The formation of the π⋯H, F⋯H and C⋯H hydrogen bonds on the C2H2⋯(HF), C2H2⋯2(HF) and C2H2⋯3(HF) complexes

Abstract

In this work, a theoretical study on the basis of structural, vibrational, electronic and topological parameters of the C2H2⋯(HF), C2H2⋯2(HF) and C2H2⋯3(HF) complexes concerning the formation of π⋯H, F⋯H and C⋯H hydrogen bonds is presented. The main difference among these complexes is not properly the interaction strength, but the hydrogen bond type whose benchmark is ruled justly by the structure. Meanwhile, the occurrence of π⋯H hydrogen bonds was unveiled in both C2H2⋯(HF) dimer and C2H2⋯3(HF) tetramer, although in latter, this interaction is stronger than C⋯H of the C2H2⋯2(HF) trimer. However, the F⋯H hydrogen bonds within the subunits of hydrofluoric acid are the strongest ones, reaching a partial covalent limit, and thereby contribute decisively to the stabilization of the tetramer structure. In line with this, the largest red-shifts were observed on the hydrofluoric acid trimer of the C2H2⋯3(HF) complex.