Synthesis, structural characterization and theoretical approach of 3-(2,6-dichlorobenzyl)-5-methyl-N-nitro-1,3,5-oxadiazinan-4-imine

•The vibrational assignments of DNOI have been carried.•Density plots of HOMO–LUMO energy surface plotted to identify donor and acceptor.•Experimentally and computational UV–Vis of the title compound are agree very well.•ESP surface plotted to get electrophilic and nucleophilic sites of the molecule.

3-(2,6-Dichlorobenzyl)-5-methyl-N-nitro-1,3,5-oxadiazinan-4-imine (DNOI) was synthesized and characterized by X-ray diffraction, FT-IR, FT-Raman and UV–Vis spectra. The X-ray diffraction study showed that DNOI has a one dimensional configuration, due to the intermolecular C9H⋯O1 and N4H⋯O2 hydrogen bonds. The benzene ring and the oxadiazine rings are tilted with respect to each other by 63.07° (C3N1C5C6). Vibrational spectra and electronic spectra measurements were made for the compound. Optimized geometrical structure and harmonic vibrational frequencies were computed with DFT (B3LYP, B3P86, and M062X) methods using 6-311++G(d,p) basis set. Assignments of the observed spectra were proposed. The equilibrium geometries computed by all of the methods were compared with X-ray diffraction results. The absorption spectra of the title compound were computed both in gas phase and in CH3OH solution using TD-B3LYP/6-311++G(d,p) and PCM-B3LYP/6-311++G(d,p) approaches, respectively. The calculated results provide a good description of positions of the bands maxima in the observed electronic spectrum. Temperature dependence of thermodynamic parameters in the range of 100–1000 K were determined, entropy, heat capacity and enthalpy changes were increasing with temperature increasing, while for Gibbs free energy is decreasing with temperature increasing. The bond orbital occupancies, contribution from parent natural bond orbital (NBO), the natural atomic hybrids was calculated and discussed.

Graphical abstractIn this work, complete vibrational assignments, electronic transitions within molecule and HOMO and LUMO energy of DNOI were studied. MESP map shows that the negative potential sites (red and yellow) are electronegative oxygen atoms, while the positive potential sites (blue) are around the hydrogen atoms. Thermodynamic properties of the title compound were also calculated.Figure optionsDownload full-size imageDownload as PowerPoint slide