Fig. 5. (a) Hydrogen bond chains in the lowest energy predicted crystal structure resulting from an extended conformer of 2. Hydrogen bonds are indicated as thin blue lines. The conformer leading to this structure is enclosed in a blue box in Fig. 4. (b) Overlay of the extended conformer of 2 with the ROY conformation from the R polymorph, showing a good steric match of the nitroaniline group to ROY. (c) Overlay of the extended conformer of 2 with the ROY conformation from the Y polymorph. The thiophene rings and urea are nearly at right angles, showing a poor steric match.