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

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.

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

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.

Interactions between Methylene Blue and Pullulan According to Molecular Orbital Calculations

2020 ◽  
Vol 140 (11) ◽  
pp. 529-533
Author(s):  
Pasika Temeepresertkij ◽  
Saranya Yenchit ◽  
Michio Iwaoka ◽  
Satoru Iwamori
Keyword(s):  
Methylene Blue ◽  
Molecular Orbital ◽  
Molecular Orbital Calculations

A pairwise additivity scheme for conformational energies of substituted ethanes

1975 ◽  
Vol 343 (1632) ◽  
pp. 1-10 ◽  
Keyword(s):  
Large Deviations ◽  
Ab Initio ◽  
Dihedral Angle ◽  
Molecular Orbital ◽  
Methyl Groups ◽  
Molecular Orbital Calculations ◽  
Linear Combinations ◽  
Strongly Interacting ◽  
Conformational Energies

Ab initio molecular orbital calculations are used to explore additivity in the conformational energies of poly-substituted ethanes in terms of conformational energies of ethane and appropriate mono- and 1,2-di-substituted derivatives. Such relations would allow complex calculations for poly-substituted ethanes to be replaced by much simpler ones on a small number of parent molecules. General expressions for the linear combinations are derived from the assumption that interactions between vicinal substituents are pairwise additive and depend only on the vicinal dihedral angle. The additivity scheme is tested for 15 ethanes, di-, tri- or tetrasubstituted by cyano and methyl groups and for a smaller number of fluoroethanes. Additivity applies to within 0.1- 0.3 k J mol -1 in the methylethanes and mostly to within about 0.7- 0.8 kJ mol -1 in cyanoethanes. Large deviations are found among the geminally substituted fluoroethanes. It is suggested that the additivity approximation is most successful in the absence of strongly interacting geminal groups. Predictions are made of conformational energies of ten hexa(cyano- and methyl-) substituted ethanes.

ChemInform Abstract: MOLECULAR ORBITAL CALCULATIONS ON THE C2H4SH+ CATION

1976 ◽  
Vol 7 (10) ◽  
pp. no-no
Author(s):  
JAMES W. GORDON ◽  
GEORGE H. SCHMID ◽  
IMRE G. CSIZMADIA
Keyword(s):  
Molecular Orbital ◽  
Molecular Orbital Calculations
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