Why SF6 is well known but, SCl6 is not ?

 Questions: Why SF6 is well known but, SCl6 is not ?

Because fluorine atom is smaller in size therefore,  6 fluorine ions  surrounded a Sulphur atom .on the other hand  SCl6 in  chlorine atom due to its larger size  and intronic repulsion between larger Cl— ions.so Sulphur hexafluoride (Sf6) is well known