The title compound, C(10)H(7)N(5)O(2), was synthesized by the reaction of 4-nitro-aniline and 2,3-dicyano-propionic acid ethyl ester. In the crystal, N-H⋯O and C-H⋯O hydrogen bonds link the mol-ecules, forming a three-dimensional network.

In the title compound, C(11)H(12)N(4)S, the thio-phene ring is roughly planar, with a maximum deviation of 0.012 (1) Å for the S atom, and makes a dihedral angle of 7.89 (8)° with the mean plane of the piperidine ring, which is in a chair conformation. The crystal packing is stabilized by pairs of centrosymmetric inter-molecular N-H⋯N hydrogen bonds, which results in the formation of a step-wis...

In the cation of the title hydrated salt, C(11)H(9)N(4)O(4) (+)·Cl(-)·H(2)O, the six-membered rings are inclined to each other at 79.0 (1)° and an intra-molecular N-H⋯O hydrogen bond occurs. In the crystal, N-H⋯Cl hydrogen bonds link two cations and two anions into centrosymmetric group, and O-H⋯Cl hydrogen bonds involving the water mol-ecules further link these groups into chains in [101]. An ...

Accurate ab initio calculations at the B3LYP/6-311 G** level have been performed on anionic and neutral structures of 4,5-dihydro-5-oxo[1,2,4]triazolo[1,5-a]pyrimidine, 4,7-dihydro-7-oxo[1,2,4]triazolo[1,5-a]pyrimidine, and 4,5-dihydro-7-amino-5-oxo[1,2,4]triazolo[1,5-a]pyrimidine compounds. The quality of the theoretical results has been tested against the experimental X-ray structures for the...