Heterocyclic Tautomerism. IV. The Solution and Crystal Structures of 1-Aryl-3-phenyl-1,2,4-triazol-5-ones

Abstract

The title compounds are shown to exist in solution and in the solid state as 4H-tautomers. X-Ray crystal structure determinations show that 1,3-diphenyl-1,2,4-triazol-5-one exists as a dimeric pair of strongly hydrogen-bonded molecules and that 3-phenyl-1-(2-pyridyl)-1,2,4- triazol-5-one exists as the 4H-tautomer stabilized by a complex network of hydrogen bonding to water molecules.