Synthesis, X‐ray Studies and Magnetic Properties of Dinuclear Ni II and Cu II Complexes Bridged by the Azo‐2,2′‐bipyridine Ligand

2003

Two new paramagnetic transition metal complexes that contain the bridging ligand azo-2,2-bipyridine (abpy) have been prepared and characterized by X-ray crystallography and magnetic susceptibility measurements. The compound [Ni2(µ-abpy)(CH3CN)2(NO3)4]·2CH3CN (1·2CH3CN) crystallizes in the triclinic space group P1 ¯ with a = 8.290(5) A u , b = 8.343(5) A u , c = 11.180(5) A u , α = 105.36(3)°, β = 94.39(3)°, γ = 107.56(3)°, V = 700.5(7) A u 3 and Z = 1. The related salt [Cu2(µ

Unusual Magnetic Behavior in the Layered Ferromagnet [Ni(C6H14N2)2]3[Fe(CN)6]2·2H2O

2002

The cyano-bridged molecular complex [Ni(C6H14N2)2]3[Fe(CN)6]2·2H2O, with a rectangular 2D structure, displays long-range ferromagnetic ordering at 14 K, and exhibits unusual magnetic properties for this type of material, as confirmed by the appearance of two different peaks in the AC magnetic susceptibility plot, and a high coercive field (2.3 kOe) and remnant magnetization (6.8 μB). (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Preface for the Forum on Molecular Magnetism: The Role of Inorganic Chemistry

2009

Molecular magnetism is a rapidly expanding field of research whose central theme is the design and study of magnetic molecules and materials with tunable properties. In the early stages of the field, which began to take shape in the 1980s, much of the effort was directed at the pursuit of molecule-based magnetic solids that order at high temperatures. These materials are basically of two types: those based on tetracyanoethylene (TCNE) and those based on cyanide. As the field rapidly evolved over the past two decades, exciting new challenges appeared on the horizon, including the use of building block approaches for the preparation of complex multifunctional magnetic materials, the fabricati…

Beyond the spin model: exchange coupling in molecular magnets with unquenched orbital angular momenta.

2011

In this critical review we review the problem of exchange interactions in polynuclear metal complexes involving orbitally degenerate metal ions. The key feature of these systems is that, in general, they carry an unquenched orbital angular momentum that manifests itself in all their magnetic properties. Thus, interest in degenerate systems involves fundamental problems related to basic models in magnetism. In particular, the conventional Heisenberg-Dirac-Van Vleck model becomes inapplicable even as an approximation. In the first part we attempt to answer two key questions, namely which theoretical tools are to be used in the case of degeneracy, and how these tools can be employed. We demons…

Synthesis and structure of charge transfer salts of tetrathiafulvalene (TTF) and tetramethyl-TTF with 2,4,7-trinitro and 2,4,5,7-tetranitro-9-fluoren…

2009

Charge transfer salts of tetrathiafulvalene (TTF) and tetramethyltetrathiafulvalene (TMTTF) with the organic acceptors 2,4,7-trinitro-9-fluorenone and 2,4,5,7-tetranitro-9-fluorenone have been prepared and characterized. The compounds (TTF)(TENF) (1), (TTF)3(TRNF)2 (2) and (TMTTF)(TRNF) (3) contain mixed stacks of alternating TTF and nitrofluorenone units. Surprisingly, the degree of charge transfer that occurs in these salts is not controlled solely by the redox potentials of the building blocks, but apparently also by the most effective intermolecular interactions in the solid, as determined from the crystal struc- tures obtained. These three compounds exhibit poor electron delocalization…

Structural diversity of cyanide-bridged bimetallic clusters based on hexacyanometallate building blocks

2002

Abstract Four new cyanide-bridged bimetallic complexes, with different geometries and nuclearities, have been synthesized and characterized by single crystal X-ray crystallography. The trinuclear compound {〚Zn(bpy)2(OH2)〛2〚Fe(CN)6〛}Cl (1)·2 MeOH·12 H2O crystallizes in the triclinic space group P 1 , with a = 12.010(2) A, b = 16.316(3) A, c = 16.325(3) A, α = 97.47(3)°, β = 92.14(3)°, γ = 92.43(3)°, V = 3166(1) A3 and Z = 4. The tetranuclear compound {〚Zn(phen)2〛2〚Fe(CN)6〛2}2– (2) cocrystallizes with 〚Zn(bpy)3〛2+ and 32 H2O molecules in the monoclinic space group C2/c with a = 42.047(8) A, b = 13.541(2) A, c = 28.781(5) A, β = 120.23(3)°, V = 14158(4) A3 and Z = 2. The pentanuclear compound …

A Rare-Earth Metal TCNQ Magnet: Synthesis, Structure, and Magnetic Properties of {[Gd2(TCNQ)5(H2O)9][Gd(TCNQ)4(H2O)3]}⋅4 H2O

2003

Synthesis, structure and magnetic properties of the one-dimensional chain compound {K[Fe(1,3,5-triazine-2,4,6-tricarboxylate)(H2O)2]·2H2O}∞

2002

The one-dimensional chain compound {[Fe(1,3,5-triazine-2,4,6-tricarboxylate)(H2O)2]}n−n was obtained from a reaction of 1,3,5-triazine-2,4,6-tricarboxylate with Fe(II) in water at room temperature. The high-spin Fe(II) centers adopt a pentagonal bipyramid geometry with unusual ligand binding modes. Magnetic measurements revealed weak magnetic interactions between paramagnetic centers; these were modeled with both axial and rhombic distortions.

Radical salts of TTF derivatives with the metal-metal bonded [Re2Cl8]2- anion

2008

Abstract Four new salts of the radical cations of TMTSF (tetramethyltetraselenafulvalene), TMTTF (tetramethyltetrathiafulvalene), BEDT-TTF (bisethylenedithiotetrathia-fulvalene) (ET) and o-Me2TTF (o-4,4′-dimethyltetrathiafulvalene) with the metal–metal bonded dianion [Re2Cl8]2− were synthesized, and their structures and physical properties investigated. The structures of these semiconducting salts feature one-dimensional stacking of the donor molecules interleaved with [Re2Cl8]2− anions and interstitial solvent molecules.

Discrete Dinuclear Complexes and Two‐Dimensional Architectures from Bridging Polynitrile and Bipyrimidine (bpym) Ligands: Syntheses, Structures and M…

2004

One-pot reactions in aqueous solutions of the polynitrile anion dcne− {2,2-dicyano-1-ethoxyethenolate = [(CN)2CC(O)OEt)]−] with the MII ions (M = Mn, Fe, Co, Cu) in the presence of bpym (2,2′-bipyrimidine) afford the first mixed dcne/bpym compounds [M2(bpym)(dcne)4(H2O)2] (1: M = Mn; 2: M = Co) and [M2(bpym)(dcne)4(H2O)4]·2H2O (3: M = Fe; 4: M = Cu). The new compounds have been characterized by IR spectroscopy and X-ray crystallography. Compounds 1 and 2 are isostructural, with each metal ion being located in an MN5O pseudo-octahedral environment with three N atoms coming from three dcne− ligands, two nitrogen atoms from bpym and one oxygen atom from a water molecule. The extended structure…

A two-dimensional magnetic architecture with bridging polynitrile and 2,2′-bipyrimidine ligands

2004

cited By 7; International audience; A new polymeric, two-dimensional compound [Co2(bpym)(dcne) 4 (H2O)2] (1) (dcne = [(CN)2CC(O) OEt)]- = 2,2-dicyano-1-ethoxyethenolate anion and bpym = 2,2'-bipyrimidine) has been synthesized and characterized by X-ray crystallography. The structure is monoclinic space group P21/a and consists of two-dimensional networks of octahedrally coordinated Co(II) ions, bridged by bis-bidentate 2,2'-bipyrimidine and μ2-dcne anions. Magnetic measurements revealed a broad maximum in the xm vs T plot at 20 K which is characteristic of antiferromagnetic exchange between the high spin cobalt(II) centres. © EDP Sciences.

A trigonal-bipyramidal cyanide cluster with single-molecule-magnet behavior: synthesis, structure, and magnetic properties of ([MnII(tmphen)2]3[MnIII…

2003

A Self-Assembled 2D Molecule-Based Magnet: The Honeycomb Layered Material {Co3Cl4(H2O)2[Co(Hbbiz)3]2}

2003

Research in the area of molecule-based magnets is rapidly expanding, owing, in part, to numerous breakthroughs in the past decade.[1] The preparation of solid-state architectures of varying dimensionalities from specifically tailored paramagnetic building blocks has proven to be very successful, and also clearly multidisciplinary. Materials science and supramolecular chemistry efforts have joined forces with classical organic and inorganic chemistry in the design of solid-state materials whose magnetic properties rival, and sometimes even exceed, those of classic inorganic solids.[2] The moleculebased strategy allows for the preparation of unusual materials that cannot otherwise be obtained…

A Comparative Structural and Magnetic Study of Three Compounds Based on the Cluster Unit M4Cl8(THF)6 (M=Mn, Fe, Co)

2001

Treatment of anhydrous M Cl 2 phases with THF under refluxing conditions leads to excision of the clusters M 4 Cl 8 (THF) 6 ( M =Fe (1), Co (3)) and dimensional reduction to the chain of clusters, {Mn 4 Cl 8 (THF) 6 (Mn(THF) 2 Cl 2 } ∞ , (2). All three compounds were isolated in high yields as crystalline materials and subjected to comprehensive magnetic studies. X-ray structures of the three compounds were performed to verify the nature of the compounds, but only the Mn derivative is discussed in detail due to the fact that the structures of the Fe and Co clusters were reported earlier. The molecular structures of M 4 Cl 8 (THF) 6 ( M =Fe, Co) consist of a rhombic arrrangement of metal ion…

Future directions in solid state chemistry: report of the NSF-sponsored workshop

2002

Abstract A long-established area of scientific excellence in Europe, solid state chemistry has emerged in the US in the past two decades as a field experiencing rapid growth and development. At its core, it is an interdisciplinary melding of chemistry, physics, engineering, and materials science, as it focuses on the design, synthesis and structural characterization of new chemical compounds and characterization of their physical properties. As a consequence of this inherently interdisciplinary character, the solid state chemistry community is highly open to the influx of new ideas and directions. The inclusionary character of the field’s culture has been a significant factor in its continu…