Crystal Structure and Magnetic Property of Novel Ln(III)-Nitronyl Nitroxide Radical Complex

Abstract

Four novel rare-earth complexes based on a new nitronyl nitroxide radical have been synthesized and characterized as: {[Ln (hfac)3(NITPhBrF)2]·0.5CH2Cl2}(Ln = Sm (1), Gd (2), Tb (3)), {[Ln (hfac)3(NITPhBrF)2]}(Ln = Dy (4)) (hfac = hexafiuoroacetylacetonate; NITPhBrF = 2-(2-fluoro-5-bromophenyl)-tetramethylimidazoline-1-oxyl-3-oxide). The single-crystal X-ray diffraction revealed that compound 1, 2 and 3 are isostructural, which crystallize in the monoclinic space group P21/n, and compound 4 is in the P-1 triclinic space group. These complexes possess mononuclear structure in which the central Ln (III) is octacoordinated by six oxygen atoms from three bidentate hfac ligands and two oxygen atoms from two NITPhBrF ligands. DC magnetic susceptibilities were measured under 1kOe in the 2 - 300 K range. The studies reveal that there exit ferromagnetic interaction between the Gd (III) and radical ligands, and the antiferromagnetic interaction between the two intramolecular radicals in Gd (2). Meanwhile complexes Tb (3) and Dy (4) exhibit antiferromagnetic interactions.