Q45 · CSIR NET Chemistry, December 2013
Paper: CSIR NET December 2013 · Subject: Inorganic Chemistry · Chapter: Bioinorganic Chemistry · Topic: Iron Sulfur Proteins · Marks: 2 · Difficulty: Hard
Oxidised form of enzyme catalase (structure A); prepared by the reaction of $[\mathrm{Fe(P)}]^{+}$ (P = porphyrin) with $\mathrm{H_2O_2}$ has green color because 
(a)Oxidation state of iron changed from $\mathrm{Fe}^{\mathrm{III}}$ to $\mathrm{Fe}^{\mathrm{IV}}$
(b)Porphyrin ring is oxidized by one electron
(c)$\pi-\pi^{*}$ transition appears in the visible region
(d)$\mathrm{Fe}^{\mathrm{IV}}$ is coordinated with anionic tyrosinate ligand in axial position.
Answer
Answer: B ✓ checked by 4AB · confidence medium
The source book printed A; on checking, B is correct — see the explanation.
Book printed (a).
Explanation
Compound I is an oxoiron(IV) porphyrin π-cation radical; the green colour arises from the oxidised porphyrin (b).
Study loop for Bioinorganic Chemistry