Gold pentafluoride

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Gold(V) fluoride
Gold(V) fluoride
Identifiers
CAS number 57542-85-5
Properties
Molecular formula AuF5
Molar mass 291.959 g/mol
Appearance red unstable solid
Melting point 60 °C (Decomposes)
Solubility in water 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 are 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 around 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[edit]

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
2
F
10
(s) + 2 Kr (g) + 2 F
2
(g)

References[edit]

  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.