A theoretical study on the hydrogen bonding interactions in HXeCCH⋯Y (Y = H2O and HF) complexes

The HXeCCH⋯H2O and HXeCCH⋯HF complexes have been investigated by ab initio calculation. Equilibrium geometry, harmonic vibrational frequencies, energies were calculated. The results show that HXeCCH tends to form π H-bond by accepting proton from H2O (or HF) when they encountered, while other complexes taking XeH or CH of HXeCCH moiety as proton donors have less stabilities. The H-bond taking CH as H-donor is characterized to be a red-shifting H-bond, while the H-bonds taking XeH as H-donors in some complexes show blue-shifting character. Meanwhile, the vXeH in π H-bonded complexes shifts to blue although these π H-bonds are red-shifting ones, which is attribute to the hyper-conjugation effects in these complexes. Moreover, the hyper-conjugation effects or the formation of the blue-shifting H-bonds lead to more (HXe)+(CCH)− ionic character, while the HXeCCH⋯H2O complex involving one CH⋯O red-shifting H-bond shows less (HXe)+(CCH)− ionic character. The localized molecular orbital energy decomposition analyses (LMO-EDA) show that the dominant stabilizing forces are exchange energies and electrostatic interactions in all complexes, while the polarization and dispersion interactions play a minor role to the stabilization of these complexes. Compared with paralleled HXeCCH⋯CO2 complex observed experimentally, there are more chances to observe π H-bonded HXeCCH⋯H2O and HXeCCH⋯HF experimentally.