A family of multi-spin rare-earth complexes based on a triazole nitronyl nitroxide radical: synthesis, structure and magnetic properties.

The combination of Ln III ions (Gd III , Tb III or Dy III ) and a triazole nitronyl nitroxide radical (4-Me-3-NITtrz) as spin carriers results in two mononuclear and one binuclear compounds, namely, [Ln(hfac) 3 (4-Me-3-NITtrz)(H 2 O)] (Ln = Gd(1), Tb(2); hfac = hexafluoroacetylacetone; 4-Me-3-NITtrz = 2-[3-(4-methyl-l,2,4-triazolyl)]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) and [Dy(hfac) 2 (4-Me-3-NITtrz) 2 ][Dy(hfac) 4 ]·CHCl 3 . Compounds 1 and 2 are isostructural and crystallize in the P 1̄ space group, whereas compound 3 crystallizes in the P 2 1 / n space group. In 1 and 2, the central Ln III ions are nine-coordinated (LnNO 8 ) in a distorted spherical capped square antiprism geometry ( C 4v ) finished by three bischelate hfac anions and one bidentate triazole radical and one aqua molecule. While 3 is a mixed-coordinated binuclear compound with Dy1 in a triangular dodecahedron ( D 2d ) coordination sphere and Dy2 in a biaugmented trigonal prism ( C 2v ) coordination sphere. Magnetic studies show that compound 2 exhibits field-induced single-molecule magnet (SMM) behavior.