The title compound, C4H4N4O7, is a bicyclic carbonate ester of 1,3-dinitroi
midazolidine-4,5-diol. It contains only C, H, N, and O, and has a remarkabl
y high density of 1.953 Mg m(-3), one of the top 12 densities in the CHNO r
ealm. Such high densities are usually only observed in strained polycyclic
ring compounds such as the nitrocubanes and hexanitrohexaaza-isowurtzitane.