FAR-INFRARED SPECTRA AND RING-PUCKERING POTENTIAL-ENERGY FUNCTION OF BICYCLO[3.1.0]HEXAN-3-ONE

The far-infrared spectrum of the ring-puckering vibration of bicyclo[3 .1.0]hexan-3-one has been recorded and analyzed. Ten closely spaced ba nds with a band origin at 86.4 cm(-1) were observed. Kinetic energy ex pansions were calculated for this molecule and also for bicyclo[3.1.0] hexane, 6-oxabicyclo[3.1.0]hexane, 3-oxabicyclo[3.1.0]hexane, and 3,6- dioxabicyclo[3.1.0]hexane, and these expansions along with published d ata were utilized to calculate the asymmetric one-dimensional ring-puc kering potential energy functions for each. For bicyclo[3.1.0]hexan-3- one the function is V (cm(-1)) (2.99 x 10(5))x(4) + (0.39 x 10(5))x(2) + (1.58 x 10(5))x(3), where x is the puckering coordinate in Angstrom . The experimental results were compared to molecular mechanics calcul ations in each case.