The correct order of [FeF6]3-, [CoF6]3-, [Ni(CO)4] and [Ni(CN)4]2- complex species based on the number of unpaired electrons present is:
- [CoF6]3- > [FeF6]3- > [Ni(CO)4] > [Ni(CN)4]2-
- [FeF6]3- > [CoF6]3- > [Ni(CN)4]2- > [Ni(CO)4]
- [FeF6]3- > [CoF6]3- > [Ni(CN)4]2- = [Ni(CO)4]
- [Ni(CN)4]2- > [FeF6]3- > [CoF6]3- > [Ni(CO)4]
Answer
(3) [FeF6]3- > [CoF6]3- > [Ni(CN)4]2- = [Ni(CO)4]
Solution
[FeF6]3-: Fe3+, 3d5, F- weak field (high spin, sp3d2) 5 unpaired
[CoF6]3-: Co3+, 3d6, high spin 4 unpaired
[Ni(CN)4]2-: Ni2+, 3d8, CN- strong field, dsp2 (square planar) 0 unpaired
[Ni(CO)4]: Ni(0), 3d10 (4s electrons paired into 3d), sp3 0 unpaired
[FeF6]3- > [CoF6]3- > [Ni(CN)4]2- = [Ni(CO)4]
Answer: (3)