Ground states of .sigma.-bonded molecules. XIV. Application of energy partitioning to the MINDO [modified intermediate neglect of differential overlap] /2 method and a study of the Cope rearrangement

Dewar, Michael J. S.; Lo, Donald H.

doi:10.1021/ja00755a014

Cited by 186 publications

(54 citation statements)

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“…[4] Hoffmann and Stohrer [5] and Dewar and Lo [6] predicted substitution patterns for semibullvalenes that would lower and eventually abandon this energy gap, and thus result in stable delocalized, bishomoaromatic semibullvalenes. [7] A similar formal mutation of shallow degenerate double-well potentials into single-minimum systems is known from the pyramidal inversion of ammonia and its derivatives.…”

Section: Dedicated To Professor William Von Eggers Doering On the Occmentioning

confidence: 99%

The Equilibrium between Localized and Delocalized States of Thermochromic Semibullvalenes and Barbaralanes—Direct Observation of Transition States of Degenerate Cope Rearrangements

Quast

Seefelder

1999

Angew. Chem. Int. Ed.

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The UV/Vis spectra of thermochromic semibullvalenes 1 and barbaralanes recorded at various temperatures yield enthalpy differences between the two degenerate classical structures 1 and 1' and the less stable species (1*) that absorb at long wavelengths. The latter species are interpreted in terms of higher, delocalized states that are located just above the flat potential energy barrier between the ground states (ΔH(0) =11 (R=H; in butyronitrile), 1 kJ mol(-1) (R=Ph)).

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Section: Dedicated To Professor William Von Eggers Doering On the Occmentioning

confidence: 99%

The Equilibrium between Localized and Delocalized States of Thermochromic Semibullvalenes and Barbaralanes—Direct Observation of Transition States of Degenerate Cope Rearrangements

Quast

Seefelder

1999

Angew. Chem. Int. Ed.

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“…This scheme was applied by Nagase et al [38] in the study of strongly interacting systems. Other partitioning schemes were proposed for the SCF energy of a molecular system, within a semiempirical formalism (Fischer and Kollmar [39] and Dewar and Lo [40]) or an ab initio formalism (Kollmar [41]). …”

Section: Swain and Luptonmentioning

confidence: 99%

“…In this work, the orbital energies are subjected to a partitioning scheme similar to those proposed by Fischer and Kollmar [39] or Dewar and Lo [40] for the total energies. To gain a further understanding of the substituent effect, the separate partitioning of the kinetic and potential energies is attempted here.…”

Section: Swain and Luptonmentioning

confidence: 99%

Theoretical study of ionization potentials in monosubstituted benzenes

Melo

Gomes

1993

Int J of Quantum Chemistry

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Monosubstituted benzenes, in which the substituents participate in the w-electron system, are studied following a classification in two classes according to the w-electronic structure of the substituent. For this type of molecule, a relation is established between the nature of the substituent and, on the one hand, the energies of the two highest occupied molecular orbitals and, on the other hand, their respective differences. The two orbitals referred to above have Ir-character and belong to the a2 and bl species if a C2" point group is assumed. Simple symmetry arguments lead to the conclusion that the a2 orbitals have, essentially, an intraring character, whereas the Ir-orbitals of the substituents do give an important contribution to the bl orbitals. Therefore, an a2 electron must have a larger interaction with the benzene ring and a smaller kinetic energy, whereas a bl electron must have a larger interaction with the substituent and a larger kinetic energy. It is also expected that the changes in the w-electronic structure of the substituent must much more influence the variations on the bl energies and on the components of orbital energies associated with the substituent than the variations on the a2 energies and on the intraring components of the orbital energies. A modified version of the MOPAC program was prepared to perform the decomposition of the orbital energies in their kinetic and potential energy components and these in their monocentric and bicentric terms.MNDO calculations on nine monosubstituted benzenes, using the modified MOPAC program, give good confirmation of the symmetry predictions and prove the consistency of the classification of the substituents that is introduced.

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“…With exception of a recent density functional approach [38], ab initio investigations had been restricted to the R 0 configuration at the PES minimum [39,40]. The degenerate Cope rearrangement in bullvalene and other hydrocarbons had been studied extensively by Dewar and co-workers with the help of semiempirical self-consistent field (SCF) methods [41,42]. Rather new many-determinantal expansions for 1,5-hexadiene have reproduced the Dewar picture of a closed-shell aromatic transition state (TS) [43].…”

Section: Introductionmentioning

confidence: 99%

On the influence of vibrational modes and intramolecular isomerization processes on the NMR parameters of bullvalene: A Feynman path integral – ab initio investigation

Böhm

Ramı́rez²,

Schulte³

2007

Chemical Physics

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Ground states of .sigma.-bonded molecules. XIV. Application of energy partitioning to the MINDO [modified intermediate neglect of differential overlap] /2 method and a study of the Cope rearrangement

Cited by 186 publications

References 1 publication

The Equilibrium between Localized and Delocalized States of Thermochromic Semibullvalenes and Barbaralanes—Direct Observation of Transition States of Degenerate Cope Rearrangements

The Equilibrium between Localized and Delocalized States of Thermochromic Semibullvalenes and Barbaralanes—Direct Observation of Transition States of Degenerate Cope Rearrangements

Theoretical study of ionization potentials in monosubstituted benzenes

On the influence of vibrational modes and intramolecular isomerization processes on the NMR parameters of bullvalene: A Feynman path integral – ab initio investigation

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