uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
1992 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 96, no 12, 8995-9004 p.Article in journal (Refereed) Published
Abstract [en]

Ab initio calculations of force constants up to fourth order and anharmonic frequencies for the uncoupled O-H stretching vibration in hydrates of the ions Li+, Na+, Mg2+, and Al3+ have been performed at the Hartree-Fock level for M(n+) (H2O)m and M(n+) (H2O)m...(H2O)2 complexes, with m = 5-7. The dependence of force constants and frequency shifts on ion type, cation-water distances, second hydration shell, hydrogen bonding and coordination number is discussed. In the optimized Li+(H2O)6 system, the OH frequency is downshifted 20 cm-1 compared to the free water molecule, whereas, in the optimized Li+ (H2O)6...(H2O)2 complex, the downshift is 120 cm-1. The corresponding numbers for the Al3+ hexaaqua complexes are - 250 and - 1215 cm-1. Frequency shifts with respect to bulk water for the cation-coordinated water molecules have been estimated from the difference between the frequencies of M(n+) (H2O)6...(H2O)2 and a (H2O)2...H2O...(H2O)2 complex. The values are + 85 cm-1 for Li+ and Na+, - 150 cm-1 for Mg2+, and - 1000 cm-1 for Al3+, to be compared with the infrared frequency shifts of + 50 for Li+ and Na+, - 155 for Mg2+ and - 500 cm-1 for Al3+ (experimental aqueous solution values from the literature). The activation energies for water exchange between the hydration shells in the hexaaqua complexes have been calculated for dissociative and associative exchange processes and suggest a dissociative mechanism to be dominant.

Place, publisher, year, edition, pages
1992. Vol. 96, no 12, 8995-9004 p.
National Category
Chemical Sciences
URN: urn:nbn:se:uu:diva-228778DOI: 10.1063/1.462257ISI: A1992HZ09800037OAI: oai:DiVA.org:uu-228778DiVA: diva2:734863
Available from: 2014-07-21 Created: 2014-07-21 Last updated: 2014-07-21

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Hermansson, Kersti
By organisation
Department of Chemistry
In the same journal
Journal of Chemical Physics
Chemical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 434 hits
ReferencesLink to record
Permanent link

Direct link