Mulliken’s electronegativity

Table 7 indicates the good agreement between these values and values of Mulliken s electronegativity, given according to equation (151) by... 

The electron affinity is the energy gained when an electron is added to a neutral gas-phase atom, and so Mulliken s electronegativities average the ability of a neutral atom to retain its outermost electrons and its ability to attract an additional electron to form an anion. 

The 6 -values are related to Mulliken s electronegativities X, according to Vandorffy by the equation... 

Given this double role, the simple scheme under discussion only holds for standard bonds. In cases like Na+ simply juxtaposed to the saturated system the effect can be evaluated by assuming that the potential created at the various sites by the juxtaposed charge is equivalent to an increase in Mulliken s electronegativity. Using expression (2 ), we obtain from eqn (3) the modified set of charges... 

Mulliken s electronegativity scale can be converted into Pauling s using the following relationship [24] ... 

As noted before in the literature the Lapladan V bcp of 1 electron density pbcp at the BCP is correlated to pbcp (and hence to the BV), but obviously also to the degree of bond imiicity (which can e.g. be expressed by the electronegativity or hardness differences of catimi and anion). Using absolute electronegativity differences Xdiff (in eV) based on Mulliken s electronegativity definition [19]... 

The W—W bond energy should be about one-sixth of the sublimation energy (note Section III-IB), and there are various schemes for estimating electronegativities, of which Mulliken s [151,152] is perhaps the most fundamental. 

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. 

This is true for our procedure for calculating partial atomic charges in a-bonded molecules (16). The method starts from Mulliken s definition of electronegativity, x> derived from atomic ionization potentials, IP, and electronegativities, EA (Equation 3)(17). 

Allen, L. C.J.Arn. Chem. Stic. 1989. 111,9003-9014, Acc. Client. Res. IWO,23, 173-176 A Am. Chem. Stic. 1992.114,1510-1511 Can. J. Chem. 1992,70.631-635. Note that Allen s spectroscopic electronegativity, like Mulliken s. will normally be expressed in terms of electron volts, but can he converted to the Pauling scale if desired. 

The only valid alternative, due to Mulliken, defines electronegativity as the mean of an atom s ionization potential and its electron affinity... 

Moreover, Gordy s electronegativity differences are proportional to those on the Mulliken scale also. 

E(Z, N) — E(Z, N— 1), that is from an ionization potential. Indeed it has already been seen in Section 7 that, for a neutral atom, n is in magnitude approximately half the ionization potential, for the case when the electron affinity is sufficiently small to be neglected. Mulliken s definition of electronegativity, namely... 

To allow for fluctuation of atomic electronegativities in response to the environment it has been proposed [120] that valence-state, rather than ground-state energies be used in Mulliken s formula to define orbital electronegativities. Despite common terminology, the valence state invoked here, is not the same as that of section 5.4, and refers to the improbable condition of an atom promoted to some hypothetical hybridized state. In the case of the carbon... 

Equation [33] is Mulliken s definition of electronegativity, so the linear coefficient in the Taylor series is the electronegativity of the atom. Mulliken s definition is consistent with other electronegativity scales. The second-order coefficient, j J, is the hardness of the atom, For semiconductors, the hardness is half the band gap, and r] is an important property in inorganic and acid-base chemistry. " Physically, IP - EA is the energy required to transfer an electron from one atom to another atom of the same type,... 

Through Mulliken s identification of dUldq as the electronegativity, we see that minimizing the energy with respect to the charges is equivalent to equalizing the electronegativities,... 

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... 

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