Dication-water interactions: M{sup 2+}(H{sub 2}O){sub n} clusters for alkaline earth metals M = Mg, Ca, Sr, Ba, and Ra

Journal Article · Thu Mar 21 04:00:00 EST 1996 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/jp952546r· OSTI ID:232519

Glendening, E D; Feller, D ^[1]

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1. Pacific Northwest National Lab., Richland, WA (United States)

Gas phase structures, binding energies, and enthalpies are reported for small M{sup 2+}(H{sub 2}O){sub n} clusters consisting of an alkaline earth dication (Mg{sup 2+}, Ca{sup 2+}, Sr{sup 2+}, Ba{sup 2+}, and Ra{sup 2+}) with one to six water molecules. Ab initio molecular orbital calculations were performed at the RHF and MP2 levels of theory using split-valence basis sets (6-31+G{sup *} with effective core potentials for the heavier alkaline earth metals). The water molecules in these clusters coordinate the dications in highly symmetric arrangements that tend to enhance electrostatic charge-dipole interactions while minimizing ligand-ligand repulsions. comparisons of the calculated structures and binding energies to higher level treatments reveal fairly reasonable agreement. The optimized M-O distances are slightly long (by 0.02-0.03 A), and binding energies are somewhat weak (by 1-3 kcal mol{sup -1} per ligand). Natural energy decomposition analysis emphasizes the importance of polarization effects in the M{sup 2+}(H{sub 2}O){sub n} clusters. Polarization is largely responsible for the nonclassical bent and pyramidal structures of the di- and trihydrates and for the nonadditive, many-body terms that contribute importantly to the binding energies. 32 refs., 4 figs., 7 tabs.

• DOE Contract Number: AC06-76RL01830; FG06-89ER75522
• OSTI ID: 232519
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 12 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
66 PHYSICS
99 GENERAL AND MISCELLANEOUS
ALKALINE EARTH METALS
BARIUM IONS
BINDING ENERGY
CALCIUM IONS
CATIONS
ENTHALPY
HYDRATION
LIGANDS
MAGNESIUM IONS
MOLECULAR ORBITAL METHOD
POLARIZATION
RADIUM IONS
SOLID CLUSTERS
STRONTIUM IONS
THEORETICAL DATA