Five- and six-membered N–H⋯S hydrogen bonding in aromatic amides

The capacity of sulfur to form intramolecular five- or six-membered S⋯H–N hydrogen bonding in aromatic amides is assessed. The five-membered S⋯H–N hydrogen bonding is observed in crystal structures of five compounds, whereas the six-membered S⋯H–N hydrogen bonding is revealed in crystal structures of three compounds. The trityl group has been used to promote formation of the weak hydrogen bonding because it efficiently inhibits the competition of the intermolecular CO⋯H–N hydrogen bonding. (2D) 1H NMR experiments indicate that both patterns also exist in chloroform.