Gong-Feng Xu

Four new lanthanide-nitronyl nitroxide (Ln(III) = Pr(III), Sm(III), Eu(III), Tm(III)) complexes and a Tb(III) complex exhibiting single-molecule magnet behavior.

Five new complexes based on rare-earth-radical [Ln(hfac)(3)(NIT-5-Br-3py)](2) (Ln = Pr (1), Sm (2), Eu (3), Tb (4), Tm (5); hfac = hexafluoroacetylacetonate; NIT-5-Br-3py = 2-(4,4,5,5-tetramethyl-3-oxylimidazoline-1-oxide)-5-bromo-3-pyridine) have been synthesized and characterized by X-ray crystal diffraction. The single-crystal structures show that these complexes have similar structures, in which a NIT-5-Br-3py molecule acts as a bridging ligand linking two Ln(III) ions through the oxygen atom of the N-O group and nitrogen atom from the pyridine ring to form a four-spin system. Both static and dynamic magnetic properties were measured for complex 4, which exhibits single-molecule magnetism behavior.

MIIIDyIII3 (M = FeIII, CoIII) Complexes: Three-Blade Propellers Exhibiting Slow Relaxation of Magnetization

[Dy(III)(HBpz(3))(2)](2+) moieties (HBpz(3)(-) = hydrotris(pyrazolyl)borate) and a 3d transition-metal ion (Fe(III) or Co(III)) have been rationally assembled using an dithiooxalato dianion ligand into 3d-4f [MDy(3)(HBpz(3))(6)(dto)(3)]·4CH(3)CN·2CH(2)Cl(2) (M = Fe (1), Co (2) complexes. Single-crystal X-ray studies reveal that three eight-coordinated Dy(III) centers in a square antiprismatic coordination environment are connecting to a central octahedral trivalent Fe or Co ion forming a propeller-type complex. The dynamics of the magnetization in the two isostructural compounds, modulated by the nature of the central M(III) metal ion, are remarkably different despite their analogous direct current (dc) magnetic properties. The slow relaxation of the magnetization observed for 2 mainly originates from isolated Dy ions, since a diamagnetic Co(III) metal ion links the magnetic Dy(III) ions. In the case of 1, the magnetic interaction between S = 1/2 Fe(III) ion and the three Dy(III) magnetic centers, although weak, generates a complex energy spectrum of magnetic states with low-lying excited states that induce a smaller energy gap than for 2 and thus a faster relaxation of the magnetization.

Two [Au(CN)2]−-bridged heterometallic coordination polymers directed by different 2,2′-bipyridyl-like ligands

Two new cyanide-bridged heterobimetallic coordination polymers constructed by using the [Au(CN)2]− building block, {Cd(bipy)[Au(CN)2]2}n (1) and {{Cd(phen)[Au(CN)2]2(H2O)}·iPrOH}n (2) (bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline), have been synthesized and characterized. Complex 1 with chiral P3112 space group exhibits a novel three-fold interpenetrating quartz-like 3-D network, which is completely unsupported by aurophilic interactions, while complex 2 with the replacement of bipy by phen shows C2/c space group and features the 1-D zigzag chain structure and an extended supramolecular 2-D array in which aurophilic interactions may play an important role in sustaining the supramolecular solid-state architectures. 1 and 2 feature various networks most likely due to the different steric hindrances of the bipy and phen ligands. In addition, the solid state photoluminescence spectrum of complex 2 exhibits a strong green emission band (λmax = 524 nm) at room temperature.

Heteropolymetallic Supramolecular Solid-State Architectures Constructed from Dicyanoaurate Ion, Phen, and 3d Metals

Two new supramolecular polymeric coordination complexes, {Zn(phen)2[Au2(CN)4](H2O)}·1.5H2O 1 and {Mn(phen)[Au2(CN)4](H2O)}·PriOH 2, have been obtained through a self-assembly process. The three-dimensional supramolecular architectures of compounds 1 and 2 are sustained by aurophilic, hydrogen-bonding, and/or π–π interactions. Gold atoms linked with aurophilic bonds arrange in a pattern not frequently observed.