Two N-{[4-(3-aryl-4-sydnonylideneamino)-5-sulfanylidene-1H-1,2,4-triazol-3-yl]methyl}benzamides as disordered ethanol monosolvates

In each of the title newly synthesized and closely related N-{[4-(3-aryl-4-sydnonylideneamino)-5-sulfanylidene-1H-1,2,4-triazol-3-yl]methyl}benzamides, which crystallized as ethanol monosolvates, the independent components are linked by hydrogen bonds to form centrosymmetric four-molecule aggregates.


Structural commentary
The molecular and crystal structures of compounds (I) and (II) are closely related and differ only in the methyl group that is attached to C44 for (II) instead of a hydrogen atom for (I): each structure can readily be refined starting from the atomic coordinates of the other, provided that the necessary adjustment is made to the substituent at atom C44 (Figs. 2 and 3). Both compounds crystallized from ethanol/DMF as ethanol monosolvates, and in each structure the ethanol component is disordered over two sets of atomic sites, having occupancies of 0.836 (6) and 0.164 (6) in (I), and 0.906 (6) and 0.094 (6) in (II).
The triazole ring is present in both structures in the 1,2,4triazol-5(4H)-thione form, as shown by the localization of the H atom on N21 in a difference-Fourier map and the subsequent refinement of its atomic coordinates, by the intermolecular hydrogen bonds (Tables 1 and 2), and by the C-S distances, 1.6657 (18) Å in (I) and 1.661 (3) Å in (II). These values are typical for those found in thiones [mean value 1.671 Å ; Allen et al., 1987], and they are far shorter than those found in aromatic thiols and thioethers (mean value 1.771 Å ).
Within the sydnone rings, the N-N distances have values typical of double bonds, viz. 1.300 (2) Å in (I) and 1.299 (3) Å in (II), while the exocyclic C O distance in each structure is shorter than that for the amidic carbonyl unit.
Of the four independent aromatic rings within the molecules of (I) and (II), no two are co-planar or even parallel, so that the molecules exhibit no internal symmetry and hence are conformationally chiral. Although there is a short intramolecular N1-H1Á Á ÁN25 contact in both (I) and (II) (Tables 1 and 2), the resulting rings are non-planar, but instead adopt an envelope conformation, folded across the line N1Á Á ÁC23. The reaction sequence leading to the formation of compounds (I) and (II). Table 1 Hydrogen-bond geometry (Å , ) for (I).  Symmetry code: (i) Àx þ 1; Ày þ 1; Àz þ 1.

Supramolecular features
The supramolecular assemblies in the crystal structures of (I) and (II) are almost identical and very simple. Within the asymmetric unit of each structure (Figs. 2 and 3), the ethanol solvent molecule is linked to the amide unit via O51-H51Á Á ÁO1 hydrogen bonds. Inversion-related pairs of these units are linked by N-HÁ Á ÁO hydrogen bonds to form a cyclic centrosymmetric four-molecular aggregate [shown only for (I) in Fig. 4] containing an R 4 4 (2) motif (Etter, 1990;Etter et al., 1990;Bernstein et al., 1995). The same motif occurs in the crystal structure of compound (II), and there are no significant direction-specific interactions between these aggregates.

Figure 2
The independent molecular components of compound (I), showing the atom-labelling scheme, the disorder of the ethanol component, and the hydrogen bonds, drawn as dashed lines, within the asymmetric unit. Displacement ellipsoids are drawn at the 30% probability level; the major disorder component of the ethanol is drawn with full lines, and the minor component is drawn with broken lines.

Figure 3
The independent molecular components of compound (II), showing the atom-labelling scheme, the disorder of the ethanol component, and the hydrogen bonds, drawn as dashed lines, within the asymmetric unit. Displacement ellipsoids are drawn at the 30% probability level; the major disorder component of the ethanol is drawn with full lines, and the minor component is drawn with broken lines. links molecules that are related by translation into C(8) chains, running parallel to [001] and [010], respectively, in the triclinic unit cells. Although no crystal structure has yet been reported for the intermediate (B) (Fig. 1) used in the synthesis of compounds (I) and (II), the fact that all of compounds (I)-(V) crystallize in the thione form makes it seem likely that the intermediate also exists in this tautomeric form in the solid state, although it may well exist as an equilibrium mixture of thione and thiol (mercapto) forms in solution, with the position of equilibrium possibly differing from one solvent to another. However, it must be emphasized that, to date, no studies have been made of the constitution of this intermediate in solution. On the other hand, a masked form of the thiol tautomer is present in 2-{5-[(1H-1,2,4-triazol-1-yl)methyl]-1,3,4-oxadiazol-2-ylthio}-1-(2,4-dichlorophenyl)ethanone (VI) (Xu et al., 2005b), where molecules which are related by a 2 1 screw axis are linked by a single C-HÁ Á ÁN hydrogen bond to form C(14) chains.

Refinement
Crystal data, data collection and refinement details are summarized in Table 3. In both compounds, the ethanol component is disordered over two sets of atomic sites having unequal occupancies: for the minor disorder components, the bond distances and the 1,3 (non-bonded) distances were restrained to be the same as the corresponding distances in the major disorder components, subjected to s.u. values of 0.01 and 0.02 Å , respectively. In addition, the anisotropic displacement parameters for corresponding pairs of partialoccupancy atoms occupying essentially the same physical  space were constrained to be the same. All H atoms, apart from those in the minor disorder components, were located in difference-Fourier maps. The H atoms bonded to C atoms were then treated as riding atoms in geometrically idealized positions with C-H distances of 0.93 Å (alkenyl and aromatic), 0.96 Å (CH 3 ) or 0.97 Å (CH 2 ), and with U iso (H) = kU eq (C), where k = 1.5 for the methyl groups, which were allowed to rotate but not to tilt, and 1.2 for all other H atoms bonded to C atoms: the H atoms bonded to C atoms in the minor disorder components were included on the same basis.
For the H atoms bonded to N atoms, the atomic coordinates were refined with U iso (H) = 1.2U eq (N), giving the N-H distances shown in Tables  SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: PLATON (Spek, 2020); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015b) and PLATON (Spek, 2020). 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ.    1H-1,2,4-triazol-3- where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.19 e Å −3 Δρ min = −0.18 e Å −3 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.  (15)