Unimolecular dissociation of primary alkanediazonium ions. Ab initio and semiempirical molecular orbital calculations

1986 ◽  
Vol 108 (17) ◽  
pp. 5104-5108 ◽  
Author(s):  
George P. Ford
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Unimolecular Dissociation ◽  
Semiempirical Molecular Orbital

CNDO/2 Calculations for Organohalides

1986 ◽  
Vol 39 (2) ◽  
pp. 233 ◽  
Author(s):  
TH Spurling ◽  
DA Winkler
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Organic Molecules ◽  
Molecular Orbital Calculations ◽  
Semiempirical Molecular Orbital

A CNDO/2 parameterization for performing semiempirical molecular orbital calculations for organic molecules containing bromine and iodine is presented; the results are superior to those from other parameterizations, and generally agree with ab initio calculations and experiment.

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.

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