coordination compounds often show various types of isomerism. The isomerism can be categorized in two main types
(a) structural isomerism
(b) stereo or space isomerism Structural isomerism arises due to the difference in structures of coordination-sempounds while stereo or space isomerism arises on account of the different positions and arrangements of ligands (atoms or groups) in space around the metal lonStructural isomerism can be classified in following types (i) tonization isomers- which give different ions in solution, e.g. `[CoBr(NH_(3))_(5)]]SO_(4)` and `[Co(SO_(4))_(5)(NH_(3))_(5)]Br`
Hydrate isomers which differ in `H_(2)O` as ligand or as hydration, e.g. `[Cr(H_(2)O)_(5)]CI_(2)(H_(2)O)]Cl_(2).H_(2)O[CrCl_(2)(H_(2)O)]CI.2H_(2)O`
(iii) Linkage isomers, which differ in atom linked to 'metal atom, e.g. `[CO(NO_(2))(NH_(3))_(5)]^(2+)`and`CO(ONO)(NH_(3))_(6)]^(2+)`
Coordination isomers- which involve interchange of ligands, e.g. `[Co(NH_(3))_(6)] [Cr(CN)_(6)]` and`[Cr(NH_(3))_(6)] [Co(CN)_(6)]`
(v) Coordination position isomerism-which arises in the bridged complexes due to the difference in the attachment of ligands with the metal atoms
QThe compounds `[Cr(H_(2)O_(6)]Cl_(3)[Cr(H_(2)O)_(5)CI]Cl_(2).H_(2)O` and `[Cr(H_(2)O)_(4)Cl_(2)]Cl2H_(2)O` exhibit

Options

A. linkage isomerism
B. geometrical isomerism
C. ionisation isomerism
D. hydrate isomerism

Answer

To solve the question regarding the isomerism exhibited by the coordination compounds `[Cr(H₂O)₆]Cl₃`, `[Cr(H₂O)₅Cl]Cl₂·H₂O`, and `[Cr(H₂O)₄Cl₂]Cl₂·H₂O`, we will analyze the types of isomerism present in these compounds step-by-step.

### Step 1: Identify the Compounds
We have three coordination compounds:
1. `[Cr(H₂O)₆]Cl₃`
2. `[Cr(H₂O)₅Cl]Cl₂·H₂O`
3. `[Cr(H₂O)₄Cl₂]Cl₂·H₂O`

### Step 2: Determine the Coordination Number and Ligands
- The central metal ion is Chromium (Cr).
- The coordination number for Cr in these compounds is 6, which is typical for Cr(III) complexes.
- The ligands in these compounds include water (H₂O) and chloride ions (Cl⁻).

### Step 3: Analyze the Isomerism
- **Hydrate Isomers**: These isomers differ in the number of water molecules that are coordinated to the metal ion versus those that are present as hydration (outside the coordination sphere).

- In `[Cr(H₂O)₆]Cl₃`, all six water molecules are coordinated to the Cr ion.
- In `[Cr(H₂O)₅Cl]Cl₂·H₂O`, five water molecules are coordinated, one chloride is coordinated, and one water molecule is outside as hydration.
- In `[Cr(H₂O)₄Cl₂]Cl₂·H₂O`, four water molecules are coordinated, two chlorides are coordinated, and two water molecules are outside as hydration.

### Step 4: Conclusion
The differences in the arrangement of water molecules as ligands and as hydration indicate that these compounds exhibit **hydrate isomerism**.

### Final Answer
The compounds exhibit **hydrate isomerism**.

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