AllChemicals — The Online Chemical Glossary | https://allchemicals.info/chemical/788-weak-field-ligand
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Quick Reference
Also Known As
Low field ligand, weak field ligand (spectrochemical series), σ-donor ligand
What is Weak Field Ligand?
A ligand that causes small d-orbital splitting (small crystal field splitting energy Δ) in transition metal complexes. Weak-field ligands produce high-spin complexes because electrons prefer to occupy higher orbitals rather than pair up. Examples include F⁻, Cl⁻, Br⁻, I⁻, and H₂O.
Properties & Characteristics
A weak field ligand is a ligand that causes only a small crystal field splitting (Δo) of the d-orbital energy levels in transition metal complexes. Examples include halide ions (F⁻, Cl⁻), water, and hydroxide. In the spectrochemical series, weak field ligands are at the lower end. They typically produce high-spin complexes where electrons occupy all d orbitals singly before pairing.
Uses & Applications
Weak field ligands are used to produce high-spin transition metal complexes used in bioinorganic chemistry and as magnetic materials. Iron(III) with weak field ligands produces high-spin complexes relevant to haemoglobin function. Understanding ligand field strength guides the design of metal complex catalysts.
Safety Information
Ligands such as cyanide and carbon monoxide are strong field but toxic. Weak field ligands include halides and water, which are less acutely toxic. The safety of a complex depends on both the metal and the ligand.
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
SynonymsLow field ligand, weak field ligand (spectrochemical series), σ-donor ligand
Frequently Asked Questions
A ligand that causes small d-orbital splitting (small crystal field splitting energy Δ) in transition metal complexes. Weak-field ligands produce high-spin complexes because electrons prefer to occupy higher orbitals rather than pair up. Examples include F⁻, Cl⁻, Br⁻, I⁻, and H₂O.
Weak field ligands are used to produce high-spin transition metal complexes used in bioinorganic chemistry and as magnetic materials. Iron(III) with weak field ligands produces high-spin complexes relevant to haemoglobin function. Understanding ligand field strength guides the design of metal comple…
Ligands such as cyanide and carbon monoxide are strong field but toxic. Weak field ligands include halides and water, which are less acutely toxic. The safety of a complex depends on both the metal and the ligand.
Editorial standards: Chemical data is sourced from peer-reviewed literature,
CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA,
and IAEA. For educational purposes only — always consult official SDS documentation and qualified
professionals before handling chemicals.
