Weak-field ligands

Definition

Weak-field ligands are ligands that produce a small splitting of the d-orbitals in a coordination complex. They typically lead to high-spin configurations in transition metal complexes.

5 Must Know Facts For Your Next Test

1. Weak-field ligands cause small energy differences between the split d-orbitals, leading to high-spin states.
2. Common examples include halides (Cl-, Br-, I-), water (H2O), and ammonia (NH3).
3. They usually form complexes with low crystal field stabilization energy (CFSE).
4. Weak-field ligands are often found at the lower end of the spectrochemical series.
5. Spectroscopic properties such as absorption spectra can differ significantly when weak-field ligands are present due to smaller d-d transitions.

Review Questions

• What is the effect of weak-field ligands on the spin state of a transition metal complex?
• Name three common weak-field ligands.
• How do weak-field ligands influence the crystal field stabilization energy (CFSE) of a coordination complex?

Related terms

Crystal Field Theory:

A model that describes the breaking of degenerate d orbitals in transition metal complexes due to ligand interactions.

High-Spin Complex:

A coordination compound where electrons occupy higher energy orbitals before pairing up, resulting from small crystal field splitting.

Spectrochemical Series:

A list of ligands ordered by their ability to split the d-orbital energies in a transition metal complex.