Bernstein et al. (1995). For bond-length data, see: Allen et al. (1987). For stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: IS5197 ).
The authors thank the Malaysian Government and Universiti Sains Malaysia (USM) for research facilities and the Fundamental Research Grant Scheme (FRGS) No. 203/PFIZIK/6711171 to conduct this work. KT thanks The Academy of Sciences for the Developing World and USM for a TWAS-USM fellowship.
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