Thermodynamic and structural relationships between the two polymorphs of 1,3-dimethylurea

Näther, C.; Döring, C.; Jess, I.; Jones, P.G.; Taouss, C.

doi:10.1107/S2052519212049329

Figure 6
Packing of polymorph (II): three chains at x = 1, y = 1 (top), x = ½, y = ½ (centre), and x = 0, y = 0 (bottom). Hydrogen bonds are indicated by dashed lines. Symmetry codes: (i) 1-x, 1-y, z; (ii) x, y, 1+z.