2,4-Diaryl-1,3-chalcogen azoles bearing pentafluorosulfanyl SF5 groups: a synthetic and structural study.

A series of new 2,4-diaryl-1,3-chalcogen azoles having pentafluorosulfanyl SF5 functional groups has been prepared by means of the two-component cyclization of the selenoamide or thioamide with α-bromoketones. The selenoamides or thioamides were obtained from the reaction of Woollins' reagent or Lawesson's reagent with 4-pentafluorosulfanylbenzonitrile, followed by hydrolysis with water. All new compounds were characterized by (1)H, (13)C, (77)Se, (19)F NMR spectroscopy, and accurate mass measurement. X-ray crystal structure analysis of the selenoamide, thioamide, and 2,4-diarylpentafluorosulfanyl-1,3-chalcogen azoles reveal that the selenoamide and thioamide have very similar structural features along with similar intermolecular interactions such as the π-π stacking and the weak N-H···E (E = S or Se) hydrogen bonding. The 2,4-diarylpentafluorosulfanyl-1,3-chalcogen azoles show the newly formed five-membered N(1)-C(2)-E(3)-C(4)-C(5) ring is either perfectly planar (and coplanar with two peripheral aryl ring planes) or near-planar. The π-π intermolecular interactions and the weak C-H···π and C-H···X (X = Br, F, O) hydrogen bonding are discussed in the cases of 2,4-diarylpentafluorosulfanyl-1,3-chalcogen azoles.