Salicylaldoxime copper complexes

A number of attempts have been made to understand the mechanism of the adsorption of chelates on oxide minerals. For instance, IR spectroscopic studies10 have indicated the presence of a basic monosalicylaldoximate copper complex as well as the bis-salicylaldoximate complex on the surface of malachite (basic copper carbonate) treated with salicylaldoxime. However, other workers4 have shown that the copper chelate is partitioned between the surface and dispersed within the solution, and that a dissolution-precipitation process is responsible for the formation of the chelate. Research into the chemistry of the interaction of chelating collectors with mineral surfaces is still in its infancy, and it can be expected that future developments will depend on a better understanding of the surface coordination chemistry involved. 

The most common hydrox y oxime ligands are salicylaldoximes, complexes of which with copper(II), nickel(II) amd palladium(II), cobalt(II), iron(II), iron(HI) and manganese(II) have been investigated extensively including crystal and molecular structures13 of the first three. In an interesting study,71 the reactions of cobalt bis chelates of this type have been studied with aluminum isopropoxide. 

Figure 5.11 X-ray crystal structure of the Cu(N03)2 complex of the zwitterionic salicylaldoxime 5.28 showing the axial binding of N03 to copper supported by hydrogen bonding interactions.27...

SlOO proteins, 577 structure, 573 Saccharomyces cerevLsiae cation transport, 559 manganese transport, 570 Salicylaldimine copper(II) complexes, 156 Salicylaldoximes adsorption minerals, 782... 

Extractants are often used with modifiers (e.g., hydrophobic alcohols, alkylphenols, sterically hindered esters of carboxylic acids, and tributyl phosphate). Modifiers are used for two different reasons first, to increase the solubility of extractants and their complexes and to avoid the formation of the third phase, and second, to modify the extraction properties, i.e., the extraction and stripping abilities. The first option is usually exploited in systems that contain various amines. The second option is associated with hydro-xyoximes and the formation of tailored blends, which optimize the extraction-stripping properties and adjust them to the aqueous feed, i.e., to the acidity and concentration of copper(II). Modifiers that form hydrogen bonds with hydroxyoxime molecules decrease their extraction ability but facilitate back-extraction with acids. Weak hydroxyoxime or j -diketone extractants (e.g., 2-hydroxy-5-alkylbenzo-phenone oxime) can also act as modifiers of strong hydroxyoxime extractants (e.g., salicylaldoxime and its alkyl derivatives). 

Figure 8. The complex of copper(II) with LIX 65N, a relative of salicylaldoxime The [CUN2O2] system is square planar and rigid, and further stabilized by two O—H- - O hydrogen bonds. Note how the two phenyl rings are forced out of this plane by van der Waals repulsions...

Several complexing ligands can be employed to determine copper in seawater. However, the best results are obtained when copper is determined after adsorptive pre-concentration as a complex with salicylaldoxime (SA) Campos and van den Berg, 1994). Analysis is carried out at neutral pH values (pH 6.5-8.5 is suitable) which means that the original sample pH can be maintained which is useful for speciation studies. 

Salicylaldoxime (I) gives a yellow-greenish precipitate of the inner complex copper salicylaldoxime (II) with acetic acid solutions of copper salts. 

The reaction of the nickel, copper, or palladium complexes M(LH)a (L= dimethylglyoxime, salicylaldoxime) with diphenylmercury and aluminium powder in refluxing toluene affords the complexes ML2Al2Ph4. Similar complexes of composition QAI2R2X2L2 (QH2=salicylaldoxime R=alkyl X=... 

The related antitumor copper salicylaldoxime complexes gave irreversible reduction with potentials of -0.47 to -0.64 V . Another class of Cu(II) coordination compounds, the thiosemicarbazones, is known to... 

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