Calculated electrostatic potentials and local surface ionization energies of para-substituted anilines as measures of substituent effects

Autor:	Tore Brinck, Jane S. Murray, Markus Haeberlein, Peter Politzer
Rok vydání:	1992
Předmět:	Chemistry Organic Chemistry Substituent Thermal ionization chemistry.chemical_element General Chemistry Ring (chemistry) Nitrogen Catalysis chemistry.chemical_compound Computational chemistry Amine gas treating Molecular orbital Ionization energy Lone pair
Zdroj:	Canadian Journal of Chemistry. 70:2209-2214
ISSN:	1480-3291 0008-4042
DOI:	10.1139/v92-277
Popis:	Using an abinitio self-consistent-field molecular orbital approach, we computed 3-21G//STO-3G* and STO-5G//STO-3G* electrostatic potentials and average local ionization energies for 17 para-substituted anilines. Our results demonstrate that the most negative potentials (Vmin) and the local surface ionization energy minima (ĪS,min) associated with the amine nitrogen lone pairs are highly sensitive indicators of the electron-donating and electron-attracting tendencies of the para substituents. We find excellent linear relationships between the 3-21G//STO-3G* amine nitrogen Vmin and ĪS,min and the σp0 Hammett constants of the substituent X; the correlation coefficients are 0.99. Correlations of slightly lesser quality are shown to exist between Vmin, ĪS,min, and σp−, σp, and pKa. Estimates of previously unknown σp0 and pKa values are given. The presence of ring carbon ĪS,minmeta to the substituent X also provides a predictive capability for determining σm values.
Databáze:	OpenAIRE
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