ENERGY LEVELS OF TRIARYLMETHYL CARBONIUM IONS

1964 ◽  
Vol 42 (4) ◽  
pp. 810-817 ◽  
Author(s):  
E. K. Ng ◽  
F. C. Adam
Keyword(s):  
Molecular Orbital ◽  
Energy Levels ◽  
Fluorescence Band ◽  
Molecular Orbital Calculations ◽  
Structure Representation ◽  
Near Ultraviolet ◽  
Carbonium Ions ◽  
Visible Spectra ◽  
Made In

The near ultraviolet and visible spectra of the various phenyl-, p-biphenyl methyl carbonium ions have been investigated and the polarization of the absorptions relative to the fluorescence band have been determined. An assignment of the transitions is made, using as a basis simple molecular orbital calculations and the expectations based on the structure representation. These are compared to the assignments made in earlier researches. The calculated intensities are found to agree favorably with the observed values.

Extended Hückel molecular orbital calculations on some titanium–oxygen systems

1968 ◽  
Vol 46 (16) ◽  
pp. 2667-2674 ◽  
Author(s):  
Yu-Ping Hsia
Keyword(s):  
Molecular Orbital ◽  
Energy Levels ◽  
Molecular Orbital Calculations ◽  
X Ray ◽  
Near Ultraviolet ◽  
Extended Hückel ◽  
Self Consistent ◽  
X Ray Absorption ◽  
Tetragonal Batio ◽  
Absorption Edges

Extended Hückel molecular orbital calculations have been performed on localized TiO68− units with the precise geometry of such a unit in solid rutile, anatase, and brookite TiO2 and tetragonal BaTiO3. The relative values of one-electron energy levels in these compounds are obtained in terms of a "self-consistent" charge and population calculation. Examination of the resulting energy levels and charge distributions has led to reasonable explanations of previously unexplained data on (1) the visible and near-ultraviolet absorption spectra of these compounds, (2) the low energy X-ray absorption edges of rutile, anatase, and brookite TiO2, and (3) the pressure dependence of the absorption edges of rutile TiO2 and tetragonal BaTiO3.

Molecular Orbital Calculations of Cu-Halides

1981 ◽  
Vol 36 (10) ◽  
pp. 1095-1099 ◽  
Author(s):  
H. Itoh
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Energy Levels ◽  
Basis Set ◽  
Orbital Energy ◽  
Ionic Character ◽  
Molecular Orbital Calculations ◽  
Ab Initio Hf ◽  
Mo Theory

An ab initio HF MO theory is applied to CuX, CuX2 (X = F and Cl) and (CuCl)3 . Although the detailed sequence of energy levels depends upon the basis set used, high-lying orbital energy levels have largely halogen p-like character, whereas low-lying orbital energy levels have largely Cu 3 d-like character. This is in agreement with the chemical intuition of a highly ionic character of these compounds.

Molecular orbital calculations on carbonium ions. II. Methyl, ethyl, and vinyl cations. The series C3H7+

1969 ◽  
Vol 91 (19) ◽  
pp. 5350-5357 ◽  
Author(s):  
Reiner Sustmann ◽  
James E. Williams ◽  
M. J. S. Dewar ◽  
Leland Cullen Allen ◽  
Paul von Rague Schleyer
Keyword(s):  
Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Methyl Ethyl ◽  
Carbonium Ions

Structure électronique et réactivité des pyridyl-isothiocyanates. Étude quantique et photoélectronique

1986 ◽  
Vol 64 (8) ◽  
pp. 1467-1473 ◽  
Author(s):  
C. Guimon ◽  
G. Pfister-Guillouzo ◽  
D. Ilavsky ◽  
M. Marchalin ◽  
A. Martvon
Keyword(s):  
Molecular Orbital ◽  
Photoelectron Spectroscopy ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Molecular Orbital Calculations ◽  
Frontier Orbitals ◽  
Secondary Interactions ◽  
Made In ◽  
Structure Electronique

On the basis of molecular orbital calculations made in association with ultraviolet photoélectron spectroscopy (ups), it is demonstrated that the regioselectivity of the cycloadditions of pyridyl-2-isothiocyanate with 1,3-dipoles is directed by frontier orbitals. The different cycloadditions (4 + 2, 2 + 3, 2 + 2) vary with the overlap of these orbitals and this shows the importance of secondary interactions, namely the localization of the orbitals on the atoms adjacent to the bonds that are formed during the addition.

Molecular orbital calculations on carbonium ions. III. Barriers in ethyl cations

1970 ◽  
Vol 92 (7) ◽  
pp. 2141-2143 ◽  
Author(s):  
James Earl. Williams ◽  
Volker. Buss ◽  
Leland Cullen. Allen ◽  
Paul von R. Schleyer ◽  
William A. Lathan ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Carbonium Ions

An Ab Initio Molecular Orbital Study of Sulfur-Substituted Carbanions: Toward an Understanding of Regiochemistry in the Chlorination of Unsymmetrical Sulfides

1997 ◽  
Vol 50 (6) ◽  
pp. 517 ◽  
Author(s):  
Jack Leon Ginsburg ◽  
Katherine Valenta Darvesh ◽  
Patricia Axworthy ◽  
Richard Francis Langler
Keyword(s):  
Free Radicals ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Dimethyl Sulfide ◽  
Experimental Results ◽  
Molecular Orbital Calculations ◽  
Molecular Orbital Study ◽  
Carbonium Ions ◽  
Moller Plesset ◽  
Better Than

Moller-Plesset molecular orbital calculations at the 6-31+G(d) level have been completed on substituted dimethyl sulfide-derived carbanions. The results are applied to the prediction of regiochemistry for chlorination of unsymmetrical sulfides. Notwithstanding the need for future improvements, regiochemical predictions based on stabilities of sulfur-substituted carbanions match experimental results better than earlier predictions based on stabilities of sulfur-substituted carbonium ions or sulfur-substituted free radicals. The present results suggest that the mechanism for the elimination step in the Pummerer rearrangement of a chlorosulfonium cation is an E 1cb-like process.

An ab initio Molecular Orbital Study of Bonding in Fluorocarbonium Ions

1971 ◽  
Vol 49 (22) ◽  
pp. 3708-3713 ◽  
Author(s):  
N. C. Baird ◽  
R. K. Datta
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Basis Set ◽  
Molecular Orbital Calculations ◽  
Minimal Basis ◽  
Fluorine Substitution ◽  
Abstraction Reaction ◽  
Carbonium Ions ◽  
Hydride Abstraction ◽  
Resonance Stabilization

Ab initio molecular orbital calculations are reported for the series of carbonium ions (CH3)+, (FCH2)+, and (F2CH)+ and for their neutral molecule counterparts CH4, CH3F, and CH2F2. The energies and wavefunctions for the carbonium ions have been calculated both with and without including the carbon 2pπ orbital in the minimal basis set in order to unravel the inductive destabilization and resonance stabilization due to fluorine substitution. The increase in bonding energy with multiple fluorine substitution is less than linear, due primarily to nonadditivity in the dative carbon–fluorine π bonding. The "saturation" effect noted previously for the hydride abstraction reaction enthalpies is shown to be due primarily to stability effects in the neutral molecules themselves rather than to energetic effects of the carbonium ions.

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