Szentpaly

L. V. Szentpaly, R. Ghosh, Theoretical Organic Chemistry 447 C. Parkanyi, Ed., Elsevier, Amsterdam (1998). 

Szentpaly, L.V. 1984. Carcinogenesis by polycyclic aromatic hydrocarbons a multilinear regression on new type PMO indices. Jour. Amer. Chem. Soc. 106 6021-6028. 

Attempts to account for this bending have emphasized two physical effects, (1) d-orbital participation,18 and (2) core polarization,19 but no clear theoretical consensus has been achieved. The calculated bending in BaH2, for example, is found to disappear with removal of either d-orbitals or a polarizable-core, suggesting that both aspects are operative. The adequacy of the core-polarization rationale was questioned, and an alternative rationalization based on differences in atomic softness between metal and ligand was proposed by Szentpaly and Schwerdtfeger.20... 

FIGURE 13.2 Correlation between electrophilicity index and EA of 54 neutral atoms and 55 simple molecules in the ground-state parabola model. (Reprinted from Parr, R.G., Szentpaly, L.V., and Liu, S.B., J. Am. Chem. Soc., 121, 1922, 1999. With permission.)... 

The wide scope of application of the electrophilicity index of Parr, Szentpaly, and Liu has been reviewed.1 Applications to electrophilic aromatic substitutions discussed are few. However, some alkylation and acylation reactions do correlate well with electrophilicity values. In the case of the nitration of toluene and chlorobenzene, correlation is not very good and it is suggested2 that electrophilicity is a kinetic quantity with inherent thermodynamic information. 

More recently, correlations of a values with purely topological reactivity indices, vie. structure count ratio and Dewar reactivity number have been extensively studied by v. Szentpaly and Herndon [33, 58], Rather satisfying correlations were obtained the correlation coefficients for obvious reasons (see Sect. 4) being nearly identical for both indices (0.959 and 0.960 respectively, sample size 27). A significant improvement was achieved with Dewar reactivity numbers calculated according to the free electron version of the PMO treatment (correlation coefficient r = 0.973). 

Most of the more previous attempts to correlate carcinogenic potency with structural features of benzenoid hydrocarbons are related to the mechanism outlined above. The different quantitative models that have been developed can be distinguished with regard to the number of independent variables. One-variable theories (e.g. the so-called bay-region theory [94]) are normally inferior compared to two- [95] and three-variable theories which refer more explicitely to the different and partly competing metabolic reaction pathways. A particularely efficient model has been developed by v. Szentpaly [96]. In his so-called MCS model three important influences on carcinogenic potency are taken into account M, the initial epoxidation... 

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