Xenon as a mediator of chemical reactions? Case of elusive gold monofluoride, AuF, and its adduct with xenon, XeAuF

We show, using Density Functional Theory calculations, that the phase diagram at T = 0 K of the 2/3 Au-0 + 1/3 (AuF3)-F-III mixture is greatly affected by the presence of elemental xenon. The formation of a quasimolecular Xe-->(AuF)-F-I adduct is expected at 16 GPa, if not precluded by a partial oxidation of Xe at pressures exceeding 7.5 GPa. The Xe-->(AuF)-F-I adduct should yield Xe and (AuF)-F-I upon careful decompression at 14 GPa. This contrasts with the behaviour of a pure (2/3 An, 1/3 AuF3) mixture, investigated by us recently, where direct synthesis of (AuF)-F-I via a comproportionation reaction is expected at substantially larger pressures (23 GPa). Presence of Xe thus facilitates the formation reaction by decreasing the required formation pressure by about one third. The most stable detected polymorph of Xe-->(AuF)-F-I is monoclinic (P2(1/m)) and it exhibits interesting features of the electronic band structure.