The coordination number of Fe in `[Fe(eta^(5)-C_(5)H_(5))_(2)]` is 2x . Then x will be ______

Answer

To determine the value of \( x \) in the coordination number of iron in the complex \([Fe(\eta^{5}-C_{5}H_{5})_{2}]\), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Ligand**: The ligand in the complex is \(\eta^{5}-C_{5}H_{5}\), which is known as cyclopentadienyl (Cp). The notation \(\eta^{5}\) indicates that the ligand is coordinating to the metal through all five carbon atoms of the ring.

2. **Determine the Coordination Number of the Ligand**: Since the cyclopentadienyl ligand coordinates through five atoms, its contribution to the coordination number of the metal (iron in this case) is 5.

3. **Count the Number of Ligands**: The complex has two cyclopentadienyl ligands (\([Fe(\eta^{5}-C_{5}H_{5})_{2}]\)). Therefore, the total coordination number contributed by both ligands is:
\[ \text{Total Coordination Number} = 2 \times 5 = 10 \]

4. **Relate Coordination Number to \( x \)**: According to the problem, the coordination number of iron is given as \( 2x \). We have calculated the coordination number to be 10. Thus, we can set up the equation:
\[ 2x = 10 \]

5. **Solve for \( x \)**: To find \( x \), divide both sides of the equation by 2:
\[ x = \frac{10}{2} = 5 \]

### Final Answer:
The value of \( x \) is \( 5 \).

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