Teflic acid is a chemical compound with the formula . This strong acid is related to orthotelluric acid, . Teflic acid has a slightly distorted octahedral molecular geometry.
Preparation Teflic acid was accidentally discovered by Engelbrecht and Sladky. Their synthesis did not yield the anticipated telluryl fluoride , but a mixture of volatile telluric compounds, containing :Engelbrecht, A.; Sladky, F. "Pentafluoro-orthotellursaure, " Angewandte Chemie 1964. 76(9), 379-380, . (25%)
Teflic acid can also be prepared from fluorosulfonic acid and barium tellurate:Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. .
It is also the first hydrolysis product of tellurium hexafluoride:
A more recent synthetic route uses elemental tellurium as the starting material. In the first step, tellurium reacts with chlorine, potassium fluoride and water to give potassium pentafluoroorthotellurate (KOTeF5):
Te + 3Cl2 + 9KF + H2O -> KOTeF5 + 2KHF2 + 6KCl
Trichloroisocyanuric acid (TCICA) can be used as the oxidant in place of elemental chlorine. In the second step, the salt is protonated with sulfuric acid to yield teflic acid:
KOTeF5 + H2SO4 -> HOTeF5 + KHSO4
Teflates
The conjugate base of teflic acid is called the teflate anion, (not to be confused with triflate). Many teflates are known, one example being , that can be pyrolysed to give acid anhydride .
The teflate anion is known to resist oxidation. This property has allowed the preparation several highly unusual species such as the hexateflates (in which M = As, Sb, Bi). Xenon forms the cation .Mercier, H. P.A.; Sanders, J. C. P.; Schrobilgen, G. J. "The Hexakis(pentafluorooxotellurato)pnictate(V) Anions, (M = As, Sb, Bi): A Series of Very Weakly Coordinating Anions" Journal of the American Chemical Society, volume 116, 2921, (1994). .
References
Further reading R.B. King; Inorganic Chemistry of Main Group Elements, VCH Publishers, New York,1994.