Strong Field Ligand
Definition and meaning of Strong Field Ligand in chemistry.
A strong field ligand is a molecule or ion that causes a large splitting of the d-orbitals in a transition metal complex. This large energy gap often forces electrons to pair up in the lower energy orbitals rather than occupy the higher energy ones.
In more detail
According to crystal field theory, ligands approach a central metal ion and create an electrostatic field that splits the degenerate d-orbitals into different energy levels. Strong field ligands interact intensely with the metal, resulting in a large crystal field splitting energy. Complexes with strong field ligands typically exhibit low-spin electron configurations because the energy required to pair electrons is less than the energy needed to overcome the large orbital splitting.
Key facts
| Field | Inorganic Chemistry |
|---|---|
| Formula | CN- |
| Splitting Energy | Large (high crystal field splitting) |
| Spin State | Typically produces low-spin complexes |
Cyanide (CN-) is a classic strong field ligand that forms low-spin complexes with many transition metals, such as in the hexacyanoferrate(II) ion, [Fe(CN)6]4-.
Frequently asked questions
How do strong field ligands affect the color of a complex?
Because they cause a large splitting of the d-orbitals, strong field ligand complexes tend to absorb higher energy light like violet or blue, and thus often appear yellow, orange, or red.