			10min:

PSEUDOROTATION IN TETRAHYDROFURAN: SUPPLEMENTARY DATA FROM THE FREE JET ROTATIONAL SPECTRUM OF THE d₈ SPECIES.

WALTHER CAMINATI, ASSIMO MARIS, SONIA MELANDRI, Dipartimento di Chimica "G. Ciamician" dell'Università, Via Selmi 2, I-40126 Bologna, Italy; JUAN C. LÓPEZ, JOSÉ L. ALONSO, Departamento de Química-Física y Química-Inorgánica, Facultad de Ciencias, Universidad de Valladolid, E-47005 Valladolid, Spain; ROLF MEYER, Sonnenbergstrasse 18, Zufikon, CH-5621, Switzerland.

Tetrahydrofuran (THF) is a model molecule for the investigation of the hindered pseudorotation in saturated five-membered rings. Two recent papers, based on millimeter-wave investigations, reported the vibrational spacings among the four lowest pseudorotation states of normal THF, and obtained contrastant results on the potential energy function: four equivalent minima, or 2 sets of two equivalent minima. In order to have more information on this problem, we planned to investigate the millimeter wave spectrum of the d₈ species. We obtained a vibrational spacing of ca 15 GHz between the two lowest pseudorotation states: a result which is not in agreement with both the above mentioned potential energy functions.