Alkaline metal-cation-containing

It is clearly revealed that 4 is a useful ligand for recovering heavy and transition metal cations, especially Ag" and Pb, from neutral water or sea water which contains a plenty of alkali and alkaline metal cations, because 43a did not extract any alkali and alkaline earth metal cation even at pH 7. 

The presence of metal salts, particularly those containing alkaline-earth cations and/or haUdes, cause some shifts in the polyborate equiUbria. This may result from direct interaction with the boron—oxygen species, or from changes in the activity of the solvent water (63). 

The addition of alkali metal or ammonium fluorides reduce the acidity of the system and shift the equilibrium between the two ions toward the formation ofNbOFs2 ions [60,61]. The shift depends on the alkalinity of the cation. The more alkaline the cation is (higher atomic weight), the stronger the shift toward NbOF52 ion formation. Fig. 48 shows typical Raman spectra of niobium-containing solutions before and after such additions were made. 

An important class of expl materials contains metallic fuels and inorganic oxidants. Examples are Tritonal (TNT/A1, 80/20), Amatols (TNT/AN, 28/80 80/20), and Minol-2 (TNT/AN/A1, 40/40/20). Oxidants other than nitrates, such as chlorates and perchlorates, may be employed. Water solns containing these cations are highly corrosive to metals. Alkaline metal salts, for example, in the presence of moisture, will pit A1 quickly (Ref 6)... 

Of course, the chemistry of zirconium cluster phases has been well described and reviewed in the literature [1-4]. Apart from a very few examples, mostly in the binary halides, almost all reduced zirconium halides contain octahedra of zirconium atoms centred on an interstitial atom Z. Several possible and experimentally realized Z include H, Be-N, K, Al-P, and the transition metals Mn-Ni. All these compounds have the general formula Ax"[(Zr6Z)Xi2X[J], with a " = alkali or alkaline earth metal cation, X=C1 Br or I, X =inner edge-bridging halide [5], X =outer exo-bonded halide, and 0[Pg.61]

There are two general classes of naturally-occurring antibiotics which influence the transport of alkali metal cations through natural and artificial membranes. The first category contains neutral macrocyclic species which usually bind potassium selectively over sodium. The second (non-cyclic) group contains monobasic acid functions which help render the alkaline metal complexes insoluble in water but soluble in non-polar solvents (Lauger, 1972 Painter Pressman, 1982). The present discussion will be restricted to (cyclic) examples from the first class. 

The mechanisms of regioselective and stereoselective 2 -E 2-photocycloadditions have been extensively reviewed. The intramolecular 2 -E 2-photocycloaddition of 2-allyl-2-(l//)-naphthalenone (13) on the surface of silica produces all four cycloadducts (14)-(17) (Scheme 4). ° Molecular mechanics have been used to study the regio- and stereo-selectivity of the 2 -E 2-photocycloadditions in complexes containing crown ether styryl dyes and alkaline earth metal cations."... 

The formation of the merocyanine form 119 can be induced by addition of heavy metal cations (Pb, La, Eu, Tb ) to a solution of a spirooxazine 118 containing a crown ether group in the B-ring (Equation 1). The chelation occurs first to the crown ether and then to the negatively charged oxygen. In contrast, 118 does not react upon addition of alkaline earth metal cations (Mg, Ca, Ba ) <2005JP0504>. 

The interaction of oxygen-containing acyclic ligands with alkali and alkaline earth metal cations has provided a burgeoning area of interest. In historic terms, this was preceded by the advent of crown ethers and the accompanying almost retrospective look at their acyclic precedents. This section is sub-divided into five parts simple chelates, metal complexes as ligands, podands, polypodands and sugars. 

Heterobinuclear complexes containing alkali or alkaline earth metal cations have been derived from mononuclear transition metal complexes of compartmental ligands (51).288 The molar conductivities of the (51)-CuLi2 series suggest that the complexes are uniunivalent electrolytes in water and so are present in solution as Li[(51b)CuLi]- H20 the corresponding di-sodium, -potassium or -cesium complexes are unibivalent electrolytes and so likely to be present in solution as M2[(51)Cu]- H20. 

When Z is a simple aquacation, two types of complex are formed depending upon the ionic radius of Z. For alkali, alkaline earth and most transition metal cations the product contains Z"+ in quasi-octahedral coordination. Equilibrium constants for reaction (6) have been determined for Li+, Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni, Cu2+ and Zn2+.93 For the transition metals, log K lies between 3 and 9, and is sensitive both to Z and to the lacunary polyanion involved. Larger cations, Sr24, Ba2+, and tri- and tetra-valent lanthanides and actinides are also able to bind two lacunary ligands in a manner similar to that illustrated in Figure 18. Although the stepwise formation of 1 1 and 2 1 complexes of the... 

The only directly accessible metal fulminates are those of mercury(II) and silver(I), very dangerously exposive solids obtained by the action of nitric acid and ethanol on the metals or their salts. Most modern preparations of fulminato complexes involve the conversion of a known amount of mercury fulminate into aqueous sodium fulminate by the action of sodium amalgam and ice-cold water the sodium fulminate solution is then allowed to react with the appropriate amount of a transition metal salt, and the resulting complex fulminato ion is precipitated as the salt of a large cation, most frequently Ph4As+ or R4N+ these are not explosive,4,35 Alkali and alkaline earth metal salts containing complex fulminato anions may be isolated from aqueous solutions, but they are reported to be as exposive as the binary silver and mercury fulminates, and are therefore usually avoided. 

Macrocyclic complexones contain more than one aminoacetic group, which is bound over the N atom to a cyclic unit as in the case of the tetraaza macrocycles (15). Different selection effects are found in the case of these ligands (see Chapters 21.1-21.3 of this volume).67 The pAT values of the acids are much higher than those of edta they almost explain the high values of the stability constants with alkaline earth and transition metal cations. The differences in log K, between Ca2+ and Mg2+ are very high and similar to those observed for egta. For the transition metals the cyclic complexones have no advantage over the non-cyclic ones such as edta and cdta. 

As already known (Addison Logan 1964), anhydrous nitrates exhibit oxidizing properties. Their oxidizing activity increases from ionic nitrates with alkali and alkaline earth metal cations to covalent nitrates with transient metal cations. Oxidation reactions result in the formation of nitrogen-containing oxides. Depending on the kind of nitrate salt and on the reaction conditions, one of these oxides can be predominant. Organic substrates can evidently serve as reductant. 

The THECOMAC database contains the stability constant, enthalpy, and entropy values for the complexations of the alkaline and alkaline earth metal cations with cyclic polyethers in water and organic solvents, and includes more than 3,500 records. Each record contains 22 textual and digital fields and 2D chemical structures of ligands. The database includes thermodynamic values for 330 cyclic polyethers containing oxygen coordination centers only.41... 

For the spironaphthoxazines conjugated with aza-15(18)-crown-5(6)-ether moieties at 6 -position of naphthalene fragment (13a,b) it was found that the addition of Li+ and alkaline earth (Mg2+, Ca2+, Sr2 and Ba2+) metal cations to 13a,b solutions results in a hypsochromic shift of the UV absorption band of the spiro form and a bathochromic shift of the absorption band of the merocyanine form in the visible region [36], In addition, the equilibrium shifts to the merocyanine form, and the lifetime of the photoinduced merocyanine form increases (Scheme 15). The isomerization of crown-containing compound 13a,b to the colored merocyanine form was promoted most strongly by the presence of metal ions, which are expected to be the best recognized by the crown ether ring (Scheme 15). 

Alfimov, M.V., Vedernikov, A.I., Gromov, S.P., Fedorov, Yu.V., Fedorova, O.A., Churakov, AV., Kuz mina, L.G., Howard, J.A.K., Bossmann, S., Braun, A, Woemer, M., Sears, D.F., Saltiel, J. (1999) Synthesis, structure and ion selective complexation of trans and cis isomers of photochromic dithia-18-crown-6 ethers, J. Am. Chem. Soc., 121, 4992-5000 b) Stanislavskii, O.B., Ushakov, E.N., Gromov, S.P., Fedorova, O.A, Alfimov, M.V. (1996) Crown-containing styryl dyes. 14. The influence of N-substitute length on the complex formation of betainic chromogenic 15-crown-5-ether with alkaline earth metal cations, Russ. Chem. Bull, 45, 564-572. 

Ushakov, E.N., Gromov, S.P., Fedorova, O.A., Pershina, Y.V., Alfimov, M.V., Barigelletti, F., Flamigni, L., Balzani, V. (1999) Sandwich-Type Complexes of Alkaline-Earth Metal Cations with a Bisstyryl Dye Containing Two Crown Ether Units, J. Phys. Chem.A, 103, 11188-11193. 

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