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Dodecahedrane is a highly symmetric icosahedral molecule. This provides a problem for optical
spectroscopy, but can be readily studies by inelastic neutron scattering (INS) spectroscopy.
Due to optical selection rules, only three of thirty unique vibrations are
observable with infrared spectroscopy, and one eight more are seen in Raman
spectroscopy.
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![[2.2]Paracyclophane, C16H16](images/dodecahedrane1.jpg)
Figure 1: Dodecahedrane shown with
hydrogens, with transparent hydrogens, and without hydrogens.
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No selection rules exist for INS spectroscopy, all
thirty vibrations are seen, see Figure 2. In part due to dodecahedrane's high symmetry and spherical shape,
its INS spectrum is especially sharp and well resolved.
INS spectroscopy provides us with
an increased number of peaks with which to fit the ab initio calculations to.
When an excellent fit (like that seen in Figure 2) is obtained, our confidence
in vibrational assignments is likewise increased.
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Figure 2: INS spectrum of dodecahedrane,
taken at approximately 10 Kelvin on the
FANS spectrometer.
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