Article,
The crystal and molecular structures of three diarylide yellow pigments, C. I. Pigments Yellow 13, 14 and 63
Dyes and Pigments, 55 (2-3): 79--89 (December 2002)
DOI: 10.1016/s0143-7208(02)00068-2
Abstract
All three pigments crystallise in the triclinic system, space group PView the MathML source, and with one molecule in the unit cell so that all molecules have crystallographic Ci symmetry. The molecules exist 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 degrees 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 arrangements. The colour and technical performance of the pigments are discussed in relation to the structural details.
