Search results for "Bimetallic"
showing 10 items of 187 documents
[Criii(L)(CN)4]−: a new building block in designing cyanide-bridged 4,2-ribbon-like chains {[Criii(L)(CN)4]2Mn(H2O)2}·nH2O [L = 2-aminomethylpyridine…
2005
The preparation, X-ray crystallography and magnetic study of compounds PPh4[Cr(ampy)(CN)4]·H2O (1), PPh4[Cr(phen)(CN)4]·H2O·CH3OH (2), {[Cr(ampy)(CN)4]2Mn(H2O)2}·6H2O (3) and {[Cr(phen)(CN)4]2Mn(H2O)2}·4H2O (4), with PPh4+ = tetraphenylphosphonium cation, ampy = 2-aminomethylpyridine and phen = 1,10-phenanthroline, are reported here. 1 and 2 are mononuclear complexes whereas 3 and 4 are 4,2-ribbon-like bimetallic chains. The magnetic properties of 1–4 were investigated in the temperature range 1.9–300 K. A quasi Curie law behaviour for a magnetically isolated spin quartet is observed for 1 and 2. Compounds 3 and 4 are ferrimagnetic CrIII2MnII chains, which exhibit a metamagnetic behaviour, …
Modeling the Geometric, Electronic, and Redox Properties of Iron(III)-Containing Amphiphiles with Asymmetric [NN′O] Headgroups
2011
Two iron(III)-containing amphiphiles 1 and 2 have been synthesized with the [NN'O] ligands HL(tBu-ODA) (2-((octadecyl(pyridin-2-ylmethyl)amino)methyl)-4,6-di-tert-butylphenol) and HL(I-ODA) (2-((octadecyl(pyridin-2-ylmethyl)amino)methyl)-4,6-diiodophenol), respectively. Compound 1 is monometallic, whereas EXAFS data suggest that 2 is a mixture of mono- and bimetallic species. The archetypical [Fe(III)(L(NN'O))(2)](+) complexes 3-9 have been isolated and characterized in order to understand the geometric, electronic, and redox properties of the amphiphiles. Preference for a monometallic or bimetallic nuclearity is dependent on (i) the nature of the solvent used for synthesis and (ii) the typ…
Mono- and Bimetallic Zwitterionic Chromium(0) and Tungsten(0) Allenyls
2015
A series of stable chiral (racemic), formally neutral, zwitterionic mono- and bimetallic M(CO)5[C(OEt)═C═CR(NHC)] (M = Cr, W) σ-allenyls are ready available by the addition of N-heterocyclic carbenes (NHCs) to Cr(0) and W(0) alkynyl Fischer carbene complexes. Different classes of NHCs, (e.g., 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene, and their six- and seven-membered analogues and 1,3-bis(dimethyl)imidazol-2-ylidene) were employed as nucleophiles in these C-C bond-forming reactions yielding the novel complexes in essentially quantitative yields. A systematic experimental and computational study of the electronic properties of the C…
Synthesis, crystal structures and magnetic properties of single and double cyanide-bridged bimetallic Fe2(III)Cu(II) zigzag chains.
2004
The bimetallic complexes [[Fe(III)(phen)(CN)4]2Cu(II)(H2O)2].4H2O (1), [[Fe(III)(phen)(CN)4]2Cu(II)].H2O (2) and [[Fe(III)(bipy)(CN)4]2Cu(II)].2H2O (3) and [[Fe(III)(bipy)(CN)4]2Cu(II)(H2O)2].4H2O (4) (phen = 1,10-phenanthroline and bipy = 2,2'-bipyridine) have been prepared and the structures of 1-3 determined by X-ray diffraction. The structure of 1 is made up of neutral cyanide-bridged Fe(III)-Cu(II) zigzag chains of formula [[Fe(III)(phen)(CN)4]2Cu(II)(H2O)2] and uncoordinated water molecules with the [Fe(phen)(CN)4]- entity acting as a bis-monodentate bridging ligand toward two trans-diaquacopper(II) units through two of its four cyanide groups in cis positions. The structure of 2 can …
Triphosphine-supported bimetallic Au(I)-M(I) (M = Ag, Cu) alkynyl clusters.
2014
The reactions of gold acetylides (AuC2R)n with triphosphine ligands PPh2-(CH2)n-PPh-(CH2)2-PPh2 (n = 1, dpmp; 2, dpep) in the presence of M(+) ions (M = Cu, Ag) lead to an assembly of the heterometallic clusters, the composition of which is determined by the steric bulkiness of the alkynyl groups and the flexibility of the phosphine motifs. For R = Ph, an unprecedented hexanuclear complex [Au5Cu(C2R)4(dpmp)2](2+) (1) was isolated, while for the aliphatic alkynes (R = 1-cyclohexanolyl, 2-borneolyl, 2,6-dimethyl-4-heptanolyl) a family of compounds based on a tetrametallic framework was prepared, [Au3Cu(C2R)3(dpmp)](+) (2, R = 1-cyclohexanolyl), [Au3M(C2R)3(dpep)]2(+2) (3, M = Cu, R = 1-cycloh…
Reactivity of the ansa-Bridged Metallocene Dichlorides [X(η5-C5H4)2]MCl2 (X = SiMe2, CMe2; M = Mo, W) toward Metallophosphide Anions [PPh2M‘(CO)x]- (…
1997
Two kinds of ansa derivatives, [SiMe2(η5-C5H4)2]MCl2 and [CMe2(η5-C5H4)2]MCl2 (M = Mo, W), are reacted with metallophosphide anions [PPh2M‘(CO)x]- (M‘ = Cr, Mo, W, x = 5; M‘ = Fe, x = 4). The silicon-bridged derivatives give the bimetallic systems [SiMe2(η5-C5H4)(η5-C5H3PPh2M‘(CO)x)]M(H)(Cl), which result from a regioselective substitution at the 3-position on the cyclopentadienyl ligand. In contrast, with the CMe2-bridged compounds, the substitution reaction occurs at the metallic center, giving μ-phosphido bimetallic complexes [CMe2(η5-C5H4)2]M(Cl)(μ-PPh2)M‘(CO)x. The solid-state structure of the bimetallic complex [CMe2(η5-C5H4)2]W(Cl)(μ-PPh2)Fe(CO)4 (7d) is reported.
Mechanical properties and accommodation processes on metallic interfaces
1998
Bimetallic joints Al/Pb, Al/Sn, Pb/Sn, Pb/Pb, etc. with clean interfaces, obtained by a special cold welding method, are used as a model of phase boundaries for investigation of accommodation processes and strength properties of interfaces. To reduce the volume diffusion-induced relaxation processes, investigations were carried out at relatively low temperatures 0.1-0.5 T m . The role of surface diffusion and the effect of phase boundary energy on the healing of micropore ensembles on interfaces was investigated. The accommodation processes on the phase boundaries are considered as a result of mechanoactivation of both the interaction and structure formation of such non-equilibrium systems.…
Thermal properties of the tetrahydrate series MtM(M'EDTA)2·4H2O {Mt, M, M' = Co(II), Ni(II), Zn(II)}
1992
Abstract We report on the specific heat data of the ordered bimetallic compounds CoCo(CoEDTA) 2 ·4H 2 O and CoCo(NiEDTA) 2 ·4H 2 O in the temperature range 1.5−15 K. The magnetic specific heat is analyzed from an Ising model that assumes three different magnetic sublattices exchange-coupled by two distinct magnetic interactions, as well as local anisotropies on tetrahedral Co and octahedral Ni sites.
Topological Versatility of Oxalate-Based Bimetallic One-Dimensional (1D) Compounds Associated with Ammonium Cations
2012
A new family of oxalate-bridged chains of formula (C(1))[Mn(H(2)O)(3)Cr(ox)(3)]·H(2)O (1), (C(2))(4)[Mn(2)(H(2)O)(3)ClCr(2)(ox)(6)]Cl·H(2)O·2C(2)H(6)O (2a), (C(2))(4)[Co(2)(H(2)O)(3)ClCr(2)(ox)(6)]Cl·2H(2)O·2C(2)H(6)O (2b), [Mn(C(3))(H(2)O)(2)Cr(ox)(3)]·H(2)O (3), and (C(4))(4)[Mn(H(2)O){Cr(ox)(3)}(2)]·H(2)O (4) [C(1)(+) = tetramethylammonium, C(2)(+) = 4-N,N-dimethylaminopyridinium, C(3)(+) = 1-hydroxyethyl-4-N,N-dimethylamino-pyridinium, C(4)(+) = 1-hydroxyethyl-4-(4'-dimethylamino-α-styryl)-pyridinium, ox(2-) = oxalate] have been synthesized by self-assembly of the (C(n))(3)[Cr(ox)(3)] (n = 1-4) mononuclear compound and the chloride salts of the corresponding metal(II) ions. The crystal …
Reaction of thiophene with mono- and bimetallic Ni–Co particles supported on γ-Al2O3 and HDS activities of obtained sulfides
2009
Abstract Reaction between thiophene and M/γ-Al2O3 (20 wt.%, M = Ni, Co, 2Ni–Co and 2Co–Ni) was studied by thermal gravimetric analysis (TGA) and by sulfidation in a fixed bed microreactor. The samples were prepared by incipient wetness impregnation followed by drying and reduction in hydrogen flow at 450 °C. Formation of bimetallic particles in samples containing both Ni and Co was confirmed by HRTEM with EDX analysis. The reaction with thiophene (20 or 40 mbar) was done at 360 °C in hydrogen atmosphere. TGA of the reaction with thiophene revealed that the initial rate of sulfidation drops sharply when going from Ni/γ-Al2O3 to Co/γ-Al2O3 (by a factor of 40 under used conditions). It follows…