Sir: r-Electron donors in a bisected conformation at the C7 (cyclopropyl) position are believed to destabilize norcaradienes either by weakening the Cl-C6 bond through HOMO- LUMO interactions'. 2 or by repulsion between filled r-electron energy level^.^ The validity of this theory not only bears on our un-derstanding of cycloheptatriene and cyclopropane properties, but also on our fundamental understanding of resonance. We now report the ...
