Homoconjugative bonds

E. The Electron Density Based Definition of a Homoconjugative Bond.. . 375... 

Cyclopropyl homoconjugation can be easily detected and described as long as one retains its topological definition. This also holds to some extent in the case of no-bond homoconjugation. However, as soon as one has to assess the chemical relevance of homoconjugation and to determine a homoconjugative bond (electron) delocalization energy, one needs, as mentioned in Section I, suitable reference compounds for comparison. 

D. Description of a Homoconjugative Bond by Bond Orders and Other Interaction Indices... 

The long C(1 )-C(7) distance in 18 and 19 are consistent with a homoaromatic formulation of each of these cations. However, as was pointed out in the introduction to this review, homoaromaticity requires more than just the presence of a long homoconjugate bond and there should be structural changes throughout the molecule that are consistent with cyclic delocalization. The conformations of 18 and 19 are such that there can be effective overlap of the cyclic 7t-systems95 96. 

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