Lithium water exchange

Fig. 6. Energy profile for water exchange around the lithium cation (relative energies B3LYP/6-311+G ) (90).

In aqueous solution metal ions are surrounded by water molecules.36 In some cases, such as the alkali ions, they are weakly bound, whereas in others, such as [Cr(H20)6]3+ or [Rh(H20)6]3+, they may be firmly bound and exchange with solvent water molecules only very slowly for the lanthanides water exchange decreases with decreasing ionic radii.37 Coordination numbers vary extensively, depending on the size of the metal ion. For example, coordination number four is common for lithium, six is most frequently found for transition metal ions 38 higher coordination numbers are not unusual for larger ions, e.g., Bi3+ can form Bi(H20)93+.39... 

Intercalation of poly(ethylene oxide) into a lithium-ion exchanged clay gives an interesting class of layered silicate nanocomposites that are lithium-ion electrolytes. Componnds have been prepared by intercalation from methanol/water solutions and by melt intercalation. Melt intercalation typically gives samples with higher polymer contents than the solution method and with higher lithium-ion conductivity though the conductivity is probably stiU too low for practical applications. 

Analysis of the relaxation time indicates that a narrow linewidth in the H NMR spectra generally implies that the protons on the surftice of M-SbA are mobile, while a wide one indicates that proton motion on the surface of M-SbA is rather restricted. The IR spectra study yield absorption bands at 2800-3200 cm to show the presence of free water in addition to the —OH of Sb-OH (2800-3000 cm ). The peaks attributed to the Sb-OH group decrease markedly with increasing uptake of Li. These results indicate that lithium ion exchange is attributed to the dehydration in the M-SbA structure. 

The investigation of lithium-isotope-exchange reactions involving the isotopic metals and the isotopic ions in aqueous solution presents social problems because of the reaction of lithium metal with water. The clue to the resolution of this... 

The exchange of lithium in a dililhium phthalocyanine is a useful tool to prepare metal (e.g., zinc) or metal-free phthalocyanines. For this purpose, the dilithium phthalocyanine is prepared by reaction of phthalonitrile and lithium alkoxide in an alcohol, e.g. pentan-l-ol. In most cases, the lithium phthalocyanine is not separated but directly converted into the respective phthalocyanine by treatment with metal salts or, in the case of metal-free phthalocyanine, with acid or water. 

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