Dicobalt edetate

Dicobalt edetate is the coordination compound with the approximate formula Co2(EDTA)(H2O)6.

Solutions of this solid have been used in Europe as an antidote to cyanide poisoning.

It is a derivative of the (non-natural) amino acid ethylenediaminetetraacetate.

Structure
The compound is polymeric in the crystalline form. Half of the Co2+ ions are bound to the EDTA2&minus; and the other Co2+ ions are bound to four water ligands as well as carboxylate ligands on the [Co(EDTA)]2&minus; entity. In aqueous solution, depolymerization occurs to give [Co(EDTA)]2&minus; and [Co(H2O)6]2+ ions, each of which is kinetically labile and has a high affinity for cyanide. Oxidants would convert the [Co(EDTA)]2&minus; into [Co(EDTA)]&minus;, which would be unreactive toward cyanide because this complex would be "inert."