The crystal and molecular structures of three diarylide yellow pigments, C. I. Pigments Yellow 13, 14 and 63

摘要

All three pigments crystallise in the triclinic system, space group P1, and with one molecule in the unit cell so that all molecules have crystallographic C_i symmetry. The molecules in the bisketohydrazone tautomeric form. The intramolecular hydrogen bonding normally associated with this structural arrangement is observed, but there is no intermolecular hydrogen bonding. The molecules are not quite planar, but deviate from planarity by only a few degress of torsional bond rotations. In each structure the molecules pack together in inclined interleaved stacks so that the ketohydrazonoarylamide groups lie above and below one another in antiparallel arangements. The colour and technical performance of the pigments are discussed in relation to the structural details.