A new lanthanide paramagnetic shift reagent containing fully fluorinated side chains

Abstract

This work describes the application of a new europium complex, europium decafluoroheptanedione, to the clarification of complex NMR spectra, i.e., it reports a new paramagnetic shift reagent. This new reagent is superior to the older, partially fluorinated complex, Eu(fod) 3, in that there is no interference from side-chain protons of the shift reagent, itself. Furthermore, due perhaps to the smaller bulk of this new reagent, relative to Eu(fod) 3, larger shifts are observed for the protons remote from the complexing site of the substrate. We also qualitatively describe the shift capacities of other lanthanide decafluoroheptanediones.