Synthesis, Crystal Structure, and Magnetic Properties of a Family of Undecanuclear [CuII9LnIII2] Nanoclusters.

The syntheses, crystal structures, and magnetic properties of a novel family of heterometallic aggregates [CuII9LnIII2(μ3-OH)8(mea)4(C3H7COO)4(NO3)2Cl6(MeOH)4(H2O)2] ·3MeOH ·2H2O [Ln = Eu ( 1), Gd ( 2), Tb ( 3), Dy ( 4)] are reported. The compounds were obtained by the direct reaction of monoethanolamine (Hmea) with CuCl2 ·2H2O and Ln(NO3)3 ·6H2O in the presence of sodium butyrate (C3H7COONa) in MeOH/MeCN solution. Compounds 1- 4 are isomorphous and have an intriguing heterometallic undecanuclear [Cu9Ln2] core that contains a [3 × 3] [Cu9] grid and two [LnCu4] tetragonal pyramids that share a common [Cu4] vertex. Compounds 1- 4 are the first high-nuclearity 3d-4f aggregates bearing a monoethanolamine (Hmea) ligand to be reported. The magnetic properties of 1- 4 have been investigated by dc and ac susceptibility measurements. A detailed magnetic analysis revealed that antiferromagnetic Cu ···Cu interactions and ferromagnetic Cu ···Gd couplings exist in [Cu9Gd2] ( 2), which exhibits a significant magnetocaloric effect. Furthermore, [Cu9Tb2] ( 3) and [Cu9Dy2] ( 4) display slow relaxation of the magnetization. [ABSTRACT FROM AUTHOR]