Some aspects of the electronic spectra of 1,3‐cyclohexadiene, <i>(E)</i>‐ and <i>(Z)</i>‐1,3,5‐hexatriene

Abstract

Abstract The electronic spectra of 1,3‐cyclohexadiene, (Z) ‐ and (E) ‐1,3,5‐hexatriene were measured and interpreted. The absorptions between 220 and 280 nm in the gas phase are π → π x ‐transitions whereas the second absorption (180‐210 nm) in these compounds is considered to be a Rydberg transition. A weak π → π x ‐transition is hidden by the latter absorption in (Z) ‐hexatriene. The band in the solution spectrum of cyclohexadiene at 190 nm is thought to correspond to the band at 175 nm in gaseous cyclohexadiene. Triplet absorption spectra were measured in heavy atom solvents (CH 2 I 2 , CHBr 3 ). A scheme of energy levels is given.