Chemistry of syn-o,o '-dibenzene

Anew and improved synthesis cis, syn-o,o'-dibenzene 1 was developed to obta in 1 in larger amounts with improved purity, syn-Dibenzene 1 undergoes ther molysis to two molecules of benzene at a rate slower than that of the therm odynamically more stable anti-dibenzene 2. Kinetic analysis revealed that t he higher thermal stability of 1 is due to the higher heat of activation in thermolysis. Photoelectron spectroscopy of 1 showed that the through-bond interaction between the two cyclohexadiene units in o,o'-dibenzenes is more important than their through-space interaction. A comparative study on the thermolyses of related syn-o,o'arene:benzene dimers suggests that thermoly ses of syn-o,o'-arene:benzene dimers proceed via their anti-isomers as an i ntermediate. syn-Dibenzene 1 also undergoes adiabatic photolysis to one mol ecule of excited benzene and one molecule of ground-state benzene in goad e fficiency. The mechanisms of these reactions an discussed.