Experimental X-ray Diffraction Study of Stacking Interaction in Crystals of Two Furazan[3,4-b]pyrazinesстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 марта 2017 г.
Аннотация:The molecular and crystal structures of two energetic fused furazans, 4H,8H-bis-furazano[3,4-b:3?,4?-e]pyrazine (1) and 4H,9H-bisfurazano[3,4-b:3?,4-g]-pyrazino[2,3-e]pyrazine (2), have been studied by single crystal X-ray diffraction analysis. These materials were found to have rather high crystal densities for organic compounds (2.032 and 1.882 g·cm?3). Very short interplanar distances between overlapping molecules in crystals (less than 3.15 Å) suggest the presence of stacking interaction between planar rings. High-resolution low-temperature X-ray diffraction data for both compounds were used to analyze the electron density distribution in the area of stacking interaction and hydrogen bonds, as interpreted through the framework of Bader?s AIM theory. A weak accumulation of the electron density, and (3, ?1) bond critical points were found in the area of this interaction between overlapping molecules in the crystal. It was established that the energy of the stacking interactions in 1 and 2 are 3.9 and 3.2 kcal/mol, which is in good agreement with previous experimental and theoretical works. On the basis of our results and literature data we analyzed the correlation between the interatomic distance and the electron density in critical point (3, ?1). This analysis revealed that the stacking interaction is a partial case of other specific interactions.