Crystal and molecular structure of the enol form of 1,1′-diphenyl-2,2′-dithiobis(butane-1,3-dione)
The crystal structure of the title compound has been determined by X-ray diffraction methods. Crystals are orthorhombic, space group Pcab, with Z= 8 in a unit cell of dimensions: a= 26.708(1), b= 18.917(7), c= 7.591(1)Å. The structure was solved by the heavy-atom method and refined by full-matrix least squares to a final R of 0.072 for 2 218 observed reflections. The butane-1,3-dione groups are planar and the phenyl groups lie at 47.8 and 50.3° to these planes. The distances between the oxygen atoms within the butanedione groups are 2.374 and 2.436 Å, indicating strong, intramolecular hydrogen bonds. The compound is in fact better named 3,3′-dihydroxy-3,3′-diphenyl-2,2′-dithiobisbut-2-en-1-one. S(1)–S(2) is 2.078 ± 0.005 Å and the dihedral angle, C(5)–S(2)–S(1)–C(17), is 66.4°.