Which of the following coordination entities should be expected to absorb light of lowest frequency?

Question

Which of the following coordination entities should be expected to absorb light of lowest frequency? (A) [Cr(en)3]3+ (B) [CrCl6]3- (C) [Cr(NH3)6]3+ (D) [Cr(CN)6]3-

Tardigrade Admin · Accepted Answer

The coordination entity, for which crystal fieid spiitting is smaller, absorbs light of Io west frequency.
Weaker the ligand fieid strength, smaller will be the crystal fieid splitting.
The order of field strength of various ligands is as

CN > e n > N H_{3} > Cl

Hence,

[C r C l_{6}]^{3 -}

due to the presence of

C l^{-}

ligand absorbs light of Iowest frequency.

Q. Which of the following coordination entities should be expected to absorb light of lowest frequency?

$[C r (e n)_{3}]^{3 +}$

$[C r C l_{6}]^{3 -}$

$[C r (N H_{3})_{6}]^{3 +}$

$[C r (CN)_{6}]^{3 -}$

Q. Which of the following coordination entities should be expected to absorb light of lowest frequency?

[Cr(en)3​]3+

[CrCl6​]3−

[Cr(NH3​)6​]3+

[Cr(CN)6​]3−

$[C r (e n)_{3}]^{3 +}$

$[C r C l_{6}]^{3 -}$

$[C r (N H_{3})_{6}]^{3 +}$

$[C r (CN)_{6}]^{3 -}$