Possible Formation of H 3 O + Cations Due to Aluminum Fluoride Interactions with Water.

The isomeric structures formed by the aluminum fluoride (AlF3 ) system and surrounding water molecules were theoretically examined by employing MP2 and CCSD(T) methods and the aug-cc-pVDZ basis set together with the polarized continuum solvation model within a self-consistent reaction field treatment. The calculations performed for the AlF3 ·n(H2 O) systems (n = 1-6) revealed that facial and meridional octahedral structures correspond to the lowest energy isomers for the AlF3 ·4H2 O, AlF3 ·5H2 O, and AlF3 ·6H2 O systems, whereas the isomers containing the H3 O+ and AlF3 OH- fragments were predicted to be less stable by only 5-7 kcal/mol, which indicates the possible formation of the hydronium cations in such systems even at room temperature.