Silver(II) fluoride

Silver(II) fluoride is a chemical compound with the formula AgF₂. It is a rare example of a silver(II) compound - silver usually exists in its +1 oxidation state. It is used as a fluorinating agent.

AgF₂ is a white crystalline powder, but it is usually black/brown due to impurities. The F/Ag ratio for most samples is < 2, typically approaching 1.75 due to contamination with Ag and oxides and carbon.

For some time, it was doubted that silver was actually in the +2 oxidation state, rather than some combination of states such as Ag^I[Ag^IIIF₄], which would be similar to silver(I,III) oxide. Neutron diffraction studies, however, confirmed its description as silver(II). The Ag^I[Ag^IIIF₄] was found to be present at high temperatures, but it was unstable with respect to AgF₂.

In the gas phase, AgF₂ is believed to have D_∞h symmetry. Per single-crystal X-ray diffraction, the silver atoms are square planar-coordinated in the solid state.

Approximately 14 kcal/mol (59 kJ/mol; 0.61 eV/f.u.) separate the ground and first excited states. The compound is paramagnetic, but it becomes ferromagnetic at temperatures below −110 °C (163 K).

AgF₂ can be synthesized by fluorinating Ag₂O with elemental fluorine. Also, at 200 °C (473 K) elemental fluorine will react with AgF or AgCl to produce AgF₂.

AgF₂ is a strong fluorinating and oxidising agent. It is formed as an intermediate in the catalysis of gaseous reactions with fluorine by silver. With fluoride ions, it forms complex ions such as AgF⁻
₃, the blue-violet AgF²⁻
₄, and AgF⁴⁻
₆.

It is used in the fluorination and preparation of organic perfluorocompounds. This type of reaction can occur in three different ways (here Z refers to any element or group attached to carbon, X is a halogen):