Dense energetic salts of N,N'-dinitrourea (DNU)

The structure of dinitrourea (DNU) as determined by X-ray single-crystal diffraction is orthorhombic; space group: Fdd2; a=12.0015(9), b=17.6425(13), c=4.5555(4); V=964.57 angstrom(3), Z=8, T=90 K; D-c=2.067 g cm(-3). The heat of formation (Delta H-f degrees(298)) of DNU in the gas phase was calculated to be 24.88 kJ mol(-1) by using the G3MP2 method based on isodesmic reactions. Eleven mono-organic salts of DNU were prepared in acetonitrile and characterized via NMR spectra, elemental analyses and DSC. Derivatives of 1,2,4-triazolium salts of DNU exhibit densities ranging from 1.75 to 1.86 g cm(-3) and detonation properties comparable with those of RDX and HMX.