Infra-Red and Raman Spectra of Polyatomic Molecules II. Cis- and Transbutene-2

Abstract

The infra‐red absorption spectra of gaseous cis‐ and transbutene‐2 have been measured with a prism spectrometer from 435 to 4000 cm^—1. The Raman spectra of these compounds as liquids have also been obtained. The accepted identification of the high boiling isomer with the cis structure is confirmed by the fact that this compound shows many more coincidences between the Raman and infra‐red spectra than the other isomer, as is to be expected if the latter approximates a molecule with a center of symmetry. The observed frequencies below 800 cm^—1 are sufficiently different for the two isomers so that it is not safe to assume that both isomers have the same vibrational entropy.