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

Mixed 3d-4f 12-azametallacrown-4 complexes, [Mn(2)Ln(2)(OH)(2)(hppt)(4)(OAc)(2)(DMF)(2)]center dot 2 DMF center dot H2O [Ln= Dy (1), Er (2), Yb (3), Tb (4) and Y (5), H(2)hppt= 3-(2-hydroxyphenyl)-5-(pyrazin-2-yl)-1,2,4-triazole)], were synthesized by reactions of H(2)hppt with Mn(OAc)(2)center dot 4H(2)O and Ln(NO3)(3)center dot 6H(2)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 mu(2)-O bridging. Magnetic measurements revealed dominant antiferromagnetic interactions between metal centers, and frequency-dependent out-of-phase (chi ''(M)) signals below 4 K suggest slow relaxation of magnetization.