| Abstract
| - This paper provides an overview of recent progress on structural data on the title compound. Theoreticalwork based on quantum mechanical calculations was performed to gain some understanding on the heterocyclictautomerism potentially exhibited by the compound. The computational studies encompassed a wide range oftautomers/conformers, allowing the determination of the most probable molecular structure. In the gas phase,the nitroimine tautomers are computed to be substantially more stable than the nitramine tautomers. Amongthree plausible nitroimine forms, special attention was given to 4,6-bis(nitroimino)-1,3,5-triazinan-2-one, whosecrystal structure was unequivocally solved by X-ray diffraction. The crystals are orthorhombic, space groupPnma with a = 6.187(2)Å, b = 13.252(5)Å, c = 8.802(4)Å, and Z = 4. The structure was solved by directmethods and refined to a final R = 0.0326. The molecule has an approximate mirror plane relating the twosymmetry related halves. The nitroimine groups are positioned in a syn−syn conformation. The least-squares(LS) plane of the heterocyclic ring and the nitroimine (N−NO2) substituent LS plane make an angle of10.05(11)°. The crystal structure is held together via hydrogen bonds that assemble the molecules in chainsrunning along the b-axis. Every H-atom is involved in bifurcated hydrogen bonds.
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