Ferrocenium tetrafluoroborate is an

organometallic compound Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and s ...

with the formula e(C₅H₅)₂F₄. This salt is composed of the cation e(C₅H₅)₂sup>+ and the tetrafluoroborate

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

(). The related

hexafluorophosphate Hexafluorophosphate is an anion with chemical formula of . It is an octahedral species that imparts no color to its salts. is isoelectronic with sulfur hexafluoride, , and the hexafluorosilicate dianion, , and hexafluoroantimonate . In this an ...

is also a popular reagent with similar properties. The cation is often abbreviated Fc⁺ or Cp₂Fe⁺. The salt is deep blue in color and

paramagnetic Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, ...

. Ferrocenium salts are sometimes used as one-electron oxidizing agents, and the reduced product,

ferrocene Ferrocene is an organometallic compound with the formula . The molecule is a complex consisting of two cyclopentadienyl rings bound to a central iron atom. It is an orange solid with a camphor-like odor, that sublimes above room temperature, ...

, is inert and readily separated from ionic products. The ferrocene–ferrocenium couple is often used as a reference in electrochemistry. The standard potential of ferrocene-ferrocenium is 0.400 V vs. the normal hydrogen electrode (NHE) and is often assumed to be invariant between different solvents.

Preparation

Commercially available, this compound may be prepared by oxidizing ferrocene typically with ferric salts followed by addition of

fluoroboric acid Fluoroboric acid or tetrafluoroboric acid (archaically, fluoboric acid) is an inorganic compound with the chemical formula +BF4−], where H+ represents the solvated proton. The solvent can be any suitably Lewis-basic entity. For instance, in w ...

. A variety of other oxidants work well also, such as

nitrosyl tetrafluoroborate Nitrosonium tetrafluoroborate, also called nitrosyl tetrafluoroborate, is a chemical compound with the chemical formula NOBF4. This colourless solid is used in organic synthesis as a nitrosating agent. NOBF4 is the nitrosonium salt of fluorob ...

. Many analogous ferrocenium salts are known.

References

{{Tetrafluoroborates Ferrocenes Tetrafluoroborates Oxidizing agents