Dihydrogen-bonded complexes of xenon dihydride with water: Ab initio calculations and topological analysis of electron localisation function (ELF)

Ab initio calculations on the structures, energetics and vibrational spectr a of ternary XeH2-(H2O)(2) complexes are presented. Three complex structure s were found involving dihydrogen bonding between the hydrogens of XeH2 and water. The lowest energy form is a cyclic structure where the mediating wa ter molecule is bound by a dihydrogen bond to XeH2 and by a traditional hyd rogen bond to the other water molecule. The complex structure is further st abilised by an attraction between the electron lone pairs of the second wat er molecule and xenon. The calculated interaction energy of this complex is -38.3 kJ mol(-1) at the CCSD(T)//MP2 level. The two other structures found are about 10-15 kJ mol(-1) less bound but they still possess relatively st rong interactions between complex subunits. The predicted vibrational spect ra of these three XeH2-(H2O)(2) complexes are strongly perturbed compared t o the unperturbed monomers, and especially strong shifts are found for the O-H and Xe-H stretching vibrations.