Assessment of the intramolecular C–H⋯X (X=F, Cl, Br) hydrogen bonding of 1,4-diphenyl-1,2,3-triazoles

The intramolecular six-membered C–H⋯X (X=F, Cl, Br) hydrogen bonding motif of halogen-substituted 1,4-diphenyl-1,2,3-triazole compounds has been assessed. Twelve triazole derivatives have been designed and prepared, which bear fluorine, chlorine or bromine atoms on the ortho- and/or para-positions of the benzene rings. 1H NMR, X-ray crystallography, and DFT calculation investigations revealed that the ortho-fluorine, chlorine, and bromine atoms of the benzene ring on the C-4 of the triazole unit all can form six-membered C–H⋯X hydrogen bonding. In contrast, only fluorine forms similar, relatively stable intramolecular hydrogen bonding on the N-1 side of the triazole unit.