A Mnemonic Device for Molecular Orbital Energies

Frost, Arthur A.; Musulin, Boris

doi:10.1063/1.1698970

Cited by 136 publications

(83 citation statements)

References 3 publications

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“…This, of course, is exactly what is anticipated from the Frost-Musulin circle mnemonic 6 (see Figure 3).…”

Section: Resultssupporting

confidence: 61%

The trouble with resonance energies: a Hückel theory topic

Langler¹

2005

Quím. Nova

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Recebido em 4/5/04; aceito em 1/2/05; publicado na web em 30/6/05Resonance energies are shown to be quasithermodynamic in character. Hence, they are generally unsuitable as bases for anticipating kinetic stabilities. Examples are provided, leading to the conclusion that those who intend the word 'aromatic' to mean chemically unreactive, need to carry out full Hückel calculations in order to rank hydrocarbons using the frontier orbital energies.

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“…This, of course, is exactly what is anticipated from the Frost-Musulin circle mnemonic 6 (see Figure 3).…”

Section: Resultssupporting

confidence: 61%

The trouble with resonance energies: a Hückel theory topic

Langler¹

2005

Quím. Nova

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“…A similar procedure is known as the Frost-Musulin mnemonic for determining the MO energies of Hückel annulenes. [2] In this case the polygon has to Abstract: Heilbronner in 1964 predicted that annulenes with "… a planar perimeter of N = 4r AOs, which would yield an open shell configuration when occupied by 4r electrons, can be twisted into a closed shell Mçbius strip perimeter without loss in p electron energy". We have been able to synthesize the first [4n]annulene with such a Mçbius topology and now present further Mçbius isomers and the details of their preparation as stable compounds.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Properties of the First Möbius Annulenes

Ajami

Heß

Köhler

et al. 2006

Chemistry A European J

127

126

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Heilbronner in 1964 predicted that annulenes with ".. a planar perimeter of N=4r AO's, which would yield an open shell configuration when occupied by 4r electrons, can be twisted into a closed shell Möbius strip perimeter without loss in pi electron energy". We have been able to synthesize the first [4n]annulene with such a Möbius topology and now present further Möbius isomers and the details of their preparation as stable compounds. To address the question whether the twist in the pi system has an effect on the properties we systematically investigate energy, geometry and magnetic parameters of a large number isomers of [16]annulenes. The Möbius twisted annulenes are consistently more aromatic than the non-twisted isomers. This is true for the parent as well as our benzoannelated systems. Our results are in contrast to those published recently by C. Castro, W. L. Karney, P. von R. Schleyer et al.

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“…This contrasts with pivoting as in Fig. 3c where there are 4N electrons in a Huckel array (21), which predicts a higher energy and open shell transition state using the Frost counterpart mnemonic (22).…”

Section: Nature Of the Bicycle And Cope Rearrangement Stepsmentioning

confidence: 75%

Some photochemical rearrangements of vinylcyclopentadienes. Mechanistic and exploratory organic photochemistry

Zimmerman¹,

Ramsden²

1984

Can. J. Chem.

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. Can. J. Chem. 62, 2592(1984. The photochemistry of 2,3-diphenyl-1,4,5-trimethyl-5-vinylcyclopentadiene and 1,2-diphenyl-3,4,5-trimethyl-5-vinylcyclopentadiene was studied. The triplet of the 2,3-diphenyl isomer was found to undergo a 1,s-vinyl migration; in contrast, the 1 ,2-diphenyl diene was unreactive. On direct irradiation, in addition to vinyl migration, four photoproducts were formed from the cyclopentadienes. These were shown to be 5,6-diphenyl-1,2,7-trimethylbicyclo[3. On a CtudiC la photochimie du diphCnyl-2,3 trimkthyl-1,4,5 vinyl-5 cyclopentadikne et du diphCnyl-1,2 trimkthyl-3,4,5 vinyl-5 cyclopentadikne. On a trouvC que 1'Ctat triplet de l'isomkre diphCny1-2,3 subit une migration 1,s du vinyle; par opposition, le diphCnyl-1,2 dikne n'est pas rkactif. Par irradiation directe, les cyclopentaditnes conduisent, en plus du produit de migration du groupe vinyle, ?I quatre photoproduits; on a dCmontrC qu'ils ont les structures suivantes: diphtnyl-5,6 trimCthy1-1,2,7 bicyclo[3.2.0] heptadikne-2,6; diphCnyl-1,s trimCthy1-2,6,7 bicyclo[3.2.0] heptaditne-2,6; diphtnyl-6,7 trimCthyl-1,2,5 bicyclo Introduction One of our main research objectives has been the elucidation of new photochemical organic reactions. It is clear that the number of ground state organic reactions is immense, a result of a century and a half of intensive efforts. In comparison, the number of photochemical reactions is minuscule. Nevertheless, the known photochemical reactions are often fascinating, primarily because of their departure from intuitive ground state expectation, and promising, primarily because patterns of behavior demonstrate the presence of understandable mechanistic factors.In recent years we have uncovered some unique rearrangements of vinylcyclopropenes affording cyclopentadienes (lc, 2; note also work by Padwa et al. (3)). We thus proceeded to investigate the photochemical behavior of the homologous vinylcyclopentadienes.

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A Mnemonic Device for Molecular Orbital Energies

Cited by 136 publications

References 3 publications

The trouble with resonance energies: a Hückel theory topic

The trouble with resonance energies: a Hückel theory topic

Synthesis and Properties of the First Möbius Annulenes

Some photochemical rearrangements of vinylcyclopentadienes. Mechanistic and exploratory organic photochemistry

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