Azole. 45.

The three title compounds, namely (Z)-1-(4,5-di­nitro­imidazol-1-yl)-3-morpholinopropan-2-one 2,4-di­nitro­phenyl­hydrazone, C₁₆H₁₇N₉O₉, (IV), (Z)-3-morpholino-1-(4-morpholino-5-nitro­imidazol-1-yl)propan-2-one 2,4-di­nitro­phenyl­hydrazone, C₂₀H₂₅N₉O₈, (Va), and (E)-3-morpholino-1-(4-morpholino-5-nitro­imidazol-1-yl)propan-2-one 2,4-di­nitro­phenylhydra­zone tetra­hydro­furan solvate, C₂₀H₂₅N₉O₈·C₄H₈O, (Vb), have been prepared and their structures determined. In (IV), the C-4 nitro group is nearly perpendicular to the imidazole ring and the C-4—NO₂ bond length is comparable to the value for a normal single Csp²—NO₂ bond. In (IV), (Va) and (Vb), the C-­5 nitro group deviates insignificantly from the imidazole plane and the C-5—NO₂ bond length is far shorter in all three compounds than C-4—NO₂ in (IV). In consequence, the C-4 nitro group in (IV) is easily replaced by morpholine, while the C-5 nitro group in (IV), (Va) and (Vb) shows an extraordinary stability on treatment with the amine. The E configuration in (Vb) is stabilized by a three-centre hydrogen bond.