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Abstract: Three new tetranuclear nickel(II) complexes of general formula [Ni4(L)2(N3)2(CH3COO)2(CH3O)2]2·xCH3OH·yH2O (HL=HL1, HL2 and HL3; x =0, y =1 for 1; x =2, y =0 for 2 and x =2, y =4 for 3) were synthesized and characterized by single crystal X-ray diffraction and magnetic measurements. Single crystal X-ray studies reveal that all three complexes exhibit similar tetranuclear face-shared defective double-cubane structure, having azido-, alk/phenoxido- and acetato-bridges. Magnetic susceptibility measurements on the complexes in the range of 300–2K indicate ferromagnetic coupling between the metal ions. The slightly different magnetic behaviors observed are probably caused by subtle structural differences between the respective [Ni4O4N2] cores induced by ligand variation. [Copyright &y& Elsevier]

The reaction of Dy(NO3)3·6H2O with the ligand 2-((1-hydroxybutan-2-ylimino)methyl)phenol (H2L, Scheme 1) generates the nonanuclear compound [Dy9L8(μ3-OH)8(μ4-OH)2(CH3OH)8](OH)(CH3OH)3(Dy9), whose single-crystal X-ray structure reveals the presence of two square pyramidal pentanuclear units assembled viathe apical metal center. The square pyramidal core of a previously reported [Dy5(μ4-OH)(μ3-OH)4(μ-η2-Ph2acac)4(η2-Ph2acac)6] (Dy5; Ph2acac = dibenzoylmethanide), is structurally related to those herein described; however, the magnetic properties of Dy9and Dy5are drastically different. Indeed, Dy5shows slow relaxation of magnetization while no out-of-phase ac signal is noticed for Dy9. The underlying mechanism is not clear due to the complexity of such systems; however, the different anisotropy of the respective structures, which is dictated by the combination of the metal topology, the ligands involved and the structural parameters of the molecule, is mostly responsible for the distinctive relaxation dynamics observed. [ABSTRACT FROM AUTHOR]

Abstract: The first complex [Mn(H2O)6][NiCo(TTHA)(H2O)2]·4H2O 1 (TTHA6− =triethylenetetraminehexaacetate) containing MnII–CoII–NiII three different 3d metal ions is synthesized and magnetic measurement suggests that ferromagnetic interactions occur between Ni2+ ions and rarely found low-spin Co2+ ions. [Copyright &y& Elsevier]

Reactions of lanthanide(III) perchlorate (Ln = Dy, Tb, and Gd), nickel(II) acetate, and ditopic ligand 2-(benzothiazol-2-ylhydrazonomethyl)-6-methoxyphenol (H2L) in a mixture of methanol and acetone in the presence of NaOH resulted in the successful assembly of novel Ln2Ni2 heterometallic clusters representing a new heterometallic 3d-4f motif. Single-crystal X-ray diffraction reveals that all compounds are isostructural, with the central core composed of distorted [Ln2Ni2O4] cubanes of the general formula [Ln2Ni2(μ3-OH)2(OH)(OAc)4(HL)2(MeOH)3](ClO4)·3MeOH [Ln = Dy (1), Tb (2), and Gd (3)]. The magnetic properties of all compounds have been investigated. Magnetic analysis on compound 3 indicates ferromagnetic Gd⋯Ni exchange interactions competing with antiferromagnetic Ni⋯Ni interactions. Compound 1 displays slow relaxation of magnetization, which is largely attributed to the presence of the anisotropic DyIII ions, and thus represents a new discrete [Dy2Ni2] heterometallic cubane exhibiting probable single-molecule magnetic behavior. [ABSTRACT FROM AUTHOR]

Abstract: Two new manganese complexes with multidentate 3-methoxysalicylaldehyde benzoylhydrazide ligand have been synthesized and structurally characterized. Variations of the reaction conditions (namely, the base, solvent or the counter ion) lead to drastic changes in the nature of the resulting coordination complexes. Depending on the anions involved a di- and a tetranuclear manganese structures are obtained. The magnetic properties of both complexes have been investigated, which show that the different complexes exhibit antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]

Two new dysprosium(III) coordination compounds, namely, [Dy4(HL)4(C6H4NH2COO)2(μ3-OH)4(u-OH)2(H2O)4] ·4CH3CN· 12H2O (1) and Dy8(HL)10(C6H4NH2COO)2(μ3-OH)8(OH)2(NO3)2(H2O)4] (2), have been synthesized from the Schiff-base ligand 2-{[(2-hydroxy-3-methoxyphenyl)methylidene]amino}benzoic acid (H2L) and dysprosium chloride (1) or dysprosium nitrate (2). Single-crystal X-ray diffraction studies reveal that compound 1 exhibits a tetranuclear cubane-like structure and that 2 is an octanuclear, bis-cubane complex. The [Dy4(μ3-OH)μ] cubane cores of 1 and 2 are structurally related; however, the magnetic properties of 1 and 2 are drastically different. Indeed, 2 shows slow relaxation of magnetization while no out-of-phase alternating current (ac) signal is noticed for 1. These significant disparities are most likely due to the different M-O-M angles observed for the respective cubane cores. [ABSTRACT FROM AUTHOR]

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

Abstract: A new oxamido-bridged vanadium(IV)-oxo complex ligand VOL (H2L=2,3-dioxo-5,6:13,14-dibenzo-7,12-diphenyl-1,4,8,11-tetraazacyclo-tetradeca-7,12-diene) (1) has been synthesized. Based on the mononuclear ligand, two trinuclear complexes [Cu(VOL)2(H2O)2](ClO4)2 ·1.5H2O (2) and [Mn(VOL)2(CH3OH)2](ClO4)2 ·5CH3OH (3) have been prepared and structurally characterized by X-ray crystallography. In complexes 2 and 3, the central ions Cu(II) and Mn(II) are connected to two VOL fragments via an exo-cis oxamido bridge. Magnetic susceptibility studies (2–300K) indicate the occurrence of ferromagnetic coupling between the paramagnetic metals in complex 2, while a weak antiferromagnetic interaction is detected in complex 3. The experiment data have been fitted according to the Heisenberg Hamiltonian , leading to J =9.09cm−1, zJ′=5.0×10−3 cm−1 for complex 2 and J =−0.27cm−1, θ =−0.03K for complex 3. [Copyright &y& Elsevier]

Abstract: Two novel 3d–4f polymers [La(H2O)4][M2TTHA(SCN)2]·H3O+ (M=Ni(1), Cu(2), H6 TTHA=triethylenetetraaminehexaacetic acid) were synthesized and characterized by X-ray single-crystal diffraction, elemental analysis, IR and magnetic properties. Two complexes show 3D framework, comprising an unusual infinite 1D chain based on heterometallic La2M2 rings (M=Ni(1), Cu(2)). [Copyright &y& Elsevier]

Two novel three-dimensional (3D) 3d–4f mixed complexes [Ln-(H2O)4][Ni2TTHA(SCN)2]·H3O+ [Ln = Pr (1), Ce (2); H6TTHA = triethylenetetraaminehexaacetic acid], based on the building blocks of [Ni2TTHA(SCN)2]4-, were synthesized and characterized by X-ray crystal diffraction and magnetic properties. The single-crystal structures show that these complexes form a 3D framework, comprised of an unusual infinite one-dimensional chain based on heterometallic Ln2Ni2 rings. The temperature-dependent magnetic susceptibilities were analyzed by an approximate model, leading to g = 2.06. Δ = 2.83, zJ′ = -0.6 cm-1 for complex 1 and g = 2.07, Δ = 1.00, zJ′ = -0.5 cm-1 for complex 2. [ABSTRACT FROM AUTHOR]