A Theory of the Annulenes

Citation

Hultgren, Glen Owen (1966) A Theory of the Annulenes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/AAK2-Y031. https://resolver.caltech.edu/CaltechETD:etd-09202002-141107

Abstract

It has been proposed that large annulenes have alternation of bond length. The height of the annulene singlet transition energies has been cited as evidence for bond alternation. This thesis shows that the mechanism of bond alternation is inadequate to reproduce the experimental spectrum of the annulenes. I am able to explain the height of the annulene singlet transitions by the use of the alternant molecular orbital method. It appears that simple MO methods and even limited C.I. treatments seriously underestimate the energy depression of the ground state through electron correlation. It is shown that the tendency towards bond length alternation exhibited by the simple MO method is an artifact of this method, and should not be taken seriously. Some of the limitations of the AMO method are examined and it is shown how the AMO method may be extended to sigma as well as pi electron

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