ROTATIONAL SPECTRUM OF AMINOCYCLOBUTANE - INTERNAL-ROTATION AND INVERSION OF THE NH2 GROUP IN THE GAUCHE-EQUATORIAL CONFORMER

The microwave spectrum of aminocyclobutane has been investigated by fr ee jet absorption millimeter-wave spectroscopy and conventional microw ave spectroscopy in the 60-78 and 26-40 GHz frequency ranges, respecti vely. The spectrum of the conformer with the amino group in the equato rial position, and the nitrogen lone electron pair gauche with respect to the adjacent hydrogen of the ring, has been assigned. Each rotatio nal transition is split into four component lines. corresponding to th e four-equivalent minima in the potential energy surface of the intern al rotation and inversion of the NH2 group. The potential energy param eters have been calculated from the measured vibrational spacings amon g the corresponding vibrational sublevels. (C) 1998 Elsevier Science B .V.