X-RAY CRYSTAL-STRUCTURE OF DISPERSE RED-167

X-ray diffractometer data have been used to determine the crystal structure of CI Disperse Red 167, an important automotive disperse dye. The structure was solved by direct methods and refined by least squares to R = 0.0442 for 1115 independent reflections. This monoazo dye possesses a planar azobenzene skeleton, as the dihedral angle between the planes made by the two aromatic rings is 1.5-degrees. The non-bonding distance between the hydrogen atom of the acetamido group and azo nitrogen N(1) is well within the expected distance for intramolecular hydrogen bonding. Interestingly, the chloro and acetamido groups lie on the same side of the azo bond, and each unit cell of this dye contains 8 molecules.