ligander

Ligander is a term occasionally encountered as a nonstandard or archaic spelling of ligand in the field of coordination chemistry. In contemporary English, ligand is the preferred term for a molecule or ion that donates an electron pair to a central atom or ion, typically a metal, to form a coordination complex.

While ligander appears in some texts or non-English usages, it is not widely recognized in major chemistry glossaries. When used in languages other than English, the corresponding term may be ligand or liganden, depending on the language.

Ligands can be classified by denticity into monodentate, bidentate, polydentate, and so on. They may be neutral (for example water, ammonia, carbon monoxide) or anionic (for example chloride, cyanide). Donor atoms include oxygen, nitrogen, sulfur, phosphorus, and carbon from CO ligands. The binding mode and denticity influence properties of the complex, including stability through the chelate effect.

Ligand chemistry is central to inorganic, organometallic, and bioinorganic chemistry and underpins catalysis, electron transfer, and enzyme active sites in metalloenzymes. Examples of coordination complexes include various transition-metal systems where ligands such as water, ammonia, halides, and cyanide coordinate to metals, as well as biologically important centers like heme and metal-containing enzymes.