Question

(f) In octahedral complexes, when 10Dq > P, they usually form
complexes
(a) high spin
(b) low spin
(c) spin free.
Colca​

Answer 1

Answer:

When 10 Dq > P in octahedral complexes, they frequently produce low spin complexes.

Let us first define CFSE, CFT in octahedral complexes and other related terms.

Explanation:

Define Crystal Field Splitting Energy or CFSE.

Crystal Field Splitting Energy (CFSE) refers to the splitting of the free metal ion's five degenerated orbitals by the ligand field into two groups with differing energies.

Low spin and High spin.

The complex with the fewest unpaired electrons is known as the low spin complex, wheres the complex with the most unpaired electrons is known as the high spin complex.

• With weak field ligands, high spin complexes are predicted since the crystal field splitting energy is low Δ.
• The converse is true for low spin complexes, where strong field ligands produce maximal electron pairing in the set of three t₂ atomic orbitals due to high Δo.

Crystal Field Splitting (CFT) in Octahedral Complexes

1. We see repulsion between electrons in d-orbitals and ligand electrons in an octahedral coordination molecule with six ligands encircling the metal atom/ion.
2. The repulsion is stronger in the case of dx²₋y² and dz² orbitals, which point towards the axes along the ligand's direction.
3. As a result, they have more energy than the average energy in the spherical crystal field.
4. The dxy, dyz and dzx orbitals, on the other hand, have smaller replusions because they are oriented between the axes.
5. As a result, the energy in these three orbitals is lower than the average energy in the spherical crystal field.

As a result, the repulsions in an octahedral coordination molecule produce two energy levels:

• t₂g - a group of three lower-energy orbitals (dxy,dyz and dzx).
• eg - a pair of higher-energy orbitals (dz² and dx²₋y²).

The first image attached is the CFT in octahedral complex.

In the given image,

• Δo or 10 Dq = The difference in energy between the two levels.
• The eg orbitals are repulsed by a factor of 0.6, whereas the 6 orbitals are repelled by a factor of Δo.
• To the extent of 0.4 Δo, the t₂g orbitals will be stabilised.

Electron Distribution in Octahedral Complex

The electron distribution in octahedal complex is given in the second image.

Hope, the concept is clear.