Lithium halide, crystal structures

Later, Tieke reported the UV- and y-irradiation polymerization of butadiene derivatives crystallized in perovskite-type layer structures [21,22]. He reported the solid-state polymerization of butadienes containing aminomethyl groups as pendant substituents that form layered perovskite halide salts to yield erythro-diisotactic 1,4-trans polymers. Interestingly, Tieke and his coworker determined the crystal structure of the polymerized compounds of some derivatives by X-ray diffraction [23,24]. From comparative X-ray studies of monomeric and polymeric crystals, a contraction of the lattice constant parallel to the polymer chain direction by approximately 8% is evident. Both the carboxylic acid and aminomethyl substituent groups are in an isotactic arrangement, resulting in diisotactic polymer chains. He also referred to the y-radiation polymerization of molecular crystals of the sorbic acid derivatives with a long alkyl chain as the N-substituent [25]. More recently, Schlitter and Beck reported the solid-state polymerization of lithium sorbate [26]. However, the details of topochemical polymerization of 1,3-diene monomers were not revealed until very recently. 

More recent work has yielded another class of carborane-based mercury-containing macrocycles 43 and 44 related to crown ethers such as I2-crown-4 and 9-crown-3. Anticrown 43 associates with one or two moles of lithium halide, depending on conditions. The X-ray crystal structure of the chloride salt is shown in Figure 15. 

Crystal Structures of Lithium Halide and Mixed Lithium Halide -Organolithium Complexes... 

Rg. 4.18 Actual crystal structures of the alkali halides (as shown by the symbols) contrasted with the predictions cl the radius ratio rule. Tie figure is divided into three regions by the lines rjr. 0.414 and r+/h- a 0.732, predicting coordination number 4 (wurizite or zinc blende, upper left), coordination number 6 (rock salt, NaCl, middle), and coordination number 8 (CsCI, lower right). The crystal radius of lithium, and to a lesser extent that of sodium, changes with coordination number, so both ihe radii with C.N. 4 (left) and C.N = 6 Iright) have been plotted. 

Lithium halides when solvated show remarkable structural diversity.28 A simple one is [LiBr-Et20]4, which has a cubic L B core with OEt2 bound to the Li atoms, whereas [(LiCl)4-3.5tmeda]2 crystallizes as a bicyclic system of fused 6- and 4-... 

In the present study, we have made X-ray diffraction, neutron diffraction with isotopic substitution, and quasi-elastic neutron scattering measurements on highly concentrated aqueous solutions of lithium halides in a wide temperature range from room temperature to below glass transition temperature, from which the microscopic behaviors of the static structure and dynamic properties of the solutions are revealed with lowering temperature. The results obtained are discussed in connection with ice nucleation, anisotropic motion of water, crystallization, and the partial recovery of hydrogen bonds. 

Although there is a general increase in c.n. s of cations with increase in ionic radius a detailed correspondence between c.n. and radius ratio is not observed for simple ionic crystals. For example, all the alkali halides at ordinary temperature and pressure except CsCl, CsBr, and Csl crystallize with the NaCl structure. For Lil and LiBr (and possibly LiCl) the radius ratio is probably less than 0-41, but the radius ratios for the lithium halides are somewhat doubtful because the interionic distances in these crystals are not consistent with constant (additive) radii ... 

The structures of the vapour molecules of some halides are closely related to the structures of the crystals (Fig. 9.18). Mass spectrometric analysis of the ions produced by electron impact shows the presence of dimers, trimers, and in some cases tetramers, in the vapours of alkali halides. In particular the lithium halide vapours contain more dimers than monomers. The structures of three of the LiX... 

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