Die konjugative Wechselwirkung zwischen π‐ und Walsh‐Orbitalen: Das Photoelektron‐Spektrum des Homofulvens

Analysis of the photoelectron spectrum of homofulvene (1) (spiro [2.4] hepta‐4,6‐diene) confirms the conclusions previously drawn concerning the direct conjugation between π‐and Walsh‐orbitals. It is shown that the resonance integral (4) appropriate for the semi‐quantitative interaction of these orbitals amounts to −1.9 eV, i.e. nearly the value for conjugating π‐orbitals (β = −2.4 to −2.5 eV). This explains the close analogy between the photoelectron spectrum of 1 and that of fulvene.