Diamagnetic lanthanide tris-β-diketonates as 'dissolving' reagents

It is proposed to use diamagnetic lanthanide tris‐β‐diketonates as auxilliary reagents to promote solubilization of organic compounds in low‐polarity solvents, thereby enhancing the NMR spectral sensitivity. For such a purpose the lanthanum complexes with fluorinated β‐diketonate ligands were shown to be the most suitable. These tris‐β‐diketonates form adducts with compounds possessing ‘hard’ Lewis base functional groups, and the adducts are more soluble than their components. The effect of the lanthanum complexes on paramagnetic shifts induced by lanthanide shift reagents was examined. A considerable increase in the shifts values was found in the presence of some lanthanum tris‐β‐diketonates.