Knowledge Bank

In recent years, various investigators have demonstrated the practicality of calculating minimum energy conformations and strain energies for hydrocarbons and related $molecules.1$ The success, however, of accurately determining structures by this method requires a moderately detailed knowledge of representative potential functions. For this reason, the method is limited to systems that are not highly strained. Since virtually no vibrational information exists for bicyclic molecules, we have undertaken investigations on a series of these hydrocarbons with the goal both of understanding their spectra and of determining a suitable potential function for use in the conformational calculation of strained systems. In the present study we discuss the infrared and Raman spectra of norbornane and nor-bornadiene (strain energies of 18.4 and 29.0 kcal/mole, respectively) and present a valence force field for assessing the consistency of the vibrational assignment.