(E)-3-Methyl-4-[(2-oxidoquinolin-1-ium-3-yl)methyleneamino]-1H-1,2,4-triazole-5(4H)-thione N,N-dimethylformamide solvate

The title 1,2,4-triazole compound, C13H11N5OS·C3H7NO, crystallizes as a 1:1 dimethylformamide (DMF) solvate. The main molecule exists in a trans configuration with respect to the acyclic C=N bond. An intramolecular C—H⋯S hydrogen bond generates an S(6) ring motif. In the synthesis, a proton is transferred from the O atom of a hydroxy group to the quinoline group N atom. The essentially planar triazole ring and quinoline ring system [maximum deviations of 0.001 (2) and 0.013 (2) Å, respectively] form a dihedral angle of 5.86 (9)°. In the crystal structure, molecules of (E)-4-[(2-hydroxy-3-quinolyl)methyleneamino]-3-methyl-1H-1,2,4-triazole-5(4H)-thione are linked into R 2 2(8) centrosymmteric dimers via N—H⋯O hydrogen bonds. These dimers are further linked into an extended three-dimensional structure by the DMF solvent molecules via intermolecular N—H⋯O and C—H⋯O hydrogen bonds. The crystal structure is consolidated by two different intermolecular π–π interactions [centroid–centroid distances = 3.6593 (12) and 3.6892 (12) Å].


Experimental
The title compound was obtained by refluxing 3-methyl-4-amino-1,2,4-triazole-5-thione (0.01 mol) and 2-hydroxy-3formyl-quinoline (0.01 mol) in ethanol (30 ml) with the addition of three drops of concentrated sulphuric acid for 3 h. The solid product obtained was collected by filtration, washed with ethanol and dried. It was then recrystallized using ethanol.
Single crystals suitable for X-ray analysis were obtained from a solution of the title compound in a mixture of ethanol and DMF by slow evaporation.
supplementary materials sup-2 Refinement Atoms H1N1 and H1N4 were located from difference Fourier map and allowed to refine freely. All other hydrogen atoms were placed in calculated positions, with C-H = 0.93 -0.96 Å, and refined using a riding model, with U iso = 1.2 or 1.5 U eq (C). A rotating group model was used for the methyl groups. The reflection (020) was omitted as the intensity was affected by the beam backstop. The highest residual electron density peak and the deepest hole are located at 1.02 and 0.42 Å, respectively, from the sulphur atom. Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme. An intramolecular hydrogen bond is shown as dashed line.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.