Despite the angular strain associated with the assembly of small rings
, 1,2-diisocyanatocubane reacts with trimethylsilyl azide under mild c
onditions to form a hexacyclic ring assembly that contains an imidazol
idone ring fused to one edge of cubane. This compound was identified a
s an azidocarbonyl-substituted cubanourea by means of X-ray crystal st
ructure analysis of the nitro-derivative, the energetic compound N-azi
docarbonyl-nitrocubanourea.