1,5-Type nonbonded O⋯S and S⋯S interactions in (acylimino) and (thioacylimino)benzothiazoline systems. Crystal structures and theoretical calculations

Abstract

Intramolecular nonbonded interactions have been observed in the crystalline structures of 6-ethoxy-2-trifluoroacetyliminobenzothiazoline ( 4 ) (S⋯O close contact) and 6-ethoxy-2-trifluorothioacetyliminobenzothiazoline ( 5 ) (S⋯S close contact). Density functional B3LYP/6-311G ∗∗ calculations were performed for all conformers and tautomers of 4 and 5 in order to explain the preference for the S⋯O and S⋯S close contact structures. The calculations agree with the observed crystallographic structures only when solvent effects are included via a continuum model, thus showing the importance of the solvent effects to establish the correct relative energies.