2,6-Di­amino-3,5-di­nitro-1,4-pyrazine di­methyl sulfoxide solvate

The title compound, C₄H₄N₆O₄·C₂H₆OS, crystallizes in the triclinic space group P. It is a di­methyl sulfoxide (DMSO) solvate of the insensitive energetic compound 2,6-di­amino-3,5-di­nitro-1,4-pyrazine (ANPZ). The structure has been determined to obtain more accurate metrical parameters for the 2,6-di­amino-3,5-di­nitro-1,4-pyrazine moiety than those obtained from unsolvated crystals which are invariably twinned. The packing motif consists of two formula units linked by strong complementary hydrogen bonds between the ANPZ units with the two DMSO solvate mol­ecules each linked by two bifurcated hydogen bonds to the two ANPZ units. This central motif is further linked into planar sheets by weaker interactions between the DMSO methyl H atoms and the O atoms from the nitro groups. This looser packing arrangement compared to ANPZ is reflected in a lower density (1.662 Mg m⁻³versus 1.812 Mg m⁻³ for ANPZ).