The alternation of bond lengths in large conjugated molecules. III. The cyclic polyenes C18H18, C24H24 and C30H30

Abstract

Abstract A theoretical study of the observed visible and ultra-violet spectra of C18H18, C24H24 and C30H30 indicates strongly that in these molecules the C—C bonds alternate in length. It is shown, furthermore, that the diamagnetic anisotropies and proton chemical shifts should indicate very sensitively the extent of bond alternation; as yet no measurements on these properties are available.