New Valence-Sandwich [Mn^II₄Mn^III₄Mn^II₄] Aggregate Showing Single-Molecule Magnet Behavior

The reaction of manganese(II) acetate, 1,1,1-tris(hydroxymethyl)methane (H3thme), and triethylamine in methanol leads to the formation of [Mn12O2(OMe)2(thme)4(OAc)10(H2O)4]·2MeOH. The [MnIII4MnII8] core consists of a central [MnIII4O6] rhombus sandwiched by two [MnII4O7] fragments. Frequency-dependent ac susceptibility and hysteresis loops in the magnetization indicate single-molecule magnet behavior with a pure quantum-tunneling regime of relaxation below 0.2 K.