Hydrogen bonding interactions in fluorinated 1,2,3-triazole derivatives

ESPITIA, EDEIMIS; TUTTOLOMONDO, MARÍA EUGENIA; ULIC, SONIA E.; ECHEVERRÍA, GUSTAVO A.; JIOS, JORGE LUIS; PIRO, OSCAR E.; PEREZ, HIRAM

NEW JOURNAL OF CHEMISTRY

ROYAL SOC CHEMISTRY

Año: 2020 vol. 44 p. 16006 - 16019

1144-0546

The study of intra- and intermolecular interactions in solid state of four related fluorinecontaining 1,2,3-triazole derivatives (1: R= -H, 2: R= -NO2, 3: R= -CH3, 4: R= -Cl) was carriedout using quantum chemical calculations, vibrational (IR and Raman) and solid phase UVVis spectroscopy, and single-crystal X-ray diffraction methods. The enol-keto / keto-enoltautomerism on the o-hydroxyacetophenone moiety was analyzed in terms of the synergybetween O-H···O intramolecular hydrogen bond strengthening and the enhancement of delocalization within the pseudo ring. The preference of the enol-keto form was attributed tothe aromatic stabilization energy. The proton in the triazole ring was located on theintermediate nitrogen atom, with no evidence of prototropie in the studied series.Compounds 1 and 4 have similar structural motifs with N-H···O hydrogen bonds connectingamino and carbonyl groups of neighboring molecules in a chain along a-axis. For 2, it was found that both oxygen atoms of the nitro substituent participate as acceptors, connectingadjacent molecules by hydrogen bonds through the N-H and O-H groups. In compound 3,the crystallization water molecule dominates the hydrogen bonding interactions, whichassociates three molecules of 3, giving rise to a three-dimensional H-bonding network.These intra and intermolecular interactions, which affect the absorption bands location ofthe involved groups, were also detected in the vibrational spectra of the studied triazole.