Salen ligand

Salen ligand
Names
Other names
2,2′-Ethylenebis(nitrilomethylidene)diphenol, N,N′-Ethylenebis(salicylimine)
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.002.161 Edit this at Wikidata
EC Number
  • 202-376-3
UNII
  • InChI=1S/C16H16N2O2/c19-15-7-3-1-5-13(15)11-17-9-10-18-12-14-6-2-4-8-16(14)20/h1-8,11-12,19-20H,9-10H2/b17-11+,18-12+
    Key: VEUMANXWQDHAJV-JYFOCSDGSA-N
  • C1=CC=C(C(=C1)/C=N/CC/N=C/C2=CC=CC=C2O)O
Properties
C16H16N2O2
Molar mass 268.32
Melting point 126 °C (259 °F; 399 K)
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H315, H319, H335
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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This article is about Salen. For Complexes of salen and related ligands, see Metal salen complexes.

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.[1] For this reason salen-type compounds are used as metal deactivators. Metal salen complexes also find use as catalysts.[2]

Synthesis and complexation

Main article: Metal salen complexes

H2salen may be synthesized by the condensation of ethylenediamine and salicylaldehyde.[3]

Salcomine, a complex of salen with cobalt
Jacobsen's salen-Mn catalyst

Complexes of salen with metal cations can often be made in situ, i.e., without isolating the H2salen.[4][5]

H2salen + M2+ → M(salen) + 2 H+

See also

References

  1. ^ Cozzi, Pier Giorgio (2004). "Metal–Salen Schiff base complexes in catalysis: practical aspects". Chem. Soc. Rev. 33 (7): 410–421. doi:10.1039/B307853C. PMID 15354222.
  2. ^ Shaw, Subrata; White, James D. (11 June 2019). "Asymmetric Catalysis Using Chiral Salen–Metal Complexes: Recent Advances". Chemical Reviews. 119 (16): 9381–9426. doi:10.1021/acs.chemrev.9b00074. PMID 31184109. S2CID 184486101.
  3. ^ Tsumaki, T. (1938). "Nebenvalenzringverbindungen. IV. Über einige innerkomplexe Kobaltsalze der Oxyaldimine". Bulletin of the Chemical Society of Japan (in German). 13 (2): 252–260. doi:10.1246/bcsj.13.252.
  4. ^ Diehl, Harvey; Hach, Clifford C. (1950). "Bis( N,N '-Disalicylalethylenediamine)-μ - Aquodicobalt(II)". Inorganic Syntheses. Vol. 3. pp. 196–201. doi:10.1002/9780470132340.ch53. ISBN 978-0-470-13234-0. {{cite book}}: |journal= ignored (help)
  5. ^ Pier Giorgio Cozzi (2004). "Metal-Salen Schiff base complexes in catalysis: Practical aspects". Chem. Soc. Rev. 33 (7): 410–421. doi:10.1039/B307853C. PMID 15354222.