scholarly journals Study of Substituent Effects and Correlations of Molecular Ionization Energies of Some Organic Compounds

2017 ◽  
Vol 6 (12) ◽  
pp. 1187-1194
Keyword(s):  
Organic Compounds ◽  
Substituent Effects ◽  
Ionization Energies ◽  
Molecular Ionization

Transmission of Electronic Effects in Substituted Pyridine-N-Oxides Studied by ESCA

1976 ◽  
Vol 31 (7) ◽  
pp. 856-857 ◽  
Author(s):  
G. Distefano ◽  
G. Spunta ◽  
F. P. Colonna ◽  
S. Pignataro
Keyword(s):  
Organic Compounds ◽  
Aromatic Ring ◽  
Solid Phase ◽  
Substituent Effects ◽  
Electronic Effects ◽  
Ionization Energies ◽  
The Subject ◽  
Aromatic Systems ◽  
Reported Data ◽  
Steric Inhibition Of Resonance

Abstract Since the first electron spectroscopic (ESCA) studies dealing with substituents effects upon core ionization energies (I.E.) of organic compounds1, little has been published on the subject. This was probably because the reported data did not always seem very meaningful. The absolute I.E. values obtainable in the solid phase are not very certain and also, the "shake-up" phenomena and the consequent broadening of the bands, which affect the I.E. values2, were not always taken into account. None the less we think that ESCA is a valuable tool for the study of substituent effects, and in particular of the transmission of electronic effects in aromatic systems. Previous work in this area has been published 2,3 , and more specifically an example of steric inhibition of resonance observed by means of ESCA I.E.'s and shake up data was recently reported4. Here we would like to report a further case in which the transmission of electronic effects through an aromatic ring is observed using ESCA.

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

1992 ◽  
Vol 70 (8) ◽  
pp. 2209-2214 ◽  
Author(s):  
Markus Haeberlein ◽  
Jane S. Murray ◽  
Tore Brinck ◽  
Peter Politzer
Keyword(s):  
Substituent Effects ◽  
Correlation Coefficients ◽  
Electrostatic Potentials ◽  
Surface Ionization ◽  
Local Surface ◽  
Substituted Anilines ◽  
Amine Nitrogen ◽  
Ionization Energies ◽  
Linear Relationships ◽  
Self Consistent Field

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.

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