Torsion angle relationship of the (17)O NMR chemical shift in alpha,beta-unsaturated carbonyl compounds.
The torsion angle effect on the isotropic shielding of (17)O nucleus in alpha,beta-unsaturated carbonyl groups is studied by means of density functional theory (DFT) calculations using a polarizable continuum model (PCM) for the solvent, employing the PBE0 functional together with the 6-311G(d,p) basis set for geometry optimization, and the 6-311+G(2d,p) basis set for calculating the NMR shielding with the gauge-including atomic orbitals (GIAO) method.This study adds new information on the sensitivity of the (17)O nucleus to conformational changes, revealing a strong dependence of the (17)O NMR chemical shift on the dihedral angle between the carbonyl and the vinyl moiety in all studied compounds; remarkable differences are observed with the data reported for alpha-diketones.
Mocci
Francesca
F
Dipartimento di Scienze Chimiche, Università di Cagliari, Complesso Universitario, S.S. 554, Bivio per Sestu, I-09042 Monserrato (CA), Italy. fmocci@unica.it
D003198:Computer Simulation; D007659:Ketones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards*; D008956:Models, Chemical; D008968:Molecular Conformation; D010103:Oxygen Isotopes; D012015:Reference Standards; D013237:Stereoisomerism
D007659:Ketones; D010103:Oxygen Isotopes