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Chemistry · Coordination Compounds

JEE Advanced 2018 — Paper 2 — Question 18

The correct option(s) regarding the complex [Co(en)(NH3)3(H2O)]3+\left[\mathrm{Co}(\mathrm{en})\left(\mathrm{NH}_{3}\right)_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}

(en=H2NCH2CH2NH2)\left(\mathrm{en}=\mathrm{H}_{2} \mathrm{NCH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\right) is (are)

  1. Option A:

    It has two geometrical isomers

    Correct
  2. Option B:

    It will have three geometrical isomers if bidentate 'en' is replaced by two cyanide ligands

    Correct
  3. Option C:

    It is paramagnetic

  4. Option D:

    It absorbs light at longer wavelength as compared to [Co(en)(NH3)4]3+\left[\mathrm{Co}(\mathrm{en})\left(\mathrm{NH}_{3}\right)_{4}\right]^{3+}

    Correct

Answer: A, B, D

Step-by-step solution

figure

Two geometrical isomers of [Co(en)(NH3)3H2O]3+\left[\mathrm{Co}(\mathrm{en})\left(\mathrm{NH}_{3}\right)_{3} \mathrm{H}_{2} \mathrm{O}\right]^{3+}

(B)

[Co(NH3)3(CN)2(H2O)]+⇒3\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{3}(\mathrm{CN})_{2}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{+} \Rightarrow 3 geometrical isomers

figure

(C)

Since (en) and NH3\mathrm{NH}_{3} are strong field ligand, so it should be diamagnetic complex

(D)

(NH3)\left(\mathrm{NH}_{3}\right) is a stronger ligand than

H2O\mathrm{H}_{2} \mathrm{O}, so, [Co(en)(NH3)4]3+\left[\mathrm{Co}(\mathrm{en})\left(\mathrm{NH}_{3}\right)_{4}\right]^{3+} should absorb shorter wavelength than [Co(en)(NH3)3(H2O)]3+\left[\mathrm{Co}(\mathrm{en})\left(\mathrm{NH}_{3}\right)_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}.

Answer key and solution verified before publishing.

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Exam
JEE Advanced 2018
Paper
Paper 2
Subject
Chemistry
Chapter
Coordination Compounds
Topic
Isomerism in Coordination Compounds

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