Which amongst the following metal carbonyls are inner orbital complex with diamagnetic property
(i) `Ni(CO)_(4)`
(ii) `Fe(CO)_(5)`
(iii) `V(CO)_(6)`
(iv) `Cr(CO)_(6)`
Select the correct code :-

Options

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

Answer

To determine which metal carbonyls are inner orbital complexes with diamagnetic properties, we will analyze each of the given complexes step by step.

### Step 1: Identify the oxidation states and electron configurations of the metals

1. **Ni(CO)₄**: Nickel (Ni) has an oxidation state of 0. Its electron configuration is [Ar] 3d⁸ 4s².
2. **Fe(CO)₅**: Iron (Fe) has an oxidation state of 0. Its electron configuration is [Ar] 3d⁶ 4s².
3. **V(CO)₆**: Vanadium (V) has an oxidation state of 0. Its electron configuration is [Ar] 3d³ 4s².
4. **Cr(CO)₆**: Chromium (Cr) has an oxidation state of 0. Its electron configuration is [Ar] 3d⁵ 4s¹.

### Step 2: Determine the hybridization of each complex

1. **Ni(CO)₄**: This complex undergoes **sp³ hybridization**.
2. **Fe(CO)₅**: This complex undergoes **dsp³ hybridization**.
3. **V(CO)₆**: This complex undergoes **d²sp³ hybridization**.
4. **Cr(CO)₆**: This complex undergoes **d²sp³ hybridization**.

### Step 3: Analyze the pairing of electrons in each complex

1. **Ni(CO)₄**: In this complex, there are unpaired electrons. Therefore, it is **paramagnetic**.
2. **Fe(CO)₅**: All electrons are paired in this complex, making it **diamagnetic**.
3. **V(CO)₆**: This complex has unpaired electrons, making it **paramagnetic**.
4. **Cr(CO)₆**: All electrons are paired in this complex, making it **diamagnetic**.

### Step 4: Classify the complexes as inner or outer orbital complexes

- **Inner orbital complexes**: These involve the use of d-orbitals that are involved in bonding (d-orbitals from the inner shell).
- **Outer orbital complexes**: These involve the use of d-orbitals from the outer shell.

1. **Ni(CO)₄**: Outer orbital complex.
2. **Fe(CO)₅**: Inner orbital complex.
3. **V(CO)₆**: Inner orbital complex.
4. **Cr(CO)₆**: Inner orbital complex.

### Conclusion

The metal carbonyls that are inner orbital complexes with diamagnetic properties are **Fe(CO)₅** and **Cr(CO)₆**.

### Final Answer

The correct code is: **(ii) Fe(CO)₅ and (iv) Cr(CO)₆**.

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