Acta Cryst. (2009). E65, o126  [ doi:10.1107/S1600536808042165 ]

3-Phenyl-1H-1,2,4-triazol-5-amine-5-phenyl-1H-1,2,4-triazol-3-amine (1/1)

A. V. Dolzhenko, G. K. Tan, L. L. Koh, A. V. Dolzhenko and W. K. Chui

Abstract: In the title compound, C₈H₈N₄·C₈H₈N₄, two tautomers, viz. 3-phenyl-1,2,4-triazol-5-amine and 5-phenyl-1,2,4-triazol-3-amine, are crystallized together in equal amounts. The 3-phenyl-1,2,4-triazol-5-amine molecule is essentially planar; the phenyl ring makes a dihedral angle of 2.3 (2)° with the mean plane of the 1,2,4-triazole ring. In the 5-phenyl-1,2,4-triazol-3-amine tautomer, the mean planes of the phenyl and 1,2,4-triazole rings form a dihedral angle of 30.8 (2)°. The -electron delocalization of the amino group with the 1,2,4-triazole nucleus in the 3-phenyl-1,2,4-triazol-5-amine molecule is more extensive than that in the 5-phenyl-1,2,4-triazol-3-amine tautomer. The molecules are linked into a two-dimensional network parallel to (100) by N-HN hydrogen bonds.

Online 17 December 2008

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