Molecular orbital estimation of reduced partition function ratios of lithium ions in ion exchanger phase of aqueous ion exchange systems

• Autorzy: Yanase S. , Oi T.
• Konferencja: Proceedings of the International Conference “2001 an Isotope Odyssey: New Application for a New Millenium", June 24-29, 2001, Zakopane, Poland
• Języki publikacji: EN

Abstrakty

EN

Structures of Li+(H2O)5SO3 --R with -R representing the methyl and other groups modeling the lithium ion in the ion exchanger phase of aqueous ion exchange systems were optimized based on the molecular orbital theory and the reduced partition function ratios (RPFRs) for the 6Li/7Li isotope substitutions were estimated. The structure around the lithium ion was nearly unchanged by the substitutions of the methyl group by the other groups. Correspondingly, the RPFR value did not vary substantially, either; the maximum decrease of 0.0008 was observed for -R = -C(C2H5)3 from that of -CH3. It was indicated that the equilibrium constant of the lithium isotope exchange reaction between the ion exchanger and the external solution phases could change by ca. 0.001 without any substantial structural change around the lithium ion in the ion exchanger phase. It was also indicated the ONIOM calculation is effective when treating isotope effects of large molecules.

Słowa kluczowe

EN

ion exchange; lithium; lithium isotopes; molecular orbital calculations; ONIOM calculations

• Wydawca: Institute of Nuclear Chemistry and Technology
• Czasopismo: Nukleonika
• Rocznik: 2002
• Tom: Vol. 47,suppl.1
• Strony: 75--79
• Opis fizyczny: Bibliogr. 6 poz., rys.

Twórcy

autor

Yanase S.

• Residential Systems and Materials Laboratory, Asahi Kasei Corporation, 1-3-1 Yakoh, Kawasaki, Kanagawa 210-0863, Japan

autor

Oi T.

• Department of Chemistry, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo 102-8554, Japan, Fax: [phone]

Bibliografia

• 1. Bigeleisen J, Mayer MG (1947) Calculation of equilibrium constants for isotopic exchange reactions. J Chem Phys 15:261–267
• 2. Huheey JE (1983) Inorganic chemistry, 3rd ed. Happer & Row, London
• 3. Humbel S, Sieber S, Morokuma K (1996) The IMOMO method: Integration of different levels of molecular orbital approximations for geometry optimization of large systems: Test for n-butane conformation and SN2 reaction: RCl + Cl–. J Chem Phys 105:1959–1967
• 4. Oi T, Kawada K, Hosoe M, Kakihana H (1991) Fractionation of lithium isotopes in cation-exchange chromatography. Sep Sci Technol 26:1353–1375 (and references cited therein)
• 5. Svensson M, Humbel S, Froese RDJ, Matsubara T, Sieber S, Morokuma K (1996) ONIOM: A multilayered integrated MO+MM method for geometry optimizations and single point energy predictions. A test for Diels-Alder reactions and Pt(P(t-Bu)3)2+H2 oxidative addition. J Phys Chem 100:19357–19363
• 6. Yanase S, Oi T (2001) Ab initio molecular orbital calculations of reduced partition function ratios of hydrated lithium ions in ion exchange systems. Z Naturforsch 56a:297–306