Motions of Compressed Hydrogens

The first question we need to ask given that the frequencies will go higher is higher than what The obvious model is norbomane. So we can carry out the calculations on norbomane, and find out what are the vibrational frequencies for the hydrogens and Ha and Hb. This is conveniently done with the MM4 program. One calculates the vibrational frequencies of the molecule, and one then looks at the C-H vibrational frequencies that are of interest, and that are in the 2800-3000 cm range in ordinary 

So this is pretty much what we expect. There are two hydrogens that are undergoing a serious mutual van der Waals repulsion, and those two hydrogens have the unusually high stretching frequencies 100-150cm above the ordinary values of those in norbomane. 

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