I. The synthesis and spectroscopy of a series of 1,3-diaryl-1,3-cyclopentadiyls and 1,4-diarylbicyclo[2.1.0]pentanes. II. Progress toward the synthesis of non-Kekulé naphthalene, a series of tetramethyleneethanes, and bi(cyclobutadienyl)
1,4-Diarylbicyco[2.1.0]pentanes 6-XY were prepared from the corresponding diazenes by thermolysis. Variable temperature NMR reveals that para substituents have only small effects on the free energies of activation at coalescence in the bridge-flip reaction. The effects correlate with the Hammett par...