Alkali metal complexes with

Novel electron-transfer reactions mediated by alkali metals complexed with crown ethers as macrocyclic ligands 98ACR55. 

Whereas alkali metal phosphinomethanides have been well studied and a large number of complexes have been structurally characterized, there are apparently no reports of alkali metal complexes with arsenic-stabilized carbanions. 

Figure 3.2. Dependence of the stability constant K on the cation diameters for alkali metal complexes with three crown ethers,...

For some solvent systems, it has not yet been possible to obtain structural information in the solid state. The ion-pair loosening ability of DMSO has been thoroughly illustrated in studies of M+-DMSO interactions in solution using several different techniques NMR 48,49 solution IR 50-52 conductometry53 and calorimetry.54 In the case of Na+, a coordination number of six has been confirmed. IR techniques have also been used to monitor alkali metal complexation with the related sulfoxides, diisopropyl and dibutyl sulfoxide.50 Solid M+-DMSO species have... 

The calcium, strontium, barium, and lead 80) complexes of 160 and 161 have also been reported. In these two ligands the six donor atoms are essentially confined in a plane these complexes thus permit study of unusual coordination geometries in species of high coordination number. Attempts to form alkali metal complexes with 160 and 161 under the same conditions as employed for the alkaline earth metal complexes have failed. The successful syntheses of complexes of the latter type indicate that the higher charge to radius ratio is of consequence when spherically charged cations are employed. Such metal ions have no apparent coordinative discrimination as the template ion 87). 

Arena. G., Cali, R., Grasso, M., Musumeci, S., and Sammartano, S. (1980). The formation of proton and alkali-metal complexes with ligands of biological interest in aqueous solution, I Potentiomtric and calometric investigations of H+ and Na complexes with citrate, tartrate and malate. Thermochim. Acta 36, 329-342. 

Vol. 16 Alkali Metal Complexes with Organic Ligands... 

Figure 10.8c shows the structure of the cryptand ligand 4,7,13,16,21,24-hexaoxa-l,10-diazabicyclo[8.8.8]hexacosane, commonly called cryptand-222 or crypt-222, where the 222 notation gives the number of O-donor atoms in each of the three chains. Cryptand-222 is an example of a bicyclic ligand which can encapsulate an alkali metal ion. Cryptands protect the complexed metal cation even more effectively than do crown ethers. They show selective coordination behaviour cryptands-211, -221 and -222 with cavity radii of 80, 110 and 140 pm, respectively, form their most stable alkali metal complexes with Li, Na+ and K+ respectively (see Table 10.1 for r on). 

Polypyridine Torand 1. Complexes of alkali metal triflates and picrates have been prepared from the monotriflate salt of torand 1, which is isolated directly from the macrocyclization reaction mixture. As shown in Figure 3, neutralization of the triflate salt with alkali metal hydroxides or carbonates gives the alkali metal complexes. With triflate or picrate counterions, torand complexes and salts partition selectively into chlorofonn rather than water. Thus 1 can be shuttled back and forth between the triflate salt and various complexes simply by washing the chloroform solution with aqueous acid or base. The free ligand is prepared by reaction of the triflate salt with tetra-n-butylammonium hydroxide in butanol/acetonitrile. Combustion microanalysis showed that the Li, Na, K, Rb and Cs complexes all have 1 1 host/guest stiochiome-try, despite the cavity/ion size mismatch at both ends of the series. The X-ray crystal... 

A cyclo-nonapeptide, isolated from linseed by Kaufmann and Tobschirbel [48] which also prevents the uptake of phalloidin (and other substances) by hepatocytes, cyclolinopeptide A, shows a certain similarity with AA in its amino acid sequence (Fig. 20) but does not form alkali-metal complexes. With the accumulation of aromatic amino acids between proline residues as an active region in mind, Kessler et al. designed some smaller cyclopeptides of which one, c(D-ProPhePheProPhePhe), exhibited somewhat stronger protection and a second less related one, called 008, showed even better protection of liver cells against phalloidin than antamanide [49]. 

The polymerization of acrylate esters by organomagnesium reagents is best described as pseudo-anionic monomer is complexed to a magnesium atom covalently bonded to carbon. The anionic polymerization of methyl methacrylate in benzene yields the syndiotactic polymer when the initiator is an alkali metal complexed with 18-dicyclohexyl-6-crown. When a solution of methyl methacrylate in toluene is placed below a solution of butyl-lithium in the same solvent at —78 °C so as to avoid any mechanical mixing, the polymer obtained has a higher isotacticity than that observed if the solutions are stirred. ... 

Daniele PG, De Robertis A, De Stefano C, Gianguzza A, Sammartano S (1990) Studies on polyfunctional o-ligands. Formation thermodynamics of simple and mixed alkali metal complexes with citrate at different ionic strengths in aqueous solution. J Chem Res S(300) (M)2316... 

Table 4. Stability constants of alkali metal complexes with DB18C6 and valynomycine in RTIL at 25 °C...

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