Crystal structure of 5-amino-4H-1,2,4-triazol-1-ium pyrazine-2-carboxyl-ate: an unexpected salt arising from the deca-rboxylation of both precursors.
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.
Department of Chemistry, CICECO - Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal.
José A
JA
Fernandes
REQUIMTE / LAQV & Departamento de Química e Bioquímica, Faculdade de Ciencias, Universidade do Porto, 4169-007 Porto, Portugal.
Bing
B
Liu
Department of Chemistry, QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal ; Department of Organic and Macromolecular Chemistry, Ghent University, B-9000 Ghent, Belgium.
João P C
JP
Tomé
REQUIMTE / LAQV & Departamento de Química e Bioquímica, Faculdade de Ciencias, Universidade do Porto, 4169-007 Porto, Portugal.
Luís
L
Cunha-Silva
Department of Chemistry, CICECO - Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal.
Filipe A
FA
Almeida Paz
crystal structure; deca­rboxylation; hydrogen bonding; ionothermal synthesis; triazolium salt; π–π stacking inter­actions