Theoretial studies of some nonbenzenoid hydrocarbons. III. Acenaphthylene, fluoranthene, and related compounds

The molecules acenaphthylene, pyracylene, fluoranthene, acefluoranthylene, and indeno[1,2,3-cd]fluoranthene have been studied using the Pariser–Parr–Pople semi-empirical SCF MO method with the core resonance integral value developed by Lo and Whitehead and Dewar etal. It has been found that with this core resonance integral value developed for the prediction of ground state properties, π* ← π spectral transitions can also be predicted with reasonably good accuracy and the results are also compared with those calculated by using the core resonance integral value proposed by Yamaguchi etal. The resonance stabilization of acefluoranthylene and indeno[1,2,3-cd]fluoranthene has been studied. The attachment of a vinyl linkage at the 1,8 centres of naphthalene, or similar attachment to anthracene and phenanthrene, reduces the resonance energy below that of the parent compounds. The resonance stabilization has been predicted for aceanthrylene and acephenanthrylene.All the molecules studied here have acenaphthylene moiety and it would be interesting to see whether there is any similarity in properties between acenaphthylene and other molecules or how the properties change with the introduction of benzene nucleus or ethylinic linkage or both in acenaphthylene moiety.