6-{5-Amino-3-tert-butyl-4-[(E)-(3-methyl-1,2,4-thiadiazol-5-yl)diazenyl]-1H-pyrazol-1-yl}-1,3,5-triazine-2,4(1H,3H)-dione–1-methylpyrrolidin-2-one–water (1/1/1)

In the title compound, C13H16N10O2S·C5H9NO·H2O, the entire 1-methylpyrrolidin-2-one (NMP) molecule is disordered over two sites with occupancies of 0.488 (5) and 0.512 (5). The six-membered triazine ring and the two five-membered pyrazole and thiadiazole rings, together with the diazene (–N=N–) linkage are almost coplanar (r.m.s. deviation for the non-H atoms = 0.0256 Å) with methyl groups from the tert-butyl substituent on the pyrazole ring located above and below the plane. Three intramolecular N—H⋯N hydrogen bonds contribute to the planarity of the system. The O atom of the NMP molecule is hydrogen bonded to an O—H group of water. In turn, the water molecule is hydrogen bonded to the mono-azo skeleton through intermolecular N—H⋯O and O—H⋯N hydrogen bonds. At both ends of the long molecular axis of the main molecule there are intermolecular N—H⋯N hydrogen bonds, arranged in a head-to-tail fashion, between the N—H group of the triazine ring of one molecule and the N atom of the thiadiazole ring of a neighboring molecule. These form a polymeric chain along [110] or [10]. The main molecules are stacked alternately along the b axis, which effectively cancels their dipole moments. In addition, pairs of alternate molecules are dimerized via intermolecular hydrogen bonds involving the solvent molecules.

In the title compound, C 13 H 16 N 10 O 2 SÁC 5 H 9 NOÁH 2 O, the entire 1-methylpyrrolidin-2-one (NMP) molecule is disordered over two sites with occupancies of 0.488 (5) and 0.512 (5). The six-membered triazine ring and the two fivemembered pyrazole and thiadiazole rings, together with the diazene (-N N-) linkage are almost coplanar (r.m.s. deviation for the non-H atoms = 0.0256 Å ) with methyl groups from the tert-butyl substituent on the pyrazole ring located above and below the plane. Three intramolecular N-HÁ Á ÁN hydrogen bonds contribute to the planarity of the system. The O atom of the NMP molecule is hydrogen bonded to an O-H group of water. In turn, the water molecule is hydrogen bonded to the mono-azo skeleton through intermolecular N-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonds. At both ends of the long molecular axis of the main molecule there are intermolecular N-HÁ Á ÁN hydrogen bonds, arranged in a head-totail fashion, between the N-H group of the triazine ring of one molecule and the N atom of the thiadiazole ring of a neighboring molecule. These form a polymeric chain along [110] or [110]. The main molecules are stacked alternately along the b axis, which effectively cancels their dipole moments. In addition, pairs of alternate molecules are dimerized via intermolecular hydrogen bonds involving the solvent molecules.

Comment
Azo pigments play an important role as colorants in the imaging and printing industries (Herbst & Hunger, 2004). Compound (I), C 13 H 16 N 9 O 2 S . C 5 H 7 NO . H 2 O, is a monoazo pigment solvated with an N-methyl-2-pyrrolidone (NMP) molecule and water. The background of the present study is set out in our paper on the Na(I) complex with the closely related bis-azo compound as a ligand (Shibata & Mizuguchi, 2010). We report here on the structure of a Na + -free monoazo compound isolated from the same reaction mixture that produced the Na(I) complex. Fig. 1 shows the ORTEP plot of I. The six-membered C1-C3,N1-N3 and two five-membered C4-C6,N4,N5 and S1,C7,C8,N8,N9 rings together with the N6-N7 azo linkage lie in a plane (rms deviation for the non-H atoms 0.0256Å) with a methyl group from the t-butyl substituent on the pyrazol ring above and below that plane. The formation of three intramolecular hydrogen bonds: N2-H2···N5, N10-H10M···N7, and N10-H10N···N3, Table 1, stabilises this planar conformation. The O4 atom of the water molecule is nearly on the same plane of the monoazo molecule: the dihedral angle between the planes N10/C6/H10M/H10M and O4/N10/H10M/H10N: 1.0 (1)°. However, the best fit planes through the NMP solvent molecule (C14A-C17A/N11A/O5A) and that of the water molecule (H4A/O4/H4B) are inclined to the above bis-azo skeleton by 124.6 (0) and 113.7 (0)°, respectively. The water molecules are hydrogen bonded to the O3A or O3B atoms of the disordered NMP molecule though O4-H4A···O3 hydrogen bonds. In turn, the O4 atom is hydrogen-bonded to the H10M-N10 amino group of the monoazo skeleton. In addition, the O4-H4B group is weakly hydrogen-bonded to both N7 and N8. At both ends of the long molecular axis of the main molecule, there are intermolecular N1-H1···N9 hydrogen bonds. These form a one-dimensional polymer chain on the molecular plane along the long molecular axis: <110> or <1-10> direction.
As shown in Fig. 2, the monoazo molecules are alternately stacked along the <010> direction in such a way to cancel their dipole moments so as to electrostatically stabilize themselves in the crystal. Each alternating pair is linked through a set of three-consecutive intermolecular hydrogen bonds. On one side of the molecule: N2-H2 (triazine ring)···O3A i or ]. An equivalent set of H-bonding interactions are found at the opposite sides of the molecules.

Experimental
The title compound was synthesized as described by Nagata et al. (2009). The structure reported here is of the Na(I) cation free product which made up approximately 20% of the product mixture by emission spectrochemical analysis. A single crystal suitable for X-ray analysis was grown from a solution in N-methy-2-pyrrolidone prepared at 100 °C. Needle shaped crystals were obtained after standing for one week.

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 > σ(F 2 ) is used only for calculating Rfactors(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.