Electronegativity index

Fig. 4. Plot of barriers to nitrogen inversion versus the Pauling electronegativity index of various substituents linked to nitrogen. The compound taken as reference is indicated by its number (see Tables 2—5) and the changing substituent is given in parentheses. One could also have used the sum of the electronegativities of all three substituents on nitrogen...

First, on the associate symbol, one could remark that the electronegativity index was historically assigned by X while the chemical hardness, which in above chemical bonding phenomenology follows the electronegativity equalization principle, should be identified by letter Y . Other literal argument was offered elsewhere (Putz, 2008b). 

When the electronegativity index is considered in Eq. (4.18) the electronegativity-based absolute aromaticity is obtained with the working form... 

Kier and Hall noticed that the quantity (S -S) jn, where n is the principal quantum number and 5 is computed with Eq. (2), correlates with the Mulliken-Jaffe electronegativities [19, 20]. This correlation suggested an application of the valence delta index to the computation of the electronic state of an atom. The index (5 -5)/n defines the Kier-Hall electronegativity KHE and it is used also to define the hydrogen E-state (HE-state) index. 

The Kier-Hall electronegativity is used to define the HE-state index HS [19] ... 

Wiener-type index from Z weighted distance matrix (Barysz matrix) Wiener-type index from mass weighted distance matrix Wiener-type index from van der Waals weighted distance matrix Wiener-type index from electronegativity weighted distance matrix Wiener-type index from polarizability weighted distance matrix Balaban J index... 

As has just been described, when a covalent bond forms between two atoms, there is no reason to assume that the pair of electrons is shared equally between the atoms. What is needed is some sort of way to provide a relative index of the ability of an atom to attract electrons. Linus Pauling developed an approach to this problem by describing a property now known as the electronegativity of an atom. This property gives a measure of the tendency of an atom in a molecule to attract electrons. Pauling devised a way to give numerical values to describe this property that makes use of the fact that the covalent bonds between atoms of different electronegativity are more stable than if they were purely... 

This shows that the change 8Fg is independent of the sign of the electronegativity change produced by the substituent group, a result in accord with the experimental flndings mentioned in Section IIB, and lends support to the notion that Fg is a useful index for free radical attack. 

The stability of a metalloporphyrin can be roughly estimated by the charge-to-radius ratio (Z/yj). Buchler et al 1 found that the stability index, SI = 100(ZAr/yj), where X is the Pauling electronegativity, predicts the stability of a metalloporphyrin to acid demetallation, and correlated the SI to the Falk-Phillips stability criteria (Table 2). 

The chromatographic capacity factor (AT ) for ester and amide derivatives of 6,6a, 7,8,9,10,10a, 11-octahydro-ll-oxodibenzo[ /]thiepine propionic acid 44, potent antiinflammatory agents, has been studied, since the parameter was widely used for the interpretation of the activity of drugs <2003RRC795>. K, was modeled topologically using molecular redundancy index (MRI), equalized electronegativity (xeq), and van der Waals volume (fw)-... 

As explained above, an encapsulation of all the atomic details is needed in order to express the NMR tensors in terms of functional quantities embedded into an inalterable theoretical frame. It is our feeling that this encapsulation is best done using the two dyads which are electronegativity/hardness on one hand, and partial charge/frontier indexes on the other hand. 

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