Metal cations, complexes

Medicine and Nutrition. A stabilized buffered suspension of selenium sulfide has been marketed for many years as Selsun Blue (Abbott Laboratories) for control of seborrheic dermatitis of the scalp. A similar sulfur or selenium sulfide shampoo containing a metallic cation complex has been prepared (122). Topical appHcation of selenium sulfide controls dermatitis, pmritis, and mange iu dogs (see Cosmetics Veterinarydrugs). 

Fig. 4.13. Space-lilling molecular model depicting a metal cation complexed by 1 R-crown-6.

Application of the reaction to the 2-azidobenzoyl derivative of diethylene glycol monomethyl ether 92, in a mixture of tetrahydrofuran and diethylene glycol monomethyl ether as the nucleophile, affords 2-(2-methoxyethoxy)ethyl 2-[2-(2-methoxyethoxy)ethoxy]-37/-azepine-3-carbo-xylate (93), which displays metal cation complexing properties towards lithium, potassium, and. to a lesser extent, barium and calcium cations.198... 

Fig. 8.6. Representation of it bonding in a alkene-metal cation complex.

Macrostructure of mucus glycoproteins in solution, 47, 345-381 Metal cations, complexes of, with carbohydrates in solution, 47, 1 -43 Molecular structure of lipid A, 50,211 -276 Monosaccharides, decomposition of, 47, 203-278... 

Sr2+ so well that it was selectively extracted from a bulk sample of a barium salt (Helgeson et al., 1973a). Binding constants for metal-cation complexes of 1,3-xylyl-crown ethers [66]—[69] carrying an additional carboxylate binding... 

Rate and equilibrium constants for metal-cation complexes of 15-crown-5 and 18-crown-6 in water at 25 °C... 

Kinetic and thermodynamic parameters for metal-cation complexation... 

Most of the work on chiral recognition in the ground state deals with salts having chiral, primary alkylammonium cations. Another approach is the chiral discrimination between two enantiomeric anions present as counterions in metal-cation complexes (Lehn et al., 1978). Discrimination between enantiomeric transition states will be dealt with in the next section together with non-chiral mimicry of enzymic catalysis. 

The bis-benzo-15-crown-5 ferrocene compound [7] containing two vinylic linkages was formed in a mixture of three isomeric components, the cis-cis, cis-trans and trans-trans isomers, which proved inseparable. However, the precedent of insignificant differences found between the magnitudes of the metal cation-induced anodic shifts in the ferrocenyl redox potentials of the respective separated cis and trans isomers [2a] and [2b] led us to use the same isomeric mixture of [7] throughout the subsequent FABMS and electrochemical group 1 and 2 metal cation complexation experiments,... 

Table 7. Stability constants (log Ks) of alkali and alkaline-earth metal cation complexes with ligands of types A, B and C... 

The alkali metal cation complexes of compounds of the valino-mycin group (valinomycin, enniatins, macrotetrolides, beauveridn, antamanide) are positively charged. 

Reaction of 175 with Cgg yields a hydroxy-functionalized fullerene that can be further derivatized. This hydroxy-fullerene was coupled with a porphyrine unit via a polyethyleneglycol-Hnker. This linker can be arranged similarly to a crown-ether to complex metal cations. Complexation is used to tune the distance between the porphyrin imit and the Cgg-moiety and thus tune the donor-acceptor properties of this porphyrin-fuUerene hybrid [177]. 

The results for reaction (15.37) for the alkali metal cations complexed with 18C6 and 15C5 are shown in Figure 15.15. As with log K, the ArZ° values (ArG°, ArH°, and TAtS°) are plotted against the radius ratio. 

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