# Do polyfluorosulfuric acids like H2SO2F4 exist?

I was thinking about a compound resembling $$\ce{H2SO4}$$ but more acidic. I thought to replace the 2 oxygens with 4 fluorine atoms getting $$\ce{H2SO2F4}$$, which might be more acidic. Does such a compound even exist?

I also tried searching another compound i.e. $$\ce{HOSF5}$$ thinking of it to be more acidic than the previous but no results.

• – Oscar Lanzi Sep 29 '18 at 9:50
• No.$\mathstrut$ – Ivan Neretin Sep 29 '18 at 10:37

As the comments imply, no dice. You can, of course, make a six-coordinate sulfur compound with the formula $$\ce{SF6}$$. But trying it with a mixture of oxide, hydroxide and fluoride ligands instead of just fluoride presents the opportunity to evolve $$\ce{HF}$$ leaving the sulfur with a lower coordination number. There is a five-coordinate compound $$\ce{SOF4}$$, but otherwise you should expect the sulfur to get down to four-coordination. So the only stable protic acids you can get with one sulfur atom and oxide, hydroxide and fluoride ligands are plain old $$\ce{H2SO4}$$ and the more strongly acidic $$\ce{HSO3F}$$.