Crystal structure of 5-amino-4H-1,2,4-triazol-1-ium pyrazine-2-carboxylate: an unexpected salt arising from the decarboxylation of both precursors

• Autor(a) principal: Fernandes, Jose A.
• Data de Publicação: 2015
• Outros Autores: Liu, Bing, Tome, Joao P. C., Cunha-Silva, Luis, Almeida Paz, Filipe A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/20535
• topic: MOLECULAR CO-CRYSTALS; CARBOXYLIC-ACIDS; IONIC LIQUIDS; 3-AMINO-1,2,4-TRIAZOLE; COCRYSTALS; ADDUCTS; 3-AMINO-1H-1,2,4-TRIAZOLE; 2-AMINOPYRIMIDINE; 3-HYDROXYPYRIDINE

Both the 3-amino-2H,4H-1,2,4-triazolium cation and the pyrazine-2-carboxylate anion in the title salt, C2H5N4+center dot C5H3N2O2-, were formed by an unexpected decarboxylation reaction, from 5-amino-1H-1,2,4-triazole-3-carboxylic acid and pyrazine-2,3-dicarboxylic acid, respectively. The dihedral angle between the pyrazine ring (r.m.s. deviation = 0.008 angstrom) and the carboxylate group in the anion is 3.7 (3)degrees. The extended structure of the salt contains a supramolecular zigzag tape in which cations and anions are engaged in strong and highly directional N-H center dot center dot center dot 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 pi-pi stacking interactions between the triazole and pyrazine rings.