A high-density energetic ammonium salt via a polynitropyrazolate counteranion†

The nitroamino group as a powerful explophore is widely employed in the design of energetic compounds. However, its strong electron-withdrawing effect often introduces acidic sites in the molecules, resulting in hygroscopicity. In this study, we successfully synthesized a high-density energetic ammonium salt (2a) by employing large 2,2′-dinitroamino-4,4′,5,5′-tetranitro-2H,2′H-3,3′-bipyrazolate as the counteranion. This salt (2a) is non-hygroscopic and exhibits the highest density among nitrogen-rich ammonium energetic salts, positioning it as a highly promising candidate for high-energy-density compounds. In addition, an aminoguanidium salt (2b) was also prepared. These salts were comprehensively characterized using X-ray diffraction, nuclear magnetic resonance, and infrared spectroscopy, with their physicochemical properties thoroughly examined.