Metal–nucleobase inter­action: bis[4-amino­pyrimidin-2(1H)-one-κN 3]dibromidozinc(II)

In the title complex, [ZnBr2(C4H5N3O)2], the central metal ion is coordinated to two bromide ions and endocyclic N atoms of the two cytosine mol­ecules leading to a distorted tetra­hedral geometry. The structure is isotypic with [CdBr2(C4H5N3O)2] [Muthiah et al. (2001). Acta Cryst. E57, m558–m560]. There are two inter­ligand N—H⋯Br hydrogen bonds, generating two hydrogen-bonded rings stabilizing the coordination sphere. The complex aggregates, forming supra­molecular chains, sheets and staircases through N—H⋯O and N—H⋯Br hydrogen bonding and π–π stacking inter­actions [centroid–centroid distance = 3.616 (2) Å]

Crystal structure of 4-amino-5-fluoro-2-oxo-2,3-dihydropyrimidin-1-ium 3-hydroxypyridine-2-carboxylate

The asymmetric unit of the title salt, C4H5FN3O+·C6H4NO3−, contains one 4-amino-5-fluoro-2-oxo-2,3-dihydropyrimidin-1-ium (5-fluorocytosinium, 5FC) cation and a 3-hydroxypicolinate (3HAP) anion. The 4-amino-5-fluoro-2-oxo-2,3-dihydropyrimidine molecule is protonated at one of the pyrimidine N atoms. The typical intramolecular N—H...F and O—H...O S(5) and S(6) hydrogen-bond ring motifs are observed in the cations and anions. The protonated N atom and 2-amine group of the 5FC cation interact with the 3HPA anion through a pair of nearly parallel N—H...O hydrogen bonds, forming a robust R22(8) ring motif. The ions are further linked by N—H...N, O—H...O, N—H...O and C—H...O hydrogen bonds, generating R22(7), R33(12) and R65(18) ring motifs, respectively, leading to supramolecular wave-like sheets parallel to (010). The crystal structure is further stabilized by C—H...π interactions, generating a three-dimensional architecture

Redetermination of the crystal structure of 2-oxo-1,3-thiazolidin-4-iminium chloride

In the redetermination of the title compound, C3H5N2OS+·CI−, the asymmetric unit consists of one independent 2-oxo-1,3-thiazolidin-4-iminium cation and one independent chloride anion. The cation interacts with a chloride anion via N—H...Cl hydrogen bonds forming a supramolecular chain along [010]. These supramolecular chains are further extended by weak C—H...Cl and C—H...O interactions, forming a two-dimensional network parallel to (001). The crystal structure is further stabilized by weak C—O...π interactions, supporting a three-dimensional architecture. The structure was previously determined by Ananthamurthy & Murthy [Z. Kristallogr. (1975). 8, 356–367] but has been redetermined with higher precision to allow the hydrogen-bonding patterns and supramolecular interactions to be investigated