Question

Which of the following is/are paramagnetic ?

• A. [Fe(CN)6]4–
• B. [Ni(CO)4]
• C. [Ni(CN)4]2–
• D. [CoF6]3–

Answer 1

Answer: (D)

$CoF6$3–

Answer 2

(1) [Fe(CN)6]4– d6 CN– is strong field ligand.

(2) [Ni(CO)4] d10 CO is strong field ligand.

(3) [Ni(CN)4]2– ; Ni2+ has 3d8 configuration and CN– is strong field ligand. So, complex is square planar and diamagnetic.

(4) [CoF6]3–d6F– being weak field ligand does not allow pairing.