Which of the following electronic configurations can leads to the formation of high spin and low spin octahedral complexes ?

Options

A. `d^(1)`
B. `d^(2)`
C. `d^(3)`
D. `d^(4)`

Explanation

To determine which electronic configurations can lead to the formation of high spin and low spin octahedral complexes, we need to analyze the distribution of d-electrons in the d-orbitals of transition metal ions in an octahedral field.

### Step-by-Step Solution:

1. **Understanding Octahedral Complexes**:
In an octahedral field, the five d-orbitals split into two energy levels: the lower energy set (t2g) which consists of three orbitals, and the higher energy set (eg) which consists of two orbitals.

2. **Filling of d-Orbitals**:
Electrons will fill the lower energy t2g orbitals first before occupying the higher energy eg orbitals. This is in accordance with Hund's rule, which states that electrons will fill degenerate orbitals singly before pairing up.

3. **Identifying High Spin and Low Spin Configurations**:
- **High Spin Complexes**: These occur when the energy difference between the t2g and eg orbitals (Δ) is small, allowing electrons to occupy the higher energy eg orbitals rather than pairing in the t2g orbitals. This typically occurs with weak field ligands.
- **Low Spin Complexes**: These occur when Δ is large, causing electrons to pair up in the t2g orbitals before occupying the eg orbitals. This typically occurs with strong field ligands.

4. **Analyzing Electron Configurations**:
- For **d1, d2, and d3 configurations**: All electrons will occupy the t2g orbitals. These configurations will always lead to high spin complexes since there are no higher energy electrons to occupy the eg orbitals.
- For **d4 configuration**: There are two possibilities:
- High spin: 3 electrons in t2g and 1 in eg (one unpaired electron in eg).
- Low spin: 4 electrons in t2g (all paired).
- For **d5 configuration**: This will always be high spin since all five electrons will occupy the t2g and eg orbitals singly.
- For **d6 configuration**: Similar to d4, it can be either high spin (4 in t2g and 2 in eg) or low spin (6 in t2g, all paired).
- For **d7 configuration**: It can also be both high spin and low spin depending on the ligand field strength.
- For **d8 and d9 configurations**: These will generally lead to low spin configurations as the electrons will pair up in the lower energy orbitals.

5. **Conclusion**:
- High spin configurations can occur for d1, d2, d3, d4 (high spin), d5, d6 (high spin), d7 (high spin), and d8 (typically low spin).
- Low spin configurations can occur for d4 (low spin), d6 (low spin), d8, and d9.