The crystal structure of C.I. Pigment Yellow 12

The X-ray crystal structure of C.I. Pigment Yellow 12, 2,2ʹ-[(3,3ʹ-dichloro[1,1ʹbiphenyl]-4,4ʹ-diyl)bis(azo)bis[3-oxo-N-phenylbutanamide], is described. This is the first reported single crystal determination for a disazoacetoacetanilide (Diarylide Yellow) pigment. The molecules exist in the bisketohydrazone form which is structurally analogous to the hydrazone form adopted by the monoazoacetoacetanilide (Hansa Yellow) pigments. Notable features of crystalline C.I. Pigment Yellow 12 are that the molecules are not constrained by crystallographic symmetry and that they are not planar. Some intramolecular hydrogen bonding is observed, but there is no intermolecular hydrogen bonding.