SbF4- has a single lone pair on Sb. Its strncture is therefore similar to SF4, with a lone pair
occupying an equatorial position. This lone pair causes considerable distortion, giving an
F- Sb - F (axial positions) angle of 155" and an F - Sb -F (equatorial) angle of 90".
SF5- has a single lone pair. Its structure is based on an octahedron, with the ion distorted
away from the lone pair, as in IF5.
SeF3+ has a single lone pair. This lone pair reduces the F- Se-F bond angle significantly,
to 94O.
EXERCISE 3-2
Predict the structures of the following ions. Include a description of distortions from the ideal
angles (for example, less than 109.5" because.. . ).