Relations between Electronic Absorption Spectra and Spatial Configurations of Conjugated Systems. IV. Polyphenyls

The ultraviolet absorption spectra and the spatial configurations of polyphenyls have been briefly surveyed, and then the most probable spatial configurations of p-terphenyl and of o-terphenyl have been inferred from the spectra by application of the method analogous to the one for biphenyl in the first part of this series, resulting in the interplanar angle of about 10° for p-terphenyl and in that of about 43° for the o-isomer. Some related compounds have also been discussed. Further, it has been shown that the length of the “single” sp2–sp2 bond of the conjugated system depends on the extent of the π–π interaction across the bond, contrary to Dewar’s recent hypothesis.