On the molecular forces (S⋯O close contact, SC6H4NH2 through-conjugation, N lone pair effect and NH⋯N hydrogen bonds) observed in the crystal structure of 2(4-amino-benzosulfonimido)-5-methyl-3H-1,3,4-thiadiazole

V. Fülöp, A. Kálmán, A. K. Basak, M. Ghosh, S. K. Mazumdar

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The structure of 2(4-amino-benzosulfonimido)-5-methyl-3H-1,3,4-thiadiazole has been established by X-ray crystallography from diffractometer data. C9H10N4O2S2 (Mr = 270.33) crystallizes in the orthorhombic system, space group Pbca with a = 10.168(1), b = 11.122(1), c = 21.237(2) Å, V = 2401.8(7) Å3, Z = 8, Dc = 1.50 g cm-3 and μ(Cu Kα) = 39.5 cm-1. The structure has been solved by direct methods and refined to R = 0.044 for 1889 observed reflections. Comparing it with the structures of the related sulfathiazole polymorphs the second nitrogen atom in the hetero ring does not alter its predominant tautomeric (imido) form, but strengthens the S⋯O close contact (2.762(2) Å) formed between the ring sulfur atom and one of the oxygens of the sulfonyl group. The coplanar new hetero ring closed by the S⋯O approach involves an antiperiplanar exocyclic N lone pair and SVIO bond arrangement resulting in an optimum n(N)σ*(SVIO) orbital interaction. As an additional result a strong SVIN(sp2) bond would be expected if the N lone pair were not involved in the formation of intermolecular NH⋯N hydrogen bonds binding molecular dimers. These altogether seem to be in favour of a "through-conjugation" (M. Colapietro, A. Domenicano, C. Marciante and G. Portalone, Z. Naturforsch., Teil B, 37 (1982) 1309) between SVI and the terminal NH2 moiety of the sulfanilamide group.

Original languageEnglish
Pages (from-to)303-310
Number of pages8
JournalJournal of Molecular Structure
Issue number3-4
Publication statusPublished - Jul 1987

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry
  • Inorganic Chemistry

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