A Molecular-Based Magnet with a Fully Interlocked Three-Dimensional Structure

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Science  23 Jul 1993:
Vol. 261, Issue 5120, pp. 447-449
DOI: 10.1126/science.261.5120.447


A compound has been synthesized with the formula (rad)2Mn2[Cu(opba)]3(DMSO)2.2H2O, where rad+ is 2-(4-N-methylpyridinium)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, opba is orthophenylenebis(oxamato), and DMSO is dimethyl sulfoxide. It consists of two nearly perpendicular graphite-like networks with edge-sharing Mn(II)6Cu(II)6 hexagons. The two networks are fully interlocked with the same topological relationship as that between adjacent rings of a necklace. The compound has three kinds of spin carriers: Mn(II) and Cu(II) ions, antiferromagnetically coupled through oxamato bridges, and rad+ radical cations, bridging the Cu(II) ions through the nitronyl nitroxide groups and forming Cu-rad chains. The temperature dependence of the magnetization reveals that below 22.5 K, the compound behaves as a magnet.