SF6 is known but SH6 is not known Lets analyze :
The SF6 is a chemical compound containing sulfur hexafluoride gas. This gas is used in many industries including semiconductor manufacturing and aerospace applications. However, this gas is toxic and dangerous. Therefore, it is necessary to monitor its concentration levels in the air.
SH6 is a chemical compound consisting of hydrogen atoms and fluorine atoms. It is also called hydrofluoric acid. This compound is commonly used in industry for cleaning metal surfaces and removing rust from steel.
SF6 is known because Fluorine (F) is a strong oxidizing agent that means it under go reduction and oxidize Sulphur(S) to its maximum oxidation state i.e. +6.
Whereas H2 is a weak oxidizing agent, so cannot oxidize S to its maximum oxidation state of +6, hence does not form SH6.
F is the most electronegative element and that’s why it can use all the 6 electron of sulphur but hydrogen can’t do so as it is not much electronegative
So the answer to question
Why SF6 is known but SH6 is not known?
Since SF₆ is a strong oxidizing agent can exhibit oxidation number +6 whereas SH₆ being a weak oxidizing agent can’t expand oxidation number +6. That’s the reason its not known