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 bule, respectively The increasing order of ligand strengh of the four ligands is

Options

A. (a) `L_4ltL_3ltL_2ltL_1`
B. (b) `L_1ltL_3ltL_2ltL_4`
C. (c) `L_3ltL_2ltL_4ltL_1`
D. (d) `L_1ltL_2ltL_4ltL_3`

Answer

B

Explanation

`{:("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 of decreasing order of energy `[:' Eprop 1//lambda]`. Therefore,
`{:(E_(Red)lt,E_(yellow)lt,E_(green)lt,E_(blue),),((L_1),(L_2),(L_3),(L_4),):}`
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 fied splitting and thus, higher field strength of the ligard.
Hence, the increasing order of ligand strength of the four ligands is
`L_1ltL_3ltL_2ltL_4`