Molecular Structure of cyclo-Octatetraene

Abstract

AN investigation of the nuclear magnetic resonance absorption spectrum of solid cyclo-octatetraene has been made with the object of obtaining information about its molecular structure. Previous determinations of the molecular structure of cyclo-octatetraene have used the techniques of infra-red and Raman spectroscopy, and of electron diffraction. The results have been explained in terms of three different molecular models : (1) the ‘crown’ (D 4) structure with alternate double and single bonds1; (2) the ‘crown’ (D 4d) structure with equivalent bonds2; (3) the ‘tub’ (D 2d) structure with double and single bonds3. Subsequent investigations have supported one or other of these models, but with no real agreement as to which is the most likely structure. Theoretical predictions of the vibrational spectra and diffraction patterns of these three molecular configurations show little difference.