Equalization of electronegativity

The idea of electronegativity has always interested chemists and there have been many scales published, which can be categorized into one- and two-parameter models. The two-parameter models assume equalization of electronegativities, i.e., charge is transferred between the atoms until they have the same electronegativity. 3.2 3,2 7 single-parameter models use other devices (including hybridization,... 

Returning to the electronegativity equalization principle within density functional formalism, it can be extended to the orbital equalization of electronegativity, as starting from the stationary equation of the atoms-in-molecule energy this will be in next exposed, by starting with a new definition of AIM. 

FIGURE 3.2 Orbital energy diagram for a molecule (Pearson, 1987), showing the electronegativity and hardness, on which basis the equalization of electronegativity and hardness principles, EE and HSAB respectively follows. 

To become familar with the algorithm for charge calculation by partial equalization of orbital electronegativity (PEOE) and by a modified Hiickel Molecular Orbital method... 

At the outset of the Partial Equalization of Orbital Electronegativities (PEOE) method [28] is the electronegativity concept in the form of Eq. (11) presented by Mulliken, who put it on a sound theoretical basis [29]. 

Figure 7-4. The procedure for Partial Equalization of Orbital Electronegativities (PEOE).

The PEOE method leads to only partial equalization of orbital electronegativities. Thus, each atom of a molecule retains, on the basis of Eq. (12), a residual electronegativity that measures its potential to attract further electrons. It has been shown that the values of residual electronegativities can be taken as a quantitative measure of the inductive effect [35]. 

Gasteiger J and M Marsili 1980. Iterative Partial Equalization of Orbital Electronegativity - Rapid Access to Atomic Charges. Tetrahedron 36 3219-3288. 

For other elements the same dependence of electronegativity will be assumed that is, a change by 0.2 z for electric charge z, increase by 0.3 for sp3 bond orbitals (relative to p bonds), and an equal decrease for d character in transargononic bonds. 

Gasteiger, J., Marsili, M. Iterative partial equalization of orbital electronegativity - a rapid access to atomic charges. Tetrahedron 1980, 36, 3219-3228. 

Nalewajski RF (1991) Normal (decoupled) representation of electronegativity equalization equations in a molecule. Int J Quant Chem 40(2) 265—285... 

Grant, J. A., R. L. Williams, and H. A. Scheraga. 1990. Ab Initio Self-Consistent Field and Potential-Dependent Partial Equalization of Orbital Electronegativity Calculations of Hydration Properties of N-Acetyl-N -Methyl-Alanineamide. Biopolymers 30, 929-949. 

No, K. T., J. A. Grant, M. S. Jhon, andH. A. Scheraga. 1990. Determination of Net Atomic Charges Using a Modified Partial Equalization of Orbital Electronegativity Method. 2. Application to Ionic and Aromatic Molecules as Models for Polypeptides, J. Phys. Chem. 94, 4740-4746. 

An extension of the above method was developed for conjugated it-systems Partial Equalization of Pi-Electronegativity (PEPE)47,48). After calculation of the charge distribution in the a-skeleton, the various resonance structures of a it-system are generated. The 7t-charge distribution is obtained by assigning weights to these... 

Probably the most important use of electronegativity values is in predicting bond polarities. For example, in the H-F bond, the shared electron pair will reside closer to the fluorine atom because it has an electronegativity of 4.0 while that of the hydrogen atom is 2.2. In other words, the electron pair is shared, but not equally. If we consider the HC1 molecule, the shared electron pair will reside closer to the chlorine atom, which has an electronegativity of 3.2, but the electron pair will be shared more... 

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