A Family of 12‐Azametallacrown‐4 Structural Motif with Heterometallic Mn^III‐Ln‐Mn^III‐Ln (Ln=Dy, Er, Yb, Tb, Y) Alternate Arrangement and Single‐Molecule Magnet Behavior

Abstract

Mixed 3d-4f 12-azametallacrown-4 complexes, [Mn2 Ln2 (OH)2 (hppt)4 (OAc)2 (DMF)2 ]⋅2 DMF⋅H2 O [Ln=Dy (1), Er (2), Yb (3), Tb (4) and Y (5), H2 hppt=3-(2-hydroxyphenyl)-5-(pyrazin-2-yl)-1,2,4-triazole)], were synthesized by reactions of H2 hppt with Mn(OAc)2 ⋅4 H2 O and Ln(NO3 )3 ⋅6 H2 O. This is the first 3d-4f azametallacrown family to incorporate Ln ions into the ring sets. These isostructural complexes exhibit alternating arrangements of two Mn and two Ln ions in the rings with each pair of metal centers bound by an NN group and μ2 -O bridging. Magnetic measurements revealed dominant antiferromagnetic interactions between metal centers, and frequency-dependent out-of-phase (${\chi {^\prime}{^\prime}_{\rm{M}} }$) signals below 4 K suggest slow relaxation of magnetization.

Slow Magnetic Relaxation in a [Na2Dy4] Complex and Coexistence of Multiple Metal Rings

“…Therefore, it is one of the challenges to synthesize lanthanide-containing complexes through choosing triazole-based ligands. Based on our previous study, [14,23] herein, we reported three new heterometallic 2p-4f complexes [Na 2 {Ln 4 (μ 3 -OH) 2 (ppt) 4 (Hppt) 2 (OAc) 2 }(DMF) 4 ] (1 • 2.5H 2 O, Ln = Dy; 2 • 2H 2 O, Ln = Er; 3, Ln = Yb) with the presence of multiple metal rings using a rigid, unsymmetrical triazole-bridge ligand with phenol and pyrazine groups. In this manuscript, we reported the syntheses, crystal structures and magnetic properties of these three complexes.…”

“…We reported the first family of heterometallic Mn/Ln azametallacrowns, and discussed their synthesis, structures and SMM behaviour. [14] These isostructural azametallacrowns display Mn/Ln ions alternating arrangements.…”

“…[16][17][18] And in the exploration of SMM, the introduction of anti-magnetic metal ions changed crystal-field effect and negative charge on the bridging donors and further influenced the magnetic properties [19] and structural frameworks. [14,20] Liu reported that Na ion served as a cationic template to assist in the formation of the crown-ether-like units. [21] The incorporation of Na ion in metallacrowns promoted the formation of new metallacrown frameworks and transferred the magnetic interactions between metal centers, as well as further changed magnetic behavior.…”

“…[1a] Although quite a few azametallacrowns have be synthesized and reported, the exploration of magnetic properties of azametallacrowns have been confined to Mn III and Fe III -complexes, [13] and fewer heterometallic or lanthanide azametallacrowns have been demonstrated. [14,15] As we all known, the unique feature of metallacrowns is that the numerous metal ions assemble into a such small volume, especially in the planar configuration, which easily impellings the alignment of single-ion magnetoanisotropy to possess large spin value as well as unexpected micir magnetostructural correlation of azametallacrown SMMs. We reported the first family of heterometallic Mn/Ln azametallacrowns, and discussed their synthesis, structures and SMM behaviour.…”

“…Comparing to metallacrowns, azametallacrowns display larger ring size with the cyclic bodies expanding from aza[9‐MC‐3] to aza[60‐MC‐20], and the structures transfer from planar to non‐planar frameworks [1a] . Although quite a few azametallacrowns have be synthesized and reported, the exploration of magnetic properties of azametallacrowns have been confined to Mn III and Fe III ‐complexes, [13] and fewer heterometallic or lanthanide azametallacrowns have been demonstrated [14,15] . As we all known, the unique feature of metallacrowns is that the numerous metal ions assemble into a such small volume, especially in the planar configuration, which easily impellings the alignment of single‐ion magnetoanisotropy to possess large spin value as well as unexpected micir magnetostructural correlation of azametallacrown SMMs.…”