Classify the following complex ions as high spin or low spin

Classify the following complex ions as high spin or low spin:

High spin
Low Spin
[CoFol3] four unpaired electrons
[Fe(CN)6] no unpaired electrons
[Fe(CN)els] five unpaired electrons
[Mn(H20)61] one unpaired electron
three unpaired electrons

The correct answer and explanation is:

Classification of Complex Ions into High Spin or Low Spin

Classifications:

1. [CoF₆]³⁻ → High Spin (Four unpaired electrons)
2. [Fe(CN)₆]³⁻ → Low Spin (No unpaired electrons)
3. [Fe(CN)₆]⁴⁻ → High Spin (Five unpaired electrons)
4. [Mn(H₂O)₆]²⁺ → Low Spin (One unpaired electron)
5. Complex with three unpaired electrons → Likely High Spin (Depending on ligand and oxidation state)

Explanation:

The classification of coordination complexes into high spin and low spin depends on the nature of the metal ion, its oxidation state, and the type of ligand surrounding it. Ligands are categorized based on the spectrochemical series, where strong field ligands (such as CN⁻) induce a larger crystal field splitting energy (Δ) and tend to form low-spin complexes. In contrast, weak field ligands (such as F⁻ and H₂O) generate a smaller Δ and favor high-spin configurations.

• [CoF₆]³⁻ (Four unpaired electrons, High Spin):
  Cobalt in the +3 oxidation state (d⁶) with fluoride ligands results in a weak crystal field. This leads to a small splitting energy, favoring the high-spin arrangement with four unpaired electrons in an octahedral geometry.
• [Fe(CN)₆]³⁻ (No unpaired electrons, Low Spin):
  Iron in +3 oxidation (d⁵) with cyanide, a strong field ligand, causes a large crystal field splitting, leading to electron pairing in the lower energy t₂g orbitals.
• [Fe(CN)₆]⁴⁻ (Five unpaired electrons, High Spin):
  In the +2 oxidation state (d⁶), Fe²⁺ can either be high spin or low spin. However, if it retains five unpaired electrons, it suggests a high-spin configuration.
• [Mn(H₂O)₆]²⁺ (One unpaired electron, Low Spin):
  Manganese in the +2 oxidation state (d⁵) with water (a weak field ligand) typically forms a high-spin complex. However, if only one unpaired electron is present, it suggests a low-spin configuration, possibly due to specific environmental factors.

This classification helps predict the magnetic properties and reactivity of these coordination complexes.