Lithium crown ether complexes

Kollig, H.P., Ellington, J.J., Weber, E.J., and Wolfe, N.L. Environmental research brief - Pathway analysis of chemical hydrolysis for 14 RCRA chemicals. Office of Research and Development. U.S. EPA Report 600/M-89/009, 1990, 6 p. Kolthoff, I.M. and Chantooni, M.K., Jr. Crown ether complexed alkali metal picrate ion pairs in water-saturated dichloro-methane as studied by electrolytic conductance and by partitioning into water. Effect of lithium chloride on partitioning, J. Chem. Eng. Data, 42(l) 49-53, 1997. 

The ability of the crown ether ligand, 12-crown-4, to separate the lithium cation from the organic moiety, thus stabilizing the SSIP structure, was also observed in the study dealing with cyclopentadienyllithium systems . As described in Section II.C.3, SSIP structures of these compounds are characterized by low x( Li) values. However, it is important to reahze that the variation found for x( Li) is basically caused by the local symmetry around the lithium cation and other highly symmetric situations will also lead to small x( Li) values. Examples are the sandwich compounds mentioned in Section n.C.3. It is thus necessary to consider also / Li and C chemical shift data in order to classify a certain complex as SSIP or CIP. 

Discrete diarylcuprate anions have been observed in crystals in which the lithium cation is complexed by crown ethers.5 Both tetrahedral Ph4Cu4 and [Ph2Cu] units have been observed in complex cuprates containing (CH3)2S as a ligand. [Ph3Cu]2- units have also been observed as parts of larger aggregates.6... 

Rhinebarger et al. [35] and Eyring et al. [36,37] have used lithium-7 nuclear magnetic resonance (NMR) chemical shift data to determine the stability constants for crown-ether complexes of Li+ in two IL systems consisting of 55/45 mole% N-butylpyridinium chloride-aluminum chloride and l-ethyl-3-methyl-imidazolium chloride-aluminum chloride. The stability constants for... 

Gerhard, A., Cobranchi, D. R, Highley, A. M., Huang, Y. H., Konya, G., Zahl, A., Eldik, R. V., Petrucci, S., Eyring, E. M., Li-7-NMR determination of stability constants as a function of temperature for lithium crown-ether complexes in a molten salt mixture, J. Phys. Chem., 98, 7923,1994. 

Bayle presented liquid crystal 34 (Scheme 19) bearing four aromatic units linked by ester and azo functional groups [56]. Two butyloxy groups are attached at the ends of the molecule and the crown ether is bound at the side of the molecule. The nematic phase exhibited by 34 is quite broad (AT = 96 K). Upon complexation with LiBF4, the nematic range diminishes with increasing amounts of added salt and disappears completely at 0.5 equiv. of added LiBF4 which is most likely due to the formation of a 2 1 crown lithium complex. From 0.2 equiv. of salt, a smectic... 

The conformational situation for twisted 2,2-diacyl compounds of type 29 is quite different from that for sodium or lithium 1,3-diketone enolates. In the latter, the ZZ form is stabilized by complexation with the cation75, and only in the presence of crown ethers is the EZ form observed76. The barrier to EZ - ZE exchange in the free carbanion is 12.9 kcal mol-1, as expected quite close to that found for 29. 

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