2-Chloro­pyrimidin-4-amine

In the title pyrimidine derivative, C₄H₄ClN₃, the 2-chloro and 4-amino substituents almost lie in the mean plane of the pyrimidine ring, with deviations of 0.003 (1) Å for the Cl atom, and 0.020 (1) Å for the N atom. In the crystal, molecules are linked via pairs of N—H...N hydrogen bonds, forming inversion dimers. These dimers are further linked via N—H...N hydrogen bonds, forming an undulating two-dimensional network lying parallel to (100).

3-Carb­oxy­pyridinium nitrate

In the crystal structure of the title compound, C₆H₆NO₂⁺·NO₃⁻, the protonated cations are linked by N—H...O hydrogen bonds into chains along the b axis. The cations and anions are also linked by N—H...O and O—H...O hydrogen bonds. C—H...O inter­actions also occur. In the cation, the ring makes a dihedral angle of 10.1 (3)° with the carboxylate group.