research article

Downfield Proton Chemical Shifts Are Not Reliable Aromaticity Indicators

Wannere, Chaitanya S.
•
Corminboeuf, Clemence  
•
Allen, Wesley D.
Show more
2005
Organic Letters

The downfield chem. shifts of arene hydrogens (delta 1H) are due only in part to the pi ring current contribution [sigma.dblvert.(pi)]; local framework effects are equally important. Neither proton chem. shifts nor even sigma.dblvert.(pi) tensor elements, per se, are reliable aromaticity indicators. Unsatd. polycyclic hydrocarbons with nonarom. quinoid structures have delta 1H and sigma.dblvert.(pi) values in the "arom. range". Conversely, numerous arom. protons, including those in five-membered ring heterocycles, resonate in the "nonarom. range". [on SciFinder (R)]

Type
research article
DOI
10.1021/ol050118q
Author(s)
Wannere, Chaitanya S.
Corminboeuf, Clemence  
Allen, Wesley D.
Schaefer, Henry F. III
Schleyer, Paul von Rague
Date Issued

2005

Published in
Organic Letters
Volume

7

Issue

8

Start page

1457

End page

1460

Subjects

Density functional theory (PW91; downfield NMR proton chem. shifts are not reliable aromaticity indicators); NMR (chem. shift; downfield NMR proton chem. shifts are not reliable aromaticity indicators); IGLO; Ring current (downfield NMR proton chem. shifts are not reliable aromaticity indicators); Polycyclic compounds Role: PRP (Properties) (hydrocarbons

•

unsatd.; downfield NMR proton chem. shifts are not reliable aromaticity indicators); Aromaticity (index; downfield NMR proton chem. shifts are not reliable aromaticity indicators); Hydrocarbons Role: PRP (Properties) (polycyclic

•

unsatd.; downfield NMR proton chem. shifts are not reliable aromaticity indicators)

•

aromaticity indicator downfield nmr proton chem

Note

CAN 142:429747 22-2 Physical Organic Chemistry Center for Computational Chemistry, Department of Chemistry,University of Georgia,Athens,GA,USA. Journal 1523-7060 written in English. 85-01-8 (Phenanthrene); 91-20-3 (Naphthalene); 92-24-0 (Naphthacene); 95-13-6 (1H-Indene); 120-12-7 (Anthracene); 253-01-0 (Cyclobuta[1,2:3,4]dicyclopentene); 257-24-9 (Heptalene); 268-37-1 (2H-Benz[f]indene); 270-53-1 (2H-Indene); 275-51-4 (Azulene); 4026-23-7 (Bicyclo[4.2.0]octa-1,3,5,7-tetraene); 850661-43-7; 850661-44-8 Role: PRP (Properties) (downfield NMR proton chem. shifts are not reliable aromaticity indicators)

Editorial or Peer reviewed

REVIEWED

Written at

OTHER

EPFL units
LCMD  
Available on Infoscience
October 22, 2007
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/13185