Chapter 3, Problem 33P

(a) To which point group does a trigonal bipyramidal ${\text{XY}}_{\text{5}}$ belong? Determine the number and symmetries of the stretching modes of vibration for this molecule. (b) The IR spectrum of gaseous ${\text{PF}}_{\text{5}}$ exhibits absorptions at 1026 and 944 ${\text{cm}}^{\text{-1}}$. Show that this observation is consistent with your answer to part (a). How many absorptionswould you expect to observe in the Raman spectrum of gaseous ${\text{PF}}_{\text{5}}$ arising from stretching modes?