An Ab Initio Investigation of the Hydration of Thallium(III) and Mercury(II).

The energies, structures, and vibrational frequencies of M(H2O)n, M = Tl3+, Hg2+, n = 0–9, 18 have been calculated at the Hartree–Fock and second order Møller–Plesset levels of theory using the CEP, LANL2, and SDD effective core potentials in combination with their associated basis sets, or with the 6-31G* and 6-31+G* basis sets. The metal–oxygen distances and totally symmetric stretching frequency of the aqua ions were compared with each other and with solution measurements. The results are consistent with thallium(III) and mercury(II) being hexacoordinate in aqueous solution. The use of symmetry is shown to be advantageous. [ABSTRACT FROM AUTHOR]