title: 2,3-Diamino-pyridinium hydrogen malonate.
abstract: In the title mol-ecular salt, C5H8N3(+)·C3H3O4(-), the cation is essentially planar, with a maximum deviation of 0.005 (1) Å for all non-H atoms. In the anion, an intra-molecular O-H⋯O hydrogen bond generates an S(6) ring. In the crystal, the cations and anions are connected via N-H⋯O hydrogen bonds and a weak C-H⋯O inter-action, forming layers parallel to the ab plane.
authors.affiliation: School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia.
authors.forename: Kaliyaperumal
authors.initials: K
authors.lastname: Thanigaimani
authors.forename: Nuridayanti Che
authors.initials: NC
authors.lastname: Khalib
authors.forename: Suhana
authors.initials: S
authors.lastname: Arshad
authors.forename: Ibrahim Abdul
authors.initials: IA
authors.lastname: Razak