SYMMETRY SPECIES CORRELATIONS AND GROUP FREQUENCIES IN CYCLOPROPANES

Author Institution: Scientific Laboratory, Ford Motor CompanyThe fundamentals of cyclopropane, cyanocyclopropane, chlorocyclopropane, and bromocyclopropane are arranged in a correlation diagram which combines---under strict adherence to the ``noncrossing rule''---the fundamentals of $C_{3}H_{5}X, X = CN, Cl, Br$ (symmetry group $C_{8}$) and $C_{3}H_{6} (D_{3h})$ with respect to the common symmetry element $\sigma_{v}$. The correlation diagram shows that the coincidence of the symmetric ring deformation modes of these molecules (1024 to $1044 cm^{-1}$), a mode which has been proposed for purposes of identification of molecules containing the cyclopropane ring, is fortuitous rather than the consequence of a ``group frequency''