1H NMR spectra of E and Z pyridine‐2‐carbaldehyde 2′‐pyridylhydrazone and related compounds

Proton magnetic resonance spectra at 100 MHz are reported for the E‐ and Z‐isomers of pyridine‐2‐carbaldehyd 2′‐ pyridylhydrazone in carbon tetrachloride, d6‐dimethylsulphoxide and d6‐benzene solutions, and for various monomethylated derivatives in d6‐dimethylsulphoxide. The spectral parameters obtained by analysis with the help of LAOCOON 3 are discussed in terms of solvent effects and the chemical shift changes consequent upon isomerisation are evaluated. Some conclusions are reached concerning the preferred conformations of the E‐ and Z‐isomers of pyridine‐2‐carbaldehyde 2′‐pyridylhydrazone.