LOCAL AROMATICITY IN BENZO- AND BENZOCYCLOBUTADIENO-ANNELATED PERYLENES
S.Marković, I.Gutman, N.Simić (UDC: 547.62:544.424.032.1)
The effects of benzo- and benzocyclobutadieno- (BCBD-) annelation on the local aromaticity of the central ring X of perylene were examined. The local aromaticity of the ring X was estimated using a graph-theory based index, ef, and two geometry-based indices, HOMA and Σ. The findings resulting from the application of the ef index are to some extent contradictory to those obtained on the basis of HOMA and Σ. Namely, the geometry-based indices indicate that the effect of benzo-annelation is opposite to that of BCBD-annelation, whereas ef predicts that angular BCBD-annelation has very little influence to the local aromaticity of the central ring of perylene. Since the geometry-based indices are more sophisticated than the graph-theory-based index, one should conclude that the predictions emanating from the application of HOMA and Σ are more reliable.