What is the Difference Between High Spin and Low Spin Complexes?
🆚 Go to Comparative Table 🆚The difference between high spin and low spin complexes lies in the arrangement of electrons and the strength of the ligand field. Here are the key differences:
- High Spin Complexes:
- Contain unpaired electrons.
- Occur when weak-field ligands decrease the energy difference (Δ) between the orbitals, resulting in high spin.
- Generally found in octahedral and tetrahedral coordination complexes.
- Paramagnetic, meaning they are attracted to magnetic fields.
- Low Spin Complexes:
- Tend to contain paired electrons.
- Occur when strong-field ligands increase the energy difference (Δ) between the orbitals, resulting in low spin.
- Generally found in square planar coordination complexes.
- Diamagnetic, meaning they are not attracted to magnetic fields.
The oxidation state of the metal also determines the ligand field strength. The higher the oxidation state, the stronger the ligand field, and the more likely the complex will be low spin. Ligand strength can be determined using the spectrochemical series, with strong-field ligands like CN⁻ and NO₂⁻ resulting in low spin, and weak-field ligands like I⁻ and Cl⁻ resulting in high spin.
Comparative Table: High Spin vs Low Spin Complexes
High spin and low spin are two possible classifications of spin states that occur in coordination compounds. These classifications come from either the ligand field theory or the crystal field theory. Here is a table comparing the differences between high spin and low spin complexes:
| Feature | High Spin Complex | Low Spin Complex |
|---|---|---|
| Electron Configuration | Unpaired electrons | Paired electrons |
| Magnetic Properties | Paramagnetic | Diamagnetic |
| Molecular Geometry | Generally, octahedral and tetrahedral complexes are high spin | Generally, square planar complexes are low spin |
| Ionic Radius | Larger for a given d-electron count | Smaller for a given d-electron count |
To determine whether a complex is high spin or low spin, you can follow these steps:
- Determine the shape of the complex (i.e., octahedral, tetrahedral, square planar).
- Determine the oxidation state of the metal center.
- Determine the d electron configuration of the metal center.
- Draw the crystal field diagram of the complex with regards to its geometry.
- Determine whether the splitting energy is greater than the pairing energy.
- Determine the strength of the ligand (i.e., spectrochemical series).
Remember that high spin complexes tend to have unpaired electrons, while low spin complexes tend to have paired electrons.
- Spin vs Orbital Angular Momentum
- Homoleptic vs Heteroleptic Complexes
- Magnetic Quantum Number vs Spin Quantum Number
- Inert vs Labile Complexes
- Spinel vs Inverse Spinel Structure
- Coordination Compound vs Complex Ion
- Activated Complex vs Transition State
- Carbonyl vs Nitrosyl Complexes
- Spinning vs Cycling
- Spin-orbit Coupling vs Russell-Saunders Effect
- Complicated vs Complex
- Square Planar vs Tetrahedral Complexes
- Dextrorotatory vs Levorotatory
- Complex Salt vs Double Salt
- Elementary vs Complex Reaction
- Paramagnetic vs Superparamagnetic
- Circular Motion vs Spinning Motion
- Positive vs Negative Supercoiling of DNA
- Fine vs Hyperfine Structure