What is an ambidentate ligand?

An ambidentate ligand is a type of ligand in coordination chemistry that has the ability to coordinate to a metal center through two different atoms. The term "ambidentate" comes from the Latin words "ambi," meaning both, and "dentate," meaning toothed or having teeth. Ambidentate ligands can bind to a metal ion through either of two different donor atoms, typically located at opposite ends of the molecule.

A common example of an ambidentate ligand is the nitrite ion (NO2^-). The nitrite ion can coordinate to a metal center through either the nitrogen atom (N) or one of the oxygen atoms (O). The coordination mode depends on the specific conditions and the metal ion involved. Another example is the thiocyanate ion (SCN^-), which can coordinate through either the sulfur (S) or nitrogen (N) atom.

The ability of ambidentate ligands to bind through different donor atoms provides flexibility in coordination chemistry and can lead to the formation of different coordination isomers depending on the specific binding mode.