Inorganic alkali metal complexes

Core structures of some lithium alkoxides and aryloxides  

Core structures of some lithium amides and imides (a) (LiTMP)4, 

Did symmetry, as shown in Fig. 12.2.5(d). Each of the three Li+ ions in a monomeric unit is coordinated by two N atoms in a chelating fashion, and linkage of units occurs through single Li-N contacts. This causes all N atoms to be five-coordinate, which leads to weakening of the Li-N and Si-N bonds. 

In this structure, Li atoms are four-coordinated, and N atoms are four- or five-coordinated. 

A large number of complexes containing the halide salts LiX (X = Cl, Br, and I) have been characterized in the solid state. The structures of some of these complexes are shown in Figs. 12.2.6(b)-(f). 

---

Crown ethers (Fig. 3.57) and cryptands (Fig. 3.58) can solubilize organic and inorganic alkali metal salts even in nonpolar organic solvents they form a complex with the cation (see Fig. 3.57c), and thus act as an organic mask (Gates, 1992). 

In comparison to alkali metal complexes of (di)organophosphide ligands, complexes of these metals with (di)organoarsenide ligands are relatively rare and few have been structurally characterized. This dearth of structural information is perhaps due in part to the relatively low importance of such complexes in inorganic and organic synthesis and to the lower stability (both thermal and photolytic) of arsenide complexes compared to their phosphide analogues. 

Though the conductivity of the PEO-alkali metal complexes (10 ohm -cm at 140°C) is fairly low in comparison with inorganic solid electrolytes such as 8-alumina(Na), RbCui6l7Cli3 and RbAg4ls at the same temperature, this can be compensated for by the facile production of thin films typically 25-500 pm thick. A cell may thus consist of a lithium or lithium-based foil as anode, an alkali metal salt-PEO complex, such as (PEO)9 LiCFsSOs (25-50 pm), as the electrolyte, and a composite cathode (50-75 pm) containing a vanadium oxide (VeOis) as the active ingredient. The vanadium oxide is one of a number of insertion compounds that permits the physical insertion lithium ions reversibly into their structure and thus allows recharging of the cell. 

The viscosity and non-Newtonian flooding characteristics of the polymer solutions decrease significantly in the presence of inorganic salts, alkali silicates, and multivalent cations. The effect can be traced back to the repression of the dissociation of polyelectrolytes, to the formation of a badly dissociating polyelectrolyte metal complex, and to the separation of such a complex fi"om the polymer solution [1054]. 

Redox systems with inorganic and organic components lodonium ions Electron-transfer agents, e.g., alkali metals, alkah-aromatic complexes, alkali metal ketyls Activated transition metal oxides... 

Fluorinations by alkali metal fluorides are often carried out in high-boiling solvents. Crown ethers have been used to solvate inorganic fluorides by complexation. 

Acetonitrile. Acetonitrile is resistant to both oxidation and reduction, is transparent in the region 200-2000 nm, and is an excellent solvent for many polar organic compounds and some inorganic salts. Its dielectric constant of 37 permits reasonably high conductivities, although there is evidence of some association (see Table 7.8). It is less basic than dimethylformamide and dimethyl sulfoxide, and therefore does not solvate alkali metal cations as strongly. However, acetonitrile forms stable complexes with Ag(I) and Cu(I) ions. 

---