A series of heterospin complexes based on lanthanides and pyridine biradicals: synthesis, structure and magnetic properties. Issue 22 (9th February 2015)

• Record Type: Journal Article
• Authors: Zhou, Shang Yong; Li, Xin; Li, Ting; Tian, Li; Liu, Zhong Yi; Wang, Xiu Guang
• Is Part Of: RSC advances. Volume 5:Issue 22(2015)
• Page Start: 17131
• Page End: 17139
• Publication Date: 2015-02-09
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c4ra15074k
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Six Ln III -biradical tri-spin complexes have been synthesized, and they exhibit interesting magnetic properties. Abstract : The combination of anisotropic Ln III ions and organic biradicals results in six isomorphous complexes, namely, [Ln(hfac)3 (NITPy m bis)2 ]2 (Ln = Pr(1 ), Nd(2 ), Sm(3 ), Gd(4 ), Tb(5 ), Dy(6 ); hfac = hexafluoroacetylacetone; NITPy m bis = (1, 3-bis-(1′-oxyl-3′-oxido-4′, 4′, 5′, 5′-tetramethyl-4, 5-hydro-1 H -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 NITPy m bis 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 complexes1–3, whereas for complexes4–6, the Ln(iii ) ions interact ferromagnetically with the radicals. Especially, for complex4, 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 complexes5 and6 exhibit frequency-dependent ac magnetic susceptibilities at low temperature, suggesting the possible presence of slow magnetic relaxation.