Chemistry of Benzene-Anthracene Cyclodimers

Article abstract of DOI:10.1021/ja00336a003

Synthesis of the formal <4?_s + 4?_s> and <4?_s + 2?_s> adducts of benzene and anthracene (1 and 2) has made possible the observation of features on the potential-energy surfaces that govern Woodward-Hoffmann-allowed and -forbidden cycloreversions.The thermal dissociation of 1 is not chemiluminescent in spite of favorable kinetic and thermodynamic parameters, and its photochemical dissociation yields excited anthracene in very high efficiency (Φ_An* = 0.80).The enthropy of activation in the thermal dissociation of 2 is negative, and the photochemical dissociation of 2 yields excited anthracene in low but appreciable efficiency (Φ_An* = 0.08).Comparision of these data clearly demonstrates orbital symmetry control of both the ground- and excited-state reactions.