Cyclam

Cyclam
Names
	IUPAC name 1,4,8,11-Tetraazacyclotetradecane
Identifiers
CAS Number	295-37-4 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:37401 ;
ChEMBL	ChEMBL125150 ;
ChemSpider	58489 ;
ECHA InfoCard	100.005.491
PubChem CID	64964;
CompTox Dashboard (EPA)	DTXSID30183698 ;
	InChI InChI=1S/C10H24N4/c1-3-11-7-9-13-5-2-6-14-10-8-12-4-1/h11-14H,1-10H2 Key: MDAXKAUIABOHTD-UHFFFAOYSA-N ;
	SMILES N1CCNCCCNCCNCCC1;
Properties
Chemical formula	C10H24N4
Molar mass	200.330 g·mol−1
Melting point	185 to 188 °C (365 to 370 °F; 458 to 461 K)
Solubility in water	5 g/100 mL (20 °C)
	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

Cyclam (1,4,8,11-tetraazacyclotetradecane) is an organic compound with the formula (NHCH₂CH₂NHCH₂CH₂CH₂)₂. It is a white solid that is soluble in water. The compound is notable as a macrocyclic ligand, which binds strongly to many transition metal cations.^[1] The compound was first prepared by the reaction of 1,3-dibromopropane and ethylenediamine.^[2]

The compound features four secondary amines. Its complexes therefore can exist as several diastereomers, depending on the relative orientation of the N–H centres. Its complexes feature alternating five- and six-membered chelate rings. The closely related ligand cyclen ((CH₂CH₂NH)₄) forms only five-membered C₂N₂M chelate rings and tends not to form square-planar complexes.

Isomers of a square planar metal cyclam complex.

N-Alkyl derivatives

Metal-cyclam complexes are prone to oxidative degradation, which is initiated by deprotonation of the secondary amine. This flaw led to the development of cyclam derivatives wherein the NH centres are replaced by tertiary amines. For example the tetramethyl derivatives are readily prepared by methylation using formaldehyde and formic acid.^[1] These oxidatively robust derivatives of cyclam have enabled a number of metal–O₂ complexes.^[3]

References

^ ^a ^b Barefield, E. Kent (2010). "Coordination chemistry of N-tetraalkylated cyclam ligands—A status report". Coord. Chem. Rev. 254: 1607–1627. doi:10.1016/j.ccr.2010.03.007.
^ Van Alphen, J. (1937). "On Aliphatic Polyamines IV". Rec. Trav. Chim. Pays-Bas. 56: 343–350.
^ Cho, J.; Sarangi, R.; Nam, W. (2012). "Mononuclear Metal–O₂ Complexes Bearing Macrocyclic N-Tetramethylated Cyclam Ligands". Acc. Chem. Res. 45: 1321–1330. doi:10.1021/ar3000019.

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[Barefield-1] Barefield, E. Kent (2010). "Coordination chemistry of N-tetraalkylated cyclam ligands—A status report". Coord. Chem. Rev. 254: 1607–1627. doi:10.1016/j.ccr.2010.03.007.

[2] Van Alphen, J. (1937). "On Aliphatic Polyamines IV". Rec. Trav. Chim. Pays-Bas. 56: 343–350.

[3] Cho, J.; Sarangi, R.; Nam, W. (2012). "Mononuclear Metal–O₂ Complexes Bearing Macrocyclic N-Tetramethylated Cyclam Ligands". Acc. Chem. Res. 45: 1321–1330. doi:10.1021/ar3000019.

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