Syntheses, crystal structures, magnetic properties of two lanthanide-nitronyl nitroxide complexes (LnIII = GdIII, PrIII)

Two complexes based on rare-earth-radical of formula {Ln(hfac)(3)[NITPh(OCH3)(3)](2)} (Ln=Gd (1), Pr(2)); hfac=hexafluoroacetylacetonate; NITPh(OCH3)(3)=2-(3',4',5'-trimethoxyphenyl)-4,4,5,5-tetramethylimidazoline -1-oxyl-3-oxide) have been synthesized and characterized by single-crystal X-ray diffraction. The single-crystal structures show that two complexes have similar structures, in which the metal ions are eight-coordinated in slightly distorted dodecahedron geometry. Two oxygen atoms of the N-O group from nitronyl nitroxide radicals and six oxygen atoms from three different hfac anions are coordinated to the metal ions. The magnetic studies show that the spin coupling between the Gd(III) ion and the radicals in the complex 1 is ferromagnetic (J=1.46 cm(-1)), while complex 2 exhibits antiferromagnetic interactions (zJ'=-0.21 cm(-1)) between Pr(III) ion and radicals. (c) 2010 Elsevier B.V. All rights reserved.