The infrared and Raman spectra of octachloro-, octafluoro-, and octahydroxycycfobutane

Abstract

Infrared and Raman spectra are reported for cyclo-C4Cl8, c-C4F8, and c-C4(OH)8. In each case the infrared measurements extended down to 35 cm−1. For c-C4Cl8 infrared data were obtained on the solid, and Raman data on the solid at room temperature and at −168°C, on a saturated CS2 solution, and on the melt at 280°C. For c-C4F8 infrared measurements were made on the gas and on the solid at ~ −173°C and Raman ones on the gas and the liquid (both at room temperature). For c-C4(OH)8 infrared data were obtained on the solid and Raman data on the solid and on an aqueous solution. These are the first vibrational results reported for c-C4Cl8, and almost the first for c-C4(OH)8. For c-C4F8 our data are more extensive and accurate than those in the literature, and require modification of 8–10 of the assignments. The results provide convincing evidence that the carbon rings in c-C4Cl8 and c-C4F8 are puckered, and that the molecules have D2d symmetry. Unfortunately the frequency of the puckering mode could not be found. In c-C4(OH)8 the evidence is equally clear that the ring is planar and the symmetry is D4h. It is suggested that this surprising result is due to internal hydrogen bonding, which provides an added constraint against folding the ring. For each molecule assignments are made to nearly all the spectroscopically-active fundamentals. Typically about half of these are certain, while the remainder are in doubt to varying degrees.