The simple, well-understood coordination chemistry of the cyanide ligand is of significant utility in the design of new single-molecule magnets. Its preference for bridging two transition metals in a linear M'-CN-M geometry permits the use of multidentate blocking ligands in directing the assembly of specific molecular architectures. This approach has been employed in the synthesis of numerous high-nuclearity constructs, including simple cubic M4M'4(CN)12 and face-centered cubic M8M'6(CN)24 coordination clusters, as well as some unexpected cluster geometries featuring as many as 27 metal centers. The ability to substitute a range of different transition metal ions into these structures enables adjustment of their magnetic properties, facilitating creation of high-spin ground states with axial magnetic anisotropy. To date, at least four different cyano-bridged single-molecule magnets have been characterized, exhibiting spin-reversal barriers as high as 25 cm(-1). Ultimately, it is envisioned that this strategy might lead to molecules possessing much larger barriers with the potential for storing information at more practical temperatures.

Two copper-mercury-chalcogenide clusters [Hg(15)Cu(20)E(25)(PPr(3))(18)] (1, E = S; 2, E = Se) are synthesized in good yield from the reaction of (Pr(3)P)(3)Cu-ESiMe(3) and (Pr(3)P)(2).Hg(OAc)(2) at low temperatures. Single-crystal X-ray analyses illustrate that the two ternary clusters are isomorphous and consist of a phosphine-stabilized core of mixed Hg, Cu, and E centers. Thermolysis of 1 leads to the formation of mercury metal and various forms of copper-sulfide. The copper-indium-sulfide cluster [Cu(6)In(8)S(13)Cl(4)(PEt(3))(12)] (3) is similarly prepared in 50% yield from (Et(3)P)(3)Cu-SSiMe(3), InCl(3), and S(SiMe(3))(2).

A complex with a [Mn(II)(6)Mn(III)(11)] core results via formal fusion of two isotropic Mn(II)(4)Mn(III)(6) supertetrahedra along a common edge leading to a high spin ground state anisotropic system showing Mvs. H hysteresis loops below 1 K.

Three one-pot syntheses leading to four examples of in situ ligand transformations are presented. These in situ reactions involve various transformations of 2-(N'-dicyanomethylene-hydrazino)-benzoic acid (DHB). The resulting ligands enabled the preparation of three new coordination compounds, which were fully characterized by infrared spectroscopy, elemental analysis, and single crystal X-ray diffraction. The complex, [Mn(III)(Lig-I)(CH(3)OH)Cl] (1), was prepared in a one-pot synthesis in which the aryl hydrazone ligand, (Lig-I)(2-), was formed by the amination of DHB resulting from the nucleophilic attack of an amino group of ethylenediamine. The linear, mixed-valence trinuclear complex, (Et(3)NH)(4)[Mn(III)(2)Mn(II)(mu-OH)(2)(Lig-II)(2)(HLig-II)(2)] (2), was synthesized using a preparation involving the in situ reaction of azide and a nitrile of DHB. Larger species can also be prepared using this technique. In a reaction involving two different in situ ligand formations, the cyclocondensation of two DHB molecules and the partial hydrolysis of a nitrile of DHB, the first example of a tetradecanuclear Mn(II) aggregate, (H(3)O)(4)[Mn(II)(14)(mu(6)-CO(3))(mu(3)-OH)(6)(HLig-III)(6)(HLig-IV)(3)(OH(2))(3)] x 92 MeCN (3), was isolated and characterized. Magnetic measurements on 2 indicate the presence of intramolecular and intermolecular antiferromagnetic interactions (J(1)/k(B) = -9.5(1) K, g = 1.95(2), and zJ'/k(B) = -0.37(5) K) while those on 3 suggest the presence of dominating antiferromagnetic interactions.