Investigation of the configuration of alkyl phenyl ketone phenylhydrazones from ab initio 1H NMR chemical shifts

Using ab initio GIAO calculations the experimental 1H NMR spectra of the E and Z isomers of alkyl phenyl ketone phenylhydrazones R1-C(Ph) = N-NH-Ph (R1 = Me, Et, iPr, and tBu) have been re-interpreted and deviations from Karabatsos' rule or from the assignment of Bellamy and Hunter have been discussed in the light of the optimized geometrical structures.