The complex compound in which metal is not present in zero oxidation state?

Options

A. `Mn_(2)(CO)_(10)`
B. `[Ni(CO)_(4)]`
C. `[cr(C_(6)H_(6))_(2)]`
D. `K[PtCI_(3)(C_(2)H_(4))]`

Answer

To determine a complex compound in which the metal is not present in the zero oxidation state, we can analyze various examples of coordination compounds and their oxidation states.

### Step-by-Step Solution:

1. **Identify Common Complexes**: Start by considering common coordination compounds that contain transition metals. Examples include complexes with ligands such as CO (carbon monoxide), C6H6 (benzene), and C2H4 (ethylene).

2. **Analyze the Ligands**:
- **CO**: Carbon monoxide is a neutral ligand, meaning it does not contribute to the overall charge of the complex.
- **C6H6 (Benzene)**: Benzene is also a neutral ligand.
- **C2H4 (Ethylene)**: Ethylene is another neutral ligand.

3. **Consider the Metal Oxidation States**:
- For a complex with CO, if we take [Ni(CO)4] as an example:
- Let the oxidation state of Ni be X. Since CO is neutral, the overall charge is 0. Therefore, X = 0, indicating that Ni is in the zero oxidation state.
- For a complex with C6H6, such as [Cr(C6H6)2] or similar, the oxidation state of Cr would also be 0 if the overall charge is neutral.
- However, if we consider a complex such as [PtCl4] or [Pt(C2H4)Cl2]:
- Here, let’s analyze [Pt(C2H4)Cl2]. The ethylene (C2H4) is neutral, and each Cl contributes -1. If we let the oxidation state of Pt be X:
- X + 2(-1) = 0 (for neutral complex)
- X - 2 = 0 → X = +2.
- Thus, in this case, platinum (Pt) is in the +2 oxidation state, which is non-zero.

4. **Conclusion**: The complex compound [Pt(C2H4)Cl2] is an example where the metal (Pt) is not in the zero oxidation state; instead, it is in the +2 oxidation state.

### Final Answer:
The complex compound in which the metal is not present in the zero oxidation state is [Pt(C2H4)Cl2].