The complex compound bearing square planar geometry is

Options

A. `Ni(CO)_(4)`
B. `[Ni(CN)_(4)]^(2-)`
C. `[Mn(CN)_(6)]^(3-)`
D. `[MnCI_(4)]^(2-)`

Answer

To determine which complex compound exhibits square planar geometry, we need to analyze the hybridization and oxidation states of the metal ions in the given complexes. The square planar geometry is typically associated with dsp² hybridization.

### Step-by-Step Solution:

1. **Identify the Metal Ions and Their Oxidation States:**
- For each complex, we need to calculate the oxidation state of the metal ion.
- For example, in the case of nickel (Ni) with a neutral ligand, the oxidation state is 0. If we have a ligand like cyanide (CN⁻), we can calculate the oxidation state by setting up the equation based on the charges.

2. **Determine the Electron Configuration:**
- Once we have the oxidation state, we can write the electron configuration of the metal ion.
- For nickel (Ni), which has an atomic number of 28, the ground state configuration is [Ar] 4s² 3d⁸. For nickel in +2 oxidation state, it will lose the two 4s electrons, resulting in 3d⁸.
- For manganese (Mn), with an atomic number of 25, the configuration is [Ar] 4s² 3d⁵. In +3 oxidation state, it will lose one 4s and two 3d electrons, resulting in 3d⁴.

3. **Analyze the Ligands:**
- Identify whether the ligands are strong field or weak field. Strong field ligands (like CO) can cause pairing of electrons, while weak field ligands (like Cl⁻) do not.
- For nickel in +2 oxidation state with strong field ligands, the 3d electrons will pair up, leading to dsp² hybridization.

4. **Determine Hybridization:**
- For square planar geometry, we need dsp² hybridization. In the case of nickel +2 with strong field ligands, it undergoes dsp² hybridization.
- For manganese +3, the hybridization is d²sp³, which leads to octahedral geometry, not square planar.

5. **Conclusion:**
- Based on the analysis, the complex with nickel in +2 oxidation state and strong field ligands exhibits square planar geometry due to dsp² hybridization. Thus, the answer is option B.

### Final Answer:
The complex compound bearing square planar geometry is **option B**.

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