Question

Which one of the following cyano complexes would exhibit the lowest value of paramagnetic behaviour? (At. Nos.: Cr = 24, Mn = 25, Fe = 26, Co = 27)

• A. \([\text{Co(CN)}_6]^{3-}\)
• B. \([\text{Fe(CN)}_6]^{3-}\)
• C. \([\text{Mn(CN)}_6]^{3-}\)
• D. [Cr(CN)₆]³-

Hint:

Strong field ligands reduce number of unpaired electrons.

Answer 1

The Correct Option is A

Step 1: CN⁻ is a strong field ligand → low spin complexes.
Step 2: [Co(CN)₆]³- has all electrons paired.