Rotational Spectrum of the Axial Form and Conformational Equilibrium in Chlorocyclobutane

The microwave spectrum of chlorocyclobutane has been investigated in the 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 vibrational satellites have been extended. The shifts of the rotational constants with respect to the ground state, the available far infrared transitions, together with the relative intensities and the dipole moments of the conformers, have been used to obtain the shape of the potential energy function hindering the ring-puckering.