Salen ligand

Salen ligand
Names
	Other names 2,2′-Ethylenebis(nitrilomethylidene)diphenol, N,N′-Ethylenebis(salicylimine)
Identifiers
CAS Number	129409-01-4 ; 94-93-9 (non-specific) ;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL594100 ;
ChemSpider	10484366 ;
ECHA InfoCard	100.002.161
EC Number	202-376-3;
PubChem CID	26518;
UNII	M122L9EGR6 ;
CompTox Dashboard (EPA)	DTXSID5059113 ;
	InChI 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;
	SMILES C1=CC=C(C(=C1)/C=N/CC/N=C/C2=CC=CC=C2O)O;
Properties
Chemical formula	C16H16N2O2
Molar mass	268.32
Melting point	126 °C (259 °F; 399 K)
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	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). verify (what is ?) Infobox references

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

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

Salcomine, a complex of salen with cobalt

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⁺

References

^ 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.
^ 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.
^ 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.
^ 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)
^ 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.

[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)

[cozzi-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.

[1]

[2]

[3]

[4]

[5]

Synthesis and complexation

See also

References