New valence-sandwich [Mn(II)4Mn(III)4Mn(II)4] 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 Mn(III)4Mn(II)8] core consists of a central Mn(III)4O6] rhombus sandwiched by two Mn(II)4O7] 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.