Issue 22, 2015

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

Abstract

The combination of anisotropic LnIII 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 LnIII 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 jRad–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.

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

Supplementary files

Article information

Article type
Paper
Submitted
26 nov. 2014
Accepted
30 janv. 2015
First published
30 janv. 2015

RSC Adv., 2015,5, 17131-17139

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

S. Y. Zhou, X. Li, T. Li, L. Tian, Z. Y. Liu and X. G. Wang, RSC Adv., 2015, 5, 17131 DOI: 10.1039/C4RA15074K

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