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Benzene spin-coupled valence bond theory

T orbital for benzene obtained from spin-coupled valence bond theory. (Figure redrawn from Gerratt ], D L oer, P B Karadakov and M Raimondi 1997. Modem valence bond theory. Chemical Society Reviews 87 100.) figure also shows the two Kekule and three Dewar benzene forms which contribute to the overall wavefunction Kekuleform contributes approximately 40.5% and each Dewar form approximately 6.4%. [Pg.146]

FIGURE 17. Schematic representation of the symmetry-unique spin-coupling patterns in cyclopropane (above) and benzene (below). In the case of cyclopropane, carbon hybrid orbitals and, in the case of benzene, carbon p n orbitals are shown. For each structure, Gallup-Norbeck occupation numbers as determined by spin-coupled valence bond theory are given. All data from Reference 51... [Pg.83]

E. C. da Silva, J. Gerratt, D. L. Cooper, M. Raimondi, J. Chem. Phys. 101, 3866 (1994). Study of the Electronic States of the Benzene Molecule Using Spin-Coupled Valence Bond Theory. [Pg.168]

Resonance between three 7r-complex structures might lead to stabilization of 1 in the sense of 7r-aromatic stabilization involving the six CC bond electrons. Therefore, Dewar has discussed the stability of in terms of a c-aromatic stabilization (Section V). However, spin-coupled valence bond theory clearly shows that 1 cannot be considered as the cr-aro-matic analogue to 7r-aromatic benzene The 7r-complex description of 1 is a (very formal) model description, which should be discarded as soon as it leads to conflicting descriptions of the properties of 1. This will be discussed in Section V. [Pg.73]

Study of the Electronic States of the Benzene Molecule Using Spin-Coupled Valence Bond Theory. [Pg.97]

As is well-known, modem valence-bond (VB) theory in its spin-coupled (SC) form (for a recent review, see Ref. 7) provides an alternative description of benzene [8-10] which, in qualitative terms, is no less convincing and is arguably even more intuitive than the MO picture with delocalized orbitals. The six n electrons are accommodated within a single product of six nonorthogonal orbitals, the spins of which are coupled in all five possible ways that lead to an overall six-electron singlet. The simultaneous optimization of the orbitals and of the weights of the five six-electron singlet spin... [Pg.328]

Other theoretical treatments which have been applied to considerations of antiaromaticity include spin-coupled theory, topological methods,and quantum statistical definitions. The relevance of spin-coupled theory has been described The comparison between the (spin-coupled) descriptions of cyclobutadiene, benzene, and cyclooctatetraene clearly indicates that the reason for the lower stability and higher reactivity of antiaromatic systems is due to a simultaneous unfavorable coupling of the spins of all valence orbitals to triplet pairs, which discourages bonding interactions and suggests diradical character. ... [Pg.3]


See other pages where Benzene spin-coupled valence bond theory is mentioned: [Pg.74]    [Pg.74]    [Pg.504]    [Pg.510]    [Pg.515]    [Pg.328]    [Pg.125]   
See also in sourсe #XX -- [ Pg.126 ]




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Spin-coupled Valence Bond

Spin-coupled valence-bond theory

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