The asymmetric unit of the second polymorph of the title compound, C(2)H(9)NO(6)P(2), contains one mol-ecule existing as a zwitterion. The N atom of the ammonio group is protonated and one of the phospho-nic acid groups is deprotonated. Bond lengths and angles are similar in both polymorphs. Besides the differences in cell parameters, the most significant structural difference between this stru...

The title mol-ecular salt, C6H8N(+)·C6H2N3O7 (-) (systematic name: 3-methyl-pyridinium 2,4,6-tri-nitro-phenolate), crystallizes in the triclinic space group P-1. The crystal structure of the monoclinic polymorph (space group P21/n) has been reported [Stilinovic & Kaitner (2011 ▸). Cryst. Growth Des. 11, 4110-4119]. In the crystal, the anion and cation are linked via bifurcated N-H⋯(O,O) hydroge...

THE ASYMMETRIC UNIT OF THE TRICLINIC POLYMORPH OF THE TITLE COMPOUND (SYSTEMATIC NAME: 4-cyano-pyridinium 2,5-dichloro-4-hy-droxy-3,6-dioxocyclo-hexa-1,4-dien-1-olate), C(6)H(5)N(2) (+)·C(6)HCl(2)O(4) (-), consists of two crystallographically independent cation-anion units, in each of which the cation and the anion are linked by an N-H⋯O hydrogen bond. In the units, the dihedral angles between ...