Abstract
Both the 3-amino-2H,4H-1,2,4-triazolium cation and the pyrazine-2-carboxyl-ate anion in the title salt, C2H5N4 (+)·C5H3N2O2 (-), were formed by an unexpected deca-rboxylation reaction, from 5-amino-1H-1,2,4-triazole-3-carb-oxy-lic acid and pyrazine-2,3-di-carb-oxy-lic acid, respectively. The dihedral angle between the pyrazine ring (r.m.s. deviation = 0.008 Å) and the carboxyl-ate group in the anion is 3.7 (3)°. The extended structure of the salt contains a supra-molecular zigzag tape in which cations and anions are engaged in strong and highly directional N-H⋯N,O hydrogen bonds, forming R 2 (2)(8) and R 2 (2)(9) graph-set motifs. The packing between the tapes is mediated by π-π stacking inter-actions between the triazole and pyrazine rings.
Highlights
The title compound is a product of decomposition of the H2atrc and H2Pzdc organic molecules by way of decarboxylation leading to, respectively, 3-amino-2H,4H-1,2,4-triazolium doi:10.1107/S205698901501172X
The cation present in the title compound is rich in groups capable of forming strong N—HÁ Á ÁN,O hydrogen-bonding interactions, many highly directional with the observed
Hydrogen atoms bound to carbon were placed at idealized positions with C—H = 0.95 A, and included in the final structural model in a riding-motion approximation with the isotropic thermal displacement parameters fixed at 1.2Ueq of the carbon atom to which they are attached
Summary
A remarkable feature of ionothermal synthesis is the fact that ionic liquids (ILs) can act simultaneously as sustainable solvents and structure-directing agents ( known as templates). This has been widely demonstrated by their potential in the discovery of unprecedented crystalline materials (Xu et al, 2013). Following our interest in the design and preparation of new types of metal-organic frameworks (MOFs), we have been exploring the use of 5-amino-1H-1,2,4triazole-3-carboxylic acid (H2atrc) and pyrazine-2,3-dicarboxylic acid (H2Pzdc) as a double-ligand system in the presence of transition metal centers using ionothermal synthetic conditions. In the presence of AgNO3 the obtained product revealed, to be an unexpected organic salt (Bond, 2007) composed of the 3-amino-2H,4H(+)-1,2,4-triazolium cation and the pyrazine-2-carboxylato anion
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