Natural-abundance I5N nuclear magnetic resonance spectra of nitrogen-containing crown ethers, cryptand ligands, other ligands with pyridine-type nitrogens and their complexes with alkali, alkaline-earth, silver(I), and thallium(I) ions are reported. The complexation shifts tend to go downfield with increasing charge and increasing ionic character of the nitrogen-to-metal-ion bond but upfield with increasing polarizability of the ion. The downfield shifts are generally more pronounced if the ions fit tightly into the cyclic ligand. For those metal ions expected to form essentially covalent bonds to nitrogen, the shifts are not easily predicted. Some of the thallium- and silver-cryptate complexes display sizable one-bond ^(15)N-metal couplings.
No takes yet. Share an insight, caveat, or question.
Foerster et al. (1980) studied this question.