AB-INITIO STUDY OF THE HYPERMAGNESIUM MG2O+ AND MG3O+ CATIONS

The geometries and vibrational frequencies of MoO+ Mg2O+, and Mg3O+ we re calculated using high level ab initio and density functional theori es. Mg2O+ (D-infinity h, (2) Sigma(g)(+)) is linear while the planar T -shaped (C-2 nu, B-2(2)) and Y-shaped fake(C-2 nu, (2)A(1)) Mg30 + str uctures are essentially degenerate. MgO+, Mg2O+ and Mg3O+ have dissoci ation energies of: MgO+, 52.2 kcal/mol (into O + Mg+); Mg2O+, 93.4 kca l/mol (MgO + Mg+); and Mg3O+, 46.8 kcal/mol (Mg2O+ + Mg). Our results agree well with the relative intensities of these cations in the time- of-flight mass spectra reported in a recent experimental study.