Abstract:
A systematic study of the structure and electronic properties of N-heterocyclic arenesulfonamides
(NHAS) was performed using experimental and theoretical methods. Ten new examples of NHAS
with pyridine and thiazole N-heterocycles were synthesized. X-ray diffraction studies on one of the
compounds suggested that the sulfonimide form is preferred; the molecule exists as a dimer due to two
strong intermolecular hydrogen bonds. The possibility of sulfonamide (N-sulfonylamine) ! sulfonimide
(N-sulfonylimine) tautomerism was explored using density functional theory (DFT) methods. The energy
difference between the two tautomers was small (o6 kcal mol1
) in the gas phase, favoring the
sulfonamide tautomer; however, with an increase in the polarity of the solvent, the preference towards
the sulfonimide tautomers increased in many examples. Electronic structural analysis of the sulfonimide
tautomers suggested the possibility of an unusual (NHC) - N coordination.
