Nuclear magnetic resonance studies of lanthanide complexes. Part I. Solvation numbers and kinetics of substrate exchange in lanthanide shift reagent systems

Abstract

Proton resonance spectra are reported for a variety of lanthanide shift reagents with four different substrates, dimethyl sulphoxide, hexamethylphosphoramide, tetramethylurea, and triethylamine. At low temperatures substrate exchange is slow on a proton resonance time-scale. Solvation numbers and bound chemical shifts were derived. In some cases the solvation numbers are solvent dependent. For many systems, quantitative kinetic data were obtained.