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 ...

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 conven ...

(). The related

hexafluorophosphate Hexafluorophosphate is an fluoroanion, anion with chemical formula of . It is an Octahedral molecular geometry, octahedral species that imparts no color to its salts. is isoelectronic with sulfur hexafluoride, , and the Hexafluorosilicic acid, h ...

is also a popular reagent with similar properties. The ferrocenium 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 chemistry, organometallic compound with the formula . The molecule is a Cyclopentadienyl complex, complex consisting of two Cyclopentadienyl anion, cyclopentadienyl rings sandwiching a central iron atom. It is an o ...

, 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 dependent on specific electrochemical conditions.

Preparation

Commercially available, this compound may be prepared by oxidizing ferrocene typically with ferric salts followed by addition of fluoroboric acid. A variety of other oxidants work well also, such as nitrosyl tetrafluoroborate. Many analogous ferrocenium salts are known.

Structure

According to

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

, the structures of the metallocene component of FcBF₄ and the parent ferrocene are very similar. The Fe-C distances in the cation are 209.5 pm, about 2% longer than the Fe-C distances in ferrocene.

References

{{Tetrafluoroborates Ferrocenes Tetrafluoroborates Oxidizing agents