Disodium 2,5-bis(phenylamino)terephthalate decahydrate, an intermediate in the industrial synthesis of quinacridone pigments.

The title compound, 2Na+.C20H14N2O4(2-).10H2O, is an intermediate in the industrial synthesis of red and violet quinacridone pigments. The structure is remarkable for two reasons. First, one of the Na+ ions is surrounded octahedrally by five water molecules and a phenyl group, although the crystal contains many more water molecules than are required for complete coordination of both Na+ ions with six water molecules each. Secondly, although the anion has almost exact molecular inversion symmetry, it is positioned on a general position; this is one of the very few exceptions to the observation of Kitajgorodskij [Advances in Structure Research by Diffraction Methods--Fortschritte der Strukturforschung mit Beugungsmethoden (1970), Vol. 3, pp. 173-247] that molecules with inversion centres always lie on crystallographic inversion centres.