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 of the central metal ion in each given complex. Square planar geometry is typically associated with Dsp² hybridization. Let's evaluate the options step by step.

### Step-by-Step Solution:

1. **Understanding Square Planar Geometry**:
- Square planar geometry arises from Dsp² hybridization. This means that one d-orbital, one s-orbital, and two p-orbitals are involved in bonding.

2. **Analyzing the Given Complexes**:
- We have the following complexes to analyze:
- Ni(CO)₄
- Ni(CN)₄²⁻
- Mn(CN)₆²⁻
- MnCl₄²⁻

3. **Evaluating Ni(CO)₄**:
- Nickel in Ni(CO)₄ has an oxidation state of 0 (since CO is a neutral ligand).
- Nickel has an atomic number of 28, with the electron configuration of [Ar] 3d⁸ 4s².
- In this case, the hybridization is sp³ (not square planar).

4. **Evaluating Ni(CN)₄²⁻**:
- For Ni(CN)₄²⁻, let x be the oxidation state of Ni. The equation is:
\[ x + 4(-1) = -2 \implies x = +2 \]
- Thus, nickel is in the +2 oxidation state, and its configuration is 3d⁸.
- The strong field ligand CN⁻ causes pairing of electrons, leading to Dsp² hybridization, which results in square planar geometry.

5. **Evaluating Mn(CN)₆²⁻**:
- For Mn(CN)₆²⁻, the oxidation state of Mn is:
\[ x + 6(-1) = -2 \implies x = +4 \]
- The electron configuration for Mn in +4 oxidation state is 3d⁴.
- With six ligands, this complex adopts octahedral geometry, not square planar.

6. **Evaluating MnCl₄²⁻**:
- For MnCl₄²⁻, the oxidation state of Mn is:
\[ x + 4(-1) = -2 \implies x = +2 \]
- The electron configuration for Mn in +2 oxidation state is 3d⁵.
- Chlorine is a weak field ligand, and with four ligands, this complex could be either tetrahedral or square planar, but it is more likely to be tetrahedral due to the weak field nature of Cl⁻.

### Conclusion:
- Among the given complexes, **Ni(CN)₄²⁻** is the only one that exhibits square planar geometry due to Dsp² hybridization.