Gold pentafluoride

Gold(V) fluoride
Names
IUPAC name
Gold(V) fluoride
Other names
Gold pentafluoride
Perauric fluoride
Identifiers
57542-85-5
Properties
AuF5
Molar mass 291.959 g/mol
Appearance red unstable solid
Melting point 60 °C (140 °F; 333 K) (decomposes)
Decomposes
Structure
Crystal structure orthorhombic (Pnma)
Hazards
Main hazards Corrosive, toxic
Related compounds
Other cations
 SbF5, BrF5, IF5
Related compounds
 AuF3, AuF7
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Gold(V) fluoride is the inorganic compound with the formula Au2F10. This fluoride compound features gold in its highest known oxidation state. This red solid dissolves in hydrogen fluoride but these solutions decompose, liberating fluorine.

The structure of gold(V) fluoride in the solid state is centrosymmetric with hexacoordinated gold and an octahedral arrangement of the fluoride centers on each gold center. It is the only known dimeric pentafluoride; other pentafluorides are monomeric (P, As, Sb, Cl, Br, I), tetrameric (Nb, Ta, Cr, Mo, W, Tc, Re, Ru, Os, Rh, Ir, Pt), or polymeric (Bi, V, U).[1] In the gas phase, a mixture of dimer and trimer in the ratio 82:18 has been observed.

Gold pentafluoride is the strongest known fluoride ion acceptor, exceeding the acceptor tendency of even antimony pentafluoride.

Synthesis

Gold(V) fluoride can be synthesized by heating gold metal in an atmosphere of oxygen and fluorine to 370 °C at 8 atmospheres to form dioxygenyl hexafluoroaurate:[2][3]

Au(s) + O2(g) + 3 F2(g) → O2AuF6(s)

This salt decomposes at 180 °C to produce the pentafluoride:

2 O2AuF6(s) → Au2F10 (s) + 2 O2(g) + F2(g)

Krypton difluoride is primarily a powerful oxidising and fluorinating agent. It can oxidise gold to its highest-known oxidation state, +5:[4]

7 KrF
2 (g) + 2 Au (s) → 2 KrF+
AuF−
6 (s) + 5 Kr (g)

KrF+
AuF−
6 decomposes at 60 °C into gold(V) fluoride and gaseous krypton and fluorine:[5]

2 KrF+
AuF−
6 → Au
2F
10 (s) + 2 Kr (g) + 2 F
2 (g)

References

  1. ↑ In-Chul Hwang, Konrad Seppelt "Gold Pentafluoride: Structure and Fluoride Ion Affinity" Angewandte Chemie International Edition 2001, volume 40, 3690-3693. doi: 10.1002/1521-3773(20011001)40:19<3690::AID-ANIE3690>3.0.CO;2-5
  2. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419.
  3. ↑ Emeléus, H. J.; Sharpe, A. G. (1983). Advances in Inorganic Chemistry and Radiochemistry. Academic Press. p. 83. ISBN 0-12-023627-3.
  4. ↑ W. Henderson (2000). Main group chemistry. Great Britain: Royal Society of Chemistry. p. 149. ISBN 0-85404-617-8.
  5. ↑ Charlie Harding; David Arthur Johnson; Rob Janes (2002). Elements of the p block. Great Britain: Royal Society of Chemistry. p. 94. ISBN 0-85404-690-9.