Chemistry Class 12 NCERT Solutions: Chapter 9 Coordination Compounds Part 6 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q: 15. Discuss the nature of bonding in the following coordination entities on the basis of valence bond theory:

(i)

(ii)

(iii)

(iv)

Answer:

In the above coordination complex, iron exists in the oxidation state. : Electronic configuration is

Orbitals of :

Q_15_i_1_Orbitals of Fe2 + Ion

As is a strong field ligand, it causes the pairing of the unpaired electrons.

Q_15_i_2_The Pairing of the Unpaired 3d Electrons

Since there are six ligands around the central metal ion, the most feasible hybridization is .

hybridized orbitals of are:

Q_15_i_3_The Hybridized Orbitals

electron pairs from ions occupy the six hybrid orbitals. Then,

Q_15_i_4_6 Pairs of Electrons

Hence, the geometry of the complex is octahedral and the complex is diamagnetic (as there are no unpaired electrons) .

(ii)

In this complex, the oxidation state of is

Orbitals of :

Q_15_ii_1_Orbitals of Fe + 3 Ion

There are ions. Thus, it will undergo or hybridization. As is a weak field ligand, it does not cause the pairing of the electrons in the orbital. Hence, the most feasible hybridization is .

hybridized orbitals of are:

Q_15_ii_2_Hybridized Orbitals of Fe
Q_15_ii_3_6 Electron Pair from F- Ions

Hence, the geometry of the complex is found to be octahedral.

(iii)

Cobalt exists in the oxidation state in the given complex.

Orbitals of :

Q_15_iii_3_Orbitals of Co ^ 3 + Ions

Oxalate is a weak field ligand. Therefore, it cannot cause the pairing of the orbital electrons. As there are ligands, hybridization has to be either hybridization.

hybridization of :

Q_15_iii_2_Hybridization of Co ^ 3 +

The electron pairs from the oxalate ions (oxalate anion is a bidentate ligand) occupy these orbitals.

Q_15_iii_3_6 Electron Pairs from 3 Oxalate Ions

Hence, the geometry of the complex is found to be octahedral.

(iv)

Cobalt exists in the oxidation state

Orbitals of ion:

Q_15_iv_1_Hybridized Orbitals

Again, fluoride ion is a weak field ligand. It cannot cause the pairing of the electrons As a result, the ion will undergo hybridization. hybridized orbitals of ion are:

Q_15_iv_2_Hybridized Orbitals
Q_15_iv_3_6 Electron Pairs from 3 Oxalate Ions

Hence, the geometry of the complex is octahedral and paramagnetic.

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