Hiickel resonance energy

Earlier definition of resonance energies comes down to an evaluation of the QMRE within the framework of the Hiickel MO method (HMO) (61MI1 75MI1 86MI1). Hiickel resonance energy (HRE) is defined as... 

We may perform the same analysis for the allyl radical and the allyl anion, respectively, by adding the energy of 4>2 to the cation with each successive addition of an electron, i.e., H (allyl radical) = 2(a + V2/3) + a and Hn allyl anion) = 2(a + s/2f) + 2a. In the hypothetical fully 7T-localized non-interacting system, each new electron would go into the non-interacting p orbital, also contributing each time a factor of a to the energy (by definition of o ). Thus, the Hiickel resonance energies of the allyl radical and the allyl anion are the same as for the allyl cation, namely, 0.83/1. 

Ichikawa, H. and Ebisawa, Y., Hartree-Fock MO theoretical approach to aromaticity. Interpretation of Hiickel resonance energy in terms of kinetic energy of ti electrons, J. Am. Chem. Soc. 107, 1161-1165 (1985). 

Hiickel resonance energy delocalization degree indices Hiickel s rule delocalization degree indices... 

The fourth approach is to use derivatives of odd-alternant hydrocarbons, such as the phenalenium radical, in which the Hiickel resonance energy is the same for the anion, the radical, and the cation, because the HOMO is a non-bonding MO [43,44]. However, the radicals seem too reactive. 

The reference structure is a nonexisting entity and can be chosen in different ways. This has led to various resonance energies namely Hiickel Resonance Energy (HRE), Dewar Resonance Energy (DRE), Topological Resonance Energy (TRE), and so on. TRE [60] has been extensively used as a measure of aromaticity and is defined as follows ... 

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