MICROWAVE STUDIES OF ROTATIONAL ISOMERISM IN ALLYLAMINE: THE N-CIS, LONE ELECTRON PAIR-GAUCHE ISOMER

Abstract

The fourth distinct rotational isomer of allylamine, the N-cis Lep-gauche form, has been identified. The isomer has two equivalent forms which are symmetrical with respect to the heavy atom plane. The possibly low barrier restricting torsion around the CN axis allows tunneling between the two minima, and the rotational spectrum is thereby perturbed, deviating from that of an ARR.The preliminary results permit the determination of the $``average”^{1}$ rotational constants of the ground state from the measured a-type lines (which generally are not split): $A = 16~ 170 \pm 120, B = 5796.0$ and $C = 4459.4$ (in MHz). The possibility of determining the potential surface"" which restricts torsion among all the existing isomeric forms, which are connected through two degrees of freedom, will be discussed.