The crystal and molecular structure of C.I. Pigment Yellow 83, a superior performance Diarylide Yellow pigment

The pigment (Y83) crystallises in the monoclinic system, space group P2₁/c, with two molecules in the unit cell. The molecules exist in the bisketohydrazone tautomeric form and have crystallographic C_i symmetry. The intra molecular hydrogen bonding normally associated with this structural arrangement is observed, but there is no inter molecular hydrogen bonding. The crystal structure differs from those of previously reported Diarylide Yellow pigments (Y12, Y13, Y14 and Y63) in that the molecules are more nearly planar and the packing arrangement involves simple inclined stacks. The difference in crystal packing for Y83 is consistent with its inability to form solid solutions with the other pigments. The colour properties and technical performance of the pigment are discussed in relation to its crystal structure. © 2003 Elsevier Science Ltd. All rights reserved.