Search results for "Molybdenum"

ChemInform Abstract: Molybdenum Pentachloride. A Multifaceted Reagent for Efficient Coupling of Aromatics

2015

ChemInform Abstract: Powerful Fluoroalkoxy Molybdenum(V) Reagent for Selective Oxidative Arene Coupling Reaction.

2014

A novel dinuclear fluoroalkoxy Mo(V)-complex is efficient as reagent for the oxidative arene coupling of electron-rich arenes with superior reactivity compared to MoCl5 and MoCl5/TiCl4.

Dynamic segregation during ferrite oxidation revealed by XPS

2002

Dynamic segregation phenomena were revealed by XPS during the oxidation of some ferrites (Fe 2.5 Ti 0.5 O 4 , Fe 2.5 Ni 0.5 O 4 , Fe 2 CrO 4 and FeCr 2 O 4 ). This kind of phenomenon induces, at a low temperature (below room temperature), drastic changes in the cationic composition of the most external layers. Dynamic segregation is a function of the cationic composition, the oxidation capability and the morphology of these ferrites. Although dynamic segregation seems to be a quite frequent phenomenon that often can be observed during ferrite oxidation, there are materials in existence where it does not appear, such as molybdenum ferrite.

[MoO2(SCPh2CO2)2]2− and [MoO(SCPh2CO2)2]− anion complexes. A theoretical structure characterization

1995

Abstract Geometry optimization of [MoO 2 (SCH 2 CO 2 ) 2 ] 2− and [MoO(SCH 2 CO 2 ) 2 ] − systems as models of [MoO 2 (SCPh 2 CO 2 ) 2 ] 2− and [MoO(SCPh 2 CO 2 ) 2 ] − anion complexes have been carried out at STO-3G, 3-21G, LANL1MB and LANL2DZ basis set levels. A comparison of the theoretical results and X-ray experimental data has been performed. STO-3G minimal basis set produces the best geometrical agreement, in particular the distances and orientations of the different ligands linked to molybdenum transition metal. A large structural overlap with STO-3G optimized geometry and X-ray data has been found for the [MoO 2 (SCPh 2 CO 2 ) 2 ] 2− and [MoO(SCPh 2 CO 2 ) 2 ] − anion complexes.

Itinerant Electron Metamagnetism in η-Carbide-Type Compound Co3Mo3C

2010

We report the magnetic properties of the cobalt molybdenum η-carbide-type compounds Co 3 Mo 3 C and Co 3 Mo 3 N. The magnetic susceptibility χ of Co 3 Mo 3 C shows a Curie–Weiss temperature dependence at high temperatures and a broad maximum at around 100 K, whereas that of Co 3 Mo 3 N shows a nearly temperature-independent enhanced Pauli paramagnetic behavior. The absence of a magnetic long-range order was confirmed by the nuclear magnetic resonance technique in both the compounds. As expected from the broad maximum of χ, we observed an itinerant electron metamagnetic transition at around 37 T in Co 3 Mo 3 C.

Monolayer Formation of Molybdenum Carbonyl on Cu(111) Revealed by Scanning Tunneling Microscopy and Density Functional Theory

2012

International audience; Molybdenum carbonyl Mo(CO)(6) was adsorbed on the Cu(111) surface at 160 K in the monolayer coverage range and studied by scanning tunneling microscopy. A well-ordered monolayer of hexacarbonyl molecules was observed experimentally for the first time. The monolayer has a hexagonal structure compatible with a (root 7 x root 7)R19 superlattice on the copper (111) plane. The arrangement and orientation of the molecules on the surface were determined by density functional theory calculations, including van der Waals interactions. The comparison of adsorption and cohesive energies reveals that the molecule-substrate interaction is stronger than the intermolecular one, whi…

Reactions of Aminobis(phenolate)‐Supported Dioxidotungsten(VI) and Dioxidomolybdenum(VI) Complexes

2006

The dioxidotungsten(VI) and -molybdenum(VI) complexes [WO2(O2NOMe)] (1), [MoO2(O2NOMe)] (2) and [{MoO2(O2NMe)}2] (3) [O2NOMe methoxyethylamino-N,N-bis(2-methylene-4,6-dimethylphenolate) dianion, O2NMe = methylamino-N,N-bis(2-methylene-4,6-dimethylphenolate) dianion] can react with chloride sources (Me3SiCl, SOCl2) to form resultant monooxido dichloro compounds [WOCl2(O2NOMe)] (4), [MoOCl2(O2NOMe)] (5) and [MoOCl2(O2NMe)] (6), respectively. The reaction of tungsten complex yields of the mixture of cis-4 and trans-4, which can be separated and characterized. The reactions of analogous molybdenum complexes with Me3SiCl yield trans isomers of 5 and 6 as individual products. Reaction of dioxidot…

Different coordination modes of a 1,1′,2,2′-ferrocenyltetraphosphine: Bi- and tri-dentate behaviour with group 6 and 7 transition metals

2002

The behaviour of 1,1′,2,2′-tetrakis(diphenylphosphino)-4,4′-di(tert-butyl)ferrocene (1), acting as a homoannular or heteroannular ligand, has been studied. Due to the cisoid disposition of the phosphino groups of each ring, different coordination modes are observed. With group 6 metal carbonyls, M(CO)6, the tetraphosphine acts exclusively as a tridentate ligand. In contrast, the reaction with MnCp(CO)3 leads to complexes showing 1,1′ and 1,2 bidentate coordination modes. All these complexes have been characterised by 1H and 31P NMR spectroscopy. The molecular structures of the molybdenum complex [(1)Mo(CO)3] (2b) and the 1,1′ manganese complex [(1)MnCp(CO)] (3) have been established by X-ra…

Synthesis and ROMP activity of aminophenol-substituted tungsten(VI) and molybdenum(VI) complexes

2008

Abstract Tungsten(VI) and molybdenum(VI) complexes [MO(L1)Cl2] and [M(X)(L2)Cl3] (X = O, NPh) with tridentate aminobis(phenolate) ligand L1 = methylamino-N,N-bis(2-methylene-4,6-dimethylphenolate) and bidentate aminophenolate ligand L2 = 2,4-di-tert-butyl-6-((dimethylamino)methyl)phenolate) were prepared and characterised. These complexes are principally stable in open atmosphere under ambient conditions. When activated with Et2AlCl, they exhibited high activity in ring-opening metathesis polymerisation (ROMP) of 2-norbornene (NBE) and its derivatives. Especially complexes [M(NPh)(L2)Cl3], which are easily available from corresponding metal oxides MO3 by a simple three-step synthesis, were …

Atomic absorption spectrometric determination of molybdenum in lubricating oils with use of emulsions

1985

Abstract Samples (0.1 g) containing molybdenum disulphide are digested with aqua regia or with a (1 + 1) hydrofluoric/nitric acid mixture, without complete destruction of the matrix, and the molybdenum is determined in an air/acetylene flame, after emulsification with a non-ionic surfactant (Nemol K-39). The detection limit is ca. 30 μg Mo g−1, and the r.s.d. is 2.9% for 6 analyses of a sample containing 6.5 mg Mo g−1.