the center of the plane. The regular square antiprism structure (SN = 8) is like a cube with the top and bottom faces twisted 45" into the antiprism arrangement, as shown in Figure 3-9. It has three different bond angles for adjacent fluorines. [T~Fh~as ] square antiprism symmetry, but is distorted from this ideal in the solid.7 (A simple cube
has only the 109.5' and 70.5" bond angles measured between two corners and the center of the cube, because all edges are equal and any square face can be taken as the bottomor top.)