DIAMAGNETIC LANTHANIDE TRIS-BETA-DIKETONATES AS DISSOLVING REAGENTS

It is proposed to use diamagnetic lanthanide tris-beta-diketonates as auxiliary reagents to promote solubilization of organic compounds in l ow-polarity solvents, thereby enhancing the NMR spectral sensitivity. For such a purpose the lanthanum complexes with fluorinated beta-diket onate ligands were shown to be the most suitable. These tris-beta-dike tonates form adducts with compounds possessing 'hard' Lewis base funct ional groups, and the adducts are more soluble than their components. The effect of the lanthanum complexes on paramagnetic shifts induced b y lanthanide shift reagents was examined. A considerable increase in t he shifts values was found in the presence of some lanthanum tris-beta -diketonates.