Discussion Forum



1)

The octahedral complex of a metal ion M3+ with four monodentate ligands L1, L2, L3  and L4   absorb wavelengths in the region of red, green, yellow and blue, respectively. The increasing order of ligand  strength of the four ligands is 


A) $ L_{4}$ < $L_{3}$ ,$L_{2}$ < $L_{1}$

B) $ L_{1}$ < $L_{3} $< $L_{2}$< $L_{4}$

C) $ L_{3}$ < $L_{2}$ < $L_{4}$ < $L_{1}$

D) $ L_{1}$ < $L_{2}$ < $L_{4} < $L_{3}$

Answer:

Option B

Explanation:

Arrange the complex formed by different ligands  L1, L2, L3  and L4, according to wavelength of their absorbed light, then use the following relation to answer the question.

 Ligand field strength $\propto$  Energy of light absorbed

           $\propto$ 1/ wavelength of light  absorbed

1732021320_12.JPG

 Wavelength of absorbed light decreases.

$\therefore$    Increasing order of energy of wavelength absorbed reflect greater extent of crystal -field splitting. Hence higher field strength of the ligand.

Energy Blue (L4)                 > green (L2)

                                         > yellow (L3)

                                         > red (L1)

$\therefore$ 

L4>L2>L3>L1   , in field strength of ligands.