The [SF₆] molecule is octahedral (point group Oh). The S atom has one s and three p orbitals represented as A1g + T1u in this octahedral environment. Each F atom has a single orbital directed towards the S atom and these transform as A1g + T1u + Eg. The Eg combination holds 4 electrons from the 6 orbitals pointed at the S atom and these are non-bonding as there is no Eg combination on S. This leaves just two electrons of the F₆ set available for bonding to the S atom.
The S atom has 6 electrons in the A1g + T1u combination but the 2 F electrons take this count to 8. Overall there are 4 bonds, one of which consists of 2 electrons in an A1g orbital and the other three bonds are represented as T1u. The S atom, in effect, presents as X2L2 to the F A1g + T1u orbitals and uses all 6 valence electrons in the 4 SF bonding orbitals while the F atoms contribute just 2. Overall there are 4 bonds, the S is hexavalent, and the 4 bonds bind all 6 F atoms. The 6 F atoms present as a set, Ⓢ, to the S atom classified as X₂Z₂.