The structural dependence of the inductive effect. Part IV. The calculation of vicinal substituent effects upon 19F shielding in freely-rotating fluoroethanes and higher fluoroalkanes

Abstract

The calculational procedure applied previously to geminal and directly bonded substituent effects upon n.m.r. shielding is extended to account for the influence of vicinal substituents. The agreement with experiment is good (±3·4 p.p.m.) for situations where there is rotational averaging between conformations of equal energy, but in other cases conformational preference causes significant deviations.