Alkali metals overview

Tab. 3.6-3. Overview of cage compounds of the type [M Om(REH)x(RE)y] of the monovalent atoms M (alkali metals and copper) and the pnictogen atoms E (P, As).

The focus of this chapter is on the electrochemistry of alkali metals, not on the specific technological developments that have led to the successful production of rechargeable lithium batteries, but given the impact of this technology, a brief overview is warranted. The evolving story of commercially successful rechargeable lithium batteries describes the balance of safety with economic concerns, and the balance of fundamental science with... 

One informative means of organizing a discussion of binary alkah metal compounds is by group in the periodic table. The overview provided below begins with binary alloys formed with other alkali metals and ends with binary compounds formed with halogens. The focus is primarily on second row elements. More detailed discussions can be found in the books concerning inorganic chemistry [26, 27]. 

An overview on the vast experimental and theoretical work on BEC recently we refer to the BEC-homepage [37]. Most experimental BEC research is carried out with alkali metal atoms and the main topics are to characterize the quantum fluid. 

The purpose of this overview is to provide a bridge between the various sorts of fundamental high temperature science, many of which are described earlier in this volume, and the areas of applications of much of this fundamental science involving specifically alkali metal vapors. Alkali metal vapors are chosen because of their unique combination of properties (Table I). 

Organolithium compounds have been more widely used than compounds of the heavier alkali metals. Smith has pubhshed an extensive review that focuses on the organometallic chemistry of sodium, potassium, mbidium, and cesium. An important textbook that covers the general aspects of organoalkali metal chemistry was written by Elschenbroich and Salzer. These publications, along with this article in the first edition of this encyclopedia, were used as foundational sources for this overview of the organometallic chemistry of the alkali metals. 

Tlie aim of this chapter is to provide an overview of materials where fast transport of alkali metal cations and protons is observed. A general discussion of factors affecting conductivity and techniques used to study ion migration paths is followed by a review of the large number of cation conductors. Materials with large alkali ions (Na-Cs) are often isostructural and therefore examined as a group. Tire lithium conductors with unique crystal structure types and proton conductors with unique conduction mechanisms are also discussed. 

Polyethers like poly(ethylene oxide) (PEG) when mixed with alkali metal salts, serve as effective complexing media to yield, often in amorphous form, ionically conducting polymeric solids. The considerable potential permselectivity and excellent redox stability of these newer processible solids is attractive for battery separator applications, and many research groups have been attracted to development of this subject. Armand[60] has published a useful overview of the available polyether conductivity, stability, interfacial kinetic, and ionic transference number literature. 

Mallis LM, Russell DH. General aspects of the chemistry of otgano-alkali metal ions. An overview of recent work. Int J Mass Spectrom. 1987 78 147-78. 

Anionic initiation has been accomplished in a variety of solvents, both polar and nonpolar. Typically, initiation can proceed by electron transfer reactions from alkali or alkaline earth metals, polycyclic aromatic radical anions, or alkali and magnesium ketyls. The other possibility includes the nucleophilic addition of organometallic compounds to the monomers. Related monofunctional initiators comprise alkyl derivatives of alkali metals or organomagnesium compounds such as Grignard reagents. Difunctional species are alkali derivatives of a-methylstyrene tetramer or the dimer of 1,1-diphenylethylene. An overview of the initiation process in carbanionic polymerization is given in Ref. [159]. 

Weber, E., and Vogtle, E, Crown-type compounds—an introductory overview, in Host-Guest Complex Chemistry, Vogtle, E, Ed., Springer Verlag, Berlin, 1981, 11. Hemery, E, Warzelhan, V, and Boileau, S., Kinetics of ring opening of propylene sulfide. 1. Alkali metal and cryptated metal carbonyl. Polymer, 21, 77, 1980. 

We have not attempted to cover all or even most aspects of crown chemistry and some may say that the inclusions are eclectic. We felt that anyone approaching the field would need an appreciation for the jargon currently abounding and for the so-called template effect since the latter has a considerable bearing on the synthetic methodology. We have, therefore, included brief discussions of these topics in the first two chapters. In chapters 3—8, we have tried to present an overview of the macrocyclic polyethers which have been prepared. We have taken a decidedly organic tack in this attempting to be comprehensive in our inclusion of alkali and alkaline earth cation binders rather than the compounds of use in transition metal chemistry. Nevertheless, many of the latter are included in concert with their overall importance. 

Up till now anionic mercury clusters have only existed as clearly separable structural units in alloys obtained by highly exothermic reactions between electropositive metals (preferably alkali and alkaline earth metals) and mercury. There is, however, weak evidence that some of the clusters might exist as intermediate species in liquid ammonia [13]. Cationic mercury clusters on the other hand are exclusively synthesized and crystallized by solvent reactions. Figure 2.4-2 gives an overview of the shapes of small monomeric and oligomeric anionic mercury clusters found in alkali and alkaline earth amalgams in comparison with a selection of cationic clusters. For isolated single mercury anions and extended network structures of mercury see Section 2.4.2.4. 

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