Monocyclic Bis(N‑nitramine) Triazole: A High-Density Energetic Material with Exceptionally Weak N-N Bond

The N-N single bond is inherently intriguing due to its high energy storage capacity, whether in polynitrogen systems or nitramine-based molecules. However, the synthesis of compounds featuring exceptionally weak N-N single bonds is often hindered by their intrinsic high reactivity and instability. Here, we report the design and synthesis of a monocyclic dual N-nitramine with an ultralow N-N bond dissociation energy: 2,4-dinitroamino-5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (2). This compound was obtained via the nitration of the diaminonation intermediate of NTO and exhibits a remarkably high crystal density (1.969 g cm^-3 at 298 K and 2.025 g cm^-3 at 100 K), along with outstanding detonation performances (Dv = 9072 m s^- 1, P = 35.3 GPa), surpassing those of RDX. Density functional theory calculations, including geometry optimization, electron density analysis, and natural bond orbital (NBO) studies, provide deeper insights into its electronic structure and bonding characteristics. Furthermore, the mono-N-amination product (3) and several of its energetic salts (4-9) were also synthesized and characterized. This work establishes a new paradigm in weak-bond chemistry, offering critical insights into the stability limits of N-N bonds and paving the way for the next generation of high-energy-density materials.