ABC26IN0053 · Bioinorganic Chemistry

Subject: Inorganic Chemistry · Chapter: Bioinorganic Chemistry · Topic: Bioinorganic Chemistry – General · Exam: CSIR-NET 2020 · Marks: 2 · Difficulty: Medium

In the catalytic cycle of Cytochrome $\mathrm{P_{450}}$, the generation of $[(\text{porphyrin})^{+\bullet}\mathrm{Fe^{IV}(O)}]$ from $[(\text{porphyrin})\mathrm{Fe^{III}(OOH)}]$ involves
(a)One electron oxidation of $[(\text{porphyrin})\mathrm{Fe^{III}(OOH)}]$
(b)Formation of the intermediate $[(\text{porphyrin})\mathrm{Fe^{IV}(OH)}]$
(c)Homolytic O-O cleavage of $[(\text{porphyrin})\mathrm{Fe^{IV}(OOH)}]$
(d)Heterolytic O-O cleavage of $[(\text{porphyrin})\mathrm{Fe^{III}(OOH)}]$
Answer
Answer (as printed): D
Explanation
In the catalytic cycle of cytochrome $\mathrm{P_{450}}$, peroxo complex $[(\text{porphyrin})\mathrm{Fe^{III}(OOH)}]$ undergoes protonation which leads to removal of one oxide ion as water via heterolytic O-O cleavage to form oxyferryl complex with one electron having been oxidized from $\pi$-HOMO of porphyrin ring leaving it as a radical cation i.e. $[(\text{porphyrin})^{+\bullet}\mathrm{Fe^{IV}(O)}]$

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