Dicobalt edetate

Dicobalt edetate
Skeletal formula of dicobalt edetate
Ball-and-stick model of the dicobalt edetate molecule
Names
Other names
Kelocyanor
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.048.227 Edit this at Wikidata
UNII
  • InChI=1S/C10H16N2O8.2Co/c13-7(14)3-11(4-8(15)16)1-2-12(5-9(17)18)6-10(19)20;;/h1-6H2,(H,13,14)(H,15,16)(H,17,18)(H,19,20);;/q;2*+2/p-4 checkY
    Key: TWAWHTJKASJPEK-UHFFFAOYSA-J checkY
  • InChI=1/C10H16N2O8.2Co/c13-7(14)3-11(4-8(15)16)1-2-12(5-9(17)18)6-10(19)20;;/h1-6H2,(H,13,14)(H,15,16)(H,17,18)(H,19,20);;/q;2*+2/p-4
    Key: TWAWHTJKASJPEK-XBHQNQODAQ
  • C(CN(CC(=O)[O-])CC(=O)[O-])N(CC(=O)[O-])CC(=O)[O-].[Co+2].[Co+2]
  • [Co+2].[Co+2].[O-]C(=O)CN(CC([O-])=O)CCN(CC([O-])=O)CC([O-])=O
Properties
C10H12Co2N2O8.6H2O
Molar mass 406.08 g/mol
514.18 g/mol (hexahydrate)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Dicobalt edetate is the coordination compound with the approximate formula Co2(EDTA)(H2O)6. It is a derivative of the (non-natural) amino acid ethylenediaminetetraacetate.

Solutions of this solid have been used in Europe as an antidote to cyanide poisoning, with the trade name Kelocyanor.[1] However, dicobalt edetate is itself toxic, particularly if there is not enough cyanide in the blood to react with it, so it is only suitable for serious cases of poisoning. In the past, workplaces in the UK that handle cyanide were recommended to keep a 'Kelocyanor kit', to be taken to the hospital along with the patient, but this practice has been discontinued since it may mislead doctors into using the antidote unnecessarily.[2]

Structure

The compound is polymeric in the crystalline form. Half of the Co2+ ions are bound to the EDTA2− and the other Co2+ ions are bound to four water ligands as well as carboxylate ligands on the [Co(EDTA)]2− entity.[3] In aqueous solution, depolymerization occurs to give [Co(EDTA)]2− and [Co(H2O)6]2+ ions, each of which is kinetically labile and has a high affinity for cyanide.

Oxidation of [Co(II)(EDTA)]2− gives [Co(III)(EDTA)]−, which is so kinetically inert that it can be resolved optically.[4]

References

  1. ^ Pickering WG (December 1985). "Cyanide toxicity and the hazards of dicobalt edetate". Br Med J (Clin Res Ed). 291 (6509): 1644. doi:10.1136/bmj.291.6509.1644-a. PMC 1418389. PMID 2866807.
  2. ^ "Cyanide poisoning – New recommendations on first aid treatment". Health and Safety Executive. Archived from the original on 20 October 2009.
  3. ^ E. F. K. Mccandlish, T. K. Michael; Rose, N. J.; Neal, J. A.; Lingafelter, E. C.; Rose, N. J. (1978). "Comparison of the Structures and Aqueous Solutions of [(O-Phenylenediaminetetraacetato(2-)]Cobalt(II) and [Ethylenediaminetetraacetato(2-)]Cobalt(II)". Inorg. Chem. 17 (6): 1383–94. doi:10.1021/ic50184a001.
  4. ^ Dwyer, F. P.; Garvan, F. L. (1960). "Resolution of the Ethylenediaminetetraacetatocobaltate(III) Ion". Inorganic Syntheses. Vol. VI. pp. 192–4. doi:10.1002/9780470132371.ch61. ISBN 978-0-470-13237-1. {{cite book}}: |journal= ignored (help)