Dancing with 5-substituted monotetrazoles, oxygen-rich ions, and silver: Towards primary explosives with positive oxygen balance and excellent energetic performance

Although numerous primary explosives have been reported to date, those with a positive oxygen balance are extremely rare. To overcome this limitation, we present two strategies to improve the oxygen balance: (1) increasing the oxygen balance in the ligands and (2) the introduction of oxygen-rich ions. By applying these strategies, a series of energetic coordination polymers (ECPs) consisting of 5-substituted monotetrazoles, oxygen-rich ions, and silver (viz. [Ag ₇ MT ₄ (NO ₃ ) ₃ ] _n , [Ag ₃ HT ₂ NO ₃ ] _n , [Ag ₇ AT ₄ (NO ₃ ) ₃ ] _n , [Ag ₅ NT ₄ NO ₃ ] _n , and [Ag ₅ NT ₄ ClO ₄ ] _n ) were prepared. Their structures were characterized using single crystal XRD, IR, and elemental analysis and their properties were evaluated in terms of density, thermal stability, mechanical sensitivity and oxygen balance. In addition, the potential structure-property relationships of these polymers were studied. All five ECPs possessed high densities ranging from 3.12 to 3.60 g cm ^-3 . DSC and TGA analysis showed that the ECPs have high thermal stability with decomposition temperatures ranging from 251 to 348 °C. All the ECPs were sensitive to stimuli and should be classified as primary explosives. Oxygen balance calculations, detonation reactions, and combustion experiments showed that [Ag ₅ NT ₄ NO ₃ ] _n and [Ag ₅ NT ₄ ClO ₄ ] _n have a positive oxygen balance, which gives the first two examples of ECP-based primary explosives exhibiting a positive oxygen balance (based on CO ₂ ). Explosion experiments showed that [Ag ₅ NT ₄ NO ₃ ] _n and [Ag ₅ NT ₄ ClO ₄ ] _n , which display a positive oxygen balance, deliver improved initiation performance when compared to [Ag ₇ MT ₄ (NO ₃ ) ₃ ] _n , [Ag ₃ HT ₂ NO ₃ ] _n , and [Ag ₇ AT ₄ (NO ₃ ) ₃ ] _n , which have a negative oxygen balance. Therefore, [Ag ₅ NT ₄ NO ₃ ] _n and [Ag ₅ NT ₄ ClO ₄ ] _n are efficient primary explosives. In addition, the positive oxygen balance of [Ag ₅ NT ₄ NO ₃ ] _n and [Ag ₅ NT ₄ ClO ₄ ] _n indicates their potential application as energetic oxidizers.