Question:
Homoleptic octahedral complexes of a metal ion ' $\mathrm{M}^{3+}$ ' with three monodentate ligands and $\mathrm{L}_{1}, \mathrm{~L}_{2}, \mathrm{~L}_{3}$ absorb wavelengths in the region of green, blue and red respectively. The increasing order of the ligand strength is :
Correct Option: , 3
Solution:
Order of $\lambda_{a b s}-L_{3}>L_{1}>L_{2}$
So $\Delta_{\mathrm{O}}$ order will be $\mathrm{L}_{2}>\mathrm{L}_{1}>\mathrm{L}_{3}$ (as $\Delta_{\mathrm{O}} \propto \frac{1}{\lambda_{\mathrm{abs}}}$ )
So order of ligand strength will be $\mathrm{L}_{2}>\mathrm{L}_{1}>\mathrm{L}_{3}$