Zur Clar'schen Theorie Lokaler Benzoider Gebiete in Kondensierten Aromaten

Abstract

AbstractsBy means of the HMO method a postulate by Clar is justified. According to this postulate certain localized benzene-like regions exist in condensed aromatic hydrocarbons. A measure of the benzene character, butene character, etc., of certain parts of these molecules is derived and a simple method to calculate it is described. The importance of these measurements for discussions of chemical reactivity is pointed out.

Correlation of Delocalization Indices and Current‐Density Maps in Polycyclic Aromatic Hydrocarbons

“…In previous work, similar reasoning can be used to reconcile NICS and MCBI. As there is a good correlation between the MCBI and other local aromaticity indices such as the Polansky index, [58,59] the same correlations will hold for these indices, and in general it is expected that the above reasoning can be used to reconcile delocalisation based and magnetic indices. The claimed evidence for multidimensionality of aromaticity vanishes in these cases, as it is apparently only a consequence of a choice of description, in terms of rings or graph circuits.…”

Aromaticity in heterocyclic analogues of benzene: comprehensive analysis of structural aspects, electron delocalization and magnetic characteristics

“…However, his idea proved to be quite good as it has been shown by quantum similarity calculations which include for instance the Polansky index 67 or later improvements using the so-called NOEL similarity measures. 68,69,70,71 Over the years, the term aromaticity has started to be used for much more diverse classes of molecules and inevitably the meaning of the term grew thinner.…”

Local Aromaticity in Polycyclic Aromatic Hydrocarbons: Electron Delocalization versus Magnetic Indices

“…Such a partitioning into local contributions can quite straightforwardly be applied to molecular electron densities and in the past few years several density-function-based local aromaticity measures were proposed. [10] Examples in this respect are the multicenter bond indices introduced for aromaticity [11][12][13][14][15][16][17] within the framework of generalized population analysis (GPA) [18][19][20] or the Polansky similarity index, [21] recently gen-…”

“…The indices considered for the comparison involve the ring-specific sixcenter index (SCI) [11][12][13][15][16][17] from GPA [18][19][20] and the Polansky similarity index (P) [21] as representatives of local, electron density-based aromaticity measures, recently introduced circuit resonance energies (CRE) [26] as representatives of local magnetic-energetic aromaticity measures, and circuit-specific ring currents as representatives of magnetic aromaticity measures. [25] The values of the two latter types of indices were taken from the studies by Aihara [26] and Anusooya et al, [25] respectively.…”