Engaging\nTwo Anions\nwith Single Cation in Energetic\nSalts: Approach for Optimization of Oxygen Balance in Energetic Materials

The field of high energy density\nmaterials faces a long-standing\nchallenge to achieve an optimum balance between energy and stability.\nWhile energetic salt formation via a combination of oxygen- and nitrogen-rich\nanions (providing energy) with nitrogen-containing cations (providing\nstability) has been a proven approach for improving physical stability,\nconstraints such as lowering density and energetic performance remain\nunresolved. This can be addressed by utilizing oxygen-containing cations\nfor salt formation. However, this approach is rarely explored because\nits synthesis is challenging. In this work, we have designed an oxygen-rich\ncationic precursor <b>2</b> by incorporating 4-amino-3,5-dinitropyrazole\nwith 3,4-diaminotriazole via an <i>N</i>-methylene-C bridge.\nFurther combination with energetic acids resulted in the formation\nof high-performing, physically stable energetic salts <b>3</b>–<b>10</b>. The salts were found to be generally more\nenergetic than the salts of respective energetic acids with previously\nreported cations and showed prominent improvement in physical stability\nwith respect to their anionic precursors. All the compounds were thoroughly\ncharacterized through IR, NMR spectroscopy, HRMS, and elemental analysis.\nSalt <b>9</b> was confirmed through <sup>15</sup>N NMR analysis,\nand salts <b>2</b> and <b>8</b> were confirmed through\nsingle-crystal X-ray diffraction. Additional analyses such as Hirshfeld\nsurface analysis, noncovalent interaction (NCI) analysis, and electrostatic\npotential studies were also carried out to correlate the structure–property\nrelationship.