Teflic acid

Teflic acid is the chemical compound with the formula HOTeF5. This strong acid is related to orthotelluric acid, Te(OH)6. Teflic acid has a slightly distorted octahedral geometry.
Preparation.
Teflic acid was accidentally discovered by Engelbrecht and Sladky. Their synthesis did not yield the anticipated telluryl fluoride TeO2F2, but a mixture of volatile telluric compounds, "i.a." HOTeF5:
Teflic acid can also be prepared from fluorosulfonic acid and barium tellurate:
It is also the first hydrolysis product of tellurium hexafluoride:
Teflates.
The conjugate base of teflic acid is called the teflate anion, F5TeO− (not to be confused with triflate). Many teflates are known, examples being B(OTeF5)3 and the acid anhydride O(TeF5)2. Pyrolysis of the boron compound gives the dimer (TeF4O)2
The teflate anion is known to resist oxidation. This property has allowed the preparation several highly unusual species such as the hexateflates M(OTeF5)6− (M = As, Sb, Bi). Xenon forms the cation Xe(OTeF5)+.