An Ab Initio Investigation of the Hydration of Tin(II)

Abstract

The structure of tin(II) is not well known in aqueous solution. The energies, structures, and vibrational frequencies of [Sn(H2O)n,]2+ 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 tin–oxygen distances and totally symmetric stretching frequency of the aquatin(II) ions were compared with each other, and with solution measurements where available.

An Ab Initio Investigation of the Hydration of Antimony(III)

“…No consensus exists on the coordination number of lead(II), with predictions ranging from 4 to 9, but our results were most consistent with a hemidirected hexaaqualead(II) species. For the smaller aquatin(II) ion (5s 2 4d 10 ), we found that the preferred hydration mode was a tricoordinate trigonal pyramidal triaquatin(II), agreeing with recent experiments [4]. We extend our work now to antimony(III), which has the same valence electron configuration as tin(II) but a higher charge.…”

“…The pairs HF/CEP-31G* and HF/CEP-121G*, and MP2/CEP-31G* and MP2/CEP-121G*, were nearly coincident with each other, with the latter pair giving slightly longer bond lengths. The variation in the Sb-O distance with the level of theory was smaller than that of Sn-O [4]. Based on our calculations, if the coordination number is indeed 5, then we would expect an average Sb-O distance of around 2.25 Å.…”