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Topic: Valence bond approach· Coordination Compounds

Given below are two statements :Statement I : Both [Co(NH_3)_6]^3+ and [CoF_6]^3- complexes are octahedral but differ in their magnetic behaviour.Statement II : [Co(NH_3)_6]^3+ is diamagnetic whereas [CoF_6]^3- is paramagnetic.In the light of the abo…

Given below are two statements :

Statement I : Both \([Co(NH_3)_6]^{3+}\) and \([CoF_6]^{3-}\) complexes are octahedral but differ in their magnetic behaviour.

Statement II : \([Co(NH_3)_6]^{3+}\) is diamagnetic whereas \([CoF_6]^{3-}\) is paramagnetic.

In the light of the above statements, choose the correct answer from the options given below:

1. Statement I is false but Statement II is true.

2. Both Statement I and Statement II are true.

3. Both Statement I and Statement II are false.

4. Statement I is true but Statement II is false.

1 answer

Best answer

Answer: 2. Both Statement I and Statement II are true.

Key idea: the ligand field strength decides pairing in \(\mathrm{Co^{3+}}\) (\(d^6\)).

  • \(\mathrm{NH_3}\) is a strong-field ligand: electrons pair up, \(t_{2g}^6\), no unpaired electrons, diamagnetic (inner orbital \(d^2sp^3\)).
  • \(\mathrm{F^-}\) is weak-field: \(t_{2g}^4e_g^2\), 4 unpaired electrons, paramagnetic (\(sp^3d^2\)).

Both complexes are octahedral. Both statements are true: option 2.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report
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