In which of the following S - S bond is not present:

Options

A. `S_(2)O_(4)^(2-)`
B. `S_(2)O_(5)^(2-)`
C. `S_(2)O_(3)^(2-)`
D. `S_(2)O_(7)^(2-)`

Explanation

To determine in which of the following compounds the S-S bond is not present, we will analyze the structures of each compound. The options given are:

1. SCN²⁻ (Thiocyanate ion)
2. S₂O₅ (Disulfur pentoxide)
3. S₂O₃ (Thiosulfate)
4. S₂O₇ (Disulfur heptoxide)

### Step 1: Analyze SCN²⁻ (Thiocyanate ion)
- The structure of SCN²⁻ can be represented as S=C=N⁻.
- In this structure, there is no S-S bond present.

### Step 2: Analyze S₂O₅ (Disulfur pentoxide)
- The structure of S₂O₅ can be represented as O=S=O and O=S=O with bridging oxygens.
- In this compound, there is a S-S bond present.

### Step 3: Analyze S₂O₃ (Thiosulfate)
- The structure of S₂O₃ can be represented as O=S=O and S=O with an additional O⁻.
- In this compound, there is a S-S bond present.

### Step 4: Analyze S₂O₇ (Disulfur heptoxide)
- The structure of S₂O₇ can be represented as O=S=O and O=S=O with bridging oxygens.
- In this compound, there is a S-S bond present.

### Conclusion
After analyzing all the options, we find that the compound in which the S-S bond is not present is **SCN²⁻ (Thiocyanate ion)**.

### Final Answer
The answer is **SCN²⁻ (Thiocyanate ion)**.