Electronegativity Jaffe

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. 

To obtain a complete picture of bonding in acid-base interactions, three separate factors must be taken into account a) the electrostatic energy of the acid-base interaction b) the covalent energy of the acid-base interaction c) the energy involved when electron transfer takes place. These results were anticipated in principle on the basis of Mulliken-Jaffe electronegativity.37... 

When investigating this question, Hinze and Jaffe [3] introduced the concept of orbital electronegativity and developed a semi-empirical method to calculate the ionization potential (ly) and electron affinity, ) of any valence state. This allowed to determine electronegativity according to Mulliken s procedure taking into account the corresponding v ence states of atoms... 

Mulliken-Jaffe The method of treating electronegativities that has the firmest theoretical basis is the... 

Electronegativities Mulliken-Jaffe system. Recall that canonical forms that are low in energy and stable... 

Many of those interested in electronegativity agree that it depends on the structure of the molecule as well as the atom. Jaffe used this idea to develop a theory of the electronegativity of orbitals rather than atoms. Such theories are useful in detailed calculations of properties that change with subtle changes in structure, but we will not discuss this aspect further. The differences between values from the different scales are relatively small, except for those of the transition metals. All will give the same.results in qualitative arguments, the way most chemists use them. 

Hinze, J. and Jaffe, H.H. (1963a) Electronegativity. III. Orbital electronegativities and electron affinities of transition metals. Can. J. Chem., 41, 1315-1328. 

Recently Parr and Pearson6 have used the b parameter to investigate the hard and soft properties of metal ions and ligands. They have termed this the absolute hardness in comparison to the Mulliken-Jaffe a parameter which they call absolute electronegativity. They provide strong arguments for the use of the absolute hardness parameter in treating hard-soft acid-base (HSAB) interactions. 

Based on the idea of orbital electronegativity introduced by Hinze-Whitehead-Jaffe, in 1981 Ponec had introduced the orbital electronegativity based on the semiempirical approximation CNDO ( complete neglecting differential overlapping , the complete neglect of the differential-orbital overlap even for the orbitals belonging to the same atom) (Ponec, 1981). 

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