In a regular octahedral molecule, $MX_{6}$, the number of $X–M–X$ bonds at 180º is:

In a regular octahedral geometry, such as that found in $SF_{6}$, the central metal atom is surrounded by six ligands . This arrangement consists of four ligands situated at the corners of a square plane with the central atom at its center, and two additional ligands positioned axially—one directly above and one directly below the plane . The $X–M–X$ bonds at 180º occur between pairs of ligands that are positioned diametrically opposite each other through the central atom. In this structure, there are exactly three such pairs: one axial pair (top to bottom) and two equatorial pairs (diagonally opposite corners of the square plane) .