Deuterium-induced 19F isotope shifts in fluoroethenes

Deuterium-induced 19F isotope shifts in the NMR spectra of 17 fluoroethenes are reported here together with other NMR parameters (1H and 19F chemical shifts and FF, HF, DF, and DH coupling constants). The two-bond (gem) and three-bond (trans) isotope shifts exhibit correlations with nuclear spin–spin coupling constants 2Jgem (HF) and 3Jtrans (HF). The isotope shifts are interpreted using derivatives of nuclear shielding with respect to bond extension derived from the 19F temperature dependence at the zero-pressure limit, and the changes in the mean bond lengths due to isotopic substitution. The latter are calculated using the previously reported Urey–Bradley force fields for these molecules. The analysis of the isotope shifts lead to estimates of the change of 19F nuclear shielding due to extension of a bond which is located at a gem, cis, or trans position relative to the resonant nucleus. These 19F nuclear shielding derivatives correlate with the nuclear spin–spin coupling constants 2Jgem(HF) , 3Jcis (HF), and 3Jtrans(HF) which share the same pathway of electronic transmission.