Hu Lu, Yin Ping, Zhao Gang, He Chunlin, Imler Gregory H, Parrish Damon A, Gao Haixiang, Shreeve Jean'ne M
Department of Chemistry , University of Idaho , Moscow , Idaho 83844-2343 , United States.
Department of Applied Chemistry , China Agricultural University , Beijing , China 100193.
J Am Chem Soc. 2018 Nov 7;140(44):15001-15007. doi: 10.1021/jacs.8b09519. Epub 2018 Oct 26.
Nitroamino-functionalized 1,2,4-triazolo[4,3- b][1,2,4,5]tetrazine (1), when combined with intermolecular hydrogen bonds (HBs) and strong noncovalent interactions between layers, results, for example, in an interlayer distance of 2.9 Å for dihydroxylammonium 3,6-dinitramino-1,2,4-triazolo[4,3- b][1,2,4,5]tetrazine (2c) with a packing coefficient of 0.805. For dihydroxylammonium 6,6'-dinitramino-3,3'-azo-1,2,4-triazolo[4,3- b][1,2,4,5]tetrazine (3b), two fused rings are linked by an azo group, which expands the conjugated system resulting in an even shorter interlayer distance of 2.7 Å and a higher packing coefficient of 0.807. These values appear to be the shortest interlayer distances and the highest packing coefficients reported for tetrazine energetic materials. With high packing coefficients, both possess high densities of 1.92 g cm and 1.99 g cm at 293 K, respectively. Compared with its precursor, the hydroxylammonium moiety serves as a buffer chain (H-N-O-H), connecting the anion and cation through hydrogen bonds, giving rise to more favorable stacking, and resulting in higher density and lower sensitivity. The sensitivities of all the hydroxylammonium salts are lower than that of their neutral precursors, such as compound 2 (3 J, >5 N) and compound 2c (25 J, 360 N). The detonation properties of 2c (detonation velocity v = 9712 m s and detonation pressure P = 43 GPa) and 3b (v = 10233 m s; P = 49 GPa) exceed those of present high explosive benchmarks, such as octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and hexanitrohexaazaisowurzitane (CL-20). The molecular structures of several of these new energetic materials are confirmed by single-crystal X-ray diffraction measurements. Using calculated and experimental results, the fused ring with a planar large π-conjugated system results in a compromise between desirable stabilities and high detonation properties, thus enhancing future utilization in the design of energetic materials.
硝基氨基官能化的1,2,4 - 三唑并[4,3 - b][1,2,4,5]四嗪（1），当与分子间氢键（HBs）以及层间强烈的非共价相互作用相结合时，例如，对于3,6 - 二硝氨基 - 1,2,4 - 三唑并[4,3 - b][1,2,4,5]四嗪二羟铵盐（2c），其层间距离为2.9 Å，堆积系数为0.805。对于6,6'-二硝氨基 - 3,3'-偶氮 - 1,2,4 - 三唑并[4,3 - b][1,2,4,5]四嗪二羟铵盐（3b），两个稠环通过一个偶氮基团相连，这扩展了共轭体系，导致层间距离更短，为2.7 Å，堆积系数更高，为0.807。这些值似乎是四嗪含能材料中报道的最短层间距离和最高堆积系数。由于堆积系数高，两者在293 K时的密度分别高达1.92 g/cm³和1.99 g/cm³。与其前体相比，羟铵部分充当缓冲链（H - N - O - H），通过氢键连接阴离子和阳离子，产生更有利的堆积，从而导致更高的密度和更低的敏感度。所有羟铵盐的敏感度均低于其相应的中性前体，如化合物2（3 J，>5 N）和化合物2c（25 J，360 N）。2c（爆速v = 9712 m/s，爆压P = 43 GPa）和3b（v = 10233 m/s；P = 49 GPa）的爆轰性能超过了目前的高爆炸药基准，如八氢 - 1,3,5,7 - 四硝基 - 1,3,5,7 - 四氮杂环辛烷（HMX）和六硝基六氮杂异伍兹烷（CL - 20）。其中几种新型含能材料的分子结构通过单晶X射线衍射测量得以确认。利用计算和实验结果表明，具有平面大π共轭体系的稠环在理想稳定性和高爆轰性能之间实现了平衡，从而提高了未来在含能材料设计中的应用价值。
