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.


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=hcλ     E1λ

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

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