Crystal field splitting

Definition

Crystal field splitting refers to the energy difference between d-orbitals in a transition metal complex when ligands approach and interact with the central metal ion. This interaction causes the degeneracy of the d-orbitals to break, leading to different energy levels.

5 Must Know Facts For Your Next Test

1. The magnitude of crystal field splitting depends on the nature of the ligands and their arrangement around the central metal ion.
2. In an octahedral field, $d_{z^2}$ and $d_{x^2-y^2}$ orbitals experience higher energy (eg set) compared to $d_{xy}$, $d_{xz}$, and $d_{yz}$ orbitals (t2g set).
3. The crystal field splitting energy ($\Delta$) can be measured using spectroscopic techniques.
4. Strong-field ligands cause a larger splitting ($\Delta$), often leading to low-spin complexes, while weak-field ligands cause smaller splitting, resulting in high-spin complexes.
5. Tetrahedral complexes typically have smaller crystal field splitting compared to octahedral complexes due to less direct interaction with ligands.

Review Questions

• What factors influence the magnitude of crystal field splitting?
• In an octahedral coordination complex, which d-orbitals are at higher energy after crystal field splitting?
• How does ligand strength affect whether a complex is high-spin or low-spin?

Related terms

Ligand Field Theory:

An extension of Crystal Field Theory that considers both electrostatic and covalent interactions between ligands and metal ions.

High-Spin Complex:

A coordination compound where weak-field ligands cause small crystal field splitting, resulting in maximum unpaired electrons.

Low-Spin Complex:

A coordination compound where strong-field ligands cause large crystal field splitting, minimizing unpaired electrons.