AN EXPERIMENTAL AND THEORETICAL STUDY OF SEMIBULLVALENES - THE SEARCH FOR A NEUTRAL BISHOMOAROMATIC COMPOUND.
Item
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Title
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AN EXPERIMENTAL AND THEORETICAL STUDY OF SEMIBULLVALENES - THE SEARCH FOR A NEUTRAL BISHOMOAROMATIC COMPOUND.
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Identifier
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AAI8312360
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identifier
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8312360
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Creator
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MILLER, LIBBY SHANA.
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Contributor
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Klaus Grohmann
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Date
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1983
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Organic
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Abstract
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The synthesis of 1,5-dimethyl-2,4,6,8-tetrakis(carbomethoxy)semibullvalene is reported. This is the first semibullvalene substituted with pi-electron acceptors at positions predicted by theory to lower the E(,act) for the Cope rearrangement. A new synthetic route was utilized which has been found applicable to the preparation of other substituted semibullvalenes. The compound was studied by x-ray crystallography and nmr spectroscopy. The x-ray structure indicates an unusual geometry; the cyclopropyl C2-C8 bond is very long (1.782 A) while the non-bonded distance (C4-C6) is shorter than in the unsubstituted compound. While the molecule does not exist in the delocalized form, it has undergone a substantial electronic rearrangement as manifested by the unusual crystal structure and the low temperature nmr results.;MNDO calculations on semibullvalene and some cyano-substituted analogs indicate that the 2,4,6,8-tetracyano and the 2,6-dicyano derivatives should have delocalized structures which are equal or lower in energy than the classical ground state. The C1-C5 methylene annelated semibullvalene is also predicted to have a homoconjugated structure of lower energy than the classical ground state.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
