Silver subfluoride explained

Silver subfluoride is the inorganic compound with the formula Ag₂F. This is an unusual example of a compound where the oxidation state of silver is fractional. The compound is produced by the reaction of silver and silver(I) fluoride:^[1]

Ag + AgF → Ag₂F

It forms small crystals with a bronze reflex and is a good conductor of electricity. On contact with water almost instant hydrolysis occurs with the precipitation of silver (Ag) powder.

Crystal structure

Ag₂F adopts the anti-CdI₂ crystal structure, i.e. the same structure as cadmium iodide, CdI₂, but with "Ag^½+" centres in the I⁻ positions and F⁻ in the Cd²⁺ positions.^[2] The shortest distance between silver atoms is 299.6 pm (compared to 289 pm in the metal).^[3]

Notes and References

1. Lee Poyer, Maurice Fielder, Hugh Harrison, Burl E. Bryant "Disilver Fluoride: (Silver “Subfluoride”)" Inorganic Syntheses, 1957, Volume 5, 92–94.
2. A Williams . Neutron powder diffraction study of silver subfluoride . . 1 . 15 . 2569–2574 . April 1989 . 10.1088/0953-8984/1/15/002 . 1989JPCM....1.2569W . 250785624 .
3. Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier