title: Long-range bonding/nonbonding interactions: a donor-acceptor resonance studied by dynamic NMR.
abstract: Long-range bonding interactions were evaluated using variable-temperature NMR spectroscopy and suitable 2'-CH2X-substituted phenylpyridines (X = Me, NMe2, OMe, F). It was found that the arylpyridyl rotational barriers were lower when electronegative atoms were bound to the α carbon of the 2' moiety. This effect was ascribed to a stabilizing interaction in the transition state due to the lone pair of the heterocyclic nitrogen with the α carbon. Computational support for this hypothesis came from CCSD(T)/6-31+G(d) calculations. Steric effects of the X moiety were ruled out by comparison of the rotational barriers of analogous biphenyls.
authors.affiliation: †Department of Chemistry, Biology and Biotechnology, University of Perugia, via Elce di Sotto 10, I-06100 Perugia, Italy.
authors.forename: Renzo
authors.initials: R
authors.lastname: Ruzziconi
authors.affiliation: †Department of Chemistry, Biology and Biotechnology, University of Perugia, via Elce di Sotto 10, I-06100 Perugia, Italy.
authors.forename: Susan
authors.initials: S
authors.lastname: Lepri
authors.affiliation: †Department of Chemistry, Biology and Biotechnology, University of Perugia, via Elce di Sotto 10, I-06100 Perugia, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Buonerba
authors.affiliation: ‡Institute of Chemical Sciences, Ecole Polytechnique Fédérale, CH-1015 Lausanne, Switzerland.
authors.forename: Manfred
authors.initials: M
authors.lastname: Schlosser
authors.affiliation: §Department of Industrial Chemistry "Toso Montanari", University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Mancinelli
authors.affiliation: §Department of Industrial Chemistry "Toso Montanari", University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Ranieri
authors.affiliation: §Department of Industrial Chemistry "Toso Montanari", University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Prati
authors.affiliation: §Department of Industrial Chemistry "Toso Montanari", University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mazzanti