Homoconjugation chemical

Stabilization of the systems due to homoconjugation is discussed. 13C and nB NMR chemical shifts of the compounds were also calculated using the individual gauge for localized orbitals (IGLO) method <2000JOC5956>. 

Further reduction in R leads to the point Rc (Figure 3) at which the bond is fully formed and normal cyclopropyl substituent interactions occur. Homoconjugation ceases to be a relevant chemical factor at point Rc and the molecule can be adequately described in terms of a cyclopropyl substituted system. 

Since conjugation and homoconjugation are parallel concepts, it is logical to base a chemically relevant definition of homoconjugation on the concept of bond (electron) delocalization ... 

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. 

Homoaromaticity as a chemical concept is based on the concepts of aromaticity and homoconjugation. In its simplest form aromaticity is an electron counting concept. Thus if there are 4q + 2 7t-electrons in a planar (or nearly planar) cyclic system, then this is considered to be aromatic. ... 

With the increasing possibilities of doing semi-empirical or even small basis set ab initio calculations on homoconjugated compounds, PMO theory was used both to predict and to rationalize the results of quantum chemical calculations on potentially homoaromatic... 

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