Crystal structure of 2,4,6-triphenylverdazyl

The stable free radical 2,4,6-triphenylverdazyl (C₂₀N₄H₁₇) crystallizes in space group P2₁2₁2₁ with four molecules per cell. The lattice constants are a = 18.467 (2), b = 9.854 (1) and c = 8.965 (1) Å. X-ray intensity data were collected on a quarter-circle diffractometer with scintillation-counter detection. The crystal structure was solved by molecular packing analysis, and was refined by structure-factor least-squares calculations using individual anisotropic temperature factors and calculated hydrogen positions. The final discrepancy index was 0.076 for 1309 reflections which were more than one standard deviation above background. The verdazyl ring is nonplanar, with the methylene carbon atom displaced 0.59 Å from the plane of the four nitrogen atoms. The phenyl groups attached to N(2) and N(4) are also warped out of the plane of the nitrogen atoms; in addition, these phenyl groups are twisted by 23 and 13°, respectively, about the phenyl–nitrogen bonds.