The self-assembly of Ln (hfac) 3 with NITPh-3, 5-bMeIm radical (NITPh-3, 5-bMeIm = 2-3′, 5′-bis (2″-methylimidazol-1″-yl) phenyl-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetonate) results in two kinds of architectures depending on the rare earth element, namely, a tetranuclear cyclic molecular cluster (NITPh-3, 5-bMeIm-H) 2Ln (hfac) 32Ln (hfac) 42 (LnIII = Pr, 1; Nd, 2) and a chain of rings (NITPh-3, 5-bMeIm) 2 (Ln (hfac) 3) 3·0. 5CHCl3n (LnIII = Gd, 3; Dy, 4). In all cases, NITPh-3, 5-bMeIm acts as a three-connecting node, but distinct coordination schemes apply. For 1 and 2, one of the imidazoles of NITPh-3, 5-bMeIm is protonated; consequently, the ligand connects three LnIII atoms by means of the two aminoxyl oxygen atoms (NO) and the second imidazole group. In the case of 3 and 4, one NO group and the two imidazole groups coordinate to Ln ions. Magnetic studies reveal ferromagnetic GdIII–ON interaction in 3 and show that Dy derivative displays field-induced slow magnetic relaxation behavior with the Ueff/kB value of 18. 41 K.
Zhang et al. (Tue,) studied this question.