Heterometallic [Mn(5)-Ln(4)] Single-Molecule Magnets with High Anisotropy Barriers.
Heterometallic [Mn(5)-Ln(4)] Single-Molecule Magnets with High Anisotropy Barriers.
The reaction of [Mn(6)O(2)(Piv)(10)(4-Me-py)(2.5)(PivH)(1.5)] (1) (py: pyridine, Piv: pivilate) with N-methyldiethanolamine (mdeaH(2)) and Ln(NO(3))(3)6 H(2)O in MeCN leads to a series of nonanuclear compounds [Mn(5)Ln(4)(O)(6)(mdea)(2)(mdeaH)(2)(Piv)(6)(NO(3))(4)(H(2)O)(2)]2 MeCN (Ln=Tb(III) (2), Dy(III) (3), Ho(III) (4), Y(III) (5)). Single-crystal X-ray diffraction shows that compounds 2-5 are isostructural, with the central core composed of two distorted {Mn(IV)Mn(III)Ln(2)O(4)} cubanes sharing a Mn(IV) vertex, representing a new heterometallic 3d-4f motif for this class of ligand. The four new compounds display single-molecule magnet (SMM) behaviour, which is modulated by the lanthanide ion used. Moreover, the values found for Delta(eff) and tau(o) for 3 of 38.6 K and 3.0×10(-9) s respectively reveal that the complex 3 exhibits the highest energy barrier recorded so far for 3d-4f SMMs. The slow relaxation of the magnetisation for 3 was confirmed by mu-SQUID measurements on an oriented single crystal and the observation of M versus H hysteresis loops below 1.9 K.
Mereacre V, Ako AM, Clérac R, Wernsdorfer W, Hewitt IJ, Anson CE, Powell AK.
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