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a) Comment on the applicability of [Fe2(S)2(SPh)4]^n shown below as a model for redox/spin states of [2Fe*2S] ferredoxin, given that the observed values of the effective magnetic moments are 0 and 1.75 for [Fe2(S)2(SPh)4]^-2 and [Fe2(S)2(SPh)4]^-3respectively

b) Explaining your reasons, use the ^57Fe Mossbauer data below to answer the following questions
i) Calculate the average oxidation state of iron in the two [3Fe-4S] ferredoxins
11) In both cases calculate the overall charge on the [3Fe-4S] core
iii) Also with the aid of diagram rationalize the s = 2 spin state of the reduced 3Fe-4S] ferredoxin

c) For a [4Fe - 4S] ferredoxin, the following series of redox reactions, shown in the attachment, are possible
i) Which of these redox couples are accessible under physiological conditions?
ii) Which redox couple represents the high-potential iron-sulfur protein system?
iii) Also, what structure changes would occur to the (Fe4S4) core during these electron transfer processes?

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Solution Preview

a. The compounds could serve as a model for 2Fe-2S ferredoxins when we compare the effective magnetic moments of the compounds with ferredoxins. The 2Fe-2S ferredoxins are diamagnetic in the ground ...

Solution Summary

The use of sulfur-iron complexes as a model for ferredoxin is discussed. Additionally, the redox couple of 4Fe-4S ferredoxin is assigned.