Among the complex ions given below which is/are outer-orbitals complex-I- `[Co(CN)_6]^(4-)`II-`[ Fe(H_2O)_6]^(2+)` III-`[Fe F_6]^(3-)` IV-`[CoF_6]^(3-)`

Options

A. II,III,IV
B. II,III only
C. I,IV only
D. II only

Answer

To determine which of the given complex ions are outer-orbital complexes, we need to analyze each complex based on the oxidation state of the central metal ion, its electronic configuration, and the nature of the ligands involved.

### Step-by-Step Solution:

**Step 1: Analyze Complex I - `[Co(CN)_6]^(4-)`**

1. **Determine the oxidation state of Co:**
\[ x + 6(-1) = -4 \implies x - 6 = -4 \implies x = +2 \]
So, the oxidation state of cobalt (Co) is +2.

2. **Determine the electronic configuration of Co:**
- Atomic number of Co = 27
- Electronic configuration: \( [Ar] 4s^2 3d^7 \)
- For Co\(^{2+}\): \( 4s^0 3d^7 \)

3. **Ligand field strength:**
- CN⁻ is a strong field ligand, which causes pairing of electrons in the d-orbitals.

4. **Final configuration:**
- The paired configuration will be \( 3d^6 \) and the two electrons from \( 4s \) will be promoted to \( 4p \).
- This results in an inner orbital complex.

**Conclusion for I:** Inner orbital complex.

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**Step 2: Analyze Complex II - `[Fe(H_2O)_6]^(2+)`**

1. **Determine the oxidation state of Fe:**
\[ x + 6(0) = +2 \implies x = +2 \]
So, the oxidation state of iron (Fe) is +2.

2. **Determine the electronic configuration of Fe:**
- Atomic number of Fe = 26
- Electronic configuration: \( [Ar] 4s^2 3d^6 \)
- For Fe\(^{2+}\): \( 4s^0 3d^6 \)

3. **Ligand field strength:**
- H₂O is a weak field ligand, which does not cause pairing of electrons.

4. **Final configuration:**
- The configuration remains \( 3d^6 \) and utilizes \( 4s \) and \( 4p \) orbitals.

**Conclusion for II:** Outer orbital complex.

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**Step 3: Analyze Complex III - `[FeF_6]^(3-)`**

1. **Determine the oxidation state of Fe:**
\[ x + 6(-1) = -3 \implies x - 6 = -3 \implies x = +3 \]
So, the oxidation state of iron (Fe) is +3.

2. **Determine the electronic configuration of Fe:**
- For Fe\(^{3+}\): \( 4s^0 3d^5 \)

3. **Ligand field strength:**
- F⁻ is a weak field ligand, which does not cause pairing of electrons.

4. **Final configuration:**
- The configuration remains \( 3d^5 \) and utilizes \( 4s \) and \( 4p \) orbitals.

**Conclusion for III:** Outer orbital complex.

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**Step 4: Analyze Complex IV - `[CoF_6]^(3-)`**

1. **Determine the oxidation state of Co:**
\[ x + 6(-1) = -3 \implies x - 6 = -3 \implies x = +3 \]
So, the oxidation state of cobalt (Co) is +3.

2. **Determine the electronic configuration of Co:**
- For Co\(^{3+}\): \( 4s^0 3d^6 \)

3. **Ligand field strength:**
- F⁻ is a weak field ligand, which does not cause pairing of electrons.

4. **Final configuration:**
- The configuration remains \( 3d^6 \) and utilizes \( 4s \) and \( 4p \) orbitals.

**Conclusion for IV:** Outer orbital complex.

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### Final Answer:
The outer-orbital complexes among the given options are:
- II: `[Fe(H_2O)_6]^(2+)`
- III: `[FeF_6]^(3-)`
- IV: `[CoF_6]^(3-)`