7-Diethylamino-2-propylsulfanyl-3-(1H-1,2,4-triazol-1-yl)-4H-thiochromen-4-one

In the title compound, C18H22N4OS2, the six-membered rings are almost coplanar, showing a dihedral angle between the mean planes of 9.0 (4)°, while the triazol ring is nearly perpendicular to the thiochromen-4-one unit, making an angle of 89.8 (4)°. In the crystal, C—H⋯N hydrogen bonds link the molecules in a stacked arrangement along the c axis.


Comment
The title compound is the key intermediate in the synthesis of a new kind of antiallergic drugs (Nohara et al., 1977). The crystal structure determination has been carried out in order to elucidate its molecular conformation (Fig. 1).
In the crystal structure, intermolecular C-H···N hydrogen bonds (Table 2) link the molecules in a stacked arrangement along the c axis (Fig. 2).

Experimental
Diethylamine (13.8 ml, 134.4 mmol) was added to a solution of 2-(allylthio)-7-fluoro-3-(1H-1,2,4-triazol-1-yl)-4H-thiochromen-4-one (5 g, 15.7 mmol) in DMSO (30 ml) containing NaOH (1.8 g, 45 mmol). The yellow solution was stirred for about 12 h at room temperature. After completion of the reaction, the solution was poured into water (50 ml). The crystalline product was isolated by filtration and washed with water (300 ml). The precipitate was recrystallized with acetone and a yellow deposit was obtained (m.p. 420 K). Crystals suitable for X-ray analysis were obtained by dissolving the crude product (1.0 g) in ethanol (30 ml) and then allowing the solution to evaporate slowly at room temperature for about 7 d.

Refinement
The H atoms were positioned geometrically with C-H = 0.93 Å for aromatic H atoms, with C-H = 0.97 Å for methylene H atoms, and with C-H = 0.96 Å for methyl H atoms. They were constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C), or 1.5U eq (C) for the methyl H atoms.  The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level.   where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.46 e Å −3 Δρ min = −0.29 e Å −3

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.