posted on 2008-05-01, 00:00authored byJiří Rais, Tatsuhiro Okada
With previous data on alkali metal and halide ions included [Rais, J.; Okada, T. Anal. Sci. 2006, 22, 533], we
analyzed rather broad data on ionic hydration from the point of view of gaseous cluster energetics. We have
now added alkaline earth cations, Zn2+, H+, OH-, Cu+, Ag+, Bi+, Pb+, and alkylammonium cations. The
present analysis revealed the octa-coordinated nature of alkaline earth cations, which is not fully pronounced
for Be2+ and Zn2+, existence of Eigen protonium complex, which is trigonally hydrated, and particular property
of the first OH-, H2O cluster. Whereas these findings are generally in accordance with theoretical model
calculation studies, we have foreseen in addition tetrahedral hydration for halide anions and Rb+ and Cs+, as
well as for alkylammonium ions. The obtained picture of the quantized solvation of ions is mirrored in the
ionization potentials of outer electrons of pertinent atoms. This is a second independent phenomenon, and
together, they invoked a common pattern formation (“Aufbau”) obeying tetra- and octa-coordinated principles.