Protonen-resonanzverschiebung in komplexen von nickel- und kobaltacetylacetonat mit alkylaminen

Abstract

The NMR shifts in nickel acetylacetonate-amine complexes can be explained by contact shift and in cobalt acetylacetonate-amine complexes by the superposition of contact and pseudocontact shifts. Contact and pseudocontact shifts were determined for the following amines: isopropylamine, tert. butylamine, isobutylamine, 3-methoxypropylamine, 2-methoxy-ethylamine, sec. butylamine, 1,3-dimethylbutylamine. For all protons that have a distance of n bonds from the paramagnetic ion, the pseudocontact shift is approximately the same. Thus, with the aid of the pseudocontact shift it is possible to determine the number of bonds between a group of protons and the amino group. Observed deviations are explained by inner hydrogen bonds or steric hindrance of neighbouring groups. Two resonances are found for the β-CH 2-group in sec. butylamine and in 1,3-dimethylbutylamine which differ in the extent of their contact shift.