Tetraxenonogold(II), gold tetraxenide(II) or AuXe is a

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

complex Complex commonly refers to: * Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe ** Complex system, a system composed of many components which may interact with each ...

with a

square planar The square planar molecular geometry in chemistry describes the stereochemistry (spatial arrangement of atoms) that is adopted by certain chemical compounds. As the name suggests, molecules of this geometry have their atoms positioned at the corne ...

configuration of atoms. It is found in the compound AuXe(SbF) ( tetraxenonogold undecafluorodiantimonate), which exists in triclinic and tetragonal crystal modifications. The AuXe ion is stabilised by interactions with the fluoride atoms of the counterion. The Au−Xe bond length is . Tetraxenonogold(II) is unusual in that it is a compound of the notoriously inert atoms

xenon Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

and

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...

. It is also unusual in that it uses xenon as a

transition metal In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that can ...

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elect ...

, and in that it contains gold in the +2 oxidation state. It can be produced by reduction of AuF₃ in the presence of

fluoroantimonic acid Fluoroantimonic acid is a mixture of hydrogen fluoride and antimony pentafluoride, containing various cations and anions (the simplest being and ). This substance is a superacid that can be over a billion times stronger than 100% pure sulfuric ...

and xenon, and crystallised at low temperature. The xenon bonds with the gold(II) ion to make this complex. It was the first description of a compound between a

noble gas The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low ch ...

and a

noble metal A noble metal is ordinarily regarded as a metallic chemical element that is generally resistant to corrosion and is usually found in nature in its raw form. Gold, platinum, and the other platinum group metals ( ruthenium, rhodium, palladium, o ...

. It was first described in 2000 by

Konrad Seppelt Konrad Seppelt (born September 2, 1944 in Leipzig) is a academic author, professor and former vice president of the Free University Berlin. Publications Popular publications Cutting Edge Konrad Seppelt, The (London) Times Higher Education Suppleme ...

and Stefan Seidel.

References

Cations Gold compounds Xenon compounds {{inorganic-compound-stub