Gold(V) fluoride

Chembox new
Name = Gold(V) fluoride
ImageFile = Gold pentafluoride.png ImageName = Gold(V) fluoride
IUPACName = Gold(V) fluoride
OtherNames = gold pentafluoride
Section1 = Chembox Identifiers
CASNo = 57542-85-5
RTECS =
Section2 = Chembox Properties
Formula = AuF₅
MolarMass = 291.959 g/mol
Appearance = red unstable solid
Density =
Solubility = Decomposes
MeltingPt = 60 °C (Decomposes)
Section3 = Chembox Structure
MolShape =
Coordination =
CrystalStruct =
Dipole =
Section7 = Chembox Hazards
ExternalMSDS =
MainHazards = Corrosive, toxic
FlashPt =
RPhrases =
SPhrases =
Section8 = Chembox Related
OtherCpds = AuF₃
OtherCations = SbF₅, BrF₅, IF₅

Gold(V) fluoride is a fluoride of gold where gold is in its highest known oxidation state. It is a red solid and is very corrosive. It is very reactive and unstable at room temperature, and liberates fluorine spontaneously. In water, it hydrolyses to fluorine and a mixture of gold hydroxides and oxides.

The structure of gold(V) fluoride in the solid state is dimeric, better represented by the formula Au₂F₁₀, with hexacoordinated gold and an octahedral arrangement of the fluorine atoms around each gold atom. It is the only known dimeric pentafluoride; other pentafluorides are monomeric (P, As, Cl, Br, I), tetrameric (Nb, Ta, Cr, Mo, W, Tc, Re, Ru, Os, Rh, Ir, Pt), or polymeric (Bi, V, U). [In-Chul Hwang, Konrad Seppelt. Gold Pentafluoride: Structure and Fluoride Ion Affinity. "Angewandte Chemie International Edition" 2001, "40", 3690-3693. doi|10.1002/1521-3773(20011001)40:19%3C3690::AID-ANIE3690%3E3.0.CO;2-5] In the gas phase, a mixture of dimer and trimer in the ratio 82:12 has been observed.

ynthesis

Gold(V) fluoride can be synthesized by heating gold metal in an atmosphere of oxygen and fluorine to 370 °C under a pressure of 8 atmospheres to form gold dioxygenyl fluoride: [Greenwood&Earnshaw]

: 2Au(s) + 2O₂(g) + 6F₂(g) → 2O₂AuF₆(s)

The complex decomposes at 180 °C to produce the compound:

: 2O₂AuF₆(s) → 2AuF₅(s) + 2O₂(g) + F₂(g)

References