Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion: Magnetic moment of [Fe(H2O)6]3+ is 5.92 BM and that of [Fe(CN)6]3– is 1.73 BM
Reason: Oxidation state of Fe in both the complexes is +3.
In the light of the above statements, choose the correct answer from the options given below
Assertion: Magnetic moment of [Fe(H2O)6]3+ is 5.92 BM and that of [Fe(CN)6]3– is 1.73 BM
Reason: Oxidation state of Fe in both the complexes is +3.
In the light of the above statements, choose the correct answer from the options given below
Both Assertion and Reason are correct and Reason is the correct explanation of Assertion
Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion
Reason is correct but Assertion is not correct
Reason is incorrect but Reason is correct
The Correct Option is A
Solution and Explanation
- Oxidation State of Fe:
- In both complexes, the oxidation state of Fe is +3. The electronic configuration of Fe3+ is [Ar] 3d5.
- Magnetic Moment of [Fe(H2O)6]3+:
- Water is a weak field ligand, so it does not cause significant splitting of the d-orbitals (according to crystal field theory).
- As a result, all five d-electrons in Fe3+ remain unpaired.
- The magnetic moment is given by the formula: μ = √n(n + 2), where n is the number of unpaired electrons.
- For 5 unpaired electrons: μ = √5(5 + 2) = √35 = 5.92 BM.
- Magnetic Moment of [Fe(CN)6]3–:
- Cyanide (CN–) is a strong field ligand, which causes significant splitting of the d-orbitals.
- This leads to the pairing of all five d-electrons in Fe3+, resulting in no unpaired electrons.
- For 1 unpaired electron: μ = √1(1 + 2) = √3 = 1.73 BM.
Conclusion:
Both the Assertion and the Reason are correct. The Reason correctly explains the differences in the magnetic moments due to the ligand field strength in the two complexes.
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Concepts Used:
Coordination Compounds
A coordination compound holds a central metal atom or ion surrounded by various oppositely charged ions or neutral molecules. These molecules or ions are re-bonded to the metal atom or ion by a coordinate bond.
Coordination entity:
A coordination entity composes of a central metal atom or ion bonded to a fixed number of ions or molecules.
Ligands:
A molecule, ion, or group which is bonded to the metal atom or ion in a complex or coordination compound by a coordinate bond is commonly called a ligand. It may be either neutral, positively, or negatively charged.