Coordination Compounds 2 Question 29
####31. 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
(2014 Main)
(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) $L _1<L _2<L _4<L _3$
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Answer:
Correct Answer: 31. (c)
Solution:
- Arrange the complex formed by different ligands $L _1, L _2, L _3$ and $L _4$, according to wavelength of their absorbed light, then use of the following relation to answer the question.
Ligand field strength $\propto$ Energy of light absorbed
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Wavelength of absorbed light decreases.
$\therefore$ Increasing order of energy of wavelengths absorbed reflect greater extent of crystal field splitting, hence, higher field strength of the ligand.
Energy blue $\left(L _4\right)>$ green $\left(L _2\right)>$ yellow $\left(L _3\right)>\operatorname{red}\left(L _1\right)$
$\therefore \quad L _4>L _2>L _3>L _1$ in field strength of ligands.
