In which species `X-O` bond order is `1.5` and contains `ppi-dpi` bond`(s)`

Options

A. `IO_(2)F_(2)`
B. `HCOO^(-)`
C. `SO_(3)^(2-)`
D. `XeO_(2)F_(2)`

Explanation

To determine the species in which the `X-O` bond order is `1.5` and contains `pπ-dπ` bonds, we will analyze the provided options step by step.

### Step 1: Analyze the first option - IO2F2⁻

1. **Identify the central atom**: In IO2F2⁻, iodine (I) is the central atom.
2. **Determine the electronic configuration**: The electronic configuration of iodine is 5S² 5P⁵ 5D⁰.
3. **Hybridization**: The presence of two double bonds with oxygen and two single bonds with fluorine suggests sp³d hybridization.
4. **Bonding**: The structure will have pπ-dπ bonding due to the involvement of the 5p orbitals of iodine and the 2p orbitals of oxygen.
5. **Count the total number of bonds**: In IO2F2⁻, there are three bonds (two double bonds with oxygen and one single bond with fluorine).
6. **Calculate the bond order**: The bond order is calculated as:
\[ \text{Bond Order} = \frac{\text{Number of bonds}}{\text{Number of bonded atoms}} = \frac{3}{2} = 1.5 \]

### Conclusion for Step 1:
- **Result**: The bond order is 1.5, and it contains pπ-dπ bonds. Thus, IO2F2⁻ is a valid candidate.

### Step 2: Analyze the second option - HCOO⁻

1. **Identify the structure**: HCOO⁻ (formate ion) has a carbon atom bonded to two oxygen atoms.
2. **Bonding**: The bonding involves pπ-pπ interactions, as carbon does not have d orbitals available for bonding.
3. **Calculate bond order**: The bond order is:
\[ \text{Bond Order} = \frac{3}{2} = 1.5 \]
4. **Conclusion**: However, it does not exhibit pπ-dπ bonding.

### Step 3: Analyze the third option - SO3²⁻

1. **Identify the structure**: SO3²⁻ has one sulfur atom bonded to three oxygen atoms.
2. **Bonding**: The structure involves one double bond and two single bonds.
3. **Calculate bond order**: The bond order is:
\[ \text{Bond Order} = \frac{4}{3} \approx 1.33 \]
4. **Conclusion**: This does not meet the requirement of a bond order of 1.5.

### Step 4: Analyze the fourth option - XeO2F2

1. **Identify the structure**: XeO2F2 has xenon as the central atom.
2. **Bonding**: The structure involves double bonds with oxygen and single bonds with fluorine.
3. **Calculate bond order**: The bond order is:
\[ \text{Bond Order} = \frac{4}{2} = 2 \]
4. **Conclusion**: This does not meet the requirement of a bond order of 1.5.

### Final Answer:
The species that has an `X-O` bond order of `1.5` and contains `pπ-dπ` bonds is **IO2F2⁻**.

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