| Abstract
| - The preparation and properties of [Mn4O3(O2CPh-R)4(dbm)3] (R = H, p-Me, p-OMe, and o-Cl;dbm- is the anion of dibenzoylmethane) single-molecule magnets (SMMs) with virtual CS symmetry arereported. They were prepared by controlled potential electrolysis in 26−80% yields. The structures comprisea distorted-cubane core of virtual CS symmetry, in contrast to the other, more common complexes of thistype with virtual C3V symmetry. Solid-state magnetic susceptibility data establish the complexes have S =9/2 ground-state spins, and ac susceptibility studies indicate they are single-molecule magnets (SMMs).Magnetization vs dc field sweeps below 1.00 K reveal hysteresis loops confirming a SMM, with a verylarge step at zero applied field diagnostic of fast quantum tunneling of magnetization (QTM) through theanisotropy barrier. The fast QTM rate suggested a significant rhombic ZFS parameter E, as expected fromthe low (virtual CS) symmetry. This was confirmed by high-frequency electron paramagnetic resonancespectroscopy on polycrystalline and single-crystal studies. The results confirm the importance of symmetryon the QTM rates.
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