Different patterns of supramolecular aggregation in three amides containing N-(benzo[d]thiazolyl) substituents

In three amides, each containing a N-(benzo[d]thiazolyl) substituent, different combinations of N—H⋯O, N—H⋯N, C—H⋯O and C—H⋯N hydrogen bonds and Br⋯Br interactions lead to supramolecular assemblies in one, two and three dimensions.


Structural commentary
In compound (I), the amide unit occupies position 6 of the benzo[d]thiazole unit, whereas in compounds (II) and (III), the amide unit is linked to the bicyclic system at position 2. In (I), (Fig. 1) the thiazole ring and the brominated aryl ring are almost parallel, with a dihedral angle between them of 5.8 (2) . However, these rings are not coplanar, as both ring systems in compound (I) are twisted out of the plane of the central amide spacer unit.
Compound (II) crystallizes with Z 0 = 2, but a search for possible additional crystallographic symmetry revealed none. The different conformations of the two independent molecules ( Fig. 2) confirm the absence of additional symmetry. For example, the dihedral angle between the thiazole ring and the nitrated phenyl ring is 46.43 (15) in molecule 1 containing atom S111, but 66.35 (13) in molecule 2 containing atom S211. Similarly, the dihedral angles between the nitro groups and the adjacent aryl rings are 34.5 (2) and 17.9 (2) in molecules 1 and 2, respectively.
The molecule of compound (III) exhibits two forms of disorder. The cyclopropylisoxazole unit is disordered over two sets of atomic sites, with occupancies 0.549 (5) and 0.451 (5), where the two orientations of the isoxazole ring are approximately related by small rotations about the N-C and C-C bonds involving atom C31 (Fig. 3). Of more interest is the disorder of the methoxy groups, where the site occupancies are constrained by short non-bonded contacts with adjacent The molecular structure of (III), showing the atom-labelling scheme and the disorder of the cyclopropylisoxazole fragment, where the major disorder component, with occupancy 0.549 (5), is drawn using full lines and the minor disorder component of this fragment, with occupancy 0.451 (5), is drawn using broken lines. The atomic sites O16, O17, C18 and C19 and the associated H atoms all have occupancy 0.5 (see Section 2). Displacement ellipsoids are drawn at the 30% probability level.

Figure 1
The molecular structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.

Figure 2
The structures of the two independent molecules in (II), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.

Figure 4
Part of the crystal structure of (I) showing the formation of a ribbon of R 3 3 (19) rings running parallel to [010] and built from N-HÁ Á ÁO and C-HÁ Á ÁN hydrogen bonds. Hydrogen bonds are drawn as dashed lines and, for the sake of clarity, the H atoms not involved in the motifs shown have been omitted.

Figure 5
Part of the crystal structure of (I), showing a chain along ([010] containing two independent BrÁ Á ÁBr interactions (shown as dashed lines). For the sake of clarity, the H atoms and the unit-cell outline have been omitted. The Br atoms marked with an asterisk (*), a hash (#), a dollar sign ($) or an ampersand (&) are at the symmetry positions (2 À x, 1 2 + y, 3 2 À z), (2 À x, À 1 2 + y, 3 2 À z), (x, 1 + y, z) and (x, À1 + y, z), respectively. Quah et al., 2012;Fun, Shahani et al., 2012;Praveen et al., 2013a,b;Nayak et al., 2014): in (I), this chain runs parallel to the [010] direction (Fig. 4). In addition, molecules that are related by the 2 1 screw axis along (0.5, y, 0.25) are linked by C-HÁ Á ÁN hydrogen bonds to form a C(6) chain, also running parallel to the [010] direction. The combination of these two chain motifs generates a ribbon of R 3 3 (19) rings along [010] (Fig. 4). Also running through the unit cell is a second ribbon of this type, related to the first by inversion, and containing molecules that are related by the 2 1 screw axis along (0.5, y, 0.75). Also present in the structure of compound (I) are two intermolecular BrÁ Á ÁBr contacts that are shorter than the van der Waals radii sum of 3.74 Å (Rowland & Taylor, 1996). Atom Br3 in the molecule at (x, y, z) makes contacts with the corresponding atoms at (2 À x, 0.5 + y, 1.5 À z) and (2 À x, À0.5 + y, 1.5 À z), with BrÁ Á ÁBr distances of 3.5812 (6) Å in each case; however, the C-BrÁ Á ÁBr angles are 92.64 (18) and 166.44 (10) , respectively (Fig. 5), which are consistent with the angular preferences found for such contacts from database analyses (Ramasubbu et al., 1986). The effects of these halogen bonds (Cavallo et al., 2016) are twofold: firstly to generate a chain running parallel to the [010] direction (Fig. 5) and thence to link the hydrogen-bonded ribbons into sheets lying parallel to the (101) plane (Fig. 6).
The two independent molecules of compound (II) are linked by two N-HÁ Á ÁN hydrogen bonds and five C-HÁ Á ÁO hydrogen bonds (Table 1), but the N-HÁ Á ÁO hydrogen bonds typical of amides are absent. The hydrogen bonds generate a three-dimensional network, whose formation can readily be analysed in terms of a number of simple sub-structures (Ferguson et al., 1998a,b;Gregson et al., 2000). In the simplest of the sub-structures, the two N-HÁ Á ÁN hydrogen bonds link the molecules within the selected asymmetric unit to form a dimer, and the other sub-structures follow the different ways in which these dimers can be linked. The C-HÁ Á ÁO hydrogen bonds involving atoms C25 and C115 link the dimers into a chain of alternating R 2 2 (8) R 3 3 (18) rings running parallel to the [001] direction (Fig. 7); this chain is weakly reinforced by a C-HÁ Á Á(arene) interaction (Table 1). In the third substructure, the C-HÁ Á ÁO hydrogen bonds involving atoms C13 and C217 link the dimers into a chain of rings containing C 4 4 (24) chains and running parallel to the [010] direction (Fig. 8)  Part of the crystal structure of (II) showing the formation of a chain of R 2 2 (8) and R 3 3 (18) rings running parallel to [001] and built from N-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds. Hydrogen bonds are drawn as dashed lines and, for the sake of clarity, the H atoms not involved in the motifs shown have been omitted.  generates a sheet lying parallel to (100) in the domain 0.5 < x < 1.0. A second sheet of the type, related to the first by the 2 1 screw axes, lies in the domain 0 < x < 0.5, and sheets of this type are linked by the C-HÁ Á ÁO hydrogen bond in involving atom C117, so forming a three-dimensional network: indeed, it is possible to identify a complex chain running parallel to the [100] direction, which defines the linkage of the (100) sheets ( Fig. 9).
Analysis of the supramolecular aggregation in compound (III) is complicated by the disorder of the isoxazole ring, since atoms O1A and N2A in the major disorder form act as hydrogen bond acceptors, but atoms O1B and N2B in the minor disorder form do not. As in (II), the N-HÁ Á ÁO hydrogen bonds typical of amides are absent from the structure of (III). Molecules of (III) that are related by a twofold rotation axis are linked into cyclic R 2 2 (8) dimers. There is also present an asymmetric three-centre C-HÁ Á Á(N,O) system having atoms O1A and N2A as the acceptors: if these sites had full occupancy, this interaction would generate a chain of rings running parallel to the [101] direction (Fig. 10). However, because of the disorder, this chain is punctuated rather than continuous.  Part of the crystal structure of (II) showing the formation of a chain of rings running parallel to [010] and built from N-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds. Hydrogen bonds are drawn as dashed lines and, for the sake of clarity, the H atoms not involved in the motifs shown have been omitted.

Figure 9
Part of the crystal structure of (II) showing the formation of a chain of rings running parallel to [100] and built from N-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds. Hydrogen bonds are drawn as dashed lines and, for the sake of clarity, the H atoms not involved in the motifs shown have been omitted.
linked to the heterocycle at position 6, the structure of (IV) contains no N-HÁ Á ÁO hydrogen bonds: instead, inversionrelated pairs of molecules are linked by pairwise N-HÁ Á ÁN hydrogen bonds to form cyclic, centrosymmetric R 2 2 (8) dimers. By contrast with (I), there are no short BrÁ Á ÁBr contacts in the structure of (IV).

Synthesis and crystallization
All reagents were obtained commercially and all were used as received. For the synthesis of compound (I), a solution of triethylamine (1.11 g, 0.01 mol) in dry toluene (5 ml) was added to a mixture of 6-aminobenzo[d]thiazole (1.50 g, 0.01 mol) and 3-bromobenzoyl chloride (2.18 g, 0.01 mol) in dry toluene (20 ml), and the resulting mixture was heated under reflux for 4 h. When the reaction was complete, as indicated by TLC monitoring, the mixture was cooled to room temperature and the triethylammonium chloride was removed by filtration. The solvent was then removed under reduced pressure and the resulting solid product was washed with water and then crystallized from ethanol solution. Yield 86%, m.p. 439-441 K: IR (cm À1 ) 3125 (

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. One bad outlier reflection (0,23,3) was omitted from the final refinement of compound (II). All H atoms, apart from those in the disordered components of compound (III), were located in difference maps. The H atoms bonded to C atoms were treated as riding atoms in geometrically idealized positions, with C-H distances of 0.93 Å (aromatic and heterocyclic), 0.96 Å (CH 3 ), 0.97 Å (CH 2 ) or 0.98 Å (aliphatic C-H) 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. 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 Table 1. For the disordered methyl group in compound N3, the site occupancies were fixed at 0.5 (see Section 2, above): when these occupancies were refined, the resulting values were 0.504 (7) and 0.496 (7), much as expected. For each of the disordered fragments in (III), the corresponding bonded distances and the 1,3 non-bonded distances were restrained to be equal, subject to s.u. values of 0.01 and 0.02 Å , respectively. In addition, the anisotropic displacement parameters for corresponding pairs of atoms in the 3-cyclopropyl-5-carbonyloxazole fragments were constrained to be equal. Subject to these conditions, the occupancies of this disordered fragment refined to 0.549 (5) and 0.451 (5). The correct orientation of the structure of the  crystal of compound (II) chosen for data collection relative to the polar axis direction was established by means of the Flack x parameter (Flack, 1983); x = 0.02 (5), calculated (Parsons et al., 2013)   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.

N-(6-Methoxybenzo[d]thiazol-2-yl)-2-nitrobenzamide (II)
Crystal data  (5) 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.

sup-12
Acta Cryst. (2021). E77, 504-511 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.