title: Measuring antiaromaticity by an analysis of ring current and coupling constant changes in a cyclopentadienone-fused dihydropyrene.
abstract: The synthesis of the chloro- and parent cyclopentadienone-fused dihydropyrenes 10 and 7 are reported. Analysis of coupling constants, and chemical shift changes between these and the nonconjugated dihydro derivatives 11 and 8, and between the benzannulene 4 and the parent annulene 12, indicates without doubt that cyclopentadienone is behaving as an antiaromatic 4n-pi system and that in its effect on the ring current of 12, cyclopentanedienone has about 80% of the effect of benzene. This is the first time that a suitable probe has been used to estimate the relative ability of a 4n-pi system to bond localize the probe in comparison to the (4n + 2)-pi system benzene.
authors.affiliation: Department of Chemistry, University of Victoria, Post Office Box 3065, Victoria, British Columbia, Canada V8W 3V6. regmitch@uvic.ca
authors.forename: Reginald H
authors.initials: RH
authors.lastname: Mitchell
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Fan
authors.forename: David J
authors.initials: DJ
authors.lastname: Berg