A family of 2p-4f complexes based on indazole radical: Syntheses, structures and magnetic properties

Abstract

Five LnIII complexes based on indazole radical have been synthesized and characterized by X-ray crystal diffraction: [Ln(hfac)3(NITIn)(H2O)]·XCH2Cl2·YC7H16 (Ln=Pr(1), Sm(2), Gd(3), hfac=hexafluoroacetylacetone; NITIn=(3-(1′-oxyl-3′-oxido-4′,4′,5′,5′-tetramethyl-4,5-hydro-1H-imidazol-2-yl)indazole) and [Ln(hfac)3(NITIn)] (Ln=Tb(4), Dy(5)). Compounds 1–3 are isostructural and crystalize in P21/n space group, while compounds 4–5 crystalize in P21/c space group. In compounds 1–3, the coordination number around the lanthanide ion is nine, and the polyhedron is in distorted 4,4,4-tricapped trigonal prism (C4v) or muffin (Cs) environment finished by three bischelate hfac− ligands, one bidentate radical ligand and one water molecular. The coordination number around the lanthanide ion in 4–5 is eight, and the polyhedron is in distorted square antiprism (D4d) environment. DC magnetic studies show that Pr, Sm, Tb and Dy complexes are paramagnetic. In addition, Tb and Dy complexes exhibit slow frequency-dependence of ac magnetic susceptibilities, which indicates the presence of slow magnetic relaxation.