Crystal structure and thermal behaviour of pyridinium styphnate.

In the crystal structure of the title mol-ecular salt, C5H6N(+)·C6H2N3O8 (-) (systematic name: pyridinium 3-hy-droxy-2,4,6-tri-nitro-phenolate), the pyridin-ium cation and the 3-hy-droxy-2,4,6-tri-nitro-phenolate anion are linked through bifurcated N-H⋯(O,O) hydrogen bonds, forming an R 1 (2)(6) ring motif. The nitro group para with respect to phenolate ion forms an intra-molecular hydrogen bond with the adjacent phenolic -OH group, which results in an S(6) ring motif. The nitro group flanked by the phenolate ion and the phenolic -OH group deviates noticeably from the benzene ring, subtending a dihedral angle of 89.2 (4)°. The other two nitro groups deviate only slightly from the plane of the benzene ring, making dihedral angles of 2.8 (4) and 3.4 (3)°. In the crystal, the 3-hy-droxy-2,4,6-tri-nitro-phenolate anions are linked through O-H⋯O hydrogen bonds, forming chains along [100]. These anionic chains, to which the cations are attached, are linked via C-H⋯O hydrogen bonds, forming a three-dimensional structure. Impact friction sensitivity tests and TGA/DTA studies on the title mol-ecular salt imply that it is an insensitive high-energy-density material.