NMR Studies of 4n π-Conjugated Polycyclic Anions: Relationship of the Energy Gap Between the Highest Occupied Molecular Orbital and the Lowest Unoccupied Molecular Orbital to Paratropicity and Electronic Structure

Mordecai Rabinovitz, Yoram Cohen

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

Abstract

The energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) determines the line shape and chemical shift of 4n π polycyclic doubly charged systems. Narrower energy gaps correspond to more significant line broadening in the 1H NMR bands. This line broadening is attributable to a singlet-triplet equilibrium that depends on the HOMO-LUMO gap. The topology of the system influences the paratropicity of these 4n π polycyclic dianions. Whereas the triphenylene dianion does not exhibit a 1H NMR spectrum, a gradual change toward a highly resolved spectrum is obtained for the tribenzo[a,c,i]phenazine dianion. A correlation between the HOMOLUMO gap and the paratropic shift of these dianions is demonstrated.
Original languageAmerican English
Title of host publicationPolynuclear Aromatic Compounds
EditorsLawrence B. Ebert
Place of PublicationWashington, DC
PublisherAmerican Chemical Society
Chapter4
Pages53-72
Number of pages20
ISBN (Electronic)9780841223998
ISBN (Print)9780841210141
DOIs
StatePublished - 1987
Externally publishedYes

Publication series

NameAdvances in Chemistry
Volume217
ISSN (Print)0065-2393

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