Synthesis, Crystal Structure, and Magnetic Properties of a Family of Undecanuclear [Cu^II₉Ln^III₂] Nanoclusters

Abstract

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.

Stepwise Investigation of the Influences of Steric Groups versus Counterions To Target Cu/Dy Complexes

“…[32][33][34][35] A key factor seems to be the nature of both the 3d coordination geometry and that of the 4f ion. When looking at the impressive, very large Cu II -Dy III clusters found in the literature, 19,20,27,29,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] it is clear that it is difficult to understand the formation pathways and to analyze the details of the individual coordination sphere of the 3d and 4f ions. On the other hand, a systematic investigation of smaller 3d-4f clusters, and in particular, as we report here, for Cu II -Dy III clusters which result from small stepwise changes in the synthetic route and where the ligand differs only in the non-coordinating part, gives insights into the directing properties of the ligand and thus for further ligand design.…”

Chiral wheel anions of copper(ii)-early lanthanides(iii) with high optical-limiting properties

“…Polynuclear 3d–4f complexes have attracted ever-increasing attention mainly due to their aesthetically pleasing structures and the observed single-molecule magnet (SMM) behavior in some compounds. 1–3 As significant members of the family of 3d–4f complexes, several mixed Cu–Ln complexes with Ln heavier than Nd have been reported: {Cu II 9 Ln III 2 }, 4 {Cu II 24 Ln III 6 } 5 and {Cu II 36 Ln III 24 } (Ln = Gd, Dy), 6 and {Cu II 6 Ln III 12 } (Ln = Gd, Tb, and Dy), 7 to name a few, whereas those with trivalent early lanthanides of larger ionic radii (La, Ce, Pr, Nd) are comparably rare. In search of new 3d–4f complexes, challenges and opportunities reside in the selection of ligands.…”