Tetraxenonogold(II), gold tetraxenide(II) or AuXe is a cationic complex with a square planar configuration of atoms. It is found in the compound AuXe(SbF) (tetraxenonogold(II) undecafluorodiantimonate), which exists in triclinic and tetragonal crystal modifications.[1] The AuXe ion is stabilised by interactions with the fluoride atoms of the counterion. The Au−Xe bond length is .[2] [3] Tetraxenonogold(II) is unusual in that it is a coordination complex of xenon, which is weakly basic. It is also unusual in that it contains gold in the +2 oxidation state. It can be produced by reduction of AuF3 by xenon in the presence of fluoroantimonic acid. The salt crystallises at low temperature.[4] Four xenon atoms bond with the gold(II) ion to make this complex.
It was the first description of a compound between a noble gas and a noble metal. It was first described in 2000 by Konrad Seppelt and Stefan Seidel. Several related compounds containing gold(III)–xenon and gold(I)–xenon bonds have since been isolated. A compound containing a mercury–xenon bond [HgXe]2+[Sb<sub>2</sub>F<sub>11</sub>]–[SbF<sub>6</sub>]– (xenonomercury(II) undecafluorodiantimonate hexafluoroantimonate) has also been isolated.[5]