Topological resonance energy aromatic stabilization

A theoretical investigation of [njcydophenacenes was reported by Aihara, who discussed stability of [njcyclophenacenes with a topological resonance energy (TRE) method [10] and proposed that the cydophenacenes are aromatic and stable... 

The main difficulty with the RE concept is the hypothetical nature of the reference structure, its choice being somewhat arbitrary. There are many ways of defining RE (M. Dewar, C. F. Wilcox, and others). Here we shall briefly examine the topological resonance energy (TRE). TRE is a nonparametric index which is directly related to the topology of a molecule and is of great practical value in predicting the aromatic stability of an arbitrary jt-network. 

The topological resonance energy model has also been used to study the aromatic stabilities of the heteronins. l//-Azonine (1) and thionin (14) were predicted to be aromatic, whereas oxonin (11) was predicted to be nonaromatic <84JHC273>. Hiickel energy levels have been calculated for the neutral S5N4 ring system <80PAC1443>. 

The topological resonance energy (TRE) is considered to be a useful measure of aromatic stabil-... 

Having reproduced our old proposal, the outcome is now briefly described. According to Aihara s (1988) topological theory of aromaticity, the resonance energy per 7t electron (repe) of 5 is calculated to be 0.0274 / , or about 60% of that of benzene (0.0454 / ). It is thus clear that there is no dramatic increase in the conjugative stability in 5. As far as aromatic stabilization in the football structure is concerned it should be regarded as an extension of two-dimensional aromaticity. Aihara Hosoya (1988) call it spherical aromaticity. 

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