Crystalline Forms of 4,4'-Methylenediantipyrine: Crystallographic Unit Cell for the Anhydrous Form, from Laboratory Powder XRD Pattern by DASH Program Package

Crystalline unit cell structure of anhydrous title compound, diantipyrinylmethane (CAS Registry No. 1251-85-0), a substance usually obtained as a by-product in Mannich type reactions of antipyrine, has been modelled by the help of powder X-ray diffraction, applying the DASH software package and crystal coordinates coming from former single crystal X-ray structure determinations (CSD codes FADDIY and FADDIY01) of its monohydrate. The unit cell of the anhydrate compound belongs to the monoclinic space group P21/a, with unit cell parameters of a = 14.604, b = 9.858, c = 14.509 Å, β = 95.56 °, V = 2078.9 Å3, Z = 4, Z ' = 1. Comparisons of FT-IR spectrum and thermal behavior of the anhydrous and monohydrated forms confirm differences in degree of hydration and solid state structure, while those of 1H- and 13C NMR-spectra show their molecular identity.