Synthesis, characterization, and magnetic study of pyrazine bridged polymeric complexes of copper(II)

Magneto-structural versatility of copper(ii)-3-phenylpropionate coordination polymers with N-donor coligands

Magneto-structural correlations are exploited in five copper(ii)-3-phenylpropionate coordination polymers with flexible N-donor coligands.

Synthesis, structure, magnetic properties and EPR spectroscopy of a copper(ii) coordination polymer with a ditopic hydrazone ligand and acetate bridges

The synthesis, structure, EPR spectroscopy and magnetic properties of a 1D coordination polymer of Cu(ii) containing two kinds of acetate bridged dimers is reported.

X-ray absorption spectroscopy study of novel inorganic-organic hybrid ferromagnetic Cu-pyz-[M(CN)8]3- assemblies

We present a unique interpretation of X-ray absorption spectroscopy (XAS) spectra at Cu:K, W:L(3), and Mo:K edges of structurally related magnetic Cu(II)-[M(V)(CN)(8)](3-) compounds. The approach results in description of the structure of novel three-dimensional (3-D) Cu(II)(3)(pyz)[M(V)(CN)(8)](2)·xH(2)O, M = W (1), Mo, (2) polymers. Assemblies 1 and 2 represent hybrid inorganic-organic compounds built of {Cu(II)[W(V)(CN)(8)](-)}(n) double-layers linked by cyanido-bridged {Cu(II)-(μ-pyz)(2+)}(n) chains. These Cu(II)-M(V) systems reveal long-range magnetic ordering with T(c) of 43 and 37 K for 1 and 2, respectively. The presence of the 3-D coordination networks and 8 cyanido-bridges at M(V) centers leads to the highest Curie temperatures and widest hysteresis loops among Cu(II)-[M(V)(CN)(8)](3-) systems.

From molecules to materials: molecular paddle-wheel synthons of macromolecules, cage compounds and metal-organic frameworks

Metal-organic frameworks (MOF) are becoming a more and more important class of functional materials. Yet, very often, the synthesis of MOFs is not easy to control and requires a profound knowledge and experience in solid state chemistry. One of the most frequently used metal connectors is the so-called 'paddle-wheel' (PW) unit, which is a well-known molecular compound type in inorganic coordination chemistry. Depending on the ligands, the geometry of PWs strictly directs the assembly of ordered networks. This review focuses on the question, to what extent ordered network structures can be accessed by typical molecular syntheses in solution, starting from molecular PW complexes to ordered macromolecules, finite cage compounds and finally, three-dimensional superstructures.

Pentachloro(pyrazine)rhenate(IV) complex as precursor of heterobimetallic pyrazine-containing Re(IV)2M(II) (M = Ni, Cu) species: synthesis, crystal structures and magnetic properties

Three novel Re(IV) mononuclear complexes of formulae NBu4[ReC15(pyz)] (1), NH2Me2[ReCl5(pyz)] (2) and NH4[ReCl5(pyz)].0.75H2O (3), (pyz being pyrazine; NBu4+ = tetra-n-butylammonium cation, NH2Me2+ = dimethylammonium cation and NH4+ = ammonium cation), were synthesized by ligand substitution reaction from [ReCl6]2- anion and pyrazine in N,N-dimethylformamide (DMF). In addition, two new heterobimetallic compounds, the salt namely [ReCl5(pyz)]2[Ni(cyclam)](4) (cyclam = 1,4,8,11-tetraazacyclotetradecane) and the heterotrinuclear [{ReCl5(mu-pyz)}2Cu(DMF)4] (5) complex, were prepared by using as precursor 1 and 3, respectively. Compounds 1-5 were characterized by single-crystal X-ray diffraction. 1-3 are made up of discrete [ReCl5(pyz)]- anions and NBu4 (1), NH2Me2+ (2) and NH4+ (3) cations. [ReCl5(pyz)]- unit interacts toward Ni(II) (4) and Cu(II) (5) metal ions through different modes. In 4 two [ReCl5(pyz)]- anions weakly interact with a [Ni(cyclam)]2+ cation through chloro atoms, while compound 5 is a heterotrinuclear pyrazine-bridged Re(IV)2Cu(II) complex made up of [ReCl5(pyz)]- anions and [Cu(DMF)4]2+ cations. The magnetic properties of 1-5 were investigated in the temperature range 1.9-300 K. The magnetic behaviour of 1 is that of a magnetically diluted Re(IV) complex with a large value of zero-field splitting of the ground state (/2D/ is ca. 18.8(1) cm(-1)), whereas those of 2 and 3 are typical of antiferromagnetically coupled systems exhibiting susceptibility maxima at 10 (2) and 12 K (3). Compound 4 shows antiferromagnetic interactions between Re(IV) metal ions, Ni(II) being diamagnetic (because of its square-planar geometry), while 5 exhibits a ferromagnetic coupling between Re(IV) and Cu(II) metal ions across the pyrazine bridges with a J(ReCu), value of +11.8(1) cm(-1).