The magnetic moment of which of the following complexes is maximum?

Options

A. `[Co(NH_(3))_(6)]^(3+)`
B. `[Ni(CN)_(4)]^(2-)`
C. `[CoF_(6)]^(3-)`
D. `[NiCl_(4)]^(2-)`

Answer

C

Explanation

(a) `[Co(NH_(3))_(6)]^(3+)`
Electronic configuration of `Co^(3+) rarr 3d^(6)4s^(0)`

`because NH_(3)` is a strong field ligand.
So, magnetic moment of `[Co(NH_(3))_(6)]^(3+)`.
`" "mu=sqrt(n(n+2))BM`
`" "mu=sqrt(0(0+2))`
`" "mu=0`
(b) `[Ni(CN)_(4)]^(2-)`
Electronic configuration of `Ni^(2+) rarr 3d^(8)4s^(0)`

`because` CN is a strong field ligand.
So, magnetic moment of `[Ni(CN)_(4)]^(2-)`.
`" "(mu)=0(0+2)`
`" "mu=0`
(c) `[CoF_(6)]^(3-)`
Electronic configuration of `Co^(3+) rarr 3d^(6)4s^(0)`

`because` [F] is a weak field ligand.
So, magnetic moment of `[CoF_(6)]^(3-)`.
`" "(mu)=sqrt(4(4+2))`
`" "mu=4.8`
(d) `[NiCl_(4)]^(2-)`
Electronic configuration of `Ni^(2+) rarr 3d^(8)4s^(0)`

`because` [Cl] is weak field ligand.
So, magnetic moment of `[NiCl_(4)]^(2-)`.
`" "mu=2.8`