MOLECULAR-ORBITAL STUDIES OF THE STRUCTURES AND REACTIONS OF SINGLY CHARGED MAGNESIUM-ION WITH WATER CLUSTERS, MG+(H2O)(N)

With ab initio molecular orbital calculations, the structures of the c ation clusters Mg+(H2O)(n) and their hydrogen-eliminated products (MgO H)(+)(H2O)(n-1) are optimized. In Mg+(H2O)(n), the hydration number of the most stable isomer is 3. In (MgOH)(+)(H2O)(n-1), all water molecu les are directly bonded to Mg+ for n less than or equal to 6. The hydr ation energy of (MgOH)(+) is larger than that of Mg+ because of the st rongly polarized (MgOH)(+) molecular ion; Mg is oxidized halfway to Mg (II). The internal energy change of the hydrogen elimination of Mg+(H2 O)(n) is positive for n = 1-5, but becomes negative for n = 6, which i s in good agreement with the product switching in the TOF spectrum rep orted in the preceding paper by Sanekata et al. The effects of isotope substitution and equilibrium constants of the hydrogen (deuterium) el imination reaction observed in their experiment can be explained quali tatively.