Question

What type of isomerism is present between
(I) [Cr(H$_2$O)$_6$]Cl$_3$ and
(II) [Cr(H$_2$O)$_5$Cl]Cl$_2 \cdot$ H$_2$O?

• A. Ionisation
• B. Coordination
• C. Hydrate
• D. Linkage

Hint:

Hydrate isomerism occurs when a molecule of water can either be part of the coordination sphere or as water of crystallization in a coordination compound.

Answer 1

The Correct Option is C

Step 1: Understanding isomerism in coordination compounds.
In coordination chemistry, hydrate isomerism occurs when water molecules are coordinated to the metal ion in different ways, either as water of crystallization or as part of the coordination sphere.
Step 2: Analyzing the options.
(A) Ionisation: Ionisation isomerism occurs when two compounds have the same molecular formula but produce different ions in solution. This is not the case here.
(B) Coordination: Coordination isomerism occurs when different ligands are coordinated to the metal center, but the two compounds in the question do not exhibit this type of isomerism.
(C) Hydrate: This is the correct answer. The two compounds differ by the presence of water in the crystal lattice (as water of crystallization).
(D) Linkage: Linkage isomerism occurs when a ligand can coordinate to the metal in more than one way, which is not applicable here.
Step 3: Conclusion.
The correct type of isomerism is hydrate isomerism as one compound has water in the coordination sphere, while the other has it as water of crystallization.