First coordination compounds based on a bis(imino nitroxide) biradical and 4f metal ions: synthesis, crystal structures and magnetic properties†
Abstract
The synthesis, crystal structures and magnetic properties of two families of heterospin complexes containing lanthanide ions and a bis(imino nitroxide) biradical (IPhIN = 1-iodo-3,5-bis(4′,4′,5′,5′-tetramethyl-4′,5′-dihydro-1H-imidazole-1′-oxyl)benzene) are reported: in [Ln2(hfac)6(IPhIN)(H2O)2] compounds, two lanthanide ions [Ln = GdIII (1) and DyIII (2)] are coordinated to the biradical, and in [Ln(hfac)3(IPhIN)(H2O)] compounds, one lanthanide ion (Ln = TbIII (3), GdIII (4) or DyIII (5)) is coordinated to the biradical. Ferromagnetic intramolecular magnetic interactions between GdIII and the biradical were found for 1 and 4, while intramolecular magnetic interactions between the radicals were ferro- and antiferromagnetic, respectively. Compound 2 shows a field induced slow relaxation of magnetization, which (under an external applied field of 2 kOe) exhibits an activation energy barrier of ΔE/kB = 27 K and a pre-exponential factor of 1.4 × 10−8 s. To support the magnetic characterization of compound 3ab initio calculations were also performed.