6,8-Di­nitro-2,4-dioxa-6,8-diazabi­cyclo­[3.3.0]­octan-3-one

The title compound, C₄H₄N₄O₇, is a bicyclic carbonate ester of 1,3-di­nitro­imidazolidine-4,5-diol. It contains only C, H, N, and O, and has a remarkably high density of 1.953 Mg m⁻³, one of the top 12 densities in the CHNO realm. Such high densities are usually only observed in strained polycyclic ring compounds such as the nitro­cubanes and hexanitro­hexa­aza­isowurtzitane.