Symmetry, topology, and aromaticity

Goldstein, M. J.; Hoffmann, Roald

doi:10.1021/ja00752a034

Cited by 242 publications

(95 citation statements)

References 3 publications

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“…The in-phase combination (p 1 p 2 ) may be regarded as a representation of the socalled laticyclic (2 2 0) homoconjugation. 4 The energy level of p-orbital of 4 is also considerably lower than that of 4. Upon forming cations, the energy level of p orbitals approximates that of s orbitals, and the interaction between the two becomes stronger.…”

Section: 20mentioning

confidence: 95%

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Solvolysis of isodrin derivatives. Evidence of long-range ?-participation in the stabilization of carbocations

Chow

1998

J. Phys. Org. Chem.

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Enhanced rates of solvolysis have been reported for some isodrin derivatives, e.g. compounds 2, 3, 6 and 7 compared with anti-7-norbornene (1). The effect has been ascribed to the formation of laticyclic (2 2 0) pdelocalization on a carbocation such as 5. However, comparable rates of solvolysis were also observed for analogous monoenes 4, 8, 9 and 12, where no adequate explanation has been provided. Molecular modeling at both semiempirical and ab initio levels shows a good correlation between the stabilization energy of the cations and their kinetic data. The enhanced rate of solvolysis for 4, 8, 9 and 12 can be rationalized by strong effects of s-bond participation in the transition state. For both series of compounds, the stabilization effect can be effectively transmitted either through space or through bonds.

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Section: 20mentioning

confidence: 95%

“…3 The structure has been classified as one of the laticyclic (2 2 0) system stabilized by 4p electrons. 3,4 Although the concept of a non-classical carbocation in the solvolysis of 7-norbornenyl derivatives has been recognized in general, 5 the effectiveness of electron delocalization on an extended system such as 5 remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Solvolysis of isodrin derivatives. Evidence of long-range ?-participation in the stabilization of carbocations

Chow

1998

J. Phys. Org. Chem.

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“…A concerted reaction is therefore interpreted as simultaneous, but not necessarily synchronous bond formation and breakage. "* Following Goldstein and Hoffman [5], Figure 3(a) illustrates the qualitative forms of the T molecular orbitals for chains of one to six atoms. We will focus the discussion on even numbers for simplicity [ Fig.…”

Section: Orbital Phases For the Wh Rulesmentioning

confidence: 99%

A gauge symmetric band model of the Woodward–Hoffmann rules

Squire

1992

Int J of Quantum Chemistry

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The Woodward-Hoffmann (WH) Rules for the prediction of relative rates and stereochemistry of concerted reactions are based on considerations of the orbital symmetry of the reactants and products. Literally hundreds of reactions have been successfully categorized by these remarkably simple-appearing Rules. This paper develops a one-dimensional band model of these Rules. By explicit inclusion of the effects of an electromagnetic field in a standard gauge-invariant fashion, it can be shown that at certain levels of field strength the model suggests that the Rules may be reversed. This is because the Rules appear in the model as a consequence of a centrifugal angular momentum barrier that can be shifted by an electromagnetic field. This barrier could account for "aromatic" stabilization. As an additional effect, the model predicts flux-dependent oscillations and persistent currents for "aromatic" molecules due to the Aharonov-Bohm effect. The possible health effects of electromagnetic fields are speculated. The likelihood of experimental observations to verify the applicability of the model is discussed.

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“…zum 9-Cyanbicyclo~4.2.1]nona-2,4,7-trien-9-yl-Anion (4 'H-NMR (CC1,): 6 = 2.23 (t, J = 6.5 Hz; 2H, CHI), 3.51 (t, J = 6.5 Hz; 2H, CH,), 5.68 (mc; 7H, olefin. H).…”

Section: Weshalb Lagert Das %Cyan-cis-bicyclo[6lo]nona-246-trimentioning

confidence: 99%