CRYSTAL STRUCTURE OF ORGANIC PIGMENTS .3. CRYSTAL STRUCTURE OF 4,4'-DIAMINO-1,1'-BIANTHRAQUINONE, C28H16N2O4

Red pigment 4,4'-diamino-1,1'-bianthraquinone (C28H16N2O4) is orthorhombic, space group Pbcn, with cell dimensions a = 12.996, 6 = 8.500, c = 17.636 Â and with four molecules in the unit cell. The x-ray structure analysis was first carried out with two-dimensional photographic data by Fourier and trial-and-error methods and then refined with three-dimensional diffractometer data. Two planes of anthraquinonyl groups belonging to a molecule make an angle of about 105° with each other. The molecules overlap each other in the direction of the b axis and form a layer connected by hydrogen bonds. These layers are connected only by van der Waals forces along the c axis. Within a layer some shorter intermolecular atomic distances than the sum of van der Waals radii were found. © 1969, Walter de Gruyter. All rights reserved.