STRUCTURES AND BOND-ENERGIES OF THE NOBLE-GAS COMPLEXES NGBEO (NG=AR,KR, XE)

The geometries, vibrational frequencies and Ng-BeO bond dissociation e nergies are calculated for the title compounds using quantum chemical methods. The electronic structure of the molecules is investigated wit h the help of the topological analysis of the electron density distrib ution. At the MP4 level of theory using effective core potentials for the noble gases and large valence basis sets (quadruple-zeta for Ng, t riple-zeta for Be and O, three d and one f type polarization functions ), the bond strengths D0 are predicted after correcting for the BSSE t o be 12.6 for XeBeO, 9.3 for KrBeO and 6.7 kcal mol-1 for ArBeO. The N g-BeO bond of ArBeO and KrBeO is caused by induced dipole interactions , but the Xe-BeO bond has small covalent contributions. The shift of t he BeO stretching frequency towards higher wave numbers upon formation of the noble ps complexes is in agreement with the observed blue-shif t of the compounds.