Question

Identify the isomerism exhibited by complex compounds \([\text{Co}(\text{NH}_{3})_{5}\text{SO}_{4}]\text{Br}\) and \([\text{Co}(\text{NH}_{3})_{5}\text{Br}]\text{SO}_{4}\)

• A. coordination isomers
• B. geometrical isomers
• C. optical isomers
• D. ionisation isomers

Hint:

The two complexes swap a ligand and a counter ion, which is ionisation isomerism.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept
Ionisation isomers have the same formula but exchange a ligand inside the coordination sphere with a counter ion outside it.

Step 2: Compare the complexes
\([\text{Co(NH}_{3})_{5}\text{SO}_{4}]\text{Br}\) has sulfate inside and bromide outside.
\([\text{Co(NH}_{3})_{5}\text{Br}]\text{SO}_{4}\) has bromide inside and sulfate outside.

Step 3: Conclude
They give different ions in solution (\(\text{Br}^{-}\) and \(\text{SO}_{4}^{2-}\) respectively), so they are ionisation isomers.

Final Answer:
The two complexes are ionisation isomers. \[ \boxed{\text{(D) }\text{ionisation isomers}} \]