A novel enneanuclear manganese complex, [Mn9O4(Mesao)(6)(MeO)(3)(O2CMe)(3)(OH)(MeOH)(2)]center dot 2.5-DMF [1; Me-saoH(2) = 2-hydroxyphenylethanone oxime], was synthesized. The structure of 1 contains an unusual [Mn9O4] core with an unprecedented defective "supertetrahedron" topology based on two parallel, onset stacked 9-MC-3 and 15-MC-6 metallacrown subunits. Magnetic studies indicate that 1 behaves as a single-molecule magnet.