Solvatochromism of heteroaromatic compounds: XXX. N-Methyltrifluoromethanesulfonamide as hydrogen-bond donor

In two-centered H-complexes with protophilic solvents, the monomer of N-methyltrifluoromethanesulfonamide I behaves as a strong H-bond donor, stronger than 4-fluorophenol and ranking second after 4-nitrophenol. In protophilic media, amide I exists as monomeric H-complexes with a two-centered H-bond and 1:2 H-complexes of the open-chair dimer with a bifurcated (three-centered) hydrogen bond. The formation of a strong bifurcated H-bond weaken the bridging N-H.‥O=S bond.