Gold(II) tetra­xenide

Other names: tetra­xenono­gold(II)

AuXe₄²⁺

18/50 common

Although the defining chemical feature of the noble gases is their unreactivity, the heavier members of this group (particularly krypton and xenon) are indeed capable of forming simple compounds upon reaction with sufficiently oxidizing species. This is because, although all noble gases possess a full octet in their neutral monatomic state, the valence electrons for heavier noble gases are sufficiently shielded and distanced from the nucleus that they may be abstracted by electron-hungry elements such as fluorine and oxygen. The AuXe₄²⁺ dication can be synthesized by reduction of gold(III) fluoride in the stabilizing presence of superacidic fluoroantimonic acid, and features a highly unusual bond between a noble gas and a noble metal, two classes of element famously characterized by their nonreactivity.