X-H⋯C hydrogen bonds in n-alkane-HX (X = F, OH) complexes are stronger than C-H⋯X hydrogen bonds

Abstract

Computational study of X-H⋯C and C-H⋯X hydrogen bonds in n-alkane-HX complexes (X =F,OH, alkane =propane, butane, pentane) has been carried out in this work. Ab initio and density functional theories were used for this study. For n-alkane-H2O complexes both O⋯H-C and O–H⋯C hydrogen bonded complex have been found, while for n-alkane-HF complexes, our attempt to optimize F⋯H-C H-bond was not successful. Like most of the hydrogen bonded systems, strong correlation between binding energy and stretching frequency of H-F and O-H stretching mode was observed. The values of electron density and Laplacian of electron density are within the accepted range for hydrogen bonds. In all these cases, X-H⋯C hydrogen bonds are found to be stronger than C-H⋯X hydrogen bonds.