Computational, <sup>1</sup>H NMR, and X-ray structural studies on 1-arylurazole tetrazane dimers
作者:Kenneth L. Martin、Gary W. Breton
DOI:10.1107/s2053229617010786
日期:2017.9.1
Nitrogen‐centered urazole radicals exist in equilibrium with tetrazane dimers in solution. The equilibrium established typically favors the free‐radical form. However, 1‐arylurazole radicals bearing substituents at the ortho position favor the dimeric form. We were able to determine the structure of one of the dimers (substituted at both ortho positions with methyl groups), namely 1,2‐(2,4‐dimethylphenyl)‐2‐[2‐(2
以氮为中心的脲基自由基与四氮烷二聚物平衡存在于溶液中。建立的平衡通常倾向于自由基形式。然而,在邻位带有取代基的1-芳基尿唑基团偏爱二聚体形式。我们能够确定一个二聚体(在两个邻位被甲基取代)的结构,即1,2-(2,4-二甲基苯基)-2- [2-(2,4-二甲基苯基)-4 -甲基-3,5-二氧杂1,2-,4-三唑啉-1-基] -4-甲基1,2,4-三唑烷-3,5-二酮,C 24 H 28 N 6 O 4,通过X射线晶体学。实验确定的结构与理论上B3LYP / 6-311G(d,p)的计算得出的几何形状非常吻合。这些1-芳基尿嘧啶二聚体的优选顺式构象会导致两个芳环接近且几乎平行,这会导致某些信号在1 H NMR光谱中产生有趣的屏蔽效果。有了这些信息,我们就能破译从邻位被甲基单取代的二聚体获得的更复杂的1 H NMR光谱。