Solvent interaction with alkali metals

A major use of ethers in the organic laboratory is as solvents for reactions. Ethers are nonpolar enough to dissolve many organic compounds, and the electrons on the oxygen can interact with alkali metal cations to help solubilize salts. In addition, ethers are nonacidic and are not very reactive. For these reasons they are especially useful in reactions involving strongly basic reagents. In addition to diethyl ether, other ethers that are commonly used as solvents are 1.2-dimethoxyethane (DME) and the cyclic ethers tetrahydrofuran (THF) and 1,4-dioxane ... 

The thermodynamic affects of complexation of 25, its monomeric component and 23 with metal ions monitored through NMR studies in nonaqueous solvents also show that in these conjugates, the positions of the pyridyl nitrogen and ethereal oxygen play a primary role in their hosting abilities for metal cations and as the distance of N and O increases, the ability of the ligand to coordinate decreases. Thus, 23 was able to interact with alkali metal cations, but this ability is lost for 25. The conductance measurements show that for all cations except Hg°, the composition of complexes of 25 is 1 1. However, 25 hosts two Hg° cations (2005JPC(B)14735). 

Tetraphenylborate salt of permethylated samarocene, like halide derivatives interacts with alkali metal compounds MR to give the corresponding complexes (Me5C5)2SmR [222]. However, when Me CjK is used as MR the reaction is complicated by participation of the solvent (THE). 

On neutralization with a series of alkali metal hydroxides or tetramethylammonium hydroxide in ethanol, weak acid 5 gave a colored solution with an absorption maximum at 615 nm independent of the cation species. This fact suggests that the phenolate anion from 5 interacts with the solvated cations or form solvent-separated ion pairs in the protic solvent, in marked contrast to those of azophenol crowns 4 with alkali metal salts. 

Parallels have been proposed between the dissolution of the alkali metals in nonaqueous solvents and the interactions of alkali metals with zeolites.The sorption of sodium or potassium vapor into dehydrated zeolites produces intensely colored compounds, ranging from burgundy red to deep blue, depending upon the metal concentration. A combination of EPR,... 

The recent application of sonochemistry to the reaction of aroyl chlorides with KCN in acetonitrile is very interesting. Aromatic acyl cyanides could also be prepared by reaction of aroyl chlorides with KCN impregnated onto XAD resins. A number of patents describe the results of the two-phase interactions of alkali metal cyanides with a solution of acyl halides or anhydrides in aprotic organic solvents, which in general run in the presence of Cu salts. ... 

Within the framework of the hypothesis of the alkali metal anion it is assumed that both electrons are at the outer s-orbital of the alkali metal and the solvent interacts with the associate as with a single negatively charged particle... 

In solvents of this kind, compounds that are formed with F-donors possess alkaline properties, whereas compounds affiliated with F-acceptors take on acidic properties. For instance, MBrF4 (where M = alkali metal) is alkaline whereas BrF2NbF6 displays the property of an acid. A typical interaction that takes place during the synthesis can be represented as follows ... 

The discovery that soluble high molecular weight polysilanes may be prepared by the reductive coupling of dichlorodialkylsilanes by alkali metals (1,2) has led to considerable work on the properties of this interesting class of polymers (3,4,5). The preparation of the polymers leaves much to be desired as frequently the high polymer is only a minor product. Mechanistic studies of the reaction with a view to improving the relevant yields have been few (6). The major ones by Zeigler (7,8,9) showed that a silylene diradical was not involved in the reaction, and stressed the importance of polymer solvent interactions. 

Interaction of lead oxide with bromide salts in phenol at the ratio Br PbO less than 2 yields the precipitation of white sediments with the general formula PbnOm(OPh)(2.z)(n-m)Brz(n-m), where n = 4 - 10, m = 1 - 4, z = 0 - 1 and formation of (n-m) moles of water. Reaction takes place in the presence of a variety of bromide salts including quaternary and alkali metal bromides. In the latter case, the presence of acoordinating solvent, e.g. MeCN, is necessary. The composition of product lead bromophenoxides depends on the Br PbO ratio, bromide salt and solvent. These complexes usually have Pb 0 ratio of 4 1 or 3 1, and variable levels of bromide (including some bromide-free complexes) (Table 3). 

It could be shown (Fig. 2) that the Li+ ion in DMSO is coordinated by four solvent molecules. y-Butyrolactone was found to be a convenient diluent in this kind of study. Contrary to DMSO (DN — 29.8), it is a rather weak donor (DN = 18.0) which appreciably dissolves alkali metal salts. Its interaction with DMSO is much weaker than that between DMSO and a metal cation. By plotting the chemical shift of the 7Li NMR signal vs. 

Incorporation of additional donor functionality into the periphery of phosphinomethanide ligands also has dramatic consequences for the structures of their alkali metal complexes. The complex [Li C(SiMe2Ph)(PMe2)2 ]3 (49) crystallizes as solvent-free cyclic tri-mers (Fig. 18), in which each lithium is primarily coordinated by two P atoms from one ligand and the carbanion center of an adjacent ligand (138, 139). This is supplemented by an essentially -interaction with the ipso and an ortho-carbon of the phenyl ring associated with the carbanion bonded to lithium. Each Li is thus bound by two P atoms, two aryl carbons, and a central carbon of the phosphinomethanide ligands. 

For this reason, the emphasis in this article is directed more towards the simulation of specific adsorption and, in particular, the recent encouraging comparison of electrochemical and UHV data for the interaction of bromine and chlorine with Ag 110 /7, 8/. A brief outline of the conclusions emerging from alkali-water coadsorption experiments is given to illustrate basic modes of ion-solvent interaction on metal surfaces and to discuss future directions of this research. 

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