The following are some normal modes of vibration for several molecules. In each case: • Determine the point group for the molecule • Determine how the vibration transforms under each symmetry operation of the point and assign the appropriate irreducible representation • State whether the vibration is IR active and'or Raman active (benzene): CC strotch C=C stretch "Breathing CC twist CC twist b. t. "Flexing Asymmetric CH and C-Cl stretches Asymmetric C-H and C-Ci stretches 9. Symmetric C-H and C-Ci stretches Symmetric C-H and C-CI stretches Asymmetric C-H stretches d. h. 0-

Draw a picture and determine the point group for EACH of the possible structural arrangements of PFnBr(5-n) for n = 0 to 5. I.e. start with PBr5 and end with PF5. Assuming a static structure, indicate the number and relative intensities of the signals that you would expect to see in the 19F NMR spectrum of each molecule. %3D

Under C4v symmetry, which irreducible representations, if any, correspond to an IR active vibration and which ones correspond to a Raman active vibration?  And which ones correspond to an IR active vibration under D2h symmetry?

Briefly describe the difference between FT-NMR and continuous wave NMR (CW-NMR) NMR methods, and describe any advantages of FT-NMR. Discuss the advantages of multi-dimensional NMR spectroscopy compared to one-dimensional experiments, using one specific multidimensional experiment as an illustrative example.