Question

When degenerate d-orbitals of an isolated atom/ion come under influence of the magnetic field of ligands, the degeneracy is lost. The two set $t_{2g}(d_{xy},d_{yz},d_{xz})$ and $(d_z^2,d_{x^2-y^2})$ are either stabilized or destabilized depending upon the nature of magnetic field. It can be expressed diagrammatically as :

The value of CFSE depends upon the nature of the ligand and a spectrochemical series has been made experimentally, for tetrahedral complexes. $\Delta$ is about 4/9 times to ${\Delta }_0$ (CFSE for octahedral complex). This energy lies in the visible region and i.e., why the electronic transition is responsible for colour. Such transitions are not possible with $d^0$ and $d^{10}$ configuration.

Crystal field stabilization energy for $[Co{F}_6{]}^{3-}$ in terms of parameter Dq is - $(\Delta =10Dq)$

• A. 4
• B. 6
• C. 12
• D. 24

Answer 1

The correct option is A 4

Option (A) is correct.

In $[Co{F}_6{]}^{3-}$ complex- high spin tetrahedral, 3 electron is their in $t_{2g}$ and 2 electrons in $e_g$.

By applying formula,

$\Delta$ for $[Co{F}_6{]}^{3-}$ complex = no. of electrons in $t_{2g}$·(-0.4)+ no. of electrons in $e_g$(0.6)

$=4.(-0.4)+2.\left(0.6\right)$

$=0.4$ $\Delta$

$=0.4\ast 10$

$=4Dq$