Using crystal field theory, draw energy level diagram, write electronic configuration of the central metal atom/ion and determine the magnetic moment value in the following
(a) $[C o F_{6}]^{3 -}, [C o (H_{2} O)_{6}]^{2 +}, [C o (C N)_{6}]^{3 -}$
(b) $F e F_{6}^{3 -}, [F e (H_{2} O)_{6}]^{2 +}, [F e (C N)_{6}]^{4 -}$

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Solution

(a) $[C o F_{6}]^{3 -}, [C o (H_{2} O)_{6}]^{2 +}, [C o (C N)_{6}]^{3 -}$

$[C o F_{6}]^{3 -}$
$F^{-}$ is a weak field ligand.

Configuration of $C o^{3 +} = 3 d^{6} (o r t_{2 g}^{4} e_{g}^{2})$
Number of unpaired electrons (n)=4
Magnetic moment $(μ) = \sqrt{n (n + 2)} = \sqrt{4 (4 + 2)} = \sqrt{24} = 4.9 B M [C o (H_{2} O)_{6}]^{2 +}$

$[C o (H_{2} O)_{6}]^{2 +}$

$H_{2} O$ is a weak field ligand.

Configuartion of $C o^{2 +} = 3 d^{7} (o r t_{2 g}^{5} e_{g}^{2})$
Number of unpaired electrons (n)=3
$μ = \sqrt{3 (3 + 2)} = \sqrt{15} = 3.87 B M$

$[C o (C N)_{6}]^{3 -}$ i.e., $C o^{3 +}$
$∵$ CN is strong field ligand.

$C o^{3 +} = 3 d^{6} (o r t_{2 g}^{6} t_{g}^{0})$
There is no unpaired electron, so it is diamagnetic.
$μ = 0$

(b) $F e F_{6}^{3 -}, [F e (H_{2} O)_{6}]^{2 +}, [F e (C N)_{6}]^{4 -}$

$[F e F_{6}]^{3 -},$

Number of unpaired electrons, n=5
$μ = \sqrt{5 (5 + 2)} = \sqrt{35} = 5.92 B M$

$[F e (H_{2} O)_{6}]^{2 +}$

$[F e (C N)_{6}]^{4 -}$

Since, $C N^{-}$ is a strong field ligand, all the electrons get paired.
$F e^{2 +} = 3 d^{6} (o r t_{2 g}^{6} e_{g}^{0})$
Because there is no unpaired electron, so it is diamagnetic in nature.

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Similar questions

Give the electronic configuration of the following complexes on the basis of crystal field splitting theory. $[C o F_{6}]^{3 -}, [F e (C N)_{6}]^{4 -}$ and $[C u (N H_{3})_{6}]^{2 +} .$

Q. What is the correct electronic configuration of the central atom in

K_{4} [F e (C N)_{6}]

based on crystal field theory ?

Q. Give the electronic configuration of the following on the basis of crystal field splitting theory.

{[C o F_{6}]}^{3 -}

and

{[C u {({N H}_{3})}_{6}]}^{2 +}

Q. (i) Draw the geometrical isomer of complex

[P t (N H_{3})_{2} C l_{2}]

.
(ii) On the basis of crystal field theory, write the electronic configuration for

d^{4}

ion if

Δ_{0} < P

.
(iii) Write the hybridization and magnetic behaviour of the complex

[N i (C O)_{4}]

.
(At. no. of Ni=28).

Q. Compare the complexes

{[F e {(H_{2} O)}_{6}]}^{2 +}

and

{[F e {(C N)}_{6}]}^{4 -}

with the help of crystal field theory.

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Using crystal field theory, draw energy level diagram, write electronic configuration of the central metal atom/ion and determine the magnetic moment value in the following (a) [CoF6]3−,[Co(H2O)6]2+,[Co(CN)6]3− (b) FeF3−6,[Fe(H2O)6]2+,[Fe(CN)6]4−