VIBRATIONAL CIRCULAR DICHROISM OF TRANS-SUBSTITUTED CYCLOPROPANES

Author Institution:Cyclopropanes with substituents in the trans-1,2 positions are optically active by virtue of their $C_{2}$ symmetry. The rigidity imposed by the three-membered ring limits the number of conformations and simplifies the analysis of vibrational modes. These factors make cyclopropanes particularly good systems for the explorations of vibrational circular dichroism (VCD). In particular the dinitrile, with $C\equiv N$ groups in the trans positions, has only one conformation. This molecule has been prepared in the resolved (+) form according to literature methods. VCD of the $C\equiv N$ stretching mode has been measured and is the first report of VCD for such a mode. VCD in the C-H stretching region for this molecule and several other cyclopropanes will also be discussed in terms of empirical correlations and comparison with predictions made by existing VCD theories