Which of the following is neutral coordination sphere ?

Options

A. `K_(4)[Fe(CN)_(6)]`
B. `[Co(NH_(3))_(6)]Cl_(3)`
C. `[Pt(NH_(3))_(2)Cl_(2)]`
D. `[Cu(NH_(3))_(4)]SO_(4)`

Answer

To determine which of the given options represents a neutral coordination sphere, we need to analyze each option based on the presence of charges.

### Step-by-Step Solution:

1. **Understanding Coordination Compounds**:
- Coordination compounds consist of a central metal atom or ion surrounded by molecules or anions called ligands. The coordination sphere is the part of the complex that contains the metal and the ligands.

2. **Identifying Neutral Coordination Sphere**:
- A neutral coordination sphere means that the overall charge of the complex ion (the part within the square brackets) is zero. This implies that the sum of the charges from the metal and the ligands must balance out to zero.

3. **Analyzing the Options**:
- Let's denote the options as follows:
- Option 1: [PCN6]
- Option 2: [CN3]
- Option 3: [Pt(NH3)2]
- Option 4: [Co(NH3)4]

4. **Checking Each Option**:
- **Option 1: [PCN6]**: This complex has a charge due to the presence of counter ions. Hence, it is not neutral.
- **Option 2: [CN3]**: Similar to option 1, this complex also has a charge and is not neutral.
- **Option 3: [Pt(NH3)2]**: Ammonia (NH3) is a neutral ligand. Since there are no counter ions present, the overall charge is zero, indicating that this is a neutral coordination sphere.
- **Option 4: [Co(NH3)4]**: While NH3 is neutral, if there are counter ions present, this complex would not be neutral.

5. **Conclusion**:
- The only option that represents a neutral coordination sphere is **Option 3: [Pt(NH3)2]**.

### Final Answer:
The neutral coordination sphere is **[Pt(NH3)2]**.