Crystal structure and theoretical studies of derivative of imidazo-1,2,4-triazine

• Molecular and crystal structure of imidazo-1,2,4-triazine derivative was analyzed.
• Arrangement of molecules in crystals was dependent on conformation of side chain.
• Conformational analysis of imidazo-1,2,4-triazine derivative was carried out.

In this study, we present the result of X-ray structure analysis of methyl [8-(3-chlorophenyl)-4-oxo-2,3,4,6,7,8-heksahydroimidazo[2,1-c][1,2,4]triazin-3-yl]acetate (1). The molecule conformation is flat, with a chlorophenyl substituent and the ester moiety lying in the plain of the heterobicyclic scaffold. Its conformation is stabilized by an intramolecular NH…O hydrogen bond. Within the crystalline structure of 1, molecules associate with one another by weak CH…O, CH…Cl and CH…π bonds. The molecular and crystal structure of 1 was compared with the previously described structurally similar compound possessing the same bicyclic rigid core and similar chemical nature of the functional ester moiety. Very interesting differences in molecules geometry and association were observed. Non-covalent bonds within the crystals are additionally visualized by determination of Hirshfeld surfaces.Moreover, the quantum chemical calculation for 1 in the gas phase were carried out. The DFT calculation methods was used to optimize of molecule geometry and obtain molecular energy profiles with respect to selected torsion angles. The quantum chemical conformational analysis that was carried out for compound 1 in the gas phase suggests that in the solid state the molecules adopt the minimum energy conformation.