Iron, coordination chemistry model

A second relevant aspect here is the consideration of models for the various dimetal species that could be important in the reactions at the ferroxidase centers. The area of di-iron metallosites has received a great deal of attention from the early 1980s since the identification of such sites in hemerythrin and the production of the first coordination chemistry model compounds for these (Chapters 8.12 and 8.13). Subsequently several other systems with this motif have been studied and the ones of most relevance to the ferroxidase centers would appear to be those involved in oxygen activation rather than transport. ... 

Other complexes containing the coordination units FeN2S2 [842] and FeN2S4 [843— 845] are also known. These compounds have due importance in coordination chemistry since they provide a possibility to study the changes of iron spin states in accessible temperature intervals [845]. Moreover, they are permanently used as models of active centers in some iron-containing nonporphyrine metalloenzymes, in particular, nitrylhydrataze [804,846-850]. 

Cobalt Inorganic Coordination Chentistry Copper Hemocyanin/Tyrosinase Models Copper Inorganic Coordination Chemistry Copper Proteins Oxidases Copper Proteins with Dinuclear Active Sites Iron Heme Proteins Dioxygen Transport Storage Iron Heme Proteins, Mono- Dioxygenases Iron Models of Proteins with Dinuclear... 

There is a large body of knowledge on the coordination chemistry of iron-sulfur complexes and iron clusters particularly directed at the modeling and nnderstanding of the action of nonheme proteins whose active sites contain iron-sulfur units. These topics are discussed in detail elsewhere in this Encyclopedia here, the emphasis is on the basic coordination chemistry. 

Rhodotorulic acid (RA), a dihydroxamate siderophore, forms dimeric complexes with iron, aluminium and chromium of the stoichiometry M2(RA)3 at neutral pH 36 188). The coordination chemistry of this siderophore is probably the most complicated of the siderophores. The combination of cis-trans, A and A configurations of two iron miters, connected by three RA molecules, makes 42 non-redundant isomers theoretically possible each can be simulated by molecular models. Recently three different isomers or mixtures of isomers of Cr2RA3 were separated by reversed phase HPLC-chromatography177). The visible spectrum of the most abundant fraction corresponds to the cis isomer the two other fractions are very similar to the visible spectrum of the trans Cr(men)3 isomer. The CD spectra, in comparison with the Cr(men)3 model complex, show two different optical isomers, assigned as A -trans and A -trans. The A isomer preparation seems also to contain a certain amount of the A configuration. This is the first time that two different, kinetically stable optical isomers have been isolated from the metal complexes of a siderophore 177). 

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