Spectra and Structure of Crystalline Cyclopropane and Cyclopropane-D6

Infrared and Raman spectra of polycrystalline C₃H₆ and C₃D₆ were measured between 10 and 3500 cm⁻¹ at 85°K. Infrared spectra of mixed C₃H₆ and C₃D₆ crystals were also obtained. From these measurements, an assignment of the origin of the multiplet splittings is proposed. An x‐ray diffraction study of crystalline C₃H₆ suggests an orthorhombic unit cell with $\text{a\hspace{0.17em}=\hspace{0.17em}10.0 Å}$ , $\text{b\hspace{0.17em}=\hspace{0.17em}6.8 Å}$ , and $\text{c\hspace{0.17em}=\hspace{0.17em}5.1 Å}$ . Density measurements, spectroscopic data, and diffraction data indicate that the site group is $C_s$ and that the space group is one of eight primitive $D_{\text{2h}}$ groups. Far‐infrared spectra of crystalline $C_3{H}_6$ showed five absorptions attributed to $\text{k\hspace{0.17em}=\hspace{0.17em}0}$ external modes.