AtBr

AtBr, formally named astatine bromide, is the interhalogen compound that would form from astatine and bromine in a 1:1 ratio. In theory, AtBr would be a diatomic molecule in the gas phase and would belong to the broader family of interhalogen compounds that includes species such as BrF and ICl. Because astatine is highly radioactive and extremely scarce, direct experimental data for AtBr are limited. Most information comes from quantum-chemical calculations and radiochemical experiments conducted with trace amounts of astatine.

Chemical and physical properties: The At–Br bond is predicted to be relatively weak, reflecting the large atomic radii and relativistic effects associated with astatine. The molecule, if formed, would be highly reactive and prone to radiolytic decomposition. Any bulk sample would rapidly decay, making measurements difficult; thus reported properties are largely contingent on isotope and experimental conditions. In the gas phase, AtBr would be expected to exist only for very short times or under cryogenic conditions; in condensed phases, it would likely be unstable toward disproportionation or hydrolysis, if encountered.

Synthesis and handling: Production is confined to specialized radiological laboratories. Possible routes include halogen exchange reactions starting from astatine-containing precursors and bromine under carefully controlled, inert, cryogenic conditions. Handling requires remote manipulation, shielded hot cells, and substantial shielding to protect researchers from alpha emissions.

Applications: AtBr has limited practical use outside of fundamental radiochemistry and theoretical studies of heavy-element interhalogen chemistry. It serves as a reference point for understanding bonding in heavy halogen systems and the behavior of astatine compounds.

See also: Astatine, Bromine, Interhalogen compounds.