Name: Bonding in Metal Carbonyls
Uploaded: 2019-07-19
Duration: 4 min 37 s
Description: Metal carbonyl is made up of metal with multiple numbers of the same ligands. Do you know such bonds are very strong? Watch this video to know the reason beh...

Question

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:

(i) ${[{CoF}_{6}]}^{3 -}, {[Co {(H_{2} O)}_{6}]}^{2 +}, {[Co {(CN)}_{6}]}^{3 -}$

(ii) ${[{FeF}_{6}]}^{3 -}, {[Fe {(H_{2} O)}_{6}]}^{2 +}, {[Fe {(CN)}_{6}]}^{4 -}$

Accepted Answer

According to the question, Crystal field theory describes A major feature of transition metals is their tendency to form complexes. A complex may be considered as consisting of a central metal atom or ion surrounded by a number of ligands. The interaction between these ligands with the central metal atom or ion is subject to crystal field theory.

In case of ${[{CoF}_{6}]}^{3 -}$ , The atomic number of cobalt is $27$ And has $3 d^{7}, 4 s^{2}$ . The oxidation number of cobalt in this complex is $+ 3$ , due to this it has $3 d^{6}$ Electronic configuration. Here fluorine is weak field ligand and forms high spin complex. In which pairing of electron do not take place. So according to C.F.T the electronic configuration of ${CO}^{+ 3}$ is ${t_{2 g}}^{4}, {e_{g}}^{2}$ . So it has $4$ Unpaired electrons and the value of magnetic moment is $4.9$ (paramagnetic).

In case of ${[Co {(CN)}_{6}]}^{3 -}$ , The atomic number of cobalt is $27$ And has $3 d^{7}, 4 s^{2}$ . The oxidation number of cobalt in this complex is $+ 3$ , due to this it has $3 d^{6}$ Electronic configuration. Here fluorine is strong field ligand and forms high low complex. In which pairing of electron taken place. So according to C.F.T the electronic configuration of ${CO}^{+ 3}$ is ${t_{2 g}}^{6}, {e_{g}}^{0}$ . So it does not have any unpaired electrons and the value of magnetic moment is $0.0$ (diamagnetic).

In case of ${[Co {(H_{2} O)}_{6}]}^{2 +}$ , The atomic number of cobalt is $27$ And has $3 d^{7}, 4 s^{2}$ . . The oxidation number of cobalt in this complex is $+ 2$ Due to this it has $3 d^{7}$ Electronic configuration. Here fluorine is weak field ligand and forms high spin complex. In which pairing of electron do not take place. So according to C.F.T the electronic configuration of ${CO}^{+ 2}$ is ${t_{2 g}}^{5}, {e_{g}}^{2}$ . So it has $3$ Unpaired electrons and the value of magnetic moment is $3.8$ (paramagnetic).

In case of ${[{FeF}_{6}]}^{3 -}$ , The atomic number of iron is $26$ And it has $3 d^{6}, 4 s^{2}$ Electronic configuration. The oxidation number of iron in this complex is $+ 3$ . So it has $3 d^{5}, 4 s^{0}$ Electronic configuration. Here fluorine is weak field ligand and forms high spin complex. In which pairing of electron do not take place. So according to C.F.T the electronic configuration of iron (III) is ${t_{2 g}}^{3}, {e_{g}}^{2}$ . So it has $5$ Unpaired electrons and the value of magnetic moment is $5.9$ -paramagnetic in nature.

In case of ${[Fe {(H_{2} O)}_{6}]}^{2 +}$ , The atomic number of iron is $26$ And it has $3 d^{6}, 4 s^{2}$ Electronic configuration. The oxidation number of iron in this complex is $+ 2$ . So it has $3 d^{6}, 4 s^{0}$ Electronic configuration. Here water is weak field ligand and forms high spin complex. In which pairing of electron do not take place. So according to C.F.T the electronic configuration of iron (II) is ${t_{2 g}}^{4}, {e_{g}}^{2}$ . So it has $4$ Unpaired electrons and the value of magnetic moment is $4.9$ -paramagnetic in nature.

In case of ${[Fe {(CN)}_{6}]}^{4 -}$ ,The atomic number of iron is $26$ And it has $3 d^{6}, 4 s^{2}$ Electronic configuration. The oxidation number of iron in this complex is $+ 2$ So it has $3 d^{6}, 4 s^{0}$ Electronic configuration. Here cyanide is strong field ligand and forms low spin complex. In which pairing of electrons are taken place. So according to C.F.T the electronic configuration of iron (II) is ${t_{2 g}}^{6}, {e_{g}}^{0}$ . So it does not have any unpaired electrons and the value of magnetic moment is $0.0$ -diamagnetic in nature.

Important Questions on Coordination Compounds

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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: (i) CoF63−,CoH2O62+,CoCN63− (ii) FeF63−,FeH2O62+,FeCN64−

Important Questions on Coordination Compounds

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