Salicylaldoxime chelation

Mixed O- and N-donor ligands. Studies of the reactivities of co-ordinated ligands have shown that bis-salicylaldoxime chelates of Ni, Pd, and Cu react with AlPh3 in benzene to yield grey diamagnetic complexes (12).35 Dimethylglyoxime complexes undergo similar reactions (see below). 

It is believed [1135,1136] that the decomposition of metal complexes of salicyaldoxime and related ligands is not initiated by scission of the coordination bond M—L, but by cleavage of another bond (L—L) in the chelate ring which has been weakened on M—L bond formation. Decomposition temperatures and values of E, measured by several non-isothermal methods were obtained for the compounds M(L—L)2 where M = Cu(II), Ni(II) or Co(II) and (L—L) = salicylaldoxime. There was parallel behaviour between the thermal stability of the solid and of the complex in solution, i.e. Co < Ni < Cu. A similar parallel did not occur when (L—L) = 2-indolecarboxylic acid, and reasons for the difference are discussed... 

Aromatic hydroxy groups also act as donors in a variety of N,0 chelating ligands, e.g. salicylaldimine, salicylaldoxime, 8-hydroxyquinoline, etc. (see Section 51.5.4). 

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. 

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. 

Diese, ebenfalls zu 6-Ring-Chelaten fiihrende Gruppierung findet man im Salicylaldoxim, das mit einer Reihe von Metallen gefarbte Chelate bildet,. 

Poly(salicylaldoxime-3,5-diylmethylene) 9 containing chelate-forming groups in the main chain was obtained by polycondensation reaction of... 

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