Given below are two statements : Statement (I) : Dimethyl glyoxime forms a six-membered covalent chelate when treated with NiCl_2 solution in presence of NH_4 OH . Statement (II) : Prussian blue precipitate contains iron both in (+2) and (+3) oxidation states. In the light of the above statements, choose the most appropriate answer from the options given below :

Statement I is false but Statement II is true

Both Statement I and Statement II are true

Statement I is true but Statement II is false

Both Statement I and Statement II are false

Coordination Compounds PYQ — JEE Main 2024 · 1 Feb · Shift 2 · Q9 with Solution

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Correct answer: A

Analyze Statement (I): Dimethyl glyoxime with $\mathrm{NiCl_2}$ in presence of $\mathrm{NH_4OH}$

Dimethyl glyoxime (DMG) is a well-known reagent for $\mathrm{Ni^{2+}}$ . It forms the red precipitate nickel dimethylglyoximate:

\mathrm{Ni^{2+} + 2H_2dmg \rightarrow Ni(dmgH)_2 + 2H^+}

Here, DMG acts as a bidentate ligand coordinating through the two nitrogen atoms of the oxime groups. Each DMG forms a chelate ring with nickel.

The important point is:

the chelate ring formed is not a six-membered covalent chelate;
it is typically described as a five-membered chelate ring involving $\mathrm{Ni-N-C-C-N}$ .

Hence, Statement (I) is false.

Analyze Statement (II): Prussian blue contains iron in both $+2$ and $+3$ oxidation states

Prussian blue is a mixed-valence iron complex, commonly represented as:

\mathrm{Fe_4[Fe(CN)_6]_3}

In this compound:

iron outside the bracket is $\mathrm{Fe^{3+}}$ ,
iron inside $\mathrm{[Fe(CN)_6]^{4-}}$ is $\mathrm{Fe^{2+}}$ .

So Prussian blue indeed contains both $\mathrm{Fe^{2+}}$ and $\mathrm{Fe^{3+}}$ .

Hence, Statement (II) is true.

Choose the correct option

Statement I: False
Statement II: True

Therefore, the correct option is:

\boxed{\text{A}}

Comparison with stored correct answer

Stored correct answer: A

My derived answer: A

So, my answer agrees with the stored correct answer.

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View written solutionFree

Correct answer: A

Analyze Statement (I): Dimethyl glyoxime with $\mathrm{NiCl_2}$ in presence of $\mathrm{NH_4OH}$

Dimethyl glyoxime (DMG) is a well-known reagent for $\mathrm{Ni^{2+}}$ . It forms the red precipitate nickel dimethylglyoximate:

\mathrm{Ni^{2+} + 2H_2dmg \rightarrow Ni(dmgH)_2 + 2H^+}

Here, DMG acts as a bidentate ligand coordinating through the two nitrogen atoms of the oxime groups. Each DMG forms a chelate ring with nickel.

The important point is:

the chelate ring formed is not a six-membered covalent chelate;
it is typically described as a five-membered chelate ring involving $\mathrm{Ni-N-C-C-N}$ .

Hence, Statement (I) is false.

Analyze Statement (II): Prussian blue contains iron in both $+2$ and $+3$ oxidation states

Prussian blue is a mixed-valence iron complex, commonly represented as:

\mathrm{Fe_4[Fe(CN)_6]_3}

In this compound:

iron outside the bracket is $\mathrm{Fe^{3+}}$ ,
iron inside $\mathrm{[Fe(CN)_6]^{4-}}$ is $\mathrm{Fe^{2+}}$ .

So Prussian blue indeed contains both $\mathrm{Fe^{2+}}$ and $\mathrm{Fe^{3+}}$ .

Hence, Statement (II) is true.

Choose the correct option

Statement I: False
Statement II: True

Therefore, the correct option is:

\boxed{\text{A}}

Comparison with stored correct answer

Stored correct answer: A

My derived answer: A

So, my answer agrees with the stored correct answer.

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