Is Sulfur hexachloride an ionic compound?

sulfur hexafluoride (SF6) is ionic bond

No, It's a molecular or covalent compound

Explanation:

Let remember the concept of a ionic bond:

The Ionic bond is when it's transfered all of the valence electrons of the atoms. This always result in charged ions (positive and negative) and it's usually given between a metal and non metal element. The metal loses electrons (has a positive charge) while the non metal gains electrons (negative charges). For example Sodium and Fluorine to form the Sodium Fluorine (Na + and F-)

In the case of SCl6 this is not ocurring. For starter, S and Cl are both non metals, so it's very unlikely that a transfer of all ions occurs. What it occurs in this case is another kind of bond, which is called covalent bond

A covalent bond is when two atoms share their electrons between them to form a stronger bond and result in a compound. In this case, the outer electrons are in the vicinity or the atoms, and then, begins to share those electrons and form a new bond and product.

In the case of SCl6, the 6 electrons of the S form a bond with one electron of each chlorine, sharing those electrons and they form the bond and a new compound.

This is something similar to what happens to the molecule of water. Therefore SCl6 it's covalent.