Free Jet Absorption Millimeter Wave Spectrum of Pyrrolidine: Assignment of a Second, Equatorial, the Most Stable Conformer.
The equatorial conformer of pyrrolidine has been discovered while investigating the rotational free jet spectrum of the pyrrolidine-water adduct. It is more stable than the axial species, previously assigned with conventional microwave spectroscopy (W. Caminati, H. Oberhammer, G. Pfafferott, R. R. Filgueira, and C. H. Gomez, 1984. J. Mol. Spectrosc., 106, 217-266). The assignment of the equatorial conformer was missed in that microwave investigation because of the accidentally zero or almost zero value of its µa dipole moment component; its low J µc-type transitions, very weak in the room temperature spectrum, are the strongest lines in the jet. Copyright 1998 Academic Press.
Dipartimento di Chimica, "G. Ciamician" dell'Universita', Via Selmi 2, Bologna, I-40126, Italy
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