Theoretical insights into the properties of the dihydrogen-bonded HXH···HCCH complexes (X = Be, Mg, and Ca)

The properties of the dihydrogen-bonded complexes of HXH···HCCH (X = Be, Mg, and Ca) were calculated by the MP2 and B3LYP methods. The optimized structures, energies and natural population analysis (NPA) were presented and analyzed in terms of their possible correlation with the interaction energies and the intermolecular H···H separations. In particular, the charge distributions were investigated to give the sp (linear) vs. sd (bent) hybridization for the CaH2···C2H2 structure. Additionally, the atoms in molecules theory of Bader (AIM) was applied to study the properties of the bond critical point of Hδ−···δ+H contact of the investigated complexes.