1-(2-Methyl-5-nitro-phenyl)guanidinium picrate.

In the crystal structure of the title salt, C(8)H(11)N(4)O(2) (+)·C(6)H(2)N(3)O(7) (-), the pictrate anion participates in extensive hydrogen bonding with the guanidinium ion group of the cation, linking the mol-ecules through N(+)-H⋯O(-) hydrogen bonds and inter-molecular N-H⋯O and C-H⋯O inter-actions. These hydrogen-bonding configurations involve two three-centre/bifurcated bonds [N-H⋯(O,O)] that are observed between two N atoms from the guanidinium ion group of the cation and the o-NO(2) and phenolate O atoms of the picrate anion. In addition, π-π inter-actions also contribute to the crystal packing, with a centroid-to-centroid distance of 3.693†(6)†à and a slippage angle of 1.614°. A significant number of conformational differences are observed between the salt in the crystal structure and the models obtained by density functional theory (DFT) calculations of the geometry-optimized structure.