Question

Using VSEPR theory, predict the probable structure of \[\ce{IBr^-_2}\].

Answer 1

1. The central atom, iodine (I), has 7 valence electrons.
2. Two bromine (Br) atoms bond with I, using 2 pairs of electrons.
3. The ion has 3 lone pairs on iodine left.
4. Electron pairs total 5 (2 bonding + 3 lone pairs).
5. The shape of the electron pair arrangement is trigonal bipyramidal.
6. Lone pairs occupy equatorial positions to minimise repulsion.
7. The resulting molecular shape with 3 lone pairs is linear. Hence, (\[\ce{IBr^-_2}\]) is linear, similar to (XeF₂) in structure.