Question

Which would exhibit coordination isomerism?

• A. [Pt(NH₃)₄Cl₂]Br₂
• B. [Co(NH₃)₅Br]²⁺SO₄ ^2-
• C. [Cr(NH₃)₆] [Co(CN)₆]
• D. [Cr(NH₃)₆]Cl₃

Answer 1

Answer: (C)

The explanation for the correct option:

Option(C) $\left[Cr{\left(N{H}_3\right)}_6\right]\left[Co{\left(CN\right)}_6\right]$

• Coordination isomerism is exhibited by [Cr(NH₃)₆] [Co(CN)₆].

• This isomerism occurs only in those complexes in which both cation and anion are complex.

• It occurs due to the exchange of ligands between cation and anion.

• Coordination isomerism occurs in compounds containing complex anionic and cationic parts and can be viewed as the interchange of one or more ligands between the cationic complex ion and the anionic complex ion.

• The compound $\left[Cr{\left(N{H}_3\right)}_6\right]\left[Co{\left(CN\right)}_6\right]$ is a coordination isomer with $\left[Co{\left(N{H}_3\right)}_6\right]\left[Cr{\left(CN\right)}_6\right]$

The explanation for the incorrect option:

(A) ${\left[Co{\left(N{H}_3\right)}_{5}Br\right]}^{+2}S{O}_4^{-2}$ does not have the anion in the form of complex, hence it could not show coordination isomerism.

(B) $\left[Pt\left(N{H}_3\right)C{l}_2\right]Br$ does not have the anion in the form of complex, hence it could not show coordination isomerism.

(C) $\left[Cr{\left(N{H}_3\right)}_6\right]C{l}_3$ does not have the anion in the form of complex, hence it could not show coordination isomerism.

Hence, $\left[Cr{\left(N{H}_3\right)}_6\right]\left[Co{\left(CN\right)}_6\right]$ shows coordination complex