Topological Resonance Energy Research Articles

Topological Resonance Energy of Linear Polyaeenes

Abstract A method for computation of the topological resonance energy (TRE) of linear polyacenes is described. When the length of the polyacene chain increases, TRE tends to 0.02 β units per π-electron, contrary to a previous prediction [1]. The ionization potential and the energy of the p-band of linear polyacenes are found to be excellently correlated with TRE.

On computation of the topological resonance energy

AbstractThe topological resonance energy (TRE) model was introduced independently by the Zagreb Group (in 1975) and by Aihara (in 1976). Several practical obstacles arise in the computation of TRE. Ways to surmount them are pointed out. Descriptions of algorithms, optimizations, and the efficient computer program are presented. Possible numerical instability is discussed.

Some more difficulties with topological resonance energy

It is shown that the graph-theoretically defined “topological resonance energy” is neither compatible with the quantum- chemical model (HMO) on which it is supposed to rely, nor with chemical experience.

A comparison of recent theoretical aromaticity indices

Abstract

On the construction of a hermitean matrix associated with the acyclic polynomial of a conjugated hydrocarbon

The graph-theoretical method of Aihara and Schaad et al. for construction of a hermitean matrix associated with the acyclic polynomial of a conjugatsd hydrocarbon is partially generalized. The procedure is demonstrated on a particular conjugated system with a shared edge. When applicable, the procedure leads to a numerically more convenient way of determining the topological resonance energy.

On perturbation graph theory

A perturbation theoretical formalism is developed which enables the calculation of the (topological) resonance energy of arbitrary heteroconjugated π-electron systems. The previous method of Herndon and Párkányi is thus generalized.

More difficulties with topological resonance energy

The topological resonance energy (TRE) method is not always able to predict the correct order of stability in a series of conjugated isomers. Stable, singlet ground state conjugated molecules may have considerably smaller TRE values than highly reactive polyradical isomers. Therefore the TRE method should not be used as a criterion of aromaticity of non-classical conjugated systems.

Delocalization and stability of o- and p-quinone methides: A HMO study

A series of twenty one p- and o-quinone methides has been investigated by the HMO method. Stability predictions for compounds I-XIII are based on a combination of their topological resonance energy, nucleophilic reactivity and dimerization ability. The obtained results have been verified by the synthesis of four new quinone methides IIb, Vb, VIa and VIb.

ChemInform Abstract: FAILURES OF THE TOPOLOGICAL RESONANCE ENERGY METHOD

Chemischer InformationsdienstVolume 11, Issue 44 Physical Organic Chemistry ChemInform Abstract: FAILURES OF THE TOPOLOGICAL RESONANCE ENERGY METHOD I. GUTMAN, I. GUTMANSearch for more papers by this author I. GUTMAN, I. GUTMANSearch for more papers by this author First published: November 4, 1980 https://doi.org/10.1002/chin.198044073Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume11, Issue44November 4, 1980 RelatedInformation

Topological resonance energies of conjugated ions, radicals, and ion radicals

Topological resonance energies of conjugated ions, radicals, and ion radicals

Topological Resonance Energies of Conjugated Structures

AbstractThe graph‐theoretical backbone of the topological resonance energy (TRE) concept is outlined and the connection with the Dewar resonance energy (DRE) approach is described. It appears that the TRE is not a new aromaticity index, but an optimal DRE‐like quantity of great practical value for understanding and predicting the aromatic stability of conjugated structures. In the TRE concept the most important result is the introduction of the acyclic polynomial which closely approximates the acyclic‐polyene reference structure. The rules for the construction of the acyclic (reference) polynomial are presented. Application of TRE to monocyclic systems, to polycyclic molecules and their radicals and ions, to homoaromatic systems, and to excited states is discussed. In most cases the agreement between the theory and experimental findings is good. However, in some examples the predictions appear to be inconsistent with reported data. The reasons for the occasional anomalies in the TRE are investigated. In addition, the problem of normalization of the TRE is considered.

Failures of the topological resonance energy method

The topological resonance energy (TRE) is nowadays considered as one of the most reliable indices of stability and aromaticity of conjugated molecules. Seven groups of examples are constructed showing that the TRE concept leads sometimes to obviously false chemical conclusions.

Artifact in the topological resonance energy method

It is demonstrated that for an arbitrary conjugated substituent R, the difference between the topological resonance energy (TRE) of the vinyl compound R-CHCH 2 and the allyl radical R-C(CH 2) 2 is negligibly small. Thus on the basis of the TRE method, the conjugated systems R-CHCH 2 and R-C(CH 2) 2 are predicted to have the same aromaticity. This is an artifact of the TRE method.

Topological resonance energy approach to homoaromaticity

Abstract

Difficulties with topological resonance energy

Some difficulties with topological resonance energy (TRE) are indicated. A strict application of the TRE concept pre-diets cyclobutasdiene to be significantly more aromatic than benzene. The reasons for such an obscure result are analysed. Some algebraic properties of a new graphic polynomial are derived.

Topological Resonance Energy is Real

Abstract It is proved that the zeros of the matching polynomial of a graph are real. Hence, topological resonance energy is also a real quantity.