Astatine compounds

The reactions involved have been typically tested with dilute solutions of astatine mixed with larger amounts of iodine.

Acting as a carrier, the iodine ensures there is sufficient material for laboratory techniques (such as filtration and precipitation) to work.

[6] Many of its apparent chemical properties have been observed using tracer studies on extremely dilute astatine solutions,[7][8] typically less than 10−10 mol·L−1.

[12][15] Only a few compounds with metals have been reported, in the form of astatides of sodium,[16] palladium, silver, thallium, and lead.

[25] This cation exists as a coordination complex in which two dative covalent bonds separately link the astatine(I) centre with each of the pyridine rings via their nitrogen atoms.

[34] Astatine is also thought to be capable of forming cations in salts with oxyanions such as iodate or dichromate; this is based on the observation that, in acidic solutions, monovalent or intermediate positive states of astatine coprecipitate with the insoluble salts of metal cations such as silver(I) iodate or thallium(I) dichromate.

[31][35] Astatine may form bonds to the other chalcogens; these include S7At+ and At(CSN)−2 with sulfur, a coordination selenourea compound with selenium, and an astatine–tellurium colloid with tellurium.

[36] Astatine is known to react with its lighter homologs iodine, bromine, and chlorine in the vapor state; these reactions produce diatomic interhalogen compounds with formulas AtI, AtBr, and AtCl.

[5] Oxidation of the element with dichromate (in nitric acid solution) showed that adding chloride turned the astatine into a molecule likely to be either AtCl or AtOCl.

[45] Demercuration reactions have produced with good yields trace quantities of 211At-containing aromatic amino acids, steroids, and imidazoles, among other compounds.