Crystallography and Mass-Spectrometry of Heptanuclear Disk Mn(II) Cluster

(1-methyl-1H-benzo[d]imidazol-2-yl) methanol (Hmbm) reacts with Mn(ClO4)2·6H2O to form heptanuclear disks [Mn7(mbm)12]·2(ClO4) (1) under ambient conditions. The heptanuclear cluster was previously described as a double calix unit with the hydroxides in the middle. The seven Mn(II) ions are essentially coplanar as expected for all edge-sharing octahedra, which can be intituled as a segment of Mg(OH)2 layer of brucite, so it is a symmetric disk. ESI–MS of crystals showed its stability in solution. Time-dependent mass spectrometry (MS) from solutions at different period of the assembly reveal a hierarchical sequence, [MnIII(mbm)2]+  → [MnII2(mbm)3]+  → [MnII4(mbm)6(ClO4)]+  → [MnIIIMnII6(mbm)12(ClO4)2]+.