Nuclear magnetic resonance contact shifts and delocalization mechanisms in Ni(II)‐dioxo complexes

Abstract The temperature dependence of the proton NMR‐spectra of bis(1,3‐diphenyl‐1,3‐propanedionato)Ni(II) and of bis(1,3‐di‐ p ‐tolyl‐1,3‐propanedionato)Ni(II) has been determined. We have interpreted the results using a model with two unpaired electrons per molecule. We conclude that the contact shifts of the various proton resonance signals result from delocalized unpaired electrons in the σ as well as the π system of the ligands.