MICROWAVE-SPECTRUM OF THE AXIAL CONFORMER AND POTENTIAL-ENERGY FUNCTION OF THE RING PUCKERING MOTION IN FLUOROCYCLOBUTANE

The microwave spectrum of fluorocyclobutane has been investigated in t he 26-40 GHz frequency range. The spectrum of the axial conformer has been assigned for the first time, while measurements of the equatorial species, and of several of its puckering vibrational satellites, have been extended. The energy of the axial conformer is 620(30) cm(-1) hi gher than that of the equatorial one. Previously reported potential en ergy functions of the ring puckering have been corrected, interpreting the available vibrational spacings, the shifts of the rotational cons tants upon puckering excitation and the centrifugal distortion constan ts with a flexible model.