Which of the following is not an organo - metallic compound ?

Options

A. `(C_2H_5)_4Pb`
B. `C_2H_5-O-Na`
C. `C_4H_9Li`
D. `[(C_5H_5)_2Fe]`

Answer

To determine which of the given compounds is not an organometallic compound, we need to understand the definition of organometallic compounds. An organometallic compound is characterized by the presence of a direct bond between a metal and a carbon atom.

Let's analyze each option step by step:

1. **Option A: C2H5 whole 4 Pb (C4H10Pb)**
- This compound contains lead (Pb) bonded directly to carbon (C) from the ethyl groups (C2H5).
- Since there is a direct bond between a metal (Pb) and carbon, this is an organometallic compound.

2. **Option B: C2H5ONa (Sodium Ethoxide)**
- In this compound, sodium (Na) is present, but it is bonded to oxygen (O) which is then bonded to carbon (C) from the ethyl group.
- There is no direct bond between sodium (Na) and carbon (C). Therefore, this is not an organometallic compound.

3. **Option C: C4H9Li (Butyllithium)**
- Here, lithium (Li) is directly bonded to carbon (C) from the butyl group (C4H9).
- Since there is a direct bond between a metal (Li) and carbon, this is an organometallic compound.

4. **Option D: C2H5 whole twice Fe (C4H10Fe)**
- In this case, iron (Fe) is directly bonded to carbon (C) from the ethyl groups.
- Thus, this is also an organometallic compound.

Based on the analysis above, the compound that is not an organometallic compound is **Option B: C2H5ONa**.

### Final Answer:
**Option B: C2H5ONa**