Die Wechselwirkung zwischen Walsh ‐ und π‐Orbitalen im 7‐Cyclopropyliden‐norbornadien

The qualitative analysis of the PE.‐spectrum of 7‐cyclopropylidene‐norbornadiene ( 3 ) shows that the ‘through‐space’ interaction of the e A ‐ Walsh orbital with the antisymmetric linear combination \documentclass{article}\pagestyle{empty}\begin{document}$ {{\pi _ - = (\pi _a - \pi _b)} \mathord{\left/ {\vphantom {{\pi _ - = (\pi _a - \pi _b)} {\sqrt 2}}} \right. \kern-\nulldelimiterspace} {\sqrt 2}} $\end{document} of the two π‐orbitals in 3 is of the same order as the analogous interaction between π‐ and the π‐orbital of the exocyclic double bond in 7‐isopropylidene‐norbornadiene ( 2 ).