Received 25 January 2013
aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia,bDepartment of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia,cH. E. J Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75720, Pakistan, and dDepartment of Pure and Applied Chemistry, University of Calabar, P. M. B. 1115, Calabar, Nigeria
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The asymmetric unit of the title compound, 2C2H6N5+·C4O42-, contains two 3,5-diamino-4H-1,2,4-triazolium cations and one squarate dianion. The squaric acid molecule donated one H atom to each of the two 3,5-diamino-1,2,4-triazole molecules at their N atoms. The squaric acid dianion has four C-O bonds which are shorter than a normal single C-O bond (1.426 Å) and are slightly longer than a normal C=O bond (1.23 Å), which indicates the degree of electron delocalization in the dianion. In the crystal, the cations and dianions are linked by N-HN and N-HO hydrogen bonds into a three-dimensional network.
For background to the acid-base chemistry of squarate acid, see: Mathew et al. (2002); Frankenbach et al. (1992); Yesilel et al. (2008); Bertolasi et al. (2001); Correa et al. (2007). For a related structure, see: Uçar et al. (2004). For the stability of the temperature controller used for 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: RZ5040 ).
HKF and WSL thank the Malaysian Government and Universiti Sains Malaysia (USM) for the Research University Grant (1001/CIPPM813040). WSL also thanks the Malaysian Government and USM for the post of Research Officer under the Research University Grant (1001/PFIZIK/811160). AJ thanks the Academy of Science for the Developing World (TWAS) for the award of a Research and Advanced Training Fellowship and the H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Pakistan, for providing research facilities. SY thanks the School of Physics, Universiti Sains Malaysia, for providing X-ray diffraction research facilities.
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