The number of unpaired electrons in the complex ion [CoF6]3- is (Atomic no. : Co = 27)
- 2
- 3
- 4
- zero
Answer
(3) 4
Solution
Oxidation state of Co: x + 6(-1) = -3 ⇒ x = +3
Co3+: [Ar] 3d6
As per NCERT, F- is a weak field ligand ⇒ no pairing; [CoF6]3- is an outer orbital (sp3d2), high spin complex.
⇒ 3d6 (high spin): t2g4 eg2 ⇒ 4 unpaired electrons
∴ Number of unpaired electrons = 4
Answer: (3)