The vibrational spectra of 1,1,4,4-tetrafluoro- and 1,1,4,4-tetrachlorobutadiene

Raman data are reported for gas, liquid and solid 1,1,4,4-tetrafluorobutadiene, F₂CCHCHCF₂, and IR data for gas and solid. The molecule has a planar trans conformation of C_2h symmetry. With the aid of Raman depolarization ratios and IR band contours, twenty of the twenty-four spectroscopically-active fundamentals can be assigned with assurance. Frequencies are suggested for the remaining four modes.Raman and IR data are reported for the liquid and solid 1,1,4,4-tetrachlorobutadiene. Mid-IR gas phase data are also reported. Again the data can be satisfactorily explained under C_2h symmetry. Fourteen fundamentals can be assigned with confidence. Suggestions have been made for the frequencies of nine other fundamentals.     

The vibrational spectra of perfluoro- and perchlorobutatriene

Raman data are reported for gas, liquid and solid perfluorobutatriene, F₂CCCCF₂, and infrared data for gas and solid. They show clearly that the molecule has the expected planar structure of D_2h symmetry. With the aid of Raman depolarization ratios and infrared band contours, twelve of the seventeen spectroscopically-active fundamentals can be assigned with assurance. Frequencies are suggested for the remaining five modes.Data for perchlorobutatriene are limited to the solid state except for some depolarization measurements in solution. Again only D_2h symmetry is acceptable. About half the fundamentals can be assigned with confidence.