Monodentát

Monodentát, in Czech, denotes a monodentate ligand in coordination chemistry, i.e., a ligand that binds to a central metal atom or ion through a single donor atom. Denticity describes how many donor sites a ligand can use to attach to the metal; a monodentate ligand has one such site and forms one bond to the metal.

Common examples of monodentate ligands include ammonia (NH3), water (H2O), chloride (Cl−), hydroxide (OH−), fluoride (F−), cyanide (CN−), and carbon monoxide (CO). Neutral donors (NH3, CO, H2O) as well as anionic donors (Cl−, CN−, OH−) can all act as monodentate ligands. Many common organometallic ligands, such as phosphines (PR3), are also monodentate.

Monodentate ligands are contrasted with bidentate ligands, which donate through two donor atoms (for example, ethylenediamine, en, binding through two nitrogens), and polydentate ligands, which have three or more donor sites (for example, EDTA, a hexadentate ligand). The use of monodentate ligands can influence the geometry and lability of a complex; they often allow easier substitution and the construction of a wide range of coordination environments, such as tetra-, penta-, or hexa-coordinated complexes, depending on the metal and other ligands present.

In practice, monodentate ligands are fundamental components in inorganic synthesis, catalysis, and organometallic chemistry, where they help tune electronic and steric properties of metal centers.