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Cyclen

Chemical compound From Wikipedia, the free encyclopedia

Cyclen

Cyclen (1,4,7,10-tetraazacyclododecane) is a aza-crown ether with the formula (CH2CH2NH)4. It is a white solid. Being structurally simple, symmetrical, and polyfunctional, cyclen has been widely investigated.[1]

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Cyclen
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Names
Preferred IUPAC name
1,4,7,10-Tetrazacyclododecane
Other names
Tetraaza-12-crown-4
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.102.391
UNII
  • InChI=1S/C8H20N4/c1-2-10-5-6-12-8-7-11-4-3-9-1/h9-12H,1-8H2 Y
    Key: QBPPRVHXOZRESW-UHFFFAOYSA-N Y
  • InChI=1/C8H20N4/c1-2-10-5-6-12-8-7-11-4-3-9-1/h9-12H,1-8H2
    Key: QBPPRVHXOZRESW-UHFFFAOYAQ
  • N1CCNCCNCCNCC1
  • C1CNCCNCCNCCN1
Properties
C8H20N4
Molar mass 172.276 g·mol−1
Appearance White solid
Melting point 110–113 °C (230–235 °F; 383–386 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis

Some syntheses exploit the Thorpe-Ingold effect to facilitate ring-formation. Illustrative is the reaction of the deprotonated tosylamides with ditosylates:[2]

TsN(CH2CH2NTsNa)2 + TsN(CH2CH2OTs)2 → (TsNCH2CH2)4

The resulting macrocycle can be deprotected with strong acid. Base gives the tetramine.

High dilution conditions result in a low reaction rate penalty and this disadvantage is removed in an alternative procedure starting from triethylenetetraamine and dithiooxamide to a bisamidine – also a bis(imidazoline) – followed by reduction and ring expansion with DIBAL.[3]

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Coordination complexes

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Structure of [Ni(cyclen)(OH2)2]2+. Color code: O = red, N = blue, Ni = dark blue, white = H, gray = C.[4]

Coordination complexes of cyclen have been studied extensively.[5][6] With a 12-membered ring, it tends to bind to four contiguous sites on octaheral metal centers. In contrast the larger cyclam ligand tens to form attach to four coplanar sites. It also forms complexes of the type [Ln(cyclen)2]3+ where Ln = lanthanide.[7]

References

Further reading

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