Partitioning of π-electrons in rings of diaza-derivatives of acenes

Abstract

A few years ago, a method was proposed for assessing the π-electron content (EC) of rings in heteroatom-containing benzenoid molecules. In this work, the effect of two nitrogen atoms at the opposite sides of a linear benzenoid molecule on the partitioning of its π-electrons was investigated. The results obtained can be explained by means of resonance-theoretical arguments.

On π-electron conjugation in the five-membered ring of fluoranthene-type benzenoid hydrocarbons

“…The ef-values of the five-membered ring follow the increase of the number of PCP constellations. Note, however, that the ef-value in F 16 is signifycantly greater than in the case of F 13 , although both F 13 and F 16 have an equal number of PCP constellations. Fig.…”

“…Our recent theoretical studies 1-6 of fluoranthene-type benzenoid hydrocarbons (FTBHs) were motivated by the fact that whereas the π-electron properties of ordinary benzenoid hydrocarbons have been investigated for almost an entire century (see the books, 7-9 the reviews, 10-13 the recent papers, [14][15][16][17][18] and the references cited therein), the paper 1 seems to be the very first systematic research of FTBHs.…”

Verifying the PCP-rule by five-center bond indices

“…The theory of benzenoid hydrocarbons 1,2 is nowadays one of the best developed areas of theoretical organic chemistry. Motivated by recent progress in this field (see the papers [3][4][5][6][7] and the references quoted therein), a systematic study [8][9][10] of a class of polycyclic conjugated systems closely related to benzenoid hydrocarbons, the acenaphthylenes and fluoranthenes, was undertaken. These differ from "true" benzenoids by possessing a five-membered ring; for examples see Fig.…”

“…1. Acenaphthylene (1) and some of its congeners (2-4), and fluoranthene (5) and some of its congeners (6)(7)(8)(9)(10)(11)(12)(13)(14). Data on the cyclic conjugation in the 5-membered ring of these compounds are given in Table I.…”