Chapter 22, Problem 115FP

A description of bonding in $Xe{F}_2$ based on the valence bond model requires the 5d orbitals of $Xe$ . A more satisfactory description uses a molecular orbital approach involving three-center bonds. Assume that bonding involves the 5p, orbital of $Xe$ and the 2p, orbitals of the two F atoms. These three atomic orbitals combine to give three molecular orbitals: one bonding, one nonbonding, and one antibonding. Recall that for bonding to occur, atomic orbitals with the same phase must overlap to form bonding molecular orbitals (see Chapter 11).
a. Construct diagrams similar to Figure 11-33 to indicate the overlap of the three atomic orbitals in forming the three molecular orbitals. Assume that the order of energy of the molecular orbitals is bonding MO< nonbonding MO < antibonding MO.
b. Sketch a molecular orbital energy-level diagram, and assign the appropriate number of electrons from fluorine and xenon to the molecular orbitals. What is the bond order?
c. With the aid of VSEPR theory, show that this molecular orbital description based on three-center bonds works well for $Xe{F}_4$ but not for $Xe{F}_8$ .