Knowledge Bank

The pseudorotational potential energies and dipole moments of several five-membered rings have been calculated using the CNDO/2 approximate quantum mechanical method of Pople, Santry and Segal. Calibration of the method for cyclopentane predicts an energy difference between the twist and bent forms of less than $4cm-1$. The calculated potential energies are fitted with a cosine barrier potential. Frequencies of permitted transitions are calculated and found to be in good agreement with experiment.