Construction of high energy density azasydnone-pyrazole compounds

The search for advanced energetic materials has shifted beyond traditional groups like nitro to explore non-conventional explosophores. Among these, the azasydnone ring stands out, combining a zero-oxygen balance with high-energy bonds (N-N, N-O, N=N) for stable energy storage. Here, we report the introduction of azasydnone rings at different positions of dinitropyrazole. Although they have the same substituent group, the change of the position of the azasydone ring makes the two compounds show great differences in crystal density (4-azasydnone-3,5-dinitropyrazole 1.830 g·cm⁻³, 5-azasydnone-3,4-dinitropyrazole 1.981 g·cm⁻³). Molecular structures are confirmed by ¹H and ¹³C NMR, IR spectroscopy, and X-ray crystal diffraction. This serves as an example of the ability to construction of high-density azasydnone compounds.