Methyl-substituted cyclopropylcarbinyl (alias vinyl-bridged ethylene) carbocations. Molecular orbital calculations and criteria for structure representation-nomenclature decisions

1982 ◽  
Vol 104 (9) ◽  
pp. 2605-2612 ◽  
Author(s):  
Lawrence R. Schmitz ◽  
Ted S. Sorensen
1964 ◽  
Vol 42 (4) ◽  
pp. 810-817 ◽  
Author(s):  
E. K. Ng ◽  
F. C. Adam

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.


2020 ◽  
Vol 140 (11) ◽  
pp. 529-533
Author(s):  
Pasika Temeepresertkij ◽  
Saranya Yenchit ◽  
Michio Iwaoka ◽  
Satoru Iwamori

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.


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

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