The title compound, C(7)H(6)N(2)O(4), is approximately planar (r.m.s. deviation = 0.026 Å for the 13 non-H atoms). The mol-ecular structure is stabilized by intra-molecular N-H⋯O hydrogen bonds, which generate S(6) ring motifs. In the crystal, mol-ecules are linked via inter-molecular N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds into a three-dimensional network.

The asymmetric unit of the title compound, C(5)H(9)N(3) (2+)·2Cl(-), contains two diprotonated 2,3-diamino-pyridine cations and four chloride anions. In the crystal structure, the anions and cations are connected by inter-molecular N-H⋯Cl and C-H⋯Cl hydrogen bonds, forming a three-dimensional network. The crystal structure is further stabilized by π-π inter-actions between pyridinium rings [cen...

In the title mol-ecular salt, (C(5)H(6)N(3)O(2))[ReO(4)], the cations and tetrahedral anions are linked by trifurcated N-H⋯(O,O,O) and bifurcated N-H⋯(O,O) hydrogen bonds, as well as weak C-H⋯O inter-actions. This results in alternating corrugated inorganic and organic layers in the crystal.

In the title compound, C9H12N2O, the mean plane through the amide group and the benzene ring form a dihedral angle of 33.93 (7)°. An intra-molecular N-H⋯O hydrogen bond is present. In the crystal, mol-ecules are linked by N-H⋯N and N-H⋯O hydrogen bonds, forming double-stranded chains parallel to the b axis.

The asymmetric unit includes two crystallographically independent equivalents of the title salt, C(6)H(7)N(2)O(2) (+)·ClO(4) (-). The cations and anions form separate layers alternating along the c axis, which are linked by N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds into a two-dimensional network parallel to (100). Further C-H⋯O contacts connect these layers, forming a three-dimensional network, in ...

The title compound, C(5)H(6)N(3)O(2) (+)·ClO(4) (-), is comprised of discrete perchlorate anions and 2-amino-3-nitro-pyridinium cations. The anion has a typical tetra-hedral geometry while the cation presents a nearly planar [maximum deviation = 0.007 (8) Å] pyridinium ring. Undulating [C(5)H(6)N(3)O(2) (+)](n) chains extending along the c-axis direction are linked via N-H⋯O hydrogen bonds. The...

In the crystal structure of the title compound, C(6)H(7)N(2)O(2) (+)·NO(3) (-), the cations are linked via C-H⋯O hydrogen bonds, forming infinite chains running along the b axis. These chains are further linked through N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds to the nitrate anions, forming well-separated infinite planar layers parallel to (001).