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.
Ruzziconi, R., Lepri, S., Buonerba, F., Schlosser, M., Mancinelli, M., Ranieri, S., et al. (2015). Long-range bonding/nonbonding interactions: A donor-acceptor resonance studied by dynamic NMR. ORGANIC LETTERS, 17(11), 2740-2743 [10.1021/acs.orglett.5b01152].
Long-range bonding/nonbonding interactions: A donor-acceptor resonance studied by dynamic NMR
MANCINELLI, MICHELE;RANIERI, SILVIA;PRATI, LUCA;MAZZANTI, ANDREA
2015
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
