The Persistence of Ribbon Orbitals in Polycyclic Alkanes

✍ Scribed by Edgar Heilbronner; Evi Honegger; Werner Zambach; Peter Schmitt; Harald Günther

• Book ID: 102856755
• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: German
• Weight: 637 KB
• Volume: 67
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19840670703

✦ Synopsis

Abstract

Equivalent bond orbital (EBO) calculations by a procedure based on recalibrated, localized bond orbitals derived from an ab initio model, suggest that the two frontier ‘ribbon’ orbitals φ~HOMO~, φ~HOMO‐1~ of polycyclic hydrocarbons consisting of all‐trans‐connected six‐membered rings are well separated in energy from the remaining manifold of σ‐orbitals. Assuming the validity of Koopmans' theorem, a PE‐spectroscopic investigation of perhydroanthracenes, 2‐methylperhydrophenalene and perhydroperylene have shown that this is indeed the case. According to the theoretical treatment these ribbon orbitals are evenly delocalized over the whole of the molecular frame and they conserve the characteristic phase relationship postulated by Hoffmann et al. [16] for cyclohexane moieties. Their behaviour under the successive introduction of centres of unsaturation, i.e., of double bonds is discussed.