A new electronic structure principle, viz., the principle of electrophilicity equalization isproposed. An analytical justification as well as a numerical support for the same is provided.

A local reactivity difference index R(k) is shown to be able to predict the local electrophilic and/or nucleophilic activation within an organic molecule. Together with the electrophilic and/or nucleophilic behavior of the center k given by the sign, the magnitude of the R(k) index accounts for the extent of the electronic activation, a behavior that allows for the use of the R(k) index as a measure of the molecular reactivity especially in polar processes.

T o put the 00 Electrophilicity Equalization Principle 00 in proper perspective vis-a-vis a recent criticism, a careful scrutiny is presented in this Comment. Applicability of that principle and the flaws associated with the said criticism are thoroughly analyzed with the help of the existing literature. It has been shown that although these popular qualitative electronic structure principles within a conceptual density functional theory framework are empirical in nature they do serve their purpose by unifying experimental data and identifying trends in a wide variety of systems and processes. An "Electrophilicity Equalization Principle" was proposed 1 which is recently criticized by Szentp aly. 2 A clarification is in order.In the proposition of an electrophilicity equalization principle, it was explicitly mentioned: 1

Electron affinity, electronegativity and electrophilicity of several neutral atoms and their positive and negative ions are calculated at various levels of theory using different basis sets in the gas phase as well as in the presence of solvent and counterions. Electron affinity and electronegativity of all the anions and dianions are negative in gas phase and accordingly the electrophilicity is unexpectedly large vis -a -vis its quadratic definition.Many of these trends get altered in case the effects of solvent and counterions are taken into account. of stable metal oxides or sulphides is generally explained in terms of the role played by the lattice energy and solvation energy 1,2 . Pearson 17-19 has shown that the electronegativity values are more or less same in the gas and the solution phases.However, the corresponding hardness values decrease on solvation.In the present work we calculate energy, electron affinity, ionization potential, electronegativity, hardness and electrophilicity of some selected atoms and their cations, dications, anions and dianions to analyze the electron accepting characteristics of those systems. Section 2 provides the numerical details while the results and discussion are presented in section 3. Finally section 4 contains some concluding remarks. Numerical DetailsAll the calculations are done at the HF/6-311+G(d), B3LYP/6-311+G(d) and MP2/6-311+G(d) levels of theory. The I and A values are calculated using eqs (3) and (1) respectively, χ using eq (2), η as 20 (I-A) , and ω using eq (4). We also use Koopmans' theorem to approximate I and A in terms of the appropriate frontier orbital energies.Calculations are also performed in the solution phase 21 , in the presence of counter ions as well as with different basis sets. Electrodonating (ω -) and electroaccepting (ω + ) powers 22 are also calculated in terms of µ -= -I, µ + = -A and η + = η -= η = (µ + -µ -). Results and DiscussionTables 1 and 2 present the calculation of the energy, ionization potential, electron affinity, electronegativity, chemical hardness and electrophilicity of selected atoms/ions in the gas phase and in aqueous phase respectively. The calculations are done by using the Koopmans' theorem through the energies of the associated frontier orbitals, at B3LYP/6-311+G(d) level of theory and the tables 3-5 present the energy, ionization potential, electron affinity, electronegativity, chemical hardness and electrophilicity of selected atoms/ions in the gas phase calculated from the ΔSCF using HF, MP2 and B3LYP levels of theory respectively. Koopmans' theorem can reproduce the expected trends in most cases but for Li and F. In case of Li, I value is overestimated while it is underestimated in case of F. Both cations and dications are highly electronegative and electrophilic, as expected. For anions and dianions both I and A and hence χ values are negative. It implies that they will not like to accept electrons. It may be noted that their ω values are very high which is counter-intuitive and definitely a and electron af...

Various isomers of the trigonal dianion metal clusters, X(3)(2-), X = Be, Mg, Ca, and their mono- and disodium complexes are optimized at the B3LYP/6-311+G(d) level. Different conceptual density functional theory based reactivity descriptors as well as the induced magnetic field values are calculated to understand the stability and aromaticity of these systems. Possibility of bond stretch isomerism is explored. Genetic algorithm results lend additional insights into the structures of these isomers.