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

Abstract

Mixed 3d-4f 12-azametallacrown-4 complexes, [Mn2Ln2(OH)2(hppt)4(OAc)2(DMF)2]·2 DMF·H2O [Ln=Dy (1), Er (2), Yb (3), Tb (4) and Y (5), H2hppt=3-(2-hydroxyphenyl)-5-(pyrazin-2-yl)-1,2,4-triazole)], were synthesized by reactions of H2hppt with Mn(OAc)2·4 H2O and Ln(NO3)3·6 H2O. 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) signals below 4 K suggest low relaxation of magnetization. Crown magnetics: Five novel heterometallic Mn-Ln complexes (Ln=Dy, Er, Yb, Tb, Y) have been reported, in which the metal ions arrange alternately with N-N bridging and display a rare Ln-containing 12-azametallacrown-4 structural motif (see figure). Magnetic measurements reveal frequency-dependent slow relaxation of magnetization.