Ncert Exercises & Solutions

Q. 50 Why are different colours observed in octahedral and tetrahedral

complexes for the same metal and same tigands?

Extent of spliting of d-orbitals is different in octahedral and tetrahedral field, CFSE in

octahedral and tetra federal field are closely related as.

$∆_{t} = (\frac{4}{9}) ∆_{0}$

Where, = crystal field splitting energy in tetrahedral field

= crystal field splitting energy in octahedral field

Wavelength fo light and CFSE are releated to each other by formula

$∆_{t} = E = \frac{h c}{λ}$
$E \propto \frac{1}{λ}$

So, higher wavelength o light is absorbed in octahedral complexes than tetrahedral

complex for same metal and ligands. Thus, different colours are obserevd.