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Two polymorphs of supramolecular isomers, a discrete dimer and a zig-zag chain, having the same chemical composition, [Mn(Hbit)Cl2] (Hbit=1-methyl-2-(1H-1,2,3-triazol-4-yl)-1H-benzo[d]imidazole), were obtained solvothermally in a one-pot synthesis. The isomers differ in a number of ways: orange blocks versus pale-yellow needles, triclinic P1 versus orthorhombic Pbcn, double µ2-Cl versus alternate single and triple µ2-Cl, coordination number 5 versus 6, and antiparallel versus parallel near-neighbor orientation of Hbit. The packing in each case is driven by the supramolecular interactions, H-bonds (N--H…Cl, C--H…Cl) and π…π overlaps, calculated to be in the range 20-36 kcalmol-1. Calculations gave a difference of only 2 kcalmol-1 in favor of the dimer, which confirms with the observation of principally the dimer at short reaction time. ESI-MS spectra of the dissolved crystals reveal the same fragments with similar distributions. The presence of two fragments at m/z 286.96 [MnIV(Hbit)Cl-2H]+ and 323.94 [MnIII (Hbit)Cl2]+ indicates that [Mn(Hbit)Cl2] is the building unit in both cases; thus, the different orientations of the ligands lead to the two polymorphs stabilized by the respective supramolecular interactions. Importantly, the chain form represents the first example with alternate single and triple µ2-Cl bridges. The magnetic interactions are weakly antiferromagnetic in both cases, with J in the range 0.07-0.34 cm-1; however, high-field EPR analysis reveals moderate magneto-anisotropy with D=0.26(1) cm-1, E=0.06(1) cm-1 and D=0.17(1) cm-1, E=0.03(1) cm-1, respectively. [ABSTRACT FROM AUTHOR]

A series of highly connected metal-organic frameworks (MOFs), [Co8(O)(OH)4(H2O)4(ina)8](NO3)2 ⋅2 C2H5OH ⋅4 H2O ( 1), [Co8(O)(OH)4(H2O)4(pba)8](NO3)2 ⋅8 C2H5OH ⋅28 H2O ( 2), and [Co8(O)(OH)4(H2O)4(pbba)8](NO3)2 ⋅guest ( 3), in which ina=isonicotinate, pba=4-pyridylbenzoate, and pbba=4-(pyridine-4-yl)phenylbenzoate, is reported. These MOFs contain a new secondary building unit (SBU), with a square Co4(μ4-O) central unit having the rare μ4-O2− motif, which is decorated by the other four peripheral cobalt atoms through μ3-OH in a windmill-like shape. This SBU holds 16 divergent connecting organic ligands, pyridyl-carboxylates, to form three different frameworks. The high porosity of desolvated 2 is shown by the efficient gas absorption of N2, CO2, CH4, and H2. In addition, 1 and 2 exhibit unusual canted antiferromagnetic behavior with spin-glass-like relaxation, with blocking temperatures that are fairly high, 20 K ( 1) and 10 K ( 2), for cobalt materials. The relationship between the metal clusters and linkers has been studied, in which the size and rotational degrees of freedom of the ligands are found to control the topology, gas sorption, and magnetic properties. [ABSTRACT FROM AUTHOR]

Hydrothermal reaction of Co(ClO4)2·6H2O with 2-ethoxy-6-(iminomethyl)phenol (Heimp) or 3-ethoxysalicylaldoxime (H2eosa) leads to the formation of two completely different CoIIcomplexes [Co7(eimp)6(OMe)6]·2ClO4(1) and [Co13(eosao)8(Heosao)6(ClO4)4]·H2O (2). Compound 1is a disc-like heptanuclear CoIIcluster with all the eimp−ligands displaying the η1: η2: η1: μ2binding mode. Compound 2is a butterfly-like nano-tridecanuclear CoIIcluster and the oximation of iminomethyl group results in its complicated binding modes. Four of the six Heosao−ligands adopt the η1: η2: η1: μ2mode and the other two take the η1: η2: η1: η1: μ3fashion, while eight eosao2−ligands are in the η2: η1: η2: μ4, η1: η3: η1: η2: μ5manner. Microwave heating during the synthetic process will dramatically improve the reaction rate and yield of 1, which however, is not valid for the formation of 2. Electrospray ionization mass spectrometry (ESI-MS) solution analysis was performed, which reveals a ligand substitution reaction of the core bridge for 1. For 2, the result of ESI-MS indicates that the Co13cluster still exists in solution, and maintains a conformation similar to that observed in the crystal structure. Magnetic studies show that 1exhibits a dominated ferromagnetic coupling between the CoIIions below 30 K, while 2is a typical antiferromagnetic system. [ABSTRACT FROM AUTHOR]

Abstract: A new cobalt(II) phosphonate, [enH2]0.5[Co(pa)(H2O)]·H2O (1) (H3pa=hydroxy-phosphono-acetic acid, HO2CCH(OH)PO3H2; en=ethylenediamine), has been hydrothermally synthesized and structurally characterized. Compound 1 has a honeycomb-like layer structure which is composed of CoO6 octahedra and μ3-pa ligands with the protonated en and lattice water molecules stabilized between the layers. Magnetic studies indicate that 1 shows weak ferromagnetic behavior, spin-glass behavior, and metamagnetic behavior. [Copyright &y& Elsevier]

One mixed-ligand complex of [Mn2(mpa)2(2,2′-bpy)2]n (1) (mpa=m-phthalate and 2,2′-bpy=2,2′-bipyridine) has been synthesized and structurally established by single-crystal X-ray diffraction. It consists of one-dimensional ribbons featuring carboxylate-bridged dinuclear units. The one-dimensional ribbons are assembled into three-dimensional networks by π–π stacking interactions. It was stable in air up to ca. 245 °C. The magnetic measurements suggest that the polymer gives weak antiferromagnetic behavior. [Copyright &y& Elsevier]

A one-dimensional manganese(II) complex, [Mn( L 2 )] n ( 1 , HL = 4-pyridyl- NH -1,2,3-triazole), has been hydrothermally synthesized at 120 °C. In the structure of 1 , the Mn(II) ions are octahedral coordinated and further bridged by L − ligands, forming a rigid 1D ribbon coordination chain. Varieties of supramolecular interactions, such as hydrogen bonds and C H ⋯ π interactions, play an important role on the stabilization of the structures. As revealed by magnetic measurement, complex 1 displays weak antiferromagnetic interaction with θ = –4.83 K, the best fit using Fisher's 1D Heisenberg model gives the intrachain magnetic coupling constant J = –0.21 cm − 1 above 30 K due to the neighboring Mn(N–N) 2 Mn rings twisted in the angle of almost 90°. [ABSTRACT FROM AUTHOR]

Abstract: A unique [Co13(mosao)8(Hmosao)6]·(ClO4)4·3DMF·MeOH·3H2O (1, H2mosao=3-methoxysalicylaldoxime) supercluster has been synthesized by a method of solvothermal reaction. The [Co13(μ 2-O)8(μ 3-O)6(μ 2-O–N)2(μ 3-O–N)8]4+ core is highly conjugated butterfly-like disc, which can be considered as fourteen distorted defective cubes sharing the neighboring faces one another. The electrospray ionization mass spectrometry (ESI-MS) analysis of 1 strongly suggests that Co13 cluster also exists in solution and maintains a conformation similar to that in the crystal structure, indicating that the significant stability of 1 in solution. Magnetic measurements of 1 reveal antiferromagnetic behaviors resulting from the cooperative magnetic coupling through multiplicate monoatomic oxygen and –N–O– exchange bridges and the odd number of spins result in relatively effective noncompensated moments at very low temperature. [Copyright &y& Elsevier]

Abstract: Solvothermal reaction assisted with microwave leads to the formation of two unique heterometallic cubic clusters [Ni3 M′(L)3(OH)(CH3CN)3]2·CH3CN (M′=K for 1 and M′=Na for 2, where L is an anion of 2-[(2-hydroxy-3-methoxy-benzylidene)-amino]-ethanesulfonate) with higher efficiency, yields and purity than those without it. The 6-metallacrown-3 [Ni3(OH)(L)3]− groups exhibit interesting ion trapping and self-assembly of size-different Na+ and K+ through form recognition and coordination activity in 1 and 2. The magnetic studies for 1 and 2 suggest that the {Ni3 M′O4} (M′=K and Na) cores both display dominant ferromagnetic interactions from the nature of the binding modes of μ 3-O (oxidophenyl) and μ 3-OH. [Copyright &y& Elsevier]