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A series of heterometallic 3d-Gd3+ complexes based on a lanthanide metalloligand, [M(H2O)6][Gd(oda)3] ⋅3 H2O [M=Cr3+ ( 1-Cr)] (H2oda=2,2′-oxydiacetic acid), [M(H2O)6][MGd(oda)3]2 ⋅3 H2O [M=Mn2+ ( 2-Mn), Fe2+ ( 2-Fe) and Co2+ ( 2-Co)], and [M3Gd2(oda)6(H2O)6] ⋅12 H2O [M=Ni2+ ( 3-Ni), Cu2+ ( 3-Cu), and Zn2+ ( 3-Zn)], are reported. Magnetic and heat-capacity studies revealed a significant impact on the magnetocaloric effect depending on the anisotropy of the 3d transition metal ions, as confirmed by comparison of the observed maximum values of −Δ Sm between complexes 2-Co and 1-Cr. In these two complexes, the 3d metal ions have the same spin ( S=3/2 for Co2+ and Cr3+ ions), and the theoretical calculation suggested a larger −Δ Sm value for 2-Co (47.8 J K−1 kg−1) than 1-Cr (37.5 J K−1 kg−1); however, the significant anisotropy of Co2+ ions in 2-Co, which can result in smaller effective spins, gives a smaller value of −Δ Sm for 2-Co (32.2 J K−1 kg−1) than for 1-Cr (35.4 J K−1 kg−1) at Δ H=9 T. [ABSTRACT FROM AUTHOR]

Abstract: Under solvothermal conditions, one polynuclear FeIII complex of formula [Fe3{(py)C(ph)O}4Cl4][FeCl4] (1) was synthesized from reaction of phenyl-pyridine-2-yl-methanone oxime (py)C(ph)NOH with FeCl3, and one FeII/FeIII/FeII complex of composition [Fe3{(py)C(ph)NO}6][CH3COO] (2) was prepared from treatment of (py)C(ph)NOH with Fe(OAc)2. The most interesting synthetic feature of complex 1 is the in situ transformation of (py)C(ph)NOH into the (py)C(ph)O− ligand. Complexes 1 and 2 were characterized by X-ray single crystal diffraction, IR spectroscopy, and elemental analysis. X-ray analysis revealed that complex 1 contains a V-shaped FeIII core with two terminal FeIII atoms displaying distorted square-pyramidal geometries and one central FeIII ion exhibiting octahedron geometry. Complex 2 is a mixed-valence linear FeII/FeIII/FeII complex with all the three metal centers displaying distorted octahedron geometries. The low-temperature magnetic susceptibility measurement for the solid sample of 1 revealed the weak antiferromagnetic FeIII…FeIII interactions. Theoretical calculations based on density functional theory were performed using the crystal structure of complex 1. [Copyright &y& Elsevier]

Abstract: The tetranuclear cubane-like complex of the formula [Ni4(HL1)3(HL2)(H2O)(CH3OH)] [CH3COO]·2CH3OH·CH3CN (1) (H3L1=3-(2-hydroxybenzylideneamino)propane-1,2-diol; H2L2=3-aminoprppane-1,2-diol) has been prepared by a one-pot reaction of nickel(II) acetate, salicylaldehyde and 3-aminopropane-1,2-diol, where the H3L1 ligand was generated in situ via the condensation reaction between salicylaldehyde and 3-aminopropane-1,2-diol. The X-ray diffraction analysis of the complex showed a Ni4O4 cubane arrangement and the coordination environments of four Ni(II) ions are different from each other. Magnetic studies indicated ferromagnetic behavior for the complex. The magnetic data were fitted and the parameters were given as g =2.43, J 1 =15.96, and J 2 =4.116. [Copyright &y& Elsevier]

Abstract: Two new copper coordination polymers generated from mixed organic ligands 4,4′-bipydine and 1,2,4-benzenetricarboxylate [Cu3(1,2,4-BTC)2(4,4′-bipy)(H2O)4] 1 and [Cu(1,2,4-HBTC)(4,4′-bipy)] 2 (1,2,4-BTC=1,2,4-benzenetricarboxylate) have been prepared hydrothermally and characterized by single crystal X-ray diffraction. Compound 1 crystallizes in the noncentrosymmetric space group , with , , , , and . Its structure contains two different one-dimensional (1-D) chains for the Cu ions, namely and ; the carboxylate of 1,2,4-BTC ligands links the two different 1-D chains into an interesting steplike neutral framework. Compound 2 crystallizes in the monoclinic space group , with , , , , , . Its structure contains novel paddle-wheel clusters Cu2(CO2)4(4,4′-bipy)2 as SBUs which are further linked by monoprotonated 1,2,4-BTC ligands into a 2-D neutral framework. The magnetic behaviors of both compounds have been studied. [Copyright &y& Elsevier]