Substituent effects on the electronic structure of metalloporphyrins: a quantitative analysis in terms of four-orbital-model parameters

1985 ◽  
Vol 89 (22) ◽  
pp. 4733-4739 ◽  
Author(s):  
J. A. Shelnutt ◽  
V. Ortiz
Keyword(s):  
Electronic Structure ◽  
Quantitative Analysis ◽  
Substituent Effects ◽  
Model Parameters

Substituent Effects on the Basicity of ortho-, meta- and para-substituted N1,N1-Dimethyl-N2-phenylformamidines in Ethanol and in Water

1992 ◽  
Vol 57 (1) ◽  
pp. 113-118
Author(s):  
Ewa Daniela Raczyńska
Keyword(s):  
Quantitative Analysis ◽  
Aqueous Ethanol ◽  
Substituent Effects ◽  
Amino Group

The relative δpKa values of ortho-, meta-, and para-substituted N1,N1-dimethyl-N2-phenylformamidines obtained in 95.6% aqueous ethanol have been compared with those in water. The comparison shows only some differences in the ortho substituent effects. The meta and para substituent effects in ethanol are not very different from those in water. Quantitative analysis of the experimental δpKa values based on the Taft equation has led to separation of the total electromeric effects into the inductive and mesomeric effects. As compared to the amino group in anilines, the formamidine group is more sensitive to the transmission of the inductive than the mesomeric effects.

Qualitative and Quantitative Analysis of Stacking Disorder in α-and β-SiC by X-ray Diffraction and Structure Modeling

1995 ◽  
Vol 410 ◽  
Author(s):  
Bogdan Palosz ◽  
Svetlana Stel'makh ◽  
Stanislaw Gierlotka
Keyword(s):  
Quantitative Analysis ◽  
Model Parameters ◽  
Qualitative And Quantitative Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Qualitative And Quantitative ◽  
Poisson Function ◽  
Diffraction Patterns ◽  
Computer Generation ◽  
Stacking Disorder

ABSTRACTA method of analysis of disordering in α- and β-SiC polycrystals by numerical modeling, and a simulation of X-ray diffraction profiles are presented. The diffraction patterns of nonperiodic structures were simulated for models of 2000 layer fragments of the structure. Computer generation of the models was based on the Poisson function describing the size distribution of the domains of basic polytypes and faults. The models were quantified by a set of input probability parameters describing relative frequencies of the occurrence of the domains of polytypes and faults. Implementation of a correlation parameter that characterizes coherence of sequential domains of a given polytype assures a good reproducibility of the simulated diffraction profiles obtained for the same set of the model parameters. Based on this method, a quantitative analysis of disordering in polycrystals of SiC annealed in the temperature range 1100–2200 °C was performed.

Etudes d'hétérocycles pentagonaux polyhétéroatomiques par résonance magnétique nucléaire du 13C. Thiazoles et thiazolo[2,3-e]tétrazoles

1978 ◽  
Vol 56 (1) ◽  
pp. 46-55 ◽  
Author(s):  
Robert Faure ◽  
Jean-Pierre Galy ◽  
Emile-Jean Vincent ◽  
José Elguero
Keyword(s):  
Electronic Structure ◽  
Comparative Study ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Thiazole Ring ◽  
Résonance Magnétique

Carbon-13 nmr spectra of 18 thiazoles with different substituents (R = CH3, C6H5, Cl, Br, NH2 et N3) have been recorded. The 13C chemical shifts and the nJ(C,H) coupling constants are discussed as a function of the nature of the substituent and the electronic structure of the thiazole ring. The 2-azido substituted thiazoles show azido-tetrazole isomerism, making possible a comparative study of substituent effects in thiazole and thiazolotetrazole rings. These studies have been extended to other heterocycles: benzothiazole, isothiazole, and isoxazole.

Insights into the Electronic Structure of Ceramics through Quantitative Analysis of Valence Electron Energy-loss Spectroscopy

2000 ◽  
Vol 6 (4) ◽  
pp. 297-306 ◽  
Author(s):  
Harald Müllejans ◽  
Roger H. French
Keyword(s):  
Electronic Structure ◽  
Quantitative Analysis ◽  
Energy Loss ◽  
Electron Energy ◽  
Valence Electron ◽  
Interband Transition ◽  
Ceramic Materials ◽  
Scanning Transmission Electron Microscope ◽  
Transition Strength ◽  
Electron Energy Loss

AbstractValence electron energy-loss (VEEL) spectroscopy was performed on six ceramic materials in a dedicated scanning transmission electron microscope (STEM). Quantitative analysis of these data is described yielding access to the complex optical properties and the electronic structure of the materials. Comparisons are made on the basis of the interband transition strength describing transitions between occupied states in the valence band and empty states in the conduction band. This proves that the quantitative analysis of VEEL data is a competitive and complementary method to be considered when investigating the electronic structure of materials. Possibilities for improvement and extension of the analysis are discussed extensively.

Zur Elektronenstruktur der Thiokumulene / The Electronic Structure of Thiocumulenes

1973 ◽  
Vol 28 (3-4) ◽  
pp. 188-195 ◽  
Author(s):  
Jürgen Kroner ◽  
Walter Strack ◽  
Florian Holsboer ◽  
Wolfgang Kosbahn
Keyword(s):  
Carbon Dioxide ◽  
Electronic Structure ◽  
Sulfur Dioxide ◽  
Gas Phase ◽  
Substituent Effects ◽  
Uv Spectra ◽  
Binding Energies ◽  
X Ray ◽  
The Core ◽  
Ci Calculations

The He(I) photoelectron(PE) spectra, the core binding energies according to X-ray photoelectron(ESCA) spectra, and the gas phase far UV spectra of the bent cumulenes sulfur dioxide, N-tert-butylsulnnylamine, and di-tert-butylsulfurdiimide are presented. The PE spectra are discussed by comparing them to those of the linear carbon analogues as carbon dioxide, tert-butylisocyanate and di-tert-butylcarbodiimide. Modified CNDO-CI calculations give satisfying interpretations of the substituent effects.

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