Iron chelate complexes

The Lo-Cat process, Hcensed by US Filter Company, and Dow/Shell s SulFerox process are additional Hquid redox processes. These processes have replaced the vanadium oxidizing agents used in the Stretford process with iron. Organic chelating compounds are used to provide water-soluble organometaHic complexes in the solution. As in the case of Stretford units, the solution is regenerated by contact with air. 

Mono- and polyl dric phenols and enols frequently form characteristically colored complexes with Fe + ions [4, 28, 29]. Here monohydric phenols usually produce reddish-violet colors, while pyrocatechol derivatives yield green chelates [4]. Detection of acetone using Legal s test is based on the formation of an iron complex [4]. The same applies to the thioglycolic acid reaction of the German Pharmacopoeia (DAB 9) [4, 30]. 

Upon formation of a metal chelate or complex, the next rate-limiting step in delivering iron to the cell is the diffusion of iron complexes through the. soil in response to diffusion gradients. In the vicinity of plant roots, metal chelates and complexes may also move by bulk flow in the transpiration stream as water moves from the soil into the plant. However, depending on their charge characteristics and hydrophobicity, metal chelators and complexes can become adsorbed to clay and organic matter, which may then decrease their mobility and bioavail-... 

In Eq. (45), KFe(II)L is the stability constant for iron(II) complexation by the competing ligand, KFe(II)sid the stability constant for the complex formed between iron(II) and the siderophore, n the number of electrons transferred, Erxn the observed redox potential for the iron(III)-siderophore system coupled with iron(II) chelation, and EFJ m sld the redox potential of the iron(III)-siderophore complex. 

Unfortunately, the iron complexes of both chelators desferal and LI are able to catalyze the formation of oxygen radicals [394,395]. Cragg et al. [395] also showed that LI exposure markedly enhanced free radical-mediated DNA damage in iron-loaded liver cells. It has been suggested that the prooxidantrantioxidant ratio of LI activity depends on the composition of complexes formed a 1 3 Fe/Ll is supposed to be inactive in the production of free radicals while the generation of radicals is possible at lower Fe/Ll ratios [395], But it should be noted that in real biological systems there is always equilibrium between iron-chelator complexes of different composition. 

When injected, it forms a stable water-soluble iron complex (ferrioxamine) that prevents the iron from entering into further chemical reactions and is readily excreted in the urine giving the urine a characteristic reddish colour. Some of it is also excreted in the faeces via the bile. It can also chelate aluminium and thus is useful in aluminium overload. It is primarily a chelator used in acute iron poisoning and chronic iron overload as in thalassemia patients needing multiple transfusions. 

The reaction of hexacyanometalates with metal complexes chelated by penta-dentate ligands may afford polynuclear complexes. The presence of the penta-dentate ligand precludes the polymerization that leads to extended systems. The preparation of a representative heptanuclear, mixed-valance iron complex, [Fe (CNFe° (salmeten))6]Cl2 6H20, is detailed herein. 

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