Ultrasound‐Assisted Formation of {Fe₆Ln/Y₄} Wheel‐Shaped Clusters and Condensed {Fe₄Ln/Y₂} Aggregates

Abstract

Two families of charge‐neutral heterometallic Fe‐4f coordination compounds comprising isobutyrate and amino alcoholate linkers were found to form exclusively upon ultrasonication irradiation. Under one‐pot conditions, the trinuclear precursor [Fe3O(O2CCHMe2)6(H2O)3](NO3)·2(MeCN)·2(H2O) reacts with Ln(NO3)3·xH2O or Y(NO3)3·6H2O, N‐butyldiethanolamine (bdeaH2) and NaN3 in methanol to yield the decanuclear clusters [Fe6M4(O2CCHMe2)8(N3)2(bdea)10]·n(solvent) (MIII = Y (1a·3MeOH), Gd (2a·2.5MeOH), Dy (3a·3.5MeOH·0.5H2O), Tb (4a·2MeOH), Ho (5a·2MeOH), as well as subsequently the hexanuclear compounds [Fe4M2(OH)2(O2CCHMe2)6(N3)2(bdea)4]·2(solvent) (MIII = Y (1b·2MeOH), Gd (2b·2MeOH), Dy (3b·2MeOH, 3c·2EtOH), Tb (4b·2MeOH), Er (6b·2MeOH), Tm (7b·2MeOH)). The {Fe6M4} clusters feature a wheel‐shaped architecture with the metal ions, interlinked by carboxylate and polyalcoholamine bridges, forming a saddle‐like ring. The hexanuclear {Fe4M2} clusters comprise two {Fe2M} triangles, connected via two bridging µ3‐OH– groups, which form a condensed core of metals additionally linked by deprotonated tripodal bdeaH2 ligands and bridging carboxylates. Magnetic measurements revealed predominant strong antiferromagnetic interactions within compounds 1–7 and out‐of‐phase signals for {Fe6Dy4} (3a·3.5MeOH·0.5H2O), {Fe6Tb4} (4a·2MeOH), and {Fe4Dy2} (3b·2MeOH).

Exploring the Role of Intramolecular Interactions in the Suppression of Quantum Tunneling of the Magnetization in a 3d-4f Single-Molecule Magnet

“…For 1−3 the Fe 2 Dy 2 central butterfly is decorated with an extra Fe III cation at each wing whereas the previous clusters are better described as four sharing defective cubanes. 22,23 In all cases the iron cations are related by a double O alkoxo bridge and the dysprosium cations are linked by a double μ 3 -OH that also links one Fe III cation. For the a-type of clusters, one of the Fe III cations does not interact directly with the lanthanides, whereas for the b-type, each Dy III interacts with three Fe III cations.…”

{Mn6IIIMnIVDy2III} Single-Molecule Magnet Based on Cubane Subunits

“…For a rational design of heterometallic polynuclear clusters with promising magnetic properties, the choice of functional groups and the chemical nature of the metal centers, their coordination geometry and oxidation states, and the reaction conditions are crucial. In particular, the synthesis of high-nuclearity carboxylate clusters by heating smaller coordination clusters with polyfunctional ligands in the solid state, in high-boiling solvents, and under solvothermal or microwave treatment has proven successful. − The ultrasonication of the chemical reagents in various solvents has recently been shown by us to be a promising tool for nanocluster formation. ,− Compared to conventional heating, such a method can improve the reaction rates, purity, and yield and is also a simple, fast, and economical green method. In this context, the unique application of the sonochemical approach has been demonstrated in the assembly of wheel-shaped {Fe 18 Ln 6 } , and {Mn 26 Dy 6 } clusters, the latter showing SMM properties .…”

Synthesis, structures, and magnetic properties of butterfly-shaped hexanuclear [FeIII4LnIII2] single-molecule magnets

“…Consequently, 3d–4f coordination compounds appear to be good candidates for promising applications in the field of molecular magnetism in high-density data storage, molecular spintronics, quantum processing, magnetically addressable liquid crystals, and magnetic alloys for refrigeration. 8–13…”

“…have been widely employed as ancillary ligands in the synthesis of 3d–4f complexes using aminopolyalcohols as ligands because the hard-donor oxygens are likely to bind to the harder oxophilic lanthanide ions while the soft-donor nitrogen is likely to bind to the softer transition metal ions. 52–55 However, the construction and synthesis of 3d–4f aminopolyalcohol compounds lacking carboxylate ancillary ligands is less developed. 56,57 Herein, we used N -methyldiethanolamine (mdeaH 2 ) as a ligand in the absence of any ancillary ligand, and synthesized a new series of Fe III 4 Ln III 2 complexes with the formula [Fe III 4 Ln III 2 (μ 3 -OH) 2 (mdea) 6 (NO 3 ) 4 (H 2 O) 2 ]·4MeOH (Ln = Y ( 1 ); Dy ( 2 )) and the diluted analogous with a Y III 1.83 Dy III 0.17 ratio ( 3 ).…”