ROTATIONAL SPECTRUM, RING PUCKERING, AND NH INVERSION OF 3-PYRROLINE

Author Institution: Laboratorium f\""{u}r Physikalische Chemie, Eidgen\""{o}ssische Technische Hochschule; Dipartimento di Chimica Fisica ed, Inorganica. Universita di BolognaThe microwave spectra of the unsaturated five-membered ring molecule 3-pyrroline $(C_{4}H_{4}N)$ and its N-deuterated species have been reinvestigated between 26.5-40 GHz. The spectra were dominated by $\mu_{a}$-type transitions which showed small splittings due to the intramolecular motion. A few $\mu_{c}$-type transitions with large splittings were located as well. For some of the transitions the $^{14}N$ quadrupole splittings were resolved. The ring puckering and the NH inversion motion are strongly coupled. From a two-dimensional flexible model treatment of the data, the potential surface was found to have saddle points at puckered ring configurations separated by a maximum at the $C_{2v}$,-symmetric configuration of the molecule