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

The combination of Ln ions (Gd, Tb or Dy) and a triazole nitronyl nitroxide radical (4-Me-3-NITtrz) as spin carriers results in two mononuclear and one binuclear compounds, namely, [Ln(hfac)(4-Me-3-NITtrz)(HO)] (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)(4-Me-3-NITtrz)][Dy(hfac)]·CHCl. Compounds 1 and 2 are isostructural and crystallize in the 1̄ space group, whereas compound 3 crystallizes in the 2/ space group. In 1 and 2, the central Ln ions are nine-coordinated (LnNO) in a distorted spherical capped square antiprism geometry ( ) 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 ( ) coordination sphere and Dy2 in a biaugmented trigonal prism ( ) coordination sphere. Magnetic studies show that compound 2 exhibits field-induced single-molecule magnet (SMM) behavior.