Heptafluoride typically refers to compounds with the formula RnMxF7y− or RnMxF7y+, where n, x, and y are independent variables and R any substituent.
The only binary heptafluorides are iodine heptafluoride (IF7), rhenium heptafluoride (ReF7), and gold heptafluoride (AuF7). Only IF7 and ReF7 are true heptafluorides, however, as AuF7 is actually a coordination complex of gold pentafluoride (AuF5) and molecular fluorine; therefore, the correct chemical formula of gold heptafluoride is actually AuF5·F2.
A commercially important heptafluoride anion is the heptafluorotantalate anion, TaF7−. It is an intermediate in the purification of tantalum. Many dimeric and oligomeric heptafluorides have been observed or proposed. One example is B2F7−.
In the area of organofluorine chemistry, many heptafluorides are known. A prominent example is heptafluorobutyric acid. This species and its conjugate base heptafluorobutyrate (C3F7CO2−) are precursors to surfactants.
Many compounds that are not discrete ions or molecules also are heptafluorides.
- J. S. Hartman, P. Stilbs "Direct observation of the heptafluorodiborate(III) ion, B2F7−" J. Chem. Soc., Chem. Commun., 1975, pages 566-567. doi:10.1039/C39750000566
- Grosse, L.; Hoppe, R. "Zur Kenntnis von Sr2RhF7" Zeitschrift für Anorganische und Allgemeine Chemie (1987), 552, 123-31.doi:10.1002/zaac.19875520914