A joined theoretical-experimental investigation on the H-1 and C-13 NMR chemical shifts of chloro-alkenes

Abstract

The H-1 and C-13 NMR chemical shifts of model chloro-alkenes are evaluated at different levels of approximation and compared to experimental data. DFT calculations employing the B3LYP exchange-correlation functional with the 6-311+G(2d,p) basis turned out to be reliable to account for most of the variations of the chemical shifts. Then, after accounting for the linear regression fits, the mean absolute error goes down to 3.8 ppm and 0.05 ppm for the C-13 and H-1 chemical shifts, respectively. Using these linear regression relationships, the NMR chemical shifts are determined for a PVC chain bearing an unsaturated defect inside a meso and a racemic dyad. These simulations, which account for the many conformations of the PVC segment, are used to interpret recent experimental spectra of PVC containing unsaturations. (c) 2007 Elsevier B.V. All rights reserved.