A Supramolecular Aggregate of Four Exchange-Biased Single-Molecule Magnets

The reaction between 3-phenyl-1,5-bis­(pyridin-2-yl)­pentane-1,5-dione dioxime (pdpdH2) and triangular [MnIII3O­(O2CMe)­(py)3]­(ClO4) (1) affords [Mn12O4(O2CMe)12(pdpd)6)]­(ClO4)4 (3). Complex 3 has a rectangular shape and consists of four [MnIII3O]7+ triangular units linked covalently by the dioximate ligands into a supramolecular [Mn3]4 tetramer. Solid-state dc and ac magnetic susceptibility measurements revealed that [Mn3]4 contains four Mn3 single-molecule magnets (SMMs), each with an S = 6 ground state. Magnetization versus dc-field sweeps on a single crystal gave hysteresis loops below 1 K that exhibited exchange-biased quantum tunneling of magnetization steps, confirming 3 to be a supramolecular aggregate of four weakly exchange-coupled SMM units.