Salen ligand

Salen refers to a tetradentate C2-symmetric ligand synthesized from salicylaldehyde (sal) and ethylenediamine (en). It may also refer to a class of compounds, which are structurally related to the classical salen ligand, primarily bis-Schiff bases. Salen ligands are notable for coordinating a wide range of different metals, which they can often stabilise in various oxidation states. For this reason salen-type compounds are used as metal deactivators. Metal salen complexes also find use as catalysts.

Synthesis and complexation
H2salen may be synthesized by the condensation of ethylenediamine and salicylaldehyde.
 * Preparation of salen.svg



Complexes of salen with metal cations can often be made in situ, i.e., without isolating the H2salen.
 * H2salen + M2+ → M(salen) + 2 H+