question_answer

The octahedral complex of a metal ion \[{{M}^{3+}}\] with fan monodentate ligands \[{{L}_{1}},\]\[{{L}_{2}},\]\[{{L}_{3}},\] and \[{{L}_{4}},\] absorbs wavelength! in the region of red, green, yellow, and blue, respectively The increasing order of ligand strength of the four Uganda 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) \[{{L}_{1}}<{{L}_{2}}<{{L}_{4}}<{{L}_{3}}\]

Correct Answer: B

Solution :

[b]

Ligand	\[{{L}_{1}}\]	\[{{L}_{2}}\]	\[{{L}_{3}}\]	\[{{L}_{4}}\]
Coloured region of absorbed wavelength	Red	Green	Yellow	Blue

Coloured regions of visible light (VIBGYOR) are arranged in the increasing order of wavelength or decreasing order of energy\[[E\infty 1/\lambda ]\]. Therefore, This suggests that \[{{L}_{4}}\]will absorb higher energy wavelength followed by\[{{L}_{2}}\],\[{{L}_{3}}\], and\[{{L}_{1}}\]. Since higher absorbed energy corresponds to greater extent of crystal field splitting and, thus, higer field strength of the ligand. Hence, the increasing order of ligand strength of the four ligands is \[{{L}_{1}}<{{L}_{3}}<{{L}_{2}}<{{L}_{4}}\]