Mixed ligand complexes of trivalent lanthanide ions with β-diketones and heterocyclic amines and their use as possible shift reagents

Abstract

Abstract Sixty new complexes of the trivalent lanthanides (except Pm and Lu) and Yttrium of the general formulae, Ln(TFAA) 3 o-phen, Ln(TFAA) 3 dipy·2H 2 O, Ln(dpm) 3 im, Ln(dpm) 3 pz, and Ln(fod) 3 o-phen where TFAA = trifluoroacetyl-acetone-H, dpm = 2,2,6,6-tetramethyl 3,5-heptane dione-H, fod = 1,1,1,2,2,3,3-heptafluoro, 7,7-dimethyl 4,6-octane dione-H, o-phen = 1,10-phenathroline, dipy = 2,2′dipyridyl, im = imidazole and pz = pyrazole, have been synthesised and characterised by elemental analyses, melting points, molar conductance, magnetic susceptibility, thermogravimetric analysis, and IR spectral studies. The trivalent lanthanide ions have a coordination number of ten in the series Ln(TFAA) 3 dipy·2H 2 O. Their avidity to enhance their coordination number is so great that een in the presence of three such bulky ligands as heptafluorooctane dione the Ln(fod) 3 still coordinates with o-phen. Hexacoordinated trivalent lanthanides act as LIS reagents but it has been observed that even the eight coordinated and very bulky Pr(fod) 3 o-phen produces dipolar shifts in the proton resonances of organic moities.