Question

Which of the following is diamagnetic?

• A. [MnCl\(_6\)]\(^{3-}\)
• B. [Fe(CN)\(_6\)]\(^{3-}\)
• C. [Co(C\(_2\)O\(_4\))\(_3\)]\(^{3-}\)
• D. [FeF\(_6\)]\(^{3-}\)

Hint:

For determining whether a complex is diamagnetic or paramagnetic, check for unpaired electrons. Diamagnetic complexes have all electrons paired.

Answer 1

The Correct Option is B

Diamagnetism is a property of materials that are repelled by a magnetic field, meaning all of their electrons are paired. For a complex to be diamagnetic, all electrons must be paired, and there should be no unpaired electrons. Let’s analyze each complex: - [MnCl\(_6\)]\(^{3-}\): Manganese in the +3 oxidation state has 4 unpaired electrons in the 3d orbitals, making this complex paramagnetic, not diamagnetic. - [Fe(CN)\(_6\)]\(^{3-}\): Iron in the +3 oxidation state (Fe\(^{3+}\)) has no unpaired electrons due to the strong field ligand CN\(^-\), which causes pairing of electrons. This complex is diamagnetic. - [Co(C\(_2\)O\(_4\))\(_3\)]\(^{3-}\): Cobalt in the +3 oxidation state has unpaired electrons, making this complex paramagnetic, not diamagnetic. - [FeF\(_6\)]\(^{3-}\): Similar to [MnCl\(_6\)]\(^{3-}\), this complex contains unpaired electrons and is paramagnetic. Thus, [Fe(CN)\(_6\)]\(^{3-}\) is the diamagnetic complex.