Search results for "Bimetallic strip"
showing 10 items of 179 documents
Thermal-,Pressure-, and Light-Induced Spin Transition in Novel Cyanide-Bridged FeII-AgI Bimetallic Compounds with Three-Dimensional Interpenetrating …
2002
[EN] Low-spin, high-spin and spin-transition behaviours have been observed for the doubly interpenetrating three-dimensional bimetallic compounds {Fe-II(pz)[Ag(CN)(2)](2)}.pz (pz= pyrazine), {Fe-II(4,4'-bipy)(2)[Ag(CN)(2)](2)} (4,4'-bipy-4,4'-bipyridine), and {Fe-II-(bpe)(2)[Ag(CN)(2)](2)} (bpe = bispyridylethylene), respectively. The single crystals of the bpe derivative undergo a spin transition with a large hysteresis loop at about 95 K. After several warming and cooling cycles, the single crystals become a microcrystalline powder with 50% spin transition. Influence of pressure- as well as light-induced excited spin-state trapping (LIESST) on the thermal 50% spin transition of the microc…
Ruthenium titanocene and ruthenium titanium half-sandwich bimetallic complexes in catalytic cyclopropanation
2005
Abstract The reaction of the phosphine functionalised titanium half-sandwich complexes 7, 9 and 10 with the binuclear complex [(p-cymene)RuCl2]2 allowed the access to three new early-late bimetallic complexes (p-cymene)[(μ-η5:η1-C5H4(CH2)nPR2)TiX3]RuCl2 (11–13). The structure of 11 (n = 0, X = Cl) has been confirmed by X-ray diffraction. The ruthenium titanium half-sandwich bimetallic complexes so formed and the ruthenium titanocene analogues 4–6 catalyse the addition of ethyl diazoacetate to styrene with high selectivity toward cyclopropanation versus metathesis contrary to the monometallic complexes (p-cymene)RuCl2PR3.
Bimetallic complexes with ruthenium and tantalocene moieties: Synthesis and use in a catalytic cyclopropanation reaction
2006
Abstract The reaction of the tantalocene dichloride monophosphines ( 1 – 2 ) with the binuclear complex [( p -cymene)RuCl 2 ] 2 gives the heterobimetallic compounds ( p -cymene)[(η 5 -C 5 H 5 )(μ-η 5 :η 1 -C 5 H 4 (CH 2 ) 2 PR 2 )TaCl 2 ]RuCl 2 ( 3 – 4 ). The air oxidation of these bimetallic species 3 – 4 , leads to the cationic hydroxo tantalum ruthenium derivatives 5 – 6 . The last ones are easily deprotonated by a base to afford the oxo analogues 7 – 8 . A preliminary assessment in catalytic cyclopropanation of styrene with tantalum ruthenium bimetallic complexes 3 – 8 as precatalysts revealed a cooperative effect with a subtle role of the early metal fragment.
Structure and Deformations of Pd−Ni Core−Shell Nanoparticles
2005
International audience; Homogeneous collections of Pd−Ni core−shell nanoparticles have been prepared by decomposition of metal−organic compounds and studied by several electron microscopy techniques: transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), energy-filtered microscopy (EFTEM), and by X-ray photoelectron spectroscopy (XPS). The physical and chemical properties of the Pd shell are supposed to depend on its electronic properties, which are influenced by the presence of the Ni core and by the deformation in the Pd lattice. Here, the interfacial structure of Pd/Ni and the lattice deformations in t…
Novel Bimetallic-Dicyanamide Extended Two- and Three-Dimensional Networks through [Cu(rac-CTH)]2+ Cation Templation
2009
Reaction of [Cu(rac-CTH)]2+ with dicyanamide and Mn2+ or Fe2+ produces three bimetallic extended structures. Complexes 1 and 2, both obtained in the same reaction pot, consist of two different (4,4) two-dimensional (2D) layers, with the [Cu(rac-CTH)(dca)]+ cations noncoordinated and coordinated to the Mn(μ1,5-dca) network for 1 and 2, respectively (rac-CTH = racemic-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Complex 2 shows an unusual monodentate coordination mode through the central amide nitrogen of the dca ligand which is first reported for a polynuclear complex. The structure of 3 consists of a three-dimensional network which can be described as a stacking of layers m…
[Ni(cyclam)(μ1,3-dca)2Cu(μ1,5-dca)2]: A Genuine 3D Bimetallic Coordination Polymer Containing Both μ1,3- and μ1,5-Bidentate Dicyanamide Bridges and …
2005
The structure of [Ni(cyclam)(μ 1 , 3 -dca) 2 Cu(μ 1 , 5 -dca) 2 ], a genuine 3D dicyanamide-bridged bimetallic coordination polymer, is made up of 2D [Cu(μ- 1 , 5 dca) 2 ] n layers connected by [Ni(cyclam)(μ 1 , 3 -dca) 2 ] bridging moieties; it exhibits a ferromagnetic exchange interaction between copper(ll) and nickel(ll) ions through the μ 1 , 3 -bidentate dicyanamide bridges.
Design of single chain magnets through cyanide-bearing six-coordinate complexes
2005
Abstract The design and preparation of stable cyanide-bearing six-coordinate complexes of formula [MIII(L)(CN)x](x + l − m)− (M = trivalent transition metal ion and L = polydentate blocking ligand) are summarized here. Their use as ligands towards either fully hydrated metal ions or coordinatively unsaturated preformed species, to afford a wide variety of low-dimensional metal assemblies whose nuclearity, dimensionality and magnetic properties can be tuned, is also reviewed. Special emphasis is put on the appropriate choice of the end-cap ligand L whose denticity determines the number of coordinated cyanide groups in the mononuclear precursors. Among the different new spin topologies obtain…
Synthesis, crystal structure and magnetic properties of the malonato-bridged bimetallic chain [Mn(II)Cu(II)(mal)2(H2O)4]·2H2O
2000
Abstract The first malonato-bridged bimetallic chain of formula [MnCu(mal)2(H2O)4]·2H2O (1) (H2mal=malonic acid) was prepared and its structure determined by X-ray diffraction methods. Each copper atom in 1 is in a square planar environment formed by four malonate-oxygens from two malonate ligands. The manganese atom is six-coordinated with four water molecules and two cis-coordinated malonate-oxygens from two malonate groups building a distorted octahedral surrounding. The malonate group acts simultaneously as bidentate and monodentate ligand towards copper and manganese atoms respectively, leading to a bimetallic chain. Two structurally different carboxylato-bridges exhibiting an anti–syn…
High proton conduction in a chiral ferromagnetic metal-organic quartz-like framework.
2011
A complex-as-ligand strategy to get a multifunctional molecular material led to a metal-organic framework with the formula (NH(4))(4)[MnCr(2)(ox)(6)]·4H(2)O. Single-crystal X-ray diffraction revealed that the anionic bimetallic coordination network adopts a chiral three-dimensional quartz-like architecture. It hosts ammonium cations and water molecules in functionalized channels. In addition to ferromagnetic ordering below T(C) = 3.0 K related to the host network, the material exhibits a very high proton conductivity of 1.1 × 10(-3) S cm(-1) at room temperature due to the guest molecules.
Density Functional Theory Investigation on the Nucleation of Homo- and Heteronuclear Metal Clusters on Defective Graphene
2016
Nucleation of homo- (Ni, Pd, Re, Pt) and heterometallic (Ni–Pd, Re–Pt) clusters on monovacancy sites of a graphene sheet has been investigated by means of periodic density functional theory calculations. It is shown that a vacant site in graphene is an effective nucleation center for both the monometallic and bimetallic clusters, whose characteristics are described in terms of structural distortions, nucleation energetics, affinities between different metal atoms, metal–carbon interactions, and ease of diffusion of metal atoms on graphene.