THEORETICAL STUDY ON DIMERS OF 2,6-DIAMINO-3,5-DINITROPYRIDINE AND ITS N-OXIDE
L.-F. Xie1, C.-C. Ye1, X.-H. Ju2, F.-Q. Zhao3
1 School of Chemical Engineering, Nanjing University of Science and Technology
2 School of Chemical Engineering, Nanjing University of Science and Technology Xi′an Modern Chemistry Research Institute, Xi′an
3 Xi′an Modern Chemistry Research Institute, Xi′an
xhju@mail.njust.edu.cn
Ключевые слова: 2, 6-diamino-3, 5-dinitropyridine, 2, 6-diamino-3, 5-dinitropyridine-1-oxide, intermolecular interaction, first-principle calculations, natural bond orbital
Страницы: 672-677
Аннотация
First-principle calculations are performed on the dimers of 2,6-diamino-3,5-dinitropyridine (ANPy) and its N-oxide (2,6-diamino-3,5-dinitropyridine-1-oxide, ANPyO). The dimers as well as the monomers are fully optimized by the DFT-B3LYP and HF methods in conjunction with 6-311G**, 6-311++G**, and cc-pVDZ basis sets. The N-O bond length of the pyridine N-oxide moiety decreases in the ANPyO dimer in the dimerization process, which results in a larger deformation energy of the ANPyO submolecule. This deformation prevents the submolecules from further close contact and the formation of strong H-bonds between the nitro and amino groups. The optimized intermolecular distances of the ANPyO dimer are in good agreement with the corresponding experimental values. There is a weak C-H⋯O hydrogen bond in the ANPyO dimer; the B3LYP method underestimates its binding energy. On the contrary, for the ANPy dimer, the binding energy obtained at the B3LYP level is larger than that obtained at the HF level. The individual O⋯H strength is stronger in the ANPy dimer than that in ANPyO, which is consistent with the O⋯H distance. The O⋯H-C type of the H-bond is stronger in the ANPyO dimer than the ordinary O⋯H-C bond due to the N-oxide oxygen atom bearing larger negative charges. The corrected binding energy for each hydrogen bond between nitro oxygen and amino hydrogen is about -5 kJ/mol in the ANPy dimer, which is stronger than that in the ANPyO dimer.
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