4,4′-Butane-1,4-diylbis[3-ethyl-1H-1,2,4-triazol-5(4H)-one] and 4-hydroxy-3-n-propyl-1H-1,2,4-triazol-5(4H)-one

The title compounds, C12H20N6O2, ( I), and C5H9N3O2, ( II), display the characteristic features of 1,2,4- triazole derivatives. Compound ( I) lies about an inversion centre which is at the mid- point of the central C - C bond. Compound ( II) also contains a planar 1,2,4- triazole ring but differs from ( I) in that it has a hydroxy group attached to the ring. Molecules of ( I) are held together in the crystal structure by intermolecular N - H center dot center dot center dot O contacts and by weak pi-pi stacking interactions between the 1,2,4- triazole moieties. Compound ( II) contains intermolecular O - H center dot center dot center dot O and N - H center dot center dot center dot O hydrogen bonds.