Crystal structure and Hirshfeld surface analysis of ethyl (3E)-5-(4-chlorophenyl)-3-{[(4-chlorophenyl)formamido]imino}-7-methyl-2H,3H,5H-[1,3]thiazolo[3,2-a]pyrimidine-6-carboxylate

The thiazole ring is planar while the pyrimidine unit fused to it adopts a screw-boat conformation In the crystal, N—H⋯N plus C—H⋯N hydrogen bonds form helical chains along the b-axis direction, which are linked into thick sheets parallel to the bc plane by C—H⋯O hydrogen bonds and π–π interactions between the formamido carbonyl groups and the thiazole rings.


Figure 3
Detail of the C-HÁ Á ÁO and C-HÁ Á ÁCl hydrogen bonds and theinteractions down the b-axis. H atoms not involved in these interactions have been omitted for clarity.
Compound (III) crystallizes in the P2 1 /n space group with one molecule in the asymmetric unit. Both the thiazolopyrimidine and the phenyl rings are flat and subtend a dihedral angle of 70.8 (1) to each other. In the crystal of (III), N-HÁ Á ÁS hydrogen bonds link the molecules into zigzag chains running along the b-axis direction. The interchain contacts are provided by weak C-HÁ Á ÁS and C-HÁ Á ÁF bonds while C-HÁ Á Á andinteractions generate the three-dimensional network.

Refinement details
Crystal data, data collection and structure refinement details are summarized in Table 4. Only the hydrogen atoms of the methyl group attached to C10 were included as riding contributions in idealized positions since independent refinement of them led to an unsatisfactory geometry for this methyl group. All the remaining C and N-bound hydrogen atoms were found in difference-Fourier maps and they were refined freely.

Acknowledgements
Author contributions are as follows: synthesis and organic chemistry parts preparation, AMA, SMAS, SAAAR; conceptualization and study guide, AMA, SKM, SMAS; financial support, MAAUM; crystal data production and validation, JTM; paper preparation and Hirshfeld study, MA, SKM.

Funding information
The support of NSF-MRI grant No. 1228232 for the purchase of the diffractometer and Tulane University for support of the   program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/1 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2020). where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.23 e Å −3 Δρ min = −0.35 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. 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. The hydrogen atoms attached to C10 were included as riding contributions in idealized positions since independent refinement of them led to an unsatisfactory geometry for this methyl group.