π-bonding is not present in

Options

A. Grignard reagent/Tetramethyl lead
B. Dibenzene chromium
C. Zeise’s salt
D. Ferrocene

Explanation

To determine where π-bonding is not present, we need to analyze the given options based on the nature of bonding in coordination compounds and organic molecules. Here is a step-by-step solution:

### Step 1: Understand π-bonding
- π-bonding occurs when two lobes of an orbital on one atom overlap with two lobes of an orbital on another atom, forming a bond. This typically happens in double and triple bonds, as well as in certain coordination compounds.

### Step 2: Identify the options
- The question asks for a compound or coordination complex where π-bonding is absent. We need to evaluate each option to see if it contains π-bonds.

### Step 3: Analyze the given examples
1. **Dibenzene (C6H4)**: This compound has a cyclic structure with alternating double bonds, which means it has π-bonding.
2. **Tetramethyl lead (Pb(CH3)4)**: This compound consists of lead bonded to four methyl groups. There are no double bonds present, indicating that there is no π-bonding.
3. **RNGX (where R is an alkyl group and X is a halogen)**: This is a general representation of alkyl halides, which typically do not have π-bonds unless there are double bonds in the alkyl group.
4. **Cyclopentadiene**: This compound has a cyclic structure with two double bonds, indicating the presence of π-bonding.

### Step 4: Conclusion
- Based on the analysis, **tetramethyl lead (Pb(CH3)4)** is the compound where π-bonding is not present.

### Final Answer
- The correct answer is **tetramethyl lead (Pb(CH3)4)**.

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