title: Why downfield proton chemical shifts are not reliable aromaticity indicators.
abstract: Traces of magnetizability, traces of magnetic shielding at the hydrogen nuclei, and nucleus-independent chemical shift are not reliable aromaticity quantifiers for planar conjugated hydrocarbons. A measure of aromaticity is provided by the out-of-plane tensor components, whose magnitude is influenced by the pi-ring currents. The failure of nucleus-independent chemical shift in this regard was proved for the molecule shown in the abstract graphic, sustaining a diatropic pi-current. The validity of the ring-current model is reaffirmed. [structure: see text]
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Modena e Reggio Emilia, via G. Campi 183, 41100 Modena, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Faglioni
authors.forename: A
authors.initials: A
authors.lastname: Ligabue
authors.forename: S
authors.initials: S
authors.lastname: Pelloni
authors.forename: A
authors.initials: A
authors.lastname: Soncini
authors.forename: R G
authors.initials: RG
authors.lastname: Viglione
authors.forename: M B
authors.initials: MB
authors.lastname: Ferraro
authors.forename: R
authors.initials: R
authors.lastname: Zanasi
authors.forename: P
authors.initials: P
authors.lastname: Lazzeretti