It has recently been shown that the 2,2,6,6-tetra-methylheptane-3,5-dione (tmhd) complexes of a number of lanthanide ions possess the useful property of inducing large chemical shifts in the proton NMR spectra of certain compounds containing OH or other nucleophilic groups1–8. The resulting spectra are frequently more readily assignable and analysable. Although europium and praseodymium appear to be the most suitable ions for such studies, the shifting effect is also observed with other lanthanide ions.5,6