A series of heterospin complexes based on lanthanides and pyridine biradicals: synthesis, structure and magnetic properties

作者：Zhou Shang Yong; Li Xin; Li Ting; Tian Li^*; Liu Zhong Yi; Wang Xiu Guang

来源：RSC Advances, 2015, 5(22): 17131-17139.

DOI：10.1039/c4ra15074k

The combination of anisotropic Ln(III) ions and organic biradicals results in six isomorphous complexes, namely, [Ln(hfac)(3)(NITPymbis)(2)](2) (Ln = Pr(1), Nd(2), Sm(3), Gd(4), Tb(5), Dy(6); hfac = hexafluoroacetylacetone; NITPymbis = (1,3-bis-(1'-oxyl-3'-oxido-4',4',5',5'-tetramethyl-4,5-hydro-1H-imidazol-2-yl) pyridine). Single-crystal X-ray diffraction studies reveal that each of them is composed of two crystallographically independent mononuclear complexes, in which one NITPymbis molecule acts as a bidentate ligand coordinated to the same Ln(III) ion through its two NO groups to form a tri-spin system. In all six complexes, the coordination number around the lanthanide ion is eight, and the polyhedron is a 4,4-bicappped trigonal prism. DC magnetic studies show that the Ln(III) ions interact antiferromagnetically with the directly bonding nitronyl nitroxide radicals in complexes 1-3, whereas for complexes 4-6, the Ln(III) ions interact ferromagnetically with the radicals. Especially, for complex 4, intramolecular ferromagnetic interaction between the two radicals is observed with j(Rad-Rad) = 10.05 cm(-1), and at low temperature, intermolecular ferromagnetic interaction also plays an important role. Both complexes 5 and 6 exhibit frequency-dependent ac magnetic susceptibilities at low temperature, suggesting the possible presence of slow magnetic relaxation.

• 出版日期2015
• 单位天津师范大学