Search results for "bimetallic"

Synthesis, Chirality, and Magnetic Properties of Bimetallic Cyanide-Bridged Two-Dimensional Ferromagnets

2006

The assembly of hexacyanoferrate(III) anions and nickel(II) bis-diamino complexes of the chiral ligand trans-cyclohexane-1,2-diamine (trans-chxn) yields cyanide-bridged two-dimensional ferromagnets of the general formula [Ni(trans-chxn)2]3[Fe(CN)6]2‚2H2O. Their crystal structure is built from cyanide-bridged bimetallic planes separated by the bulky chxn ligands, giving rise to a large interlayer distance ( d ) 11.7 A). These materials order ferromagnetically at the Curie temperature TC ) 14 K. AC susceptibility measurements evidence an unusual magnetic behavior below TC, with a marked frequency dependence. A thorough magnetic analysis demonstrates that this complex behavior is due to the pi…

Cobalt(II)-Copper(II) Bimetallic Chains as a New Class of Single-Chain Magnets

2004

Synthesis, characterization and crystal structure of the bimetallic cyano-bridged [(η5-C5H5)(PPh3)2Ru(μ-CN)Ru(PPh3)2(η5-C5H5)][PF6]

2005

Abstract The bimetallic cyano-bridged [(η 5 -C 5 H 5 )(PPh 3 ) 2 Ru(μ-CN)Ru(PPh 3 ) 2 (η 5 -C 5 H 5 )][PF 6 ] ( 1 ) was prepared by reaction of [(η 5 -C 5 H 5 )(PPh 3 ) 2 RuCl] with N , N ′-bis(cyanomethyl)ethylenediamine. The single crystal structure determined by X-ray diffraction showed crystallization on the triclinic P1 space group with a perfect alignment of the cyanide bridges. This accentric crystallization was explored having in view the NLO properties at the macroscopic level, determined by the Kurtz Powder technique. Besides the very low efficiency values for the second harmonic generation, the value obtained for the bimetallic complex 1 showed to be higher than one of the parent…

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…