Bao-Qing Ma

A two-fold interpenetrated three-dimensional cobalt(II) complex with dual dicyanamide and 4,4′-bipyridine bridges

A three-dimensional cobalt(II) coordination polymer, Co(4,4′-bpy)[N(CN)2]2, was constructed using dicyanamide and 4,4′-bipyridine bridges; it consists of two-fold interpenetrated α-Po-like networks.

One-dimensional coordination polymers [Co(acac)2pz]n and [Co(acac)2(4,4′-bipy)]n (acac=acetylacetone, pz=pyrazine, bipy=4,4′-bipyridine): synthesis, structures and magnetic properties

Abstract Two one-dimensional coordination polymers [Co(acac)2pz]n (1) and [Co(acac)2(4,4′-bipy)]n (2) have been synthesized by reaction of Co(acac)2(H2O)2 with pyrazine and 4,4′-bipyridine, respectively. They have a similar structural motif, consisting of one-dimensional linear chain structure linked via bridging pyrazine or 4,4′-bipyridine, and the acac chelated to the Co(II) ion. A compared magnetic investigation shows very similar magnetic behavior for the two compounds, demonstrating the similarity of pyrazine and 4,4′-bipyridine in mediating the magnetic coupling interactions.

Oxo-centered regular octahedral lanthanide clusters

Reaction of Ln(ClO4)3 (Ln=Nd or Gd) with L-serine at pH 6.0 yielded the aqua hexanuclear clusters [Nd6(μ6-O)(μ3-OH)8(H2O)24](ClO4)8·6 H2O (1) and [Gd6(μ6-O)(μ3-OH)8(H2O)24](ClO4)8·6 H2O (2). They are isomorphous and comprised of a regular octahedron of 6 lanthanide ions encapsulating a μ6-O2− anion and capped by a μ3-OH group on each face. The structure can also be regarded as an oxo-centered octahedron embedded in a cube formed by 8 μ3-OH groups.

Low temperature synthesis and magnetism of La0.75Ca0.25MnO3 nanoparticles

We have reported here a new route to synthesize nanosized La0.75Ca0.25MnO3 perovskite crystalline complex oxides at a calcination temperature of 450‐6008C using the amorphous molecular alloy of La‐Ca‐Mn‐DTPA as precursors. The size and topography of the oxides are dependent on the calcinating temperature of the precursors. The resulting particle size is in a range of 20‐100 nm as determined by transmission electron microscopy. The magnetization of La0.75Ca0.25MnO3 nanophase is strikingly dependent on the particle size. The magnetoresistance of the samples shows spin-polarized tunneling behavior at low temperatures. q 2000 Elsevier Science Ltd. All rights reserved.

The formation of Gd4O4 cubane cluster controlled by L-valine

Hydrolysis of Gd(ClO4)3 controlled by L-valine yields a novel tetranuclear cubane cluster [Gd4(μ3-OH)4(Hval)3(val)3(H2O)8](ClO4)5·8 H2O.

3D Self-penetrating coordination network constructed by dicyanamide and 1,2-bis(4-pyridyl)ethane-N,N′-dioxide (bpeado)

The complexes of formulae M(dca)2(bpeado) (M = Mn (1), Fe (2), Co (3), Ni (4), Cu (5); dca = dicyanamide; bpeado = 1,2-bis(4-pyridyl)ethane-N,N′-dioxide) have been synthesized and characterized by X-ray single crystal diffraction. Compounds 1–5 contain 3D self-penetrating networks, in which bidentate dca ligands bridge the octahedral metal ions to form square-grid like M(dca)2 sheets and these sheets are further connected by criss-crossing bpeado to give a 3D self-penetrating network. Variable temperature magnetic susceptibility studies have shown that these compounds generally display very weak antiferromagnetic coupling because of the long bpeado and μ1,5-dca pathways. Consequently, no magnetic ordering was found.

A dimer structure {[Cu(phen)2Cl][OH]·6H2O}2 constructed through C–H⋯Cl hydrogen bondings and π–π interactions

Abstract The first near regular trigonal bipyramid [Cu(phen)2Cl]+ type compound has been synthesized, which possesses a dimer structure constituted through C–H⋯Cl hydrogen bondings and π–π interactions between phen rings.

Two novel types of Ln 2 M 2 clusters bridged by cyanide and carboxylate simultaneously

Two novel complexes [Sm 2 (Ac) 2 (phen) 4 (H 2 O) 2 {Fe(CN) 5 (NO)} 2 ] 1 and [Dy 2 Ac) 2 (phen) 4 (H 2 O) 2 {Fe(CN) 5 (NO)} 2 ] . 8H 2 O 2 have been synthesized and structurally and magnetically characterized. Complex I crystallizes in the orthorhombic space group of Aba2 with a = 18.6179(3), b = 16.2001(3), c = 20.9875(4) A, and Z = 4, while complex 2 crystallizes in the monoclinic space group P2 1 /n with a = 12.0748(3), b = 27.3276(5), c = 22.9096(6) A, β = 93.1001(8)°, and Z = 4. A cyanide and carboxylate anions are bridging tetranuclear clusters, but exhibit different structural features. In 1, two [Fe(CN) 5 (NO)] 2- fragments connect the same Sm 3+ cation in a [Sm 2 (Ac) 2 ] dimer unit to produce a T-shaped motif. In 2, two [Fe(CN) 5 (NO)] 2- fragments attach to the two different Dy 3+ cations in a [Dy 2 (Ac) 2 ] dimer unit, leading to a U-shaped topology. Both examples represent novel structural types among tetranuclear Ln 2 M 2 clusters.

Structure and Magnetism of Cyano-Bridged Hetero-Binuclear Complexes RE(dpdo)2(H2O)3Fe(CN)6·4H2O (RE˭Gd, Y)

Abstract Two heterobinuclear cyano-bridged RE-Fe complexes RE(dpdo)2(H2O)3Fe(CN)6 ·4H2O (RE˭Gd,Y; dpdo=2,2′-Dipyridyl N.N′-Dioxide) were synthesized with identical structure. Gd-Fe complex crystallizes in triclinic crystal system, space group P-1 with a = 10.305(2), b = 12.475(1), c = 13.903(1)A, α = 85.34(1), β = 88.08(1), γ = 70.54(1)°, V = 1679.6(4) A3, Z = 2. In Gd-Fe binuclear unit, Gd3± is eight coordinated by one N atom from one CN− group, four O atoms from two bidentate dpdo molecules and three O atoms from water molecules, forming a square anti-prism. Gd and Fe are bridged via one CN− group from Fe(CN)6 3− ion with Gd-Fe separation 5.507(1)A. The nearest inter-molecular distances of Gd-Fe, Gd-Gd, Fe-Fe are 7.457(1), 7.984(1), and 8.409(1)A respectively. There are hydrogen bond intra- and inter-molecular connections. The intra-molecular coupling of Gd-Fe is weakly ferromagnetic, meanwhile the interactions between the binuclear units are weakly antiferromagnetic in character.

Synthesis and structure of bis(dibenzoylmethane) copper(II)

Bis(dibenzoylmethane)copper Cu(dbm)2 has been synthesized and its structure determined by x-ray diffraction. It crystallizes in the monoclinic system, space group C2/c, with a = 25.936(3), b = 5.9806(8), c = 16.4908(16) Å, β = 114.998(8)°, Z = 4, and V = 2318.3(4) Å3. The Cu atom is located at a symmetry center and surrounded by four O atoms from two dbm molecules to form a plane square coordination environment. On the a–c plane the molecules are orderly arranged to result in a layered structure, and parallel to crystallographic b-axis they form a molecular column due to the effect of aromatic stacking.