Structure of 2-nitro-1,3-bis(phenylthio)benzene, C18H13NO2S2

Abstract

M r = 339.44, monoclinic, P2Jc, a = 7.640(3), b- 13.499 (2), c= 15.587 (6)A, t= 96.818 (11) °, V= 1596.2 (9) A 3, Z= 4, Ox= 1.41 gcm -a, 2(Mo K~t) = 0.71069 A, g = 3.27 cm -~, F(000)=704, T= 163K, R=0.041 for 2856 ob- served reflections. Close, non-bonded interactions of 2.733 (2) and 2.748 (2)A are observed between the S atoms and the O atoms. The nitro group is twisted out of the plane of the central phenyl ring by 40.69 (7) °. The molecule has approximate twofold symmetry with the twofold axis lying along the C-N bond axis and, therefore, the terminal phenyl rings are equivalent. Introduction. Analysis of the IaC NMR spin lattice (T~) relaxation measurements of 3-nitro-2-(2-pyridylthio)- pyridine (Kimura, Simonsen, Caldwell & Martin, 1981) showed the non-nitro-substituted pyridine ring to reorient anisotropieally by free rotation about the C-S bond while the nitro-substituted ring did not. A subsequent X-ray structure determination showed a close S...O contact and asymmetric C-S bond distances with the shorter distance being to the C atom of the substituted ring. It was concluded that this S...O contact inhibited free rotation of the substituted ring in solution and was responsible for the difference in the motional behavior of the rings. Preliminary ~3C NMR studies on the title compound indicated that the terminal phenyl rings were non-equivalent and an X-ray structure determination was undertaken to see if such asymmetry persisted in the solid state as well. Experimental. The title compound was synthesized by the method of Miller (1976), and a yellow, plate-like crystal of approximate dimensions 0.40 × 0.66 × 0.15 mm was cut from a larger crystal obtained by slow evaporation from an ethanol solution. Data collected on a Syntex P21 diffractometer with a graphite monochromator and equipped with Syntex LT-1 low- temperature delivery system. Lattice parameters ob- tained by least-squares refinement of setting angles of 45 reflections with 20 between 21.2 and 30.0 °. og-Scan technique, 3668 unique reflections, 20 range 4-55 ° ,