Crystal structure determination of N,N′-1,4-phenylene-bis(3-oxobutanamide) from laboratory powder diffraction data

The compound N,N'-1,4-phenylene-bis(3-oxobutanamide) is an industrial intermediate used in the synthesis of azo pigments. Crystallisation experiments only led to the dihydrate form; drying the dihydrate at 120 degrees C leads to an anhydrous form, but suitable single crystals of the anhydrous form could not be grown. Therefore, its crystal structure was determined from laboratory powder diffraction data. The structure was solved by real-space methods using the program DASH and refined by the Rietveld method using the program TOPAS. The anhydrous form crystallises in P2(1)/c, Z = 2 with lattice parameters a = 16.9749(5) angstrom, b = 4.8648(1) angstrom, c = 8.5372(2) angstrom, beta = 93.396(2)degrees. The crystal structure of the dihydrate was determined by single-crystal structure analysis. The dihydrate crystallises in P (1) over bar, Z = 1 with a = 5.0116(1) angstrom, b = 5.2199(2) angstrom, c = 14.7803(5) angstrom, alpha = 88.396(1)degrees, beta = 80.250(1)degrees, gamma = 81.439(1)degrees. In both crystal structures the molecule, which has a centre of symmetry, is situated on an inversion centre. For the anhydrous form dispersion-corrected DFT calculations were used to confirm the structure.