2.2.2-Cryptand


[2.2.2]-Cryptand is the organic compound with the formula {N[(CH2CH2OCH2CH2OCH2CH2)3N}. This bicyclic molecule is the most studied member of the cryptand family of chelating agents.[2] It is a white solid. Many analogous compounds are known. Their high affinity for alkali metal cations illustrates the advantages of "preorganization", a concept within the area of supramolecular chemistry.

[2.2.2]Cryptand
Names
Systematic IUPAC name
4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane
Other names
Cryptating agent 222[1]
Identifiers
3D model (JSmol)
Abbreviations Crypt-222
620282
ChemSpider
ECHA InfoCard 100.041.770
EC Number
  • 245-962-4
MeSH Cryptating+agent+222
RTECS number
  • MP4750000
UNII
Properties
C
18N
2H
36O
6
Molar mass 376.4882 g mol−1
Melting point 68 to 71 °C (154 to 160 °F; 341 to 344 K)
Hazards
GHS pictograms
GHS Signal word Warning
GHS hazard statements
 H315, H319, H335
P261, P305+351+338
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

For the design and synthesiis of [2.2.2]cryptand,[3] Jean-Marie Lehn shared the Nobel Prize in Chemistry. The compound was originally prepared starting with the diacylation of the diamine-diether:[4]

[CH2OCH2CH2NH2]2 + [CH2OCH2COCl]2 → [CH2OCH2CH2NHC(O)CH2]2 + 2 HCl

The resulting macrocyclic diamide is reduced by lithium aluminium hydride. The resulting macrocyclic diamine tetraether reacts with a second equivalent of [CH2OCH2COCl]2 to produce the macrobicyclic diamide. This di(tertiary)amide is reduced to the diamine by diborane.

[2.2.2]Cryptand binds K+ as an octadentate N2O6 ligand. The resulting cation [K(cryptand)]+ is lipophilic.

Structure of [2.2.2]-cryptand encapsulating a potassium cation (purple) as determined by X-ray crystallography.[5]

References
  1. In the Nomenclature of Inorganic Chemistry (2005), IUPAC recommends the abbreviation "crypt-222".
  2. Kang, Sung Ok; Llinares, José M.; Day, Victor W.; Bowman-James, Kristin (2010). "Cryptand-like anion receptors". Chemical Society Reviews. 39 (10): 3980–4003. doi:10.1039/C0CS00083C. PMID 20820597.
  3. Dietrich, B.; Lehn, J.M.; Sauvage, J.P. (1969). "Les Cryptates". Tetrahedron Letters. 10 (34): 2889–2892. doi:10.1016/S0040-4039(01)88300-3.
  4. Dietrich, B.; Lehn, J.M.; Sauvage, J.P. (1969). "Diaza-polyoxa-macrocycles et macrobicycles". Tetrahedron Letters. 10 (34): 2885–2888. doi:10.1016/S0040-4039(01)88299-X.
  5. Alberto, R.; Ortner, K.; Wheatley, N.; Schibli, R.; Schubiger, A. P. (2001). "Synthesis and properties of boranocarbonate: a convenient in situ CO source for the aqueous preparation of [99mTc(OH2)3(CO)3]+". J. Am. Chem. Soc. 121 (13): 3135–3136. doi:10.1021/ja003932b. PMID 11457025.
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