DFT analysis of substituent effects on electron-donating efficacy of pyridine

Hamid, Amer A. G. Al Abdel; Kanan, Sofian M.; Tahat, Ziyad A.

doi:10.1007/s11164-014-1783-6

Cited by 7 publications

(2 citation statements)

References 42 publications

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“…Atomic polar tensor (APT) [34,35] charges are one of a multitude of charge localization schemes. We discuss APT charges herein, because they have been shown to be reliable to investigate the charge density localization and delocalization, [36] e. g ., when studying substituent effects on electron‐donating efficacy of pyridine [37] . The change in the APT charges upon ionization can be thought of as the weights of the resonance structures in the cation.…”

Section: Resultsmentioning

confidence: 99%

“…We discuss APT charges herein, because they have been shown to be reliable to investigate the charge density localization and delocalization, [36] e. g., when studying substituent effects on electron-donating efficacy of pyridine. [37] The change in the APT charges upon ionization can be thought of as the weights of the resonance structures in the cation. As seen in Figure 4c, the APT charges of the methylene (CH 2 ), the ortho, and para > CH groups increase by ca.…”

Section: Aligned With the Minimum Geometry Ofmentioning

confidence: 99%

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Lutidyl Radical Photoelectron Spectra Reveal Additive Substituent Effects on Benzyl Derivatives’ Ionization Energy

et al. 2023

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Understanding how isomerism influences photoelectron spectra helps in the assignment and analysis of reactive mixtures, especially for heterocycles with numerous isomers. Threshold photoelectron spectra of lutidyl radical isomers, i. e., benzyl derivatives with a nitrogen heteroatom and a methyl substituent, are recorded using vacuum ultraviolet synchrotron radiation. The radicals are produced by flash pyrolysis from aminomethyl methylpyridine precursors. Experimental ionization energies are determined to be 7.54, 7.50, and 7.45 eV for 2,4‐, 2,6‐ and 3,5‐lutidyl, respectively, in excellent agreement with composite method calculations. Franck–Condon simulations aid the TPES assignment but are also shown to exhibit artifacts if large‐amplitude motions, notably the methyl internal rotation are assumed to be active in the double harmonic approximation. Based on calculated adiabatic ionization energies (AIE) of benzyl, picolyl, and xylyl radicals, the N and CH3 substituent effects are found to be additive, position‐dependent and decrease in the para>ortho≳meta order in magnitude with the nitrogen heteroatom increasing and the methyl substituent decreasing the AIE. These effects are discussed in light of the charge distribution upon ionization. The additivity of the substituent effects also helps predict the influence of substituents on the binding energy of the unpaired electron in analogous radicals.

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Section: Resultsmentioning

confidence: 99%

Section: Aligned With the Minimum Geometry Ofmentioning

confidence: 99%

Lutidyl Radical Photoelectron Spectra Reveal Additive Substituent Effects on Benzyl Derivatives’ Ionization Energy

et al. 2023

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Exploring chelating features of simple diacid chelates with Hg(II), Cd(II), and Pb(II) ions: theoretical study by density functional theory

Hamid

Amer²

2019

Struct Chem

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The substituent effect of π-electron delocalization in N-methylamino-nitropyridine derivatives: crystal structure and DFT calculations

et al. 2020

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The crystal and molecular structures of 3-(N-methylamino)-2-nitropyridine, 5-(N-methylamino)-2-nitropyridine and 2-(Nmethylamino)-5-nitropyridine have been characterized by X-ray diffraction. To perform conformational analysis, the geometries of the compounds as well as their conformers and rotamers were optimized at the B3LYP/6-311++G(3df,3pd) level. The resulting data were used to analyze the π-electron delocalization effect in relation to the methylamino group rotation in ortho-, metaand para-substitution positions. Quantitative aromaticity indices were calculated based on which we estimated the electronic structures of the analyzed compounds. The substituent effect of the methylamino and nitro groups was also characterized by related descriptors, i.e., charge of the Substituent Active Region (cSAR(X)) calculated based on the Hirshfeld charges and Substituent Effect Stabilization Energy (SESE). It has been shown that all the used parameters were found to be mutually interrelated with much better correlations for the metaand parathan the ortho-derivatives. The rotation of the methylamino group relative to the aromatic fragment has an effect on the change in delocalization of the π-electrons of the pyridine ring. Relations between cSAR(NHCH 3) and cSAR(NO 2) show almost identical sensitivity of the substituent effect in metaand para-substituted derivatives, whereas in ortho-substituted analogs, different kinds of intramolecular interactions have been revealed. Furthermore, the analyzed dependency of SESE values on the torsional angle of the methylamino group indicates that an increase in the electronattracting power of the substituent leads to a decrease in energy.

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DFT analysis of substituent effects on electron-donating efficacy of pyridine

Cited by 7 publications

References 42 publications

Lutidyl Radical Photoelectron Spectra Reveal Additive Substituent Effects on Benzyl Derivatives’ Ionization Energy

Lutidyl Radical Photoelectron Spectra Reveal Additive Substituent Effects on Benzyl Derivatives’ Ionization Energy

Exploring chelating features of simple diacid chelates with Hg(II), Cd(II), and Pb(II) ions: theoretical study by density functional theory

The substituent effect of π-electron delocalization in N-methylamino-nitropyridine derivatives: crystal structure and DFT calculations

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