Which of the following organometallic compounds iso and`pi` bonded?

Options

A. `[Fe(r_(1)^(5)-C_(5)H_(5))_(2)]`
B. `K[PtCI_(3)(n^(2)-C_(2)H_(4))]`
C. `[Co(CO)_(5)NH_(3)]^(2+)`
D. `Fe(CH_(3))_(3)`

Answer

To determine which of the following organometallic compounds is both sigma and pi-bonded, we will analyze the given compounds step by step.

### Step 1: Identify the Compounds
Let's consider the compounds mentioned in the video transcript:
1. **Fe(C5H5)2** (Cyclopentadienyl complex)
2. **K[PtCl3(C2H4)]** (Ethylene complex)
3. **[Co(CO)5(NH3)]2+** (Carbonyl complex)
4. **Fe(CH3)3** (Methyl complex)

### Step 2: Analyze Each Compound

#### Compound 1: Fe(C5H5)2
- **Structure**: Iron is coordinated with two cyclopentadienyl ligands (C5H5).
- **Bonding**: The bonding here is primarily through π-bonds as the cyclopentadienyl anion acts as a π-acceptor. There is no sigma bond between the iron and the cyclopentadienyl; hence, this compound is only π-bonded.

#### Compound 2: K[PtCl3(C2H4)]
- **Structure**: Potassium is outside, and platinum is coordinated with three chloride ions and one ethylene molecule.
- **Bonding**: The ethylene (C2H4) forms a π-bond with platinum, but there is also a sigma bond formed between the platinum and the ethylene. Thus, this compound has both sigma and pi bonding.

#### Compound 3: [Co(CO)5(NH3)]2+
- **Structure**: Cobalt is coordinated with five carbonyl (CO) ligands and one ammonia (NH3) ligand.
- **Bonding**: The CO ligands form strong sigma bonds with cobalt and also participate in π-backbonding (where the lone pair on CO donates to the metal). Therefore, this compound has both sigma and pi bonding.

#### Compound 4: Fe(CH3)3
- **Structure**: Iron is bonded to three methyl groups.
- **Bonding**: The bonding here is primarily through sigma bonds as the iron forms single bonds with each methyl group. There are no π-bonds present in this compound.

### Step 3: Conclusion
From the analysis:
- **Fe(C5H5)2**: Only π-bonded
- **K[PtCl3(C2H4)]**: Sigma and π-bonded
- **[Co(CO)5(NH3)]2+**: Sigma and π-bonded
- **Fe(CH3)3**: Only sigma-bonded

Thus, the organometallic compounds that are both sigma and pi-bonded are **K[PtCl3(C2H4)]** and **[Co(CO)5(NH3)]2+**.

### Final Answer
The compounds that are both sigma and pi-bonded are **K[PtCl3(C2H4)]** and **[Co(CO)5(NH3)]2+**.

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