Which pair of isomers illustrates the concept of ionisation isomers ?

Options

A. `[Cr(SCN)(NH_(3))_(5)]^(2+) and [Cr(NCS)(NH_(3))_(5)]^(2+)`
B. `[CoCl(NH_(3))_(5)]SO_(4) and [Co(SO_(4))(NH_(3))_(5)]Cl`
C. `cis[PtCl_(2)(NH_(3))_(2)] and "trans" [PtCl_(2)(NH_(3))_(2)]`
D. `(+)-[Co(en)_(3)]^(3+) and (-)-[Co(en)_(3)]^(3+)`

Answer

To solve the question regarding which pair of isomers illustrates the concept of ionization isomers, we will follow these steps:

### Step 1: Understand Ionization Isomers
Ionization isomers are compounds that have the same molecular formula but produce different ions when dissolved in solution. This typically occurs when a ligand can either be part of the coordination sphere or exist as a free ion outside of it.

**Hint:** Look for compounds that can yield different ions upon dissolution.

### Step 2: Analyze the Given Options
We will evaluate each option to determine if they can produce different ions.

- **Option A:** \( \text{[Cr(SCN)(NH}_3)_5]^{2+} \) and \( \text{[Cr(NCS)(NH}_3)_5]^{2+} \)
- Both complexes do not have any ligands that can ionize outside the coordination sphere. Therefore, they do not show ionization isomerism.

**Hint:** Check if any ligands can be released as free ions.

- **Option B:** \( \text{[CoCl(NH}_3)_5SO_4] \) and \( \text{[CoSO_4(NH}_3)_5Cl] \)
- When \( \text{[CoCl(NH}_3)_5SO_4] \) ionizes, it produces \( \text{[Co(NH}_3)_5]^{2+} \) and \( \text{SO}_4^{2-} \).
- When \( \text{[CoSO_4(NH}_3)_5Cl] \) ionizes, it produces \( \text{[Co(NH}_3)_5]^{2+} \) and \( \text{Cl}^- \).
- Both complexes produce different ions upon ionization, thus they are ionization isomers.

**Hint:** Identify the ions produced from each complex upon dissolution.

- **Option C:** \( \text{cis-[PtCl}_2(NH_3)_2] \) and \( \text{trans-[PtCl}_2(NH_3)_2] \)
- These are geometrical isomers (cis-trans isomers) and do not involve any ionization. They do not produce different ions.

**Hint:** Consider the geometric arrangement of ligands and whether they can ionize.

- **Option D:** \( \text{[Co(en)_3]^{3+}} \) and \( \text{[Co(en)_3]^{3-}} \)
- These are not ionization isomers as they do not represent different ionization states of the same compound; they are simply different charges.

**Hint:** Check if both species have the same composition but yield different ions.

### Step 3: Conclusion
After analyzing all the options, we find that **Option B** is the correct answer, as it illustrates the concept of ionization isomers by producing different ions from the same coordination compound.

**Final Answer:** Option B: \( \text{[CoCl(NH}_3)_5SO_4] \) and \( \text{[CoSO_4(NH}_3)_5Cl] \) illustrate ionization isomers.