The octahedral complex of a metal ion $\mathrm{M}^{3+}$ with four monodentate ligands $\mathrm{L}_{1}, \mathrm{~L}_{2}, \mathrm{~L}_{3}$ and $\mathrm{L}_{4}$ absorb wavelengths in the region of red, green, yellow and blue, respectively. The increasing order of ligand strength of the four ligands is:

(D) $\mathrm{L}_{1}<\mathrm{L}_{3}<\mathrm{L}_{2}<\mathrm{L}_{4}$

(A) $\mathrm{L}_{3}<\mathrm{L}_{2}<\mathrm{L}_{4}<\mathrm{L}_{1}$

(B) $\mathrm{L}_{1}<\mathrm{L}_{2}<\mathrm{L}_{4}<\mathrm{L}_{3}$

(C) $\mathrm{L}_{4}<\mathrm{L}_{3}<\mathrm{L}_{2}<\mathrm{L}_{1}$

JEE Main · 2014 · 06 Apr 2014 · Offline · Coordination Compounds

The octahedral complex of a metal ion

M^{3 +}

with four monodentate ligands

L_{1}, L_{2}, L_{3}

and

L_{4}

absorb wavelengths in the region of red, green, yellow and blue, respectively. The increasing order of ligand strength of the four ligands is:

Answer: (D)

A stronger ligand splits the

d

levels more and so makes the complex absorb higher-energy, shorter-wavelength light. Among the colours absorbed, the energy order is red

<

yellow

<

green

<

blue. Matching each to its ligand, where

L_{1}

absorbs red,

L_{3}

yellow,

L_{2}

green and

L_{4}

blue, the field strength rises in the same order,

L_{1} < L_{3} < L_{2} < L_{4}

JEE Main · 2014 · 06 Apr 2014 · Offline · Single correct option